From 524eb4491f4a31efea81ede387e1e1c5a0d51830 Mon Sep 17 00:00:00 2001
From: Antoine C <mixxx@acolombier.dev>
Date: Tue, 26 Mar 2024 15:25:27 +0000
Subject: [PATCH 1/2] feat: add a waveform overlay visual for slip position

---
 CMakeLists.txt                                |   2 +
 res/skins/Deere/deck_waveform.xml             |   3 +
 res/skins/LateNight/decks/overview.xml        |   1 +
 res/skins/LateNight/skin.xml                  |   2 +
 res/skins/LateNight/waveform.xml              |   3 +
 res/skins/Tango/decks/overview.xml            |   3 +
 res/skins/Tango/waveform.xml                  |   3 +
 src/shaders/slipmodeshader.cpp                |  60 ++++++++++
 src/shaders/slipmodeshader.h                  |  35 ++++++
 .../allshader/waveformrenderbeat.cpp          |  23 ++--
 .../renderers/allshader/waveformrenderbeat.h  |   6 +-
 .../allshader/waveformrendererpreroll.cpp     |  32 ++++--
 .../allshader/waveformrendererpreroll.h       |  10 +-
 .../allshader/waveformrendererrgb.cpp         |  20 ++--
 .../renderers/allshader/waveformrendererrgb.h |   6 +-
 .../allshader/waveformrendererslipmode.cpp    | 107 ++++++++++++++++++
 .../allshader/waveformrendererslipmode.h      |  42 +++++++
 .../allshader/waveformrendermark.cpp          |  29 ++++-
 .../renderers/allshader/waveformrendermark.h  |   6 +-
 .../renderers/waveformrendererabstract.h      |   7 ++
 .../renderers/waveformwidgetrenderer.cpp      |  62 ++++++----
 .../renderers/waveformwidgetrenderer.h        |  50 ++++----
 .../widgets/allshader/rgbwaveformwidget.cpp   |   7 ++
 23 files changed, 446 insertions(+), 73 deletions(-)
 create mode 100644 src/shaders/slipmodeshader.cpp
 create mode 100644 src/shaders/slipmodeshader.h
 create mode 100644 src/waveform/renderers/allshader/waveformrendererslipmode.cpp
 create mode 100644 src/waveform/renderers/allshader/waveformrendererslipmode.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7c67775d256..6f1f14cb286 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1497,6 +1497,7 @@ endif()
 if(QOPENGL)
   target_sources(mixxx-lib PRIVATE
     src/shaders/endoftrackshader.cpp
+    src/shaders/slipmodeshader.cpp
     src/shaders/patternshader.cpp
     src/shaders/rgbashader.cpp
     src/shaders/rgbshader.cpp
@@ -1510,6 +1511,7 @@ if(QOPENGL)
     src/waveform/renderers/allshader/waveformrenderbeat.cpp
     src/waveform/renderers/allshader/waveformrenderer.cpp
     src/waveform/renderers/allshader/waveformrendererendoftrack.cpp
+    src/waveform/renderers/allshader/waveformrendererslipmode.cpp
     src/waveform/renderers/allshader/waveformrendererfiltered.cpp
     src/waveform/renderers/allshader/waveformrendererhsv.cpp
     src/waveform/renderers/allshader/waveformrendererlrrgb.cpp
diff --git a/res/skins/Deere/deck_waveform.xml b/res/skins/Deere/deck_waveform.xml
index 344879676d4..e7cf2dd245d 100644
--- a/res/skins/Deere/deck_waveform.xml
+++ b/res/skins/Deere/deck_waveform.xml
@@ -30,6 +30,9 @@
         <BeatColor>#ffffff</BeatColor>
         <PlayPosColor>#00FF00</PlayPosColor>
         <EndOfTrackColor>#EA0000</EndOfTrackColor>
+        <SlipBorderOutlineColor>#f08c00</SlipBorderOutlineColor>
+        <SlipBorderTopOutlineSize>10</SlipBorderTopOutlineSize>
+        <SlipBorderBottomOutlineSize>10</SlipBorderBottomOutlineSize>
         <AxesColor></AxesColor>
         <Align></Align>
         <DefaultMark>
diff --git a/res/skins/LateNight/decks/overview.xml b/res/skins/LateNight/decks/overview.xml
index 986889398a9..eb9f25e50ac 100644
--- a/res/skins/LateNight/decks/overview.xml
+++ b/res/skins/LateNight/decks/overview.xml
@@ -18,6 +18,7 @@
     <PlayedOverlayColor><Variable name="PlayedOverlayColor"/></PlayedOverlayColor>
     <PlayPosColor><Variable name="PlayPosColor"/></PlayPosColor>
     <EndOfTrackColor><Variable name="EndOfTrackColor"/></EndOfTrackColor>
+    <SlipBorderOutlineColor><Variable name="SlipBorderOutlineColor"/></SlipBorderOutlineColor>
     <PassthroughLabelColor><Variable name="PassthroughLabelColor"/></PassthroughLabelColor>
     <LabelFontSize><Variable name="OverviewFontSize"/></LabelFontSize>
     <DimBrightThreshold><Variable name="DimBrightThresholdOverview"/></DimBrightThreshold>
diff --git a/res/skins/LateNight/skin.xml b/res/skins/LateNight/skin.xml
index 0a7cbe7785c..9b4334dcc9d 100644
--- a/res/skins/LateNight/skin.xml
+++ b/res/skins/LateNight/skin.xml
@@ -172,6 +172,7 @@
       <SetVariable name="IntroOutroColor">#2c5c9a</SetVariable>
       <SetVariable name="PlayedOverlayColor">#dd151515</SetVariable>
       <SetVariable name="EndOfTrackColor">#f856e7</SetVariable>
+      <SetVariable name="SlipBorderOutlineColor">#f08c00</SetVariable>
       <SetVariable name="PassthroughLabelColor">#b24c12</SetVariable>
       <SetVariable name="OverviewFontSizeDeck">13</SetVariable>
       <SetVariable name="OverviewFontSizeDeckMini">11</SetVariable>
@@ -277,6 +278,7 @@
       <SetVariable name="IntroOutroColor">#0000ff</SetVariable>
       <SetVariable name="PlayedOverlayColor">#bb000000</SetVariable>
       <SetVariable name="EndOfTrackColor">#f856e7</SetVariable>
+      <SetVariable name="SlipBorderOutlineColor">#1af000</SetVariable>
       <SetVariable name="PassthroughLabelColor">#d09300</SetVariable>
       <SetVariable name="OverviewFontSizeDeck">13</SetVariable>
       <SetVariable name="OverviewFontSizeDeckMini">11</SetVariable>
diff --git a/res/skins/LateNight/waveform.xml b/res/skins/LateNight/waveform.xml
index db51b0b65a8..10693ded09e 100644
--- a/res/skins/LateNight/waveform.xml
+++ b/res/skins/LateNight/waveform.xml
@@ -30,6 +30,9 @@
             <BeatHighlightColor></BeatHighlightColor>
             <PlayPosColor><Variable name="PlayPosColor"/></PlayPosColor>
             <EndOfTrackColor><Variable name="EndOfTrackColor"/></EndOfTrackColor>
+            <SlipBorderOutlineColor><Variable name="SlipBorderOutlineColor"/></SlipBorderOutlineColor>
+            <SlipBorderTopOutlineSize>10</SlipBorderTopOutlineSize>
+            <SlipBorderBottomOutlineSize>20</SlipBorderBottomOutlineSize>
             <PassthroughLabelColor><Variable name="PassthroughLabelColor"/></PassthroughLabelColor>
             <DimBrightThreshold><Variable name="DimBrightThresholdWaveform"/></DimBrightThreshold>
             <!--
diff --git a/res/skins/Tango/decks/overview.xml b/res/skins/Tango/decks/overview.xml
index 2765b9fb575..6add2b70d38 100644
--- a/res/skins/Tango/decks/overview.xml
+++ b/res/skins/Tango/decks/overview.xml
@@ -26,6 +26,9 @@ Variables:
     <PlayPosColor>#FF4300</PlayPosColor>
     <PlayedOverlayColor><Variable name="PlayedOverlayColor"/></PlayedOverlayColor>
     <EndOfTrackColor><Variable name="EndOfTrackColor"/></EndOfTrackColor>
+    <SlipBorderOutlineColor><Variable name="SlipBorderOutlineColor"/></SlipBorderOutlineColor>
+    <SlipBorderTopOutlineSize><Variable name="SlipBorderTopOutlineSize"/></SlipBorderTopOutlineSize>
+    <SlipBorderBottomOutlineSize><Variable name="SlipBorderBottomOutlineSize"/></SlipBorderBottomOutlineSize>
     <LabelTextColor>#ffffff</LabelTextColor>
     <LabelBackgroundColor>#85000000</LabelBackgroundColor>
     <DefaultMark>
diff --git a/res/skins/Tango/waveform.xml b/res/skins/Tango/waveform.xml
index ec8d0e8c19f..86f7272e22e 100644
--- a/res/skins/Tango/waveform.xml
+++ b/res/skins/Tango/waveform.xml
@@ -31,6 +31,9 @@ Variables:
         <BeatColor>#ffffff</BeatColor>
         <PlayPosColor>#FF4300</PlayPosColor>
         <EndOfTrackColor><Variable name="EndOfTrackColor"/></EndOfTrackColor>
+        <SlipBorderOutlineColor><Variable name="SlipBorderOutlineColor"/></SlipBorderOutlineColor>
+        <SlipBorderTopOutlineSize><Variable name="SlipBorderTopOutlineSize"/></SlipBorderTopOutlineSize>
+        <SlipBorderBottomOutlineSize><Variable name="SlipBorderBottomOutlineSize"/></SlipBorderBottomOutlineSize>
         <DefaultMark>
           <Align>bottom|right</Align>
           <Color>#666666</Color>
diff --git a/src/shaders/slipmodeshader.cpp b/src/shaders/slipmodeshader.cpp
new file mode 100644
index 00000000000..b176e217840
--- /dev/null
+++ b/src/shaders/slipmodeshader.cpp
@@ -0,0 +1,60 @@
+#include "shaders/slipmodeshader.h"
+
+using namespace mixxx;
+
+void SlipModeShader::init() {
+    QString vertexShaderCode = QStringLiteral(R"--(
+#version 150
+attribute highp vec4 position; // use vec4 here (will be padded) to assign directly to gl_Position
+
+out highp vec4 vposition;
+
+void main()
+{
+    vposition = position;
+    gl_Position = position;
+}
+)--");
+
+    QString fragmentShaderCode = QStringLiteral(R"--(
+#version 120
+uniform highp vec4 color;
+uniform highp vec2 borders;
+uniform highp vec2 dimension;
+
+in highp vec4 vposition;
+
+void main()
+{
+
+    float xBorder = abs(dimension.x*vposition.x);
+    float yBorder = dimension.y*vposition.y;
+    float upperBoard = borders.x;
+    float lowerBoard = borders.y;
+
+    if (yBorder < 0){
+        float borderAlpha = max(
+            0, 
+            lowerBoard + yBorder
+        ) / lowerBoard;
+        gl_FragColor = vec4(color.xyz, mix(0, color.w, borderAlpha));
+
+    } else if( (xBorder > dimension.x - upperBoard && yBorder >= 0) || yBorder > dimension.y - upperBoard)
+    {
+        float borderAlpha = max(0, max(
+            yBorder - dimension.y, 
+            xBorder - dimension.x) + upperBoard) / upperBoard;
+        gl_FragColor = vec4(mix(vec3(0, 0, 0), color.rgb, min(color.w, borderAlpha)), 1);
+    } else {
+        gl_FragColor = vec4(0, 0, 0, 1);
+    }
+}
+)--");
+
+    load(vertexShaderCode, fragmentShaderCode);
+
+    m_positionLocation = attributeLocation("position");
+    m_boarderLocation = uniformLocation("borders");
+    m_dimensionLocation = uniformLocation("dimension");
+    m_colorLocation = uniformLocation("color");
+}
diff --git a/src/shaders/slipmodeshader.h b/src/shaders/slipmodeshader.h
new file mode 100644
index 00000000000..3397f881955
--- /dev/null
+++ b/src/shaders/slipmodeshader.h
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "shaders/shader.h"
+
+namespace mixxx {
+class SlipModeShader;
+}
+
+class mixxx::SlipModeShader : public mixxx::Shader {
+  public:
+    SlipModeShader() = default;
+    ~SlipModeShader() = default;
+    void init();
+
+    int positionLocation() const {
+        return m_positionLocation;
+    }
+    int dimensionLocation() const {
+        return m_dimensionLocation;
+    }
+    int colorLocation() const {
+        return m_colorLocation;
+    }
+    int boarderLocation() const {
+        return m_boarderLocation;
+    }
+
+  private:
+    int m_positionLocation;
+    int m_dimensionLocation;
+    int m_colorLocation;
+    int m_boarderLocation;
+
+    DISALLOW_COPY_AND_ASSIGN(SlipModeShader)
+};
diff --git a/src/waveform/renderers/allshader/waveformrenderbeat.cpp b/src/waveform/renderers/allshader/waveformrenderbeat.cpp
index 9db24bcbb6a..efc04efb6ae 100644
--- a/src/waveform/renderers/allshader/waveformrenderbeat.cpp
+++ b/src/waveform/renderers/allshader/waveformrenderbeat.cpp
@@ -10,8 +10,10 @@
 
 namespace allshader {
 
-WaveformRenderBeat::WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget)
-        : WaveformRenderer(waveformWidget) {
+WaveformRenderBeat::WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget,
+        ::WaveformRendererAbstract::Type type)
+        : WaveformRenderer(waveformWidget),
+          m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
 
 void WaveformRenderBeat::initializeGL() {
@@ -27,10 +29,13 @@ void WaveformRenderBeat::setup(const QDomNode& node, const SkinContext& context)
 void WaveformRenderBeat::paintGL() {
     TrackPointer trackInfo = m_waveformRenderer->getTrackInfo();
 
-    if (!trackInfo) {
+    if (!trackInfo || (m_isSlipRenderer && !m_waveformRenderer->isSlipActive())) {
         return;
     }
 
+    auto positionType = m_isSlipRenderer ? ::WaveformRendererAbstract::Slip
+                                         : ::WaveformRendererAbstract::Play;
+
     mixxx::BeatsPointer trackBeats = trackInfo->getBeats();
     if (!trackBeats) {
         return;
@@ -54,9 +59,9 @@ void WaveformRenderBeat::paintGL() {
     }
 
     const double firstDisplayedPosition =
-            m_waveformRenderer->getFirstDisplayedPosition();
+            m_waveformRenderer->getFirstDisplayedPosition(positionType);
     const double lastDisplayedPosition =
-            m_waveformRenderer->getLastDisplayedPosition();
+            m_waveformRenderer->getLastDisplayedPosition(positionType);
 
     const auto startPosition = mixxx::audio::FramePos::fromEngineSamplePos(
             firstDisplayedPosition * trackSamples);
@@ -91,14 +96,18 @@ void WaveformRenderBeat::paintGL() {
             ++it) {
         double beatPosition = it->toEngineSamplePos();
         double xBeatPoint =
-                m_waveformRenderer->transformSamplePositionInRendererWorld(beatPosition);
+                m_waveformRenderer->transformSamplePositionInRendererWorld(
+                        beatPosition, positionType);
 
         xBeatPoint = qRound(xBeatPoint * devicePixelRatio) / devicePixelRatio;
 
         const float x1 = static_cast<float>(xBeatPoint);
         const float x2 = x1 + 1.f;
 
-        m_vertices.addRectangle(x1, 0.f, x2, rendererBreadth);
+        m_vertices.addRectangle(x1,
+                0.f,
+                x2,
+                m_isSlipRenderer ? rendererBreadth / 2 : rendererBreadth);
     }
 
     DEBUG_ASSERT(reserved == m_vertices.size());
diff --git a/src/waveform/renderers/allshader/waveformrenderbeat.h b/src/waveform/renderers/allshader/waveformrenderbeat.h
index 46411fe7372..01912ae9083 100644
--- a/src/waveform/renderers/allshader/waveformrenderbeat.h
+++ b/src/waveform/renderers/allshader/waveformrenderbeat.h
@@ -16,7 +16,9 @@ class WaveformRenderBeat;
 
 class allshader::WaveformRenderBeat final : public allshader::WaveformRenderer {
   public:
-    explicit WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget);
+    explicit WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget,
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play);
 
     void setup(const QDomNode& node, const SkinContext& context) override;
     void paintGL() override;
@@ -27,5 +29,7 @@ class allshader::WaveformRenderBeat final : public allshader::WaveformRenderer {
     QColor m_color;
     VertexData m_vertices;
 
+    bool m_isSlipRenderer;
+
     DISALLOW_COPY_AND_ASSIGN(WaveformRenderBeat);
 };
diff --git a/src/waveform/renderers/allshader/waveformrendererpreroll.cpp b/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
index a54f4828285..60beca4ee9e 100644
--- a/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
+++ b/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
@@ -60,8 +60,11 @@ std::unique_ptr<QOpenGLTexture> generateTexture(float markerLength,
 
 namespace allshader {
 
-WaveformRendererPreroll::WaveformRendererPreroll(WaveformWidgetRenderer* waveformWidget)
-        : WaveformRenderer(waveformWidget) {
+WaveformRendererPreroll::WaveformRendererPreroll(
+        WaveformWidgetRenderer* waveformWidget,
+        ::WaveformRendererAbstract::Type type)
+        : WaveformRenderer(waveformWidget),
+          m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
 
 WaveformRendererPreroll::~WaveformRendererPreroll() = default;
@@ -79,12 +82,16 @@ void WaveformRendererPreroll::initializeGL() {
 
 void WaveformRendererPreroll::paintGL() {
     const TrackPointer track = m_waveformRenderer->getTrackInfo();
-    if (!track) {
+    if (!track || (m_isSlipRenderer && !m_waveformRenderer->isSlipActive())) {
         return;
     }
 
-    const double firstDisplayedPosition = m_waveformRenderer->getFirstDisplayedPosition();
-    const double lastDisplayedPosition = m_waveformRenderer->getLastDisplayedPosition();
+    auto positionType = m_isSlipRenderer ? ::WaveformRendererAbstract::Slip
+                                         : ::WaveformRendererAbstract::Play;
+
+    const double firstDisplayedPosition =
+            m_waveformRenderer->getFirstDisplayedPosition(positionType);
+    const double lastDisplayedPosition = m_waveformRenderer->getLastDisplayedPosition(positionType);
 
     // Check if the pre- or post-roll is on screen. If so, draw little triangles
     // to indicate the respective zones.
@@ -99,7 +106,7 @@ void WaveformRendererPreroll::paintGL() {
     const double vSamplesPerPixel = m_waveformRenderer->getVisualSamplePerPixel();
     const double numberOfVSamples = m_waveformRenderer->getLength() * vSamplesPerPixel;
 
-    const int currentVSamplePosition = m_waveformRenderer->getPlayPosVSample();
+    const int currentVSamplePosition = m_waveformRenderer->getPlayPosVSample(positionType);
     const int totalVSamples = m_waveformRenderer->getTotalVSample();
 
     const float markerBreadth = m_waveformRenderer->getBreadth() * 0.4f;
@@ -166,7 +173,7 @@ void WaveformRendererPreroll::paintGL() {
         drawPattern(x,
                 halfBreadth - halfMarkerBreadth,
                 0.f,
-                halfBreadth + halfMarkerBreadth,
+                m_isSlipRenderer ? halfBreadth : halfBreadth + halfMarkerBreadth,
                 x / markerLength);
     }
 
@@ -187,7 +194,7 @@ void WaveformRendererPreroll::paintGL() {
         drawPattern(x,
                 halfBreadth - halfMarkerBreadth,
                 end,
-                halfBreadth + halfMarkerBreadth,
+                m_isSlipRenderer ? halfBreadth : halfBreadth + halfMarkerBreadth,
                 (end - x) / markerLength);
     }
 
@@ -206,7 +213,14 @@ void WaveformRendererPreroll::drawPattern(
     const int texcoordLocation = m_shader.texcoordLocation();
 
     const std::array<float, 8> positionArray = {x1, y1, x2, y1, x1, y2, x2, y2};
-    const std::array<float, 8> texcoordArray = {0.f, 0.f, 1.f, 0.f, 0.f, 1.f, 1.f, 1.f};
+    const std::array<float, 8> texcoordArray = {0.f,
+            0.f,
+            1.f,
+            0.f,
+            0.f,
+            m_isSlipRenderer ? 0.5f : 1.f,
+            1.f,
+            m_isSlipRenderer ? 0.5f : 1.f};
     m_shader.setUniformValue(repetitionsLocation, QVector2D(repetitions, 1.0));
 
     m_shader.setAttributeArray(
diff --git a/src/waveform/renderers/allshader/waveformrendererpreroll.h b/src/waveform/renderers/allshader/waveformrendererpreroll.h
index c8163c2dc87..ec54b17c8c5 100644
--- a/src/waveform/renderers/allshader/waveformrendererpreroll.h
+++ b/src/waveform/renderers/allshader/waveformrendererpreroll.h
@@ -15,11 +15,15 @@ class QOpenGLTexture;
 
 namespace allshader {
 class WaveformRendererPreroll;
+class WaveformRendererSlipPreroll;
 }
 
-class allshader::WaveformRendererPreroll final : public allshader::WaveformRenderer {
+class allshader::WaveformRendererPreroll : public allshader::WaveformRenderer {
   public:
-    explicit WaveformRendererPreroll(WaveformWidgetRenderer* waveformWidgetRenderer);
+    explicit WaveformRendererPreroll(
+            WaveformWidgetRenderer* waveformWidgetRenderer,
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play);
     ~WaveformRendererPreroll() override;
 
     void setup(const QDomNode& node, const SkinContext& context) override;
@@ -35,5 +39,7 @@ class allshader::WaveformRendererPreroll final : public allshader::WaveformRende
     float m_markerLength{};
     std::unique_ptr<QOpenGLTexture> m_pTexture;
 
+    bool m_isSlipRenderer;
+
     DISALLOW_COPY_AND_ASSIGN(WaveformRendererPreroll);
 };
diff --git a/src/waveform/renderers/allshader/waveformrendererrgb.cpp b/src/waveform/renderers/allshader/waveformrendererrgb.cpp
index a1c18a6c58a..f83044b9e53 100644
--- a/src/waveform/renderers/allshader/waveformrendererrgb.cpp
+++ b/src/waveform/renderers/allshader/waveformrendererrgb.cpp
@@ -14,9 +14,10 @@ inline float math_pow2(float x) {
 }
 } // namespace
 
-WaveformRendererRGB::WaveformRendererRGB(
-        WaveformWidgetRenderer* waveformWidget)
-        : WaveformRendererSignalBase(waveformWidget) {
+WaveformRendererRGB::WaveformRendererRGB(WaveformWidgetRenderer* waveformWidget,
+        ::WaveformRendererAbstract::Type type)
+        : WaveformRendererSignalBase(waveformWidget),
+          m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
 
 void WaveformRendererRGB::onSetup(const QDomNode& node) {
@@ -30,10 +31,13 @@ void WaveformRendererRGB::initializeGL() {
 
 void WaveformRendererRGB::paintGL() {
     TrackPointer pTrack = m_waveformRenderer->getTrackInfo();
-    if (!pTrack) {
+    if (!pTrack || (m_isSlipRenderer && !m_waveformRenderer->isSlipActive())) {
         return;
     }
 
+    auto positionType = m_isSlipRenderer ? ::WaveformRendererAbstract::Slip
+                                         : ::WaveformRendererAbstract::Play;
+
     ConstWaveformPointer waveform = pTrack->getWaveform();
     if (waveform.isNull()) {
         return;
@@ -55,9 +59,9 @@ void WaveformRendererRGB::paintGL() {
     // See waveformrenderersimple.cpp for a detailed explanation of the frame and index calculation
     const int visualFramesSize = dataSize / 2;
     const double firstVisualFrame =
-            m_waveformRenderer->getFirstDisplayedPosition() * visualFramesSize;
+            m_waveformRenderer->getFirstDisplayedPosition(positionType) * visualFramesSize;
     const double lastVisualFrame =
-            m_waveformRenderer->getLastDisplayedPosition() * visualFramesSize;
+            m_waveformRenderer->getLastDisplayedPosition(positionType) * visualFramesSize;
 
     // Represents the # of visual frames per horizontal pixel.
     const double visualIncrementPerPixel =
@@ -99,7 +103,7 @@ void WaveformRendererRGB::paintGL() {
     m_vertices.addRectangle(0.f,
             halfBreadth - 0.5f * devicePixelRatio,
             static_cast<float>(length),
-            halfBreadth + 0.5f * devicePixelRatio);
+            m_isSlipRenderer ? halfBreadth : halfBreadth + 0.5f * devicePixelRatio);
     m_colors.addForRectangle(
             static_cast<float>(m_axesColor_r),
             static_cast<float>(m_axesColor_g),
@@ -190,7 +194,7 @@ void WaveformRendererRGB::paintGL() {
         m_vertices.addRectangle(fpos - 0.5f,
                 halfBreadth - heightFactor * maxAllChn[0],
                 fpos + 0.5f,
-                halfBreadth + heightFactor * maxAllChn[1]);
+                m_isSlipRenderer ? halfBreadth : halfBreadth + heightFactor * maxAllChn[1]);
         m_colors.addForRectangle(red, green, blue);
 
         xVisualFrame += visualIncrementPerPixel;
diff --git a/src/waveform/renderers/allshader/waveformrendererrgb.h b/src/waveform/renderers/allshader/waveformrendererrgb.h
index 49178842d33..a7c1a1983fb 100644
--- a/src/waveform/renderers/allshader/waveformrendererrgb.h
+++ b/src/waveform/renderers/allshader/waveformrendererrgb.h
@@ -12,7 +12,9 @@ class WaveformRendererRGB;
 
 class allshader::WaveformRendererRGB final : public allshader::WaveformRendererSignalBase {
   public:
-    explicit WaveformRendererRGB(WaveformWidgetRenderer* waveformWidget);
+    explicit WaveformRendererRGB(WaveformWidgetRenderer* waveformWidget,
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play);
 
     // override ::WaveformRendererSignalBase
     void onSetup(const QDomNode& node) override;
@@ -25,5 +27,7 @@ class allshader::WaveformRendererRGB final : public allshader::WaveformRendererS
     VertexData m_vertices;
     RGBData m_colors;
 
+    bool m_isSlipRenderer;
+
     DISALLOW_COPY_AND_ASSIGN(WaveformRendererRGB);
 };
diff --git a/src/waveform/renderers/allshader/waveformrendererslipmode.cpp b/src/waveform/renderers/allshader/waveformrendererslipmode.cpp
new file mode 100644
index 00000000000..2f16f579b15
--- /dev/null
+++ b/src/waveform/renderers/allshader/waveformrendererslipmode.cpp
@@ -0,0 +1,107 @@
+#include "waveform/renderers/allshader/waveformrendererslipmode.h"
+
+#include <QDomNode>
+#include <memory>
+
+#include "control/controlproxy.h"
+#include "waveform/renderers/waveformwidgetrenderer.h"
+#include "waveform/waveformwidgetfactory.h"
+#include "widget/wskincolor.h"
+
+namespace {
+
+constexpr int kBlinkingPeriodMillis = 1600;
+constexpr float positionArray[] = {-1.f, -1.f, 1.f, -1.f, -1.f, 1.f, 1.f, 1.f};
+
+} // anonymous namespace
+
+namespace allshader {
+
+WaveformRendererSlipMode::WaveformRendererSlipMode(
+        WaveformWidgetRenderer* waveformWidget)
+        : WaveformRenderer(waveformWidget),
+          m_pSlipMode(nullptr),
+          m_slipBorderTopOutlineSize(10.f),
+          m_slipBorderBottomOutlineSize(10.f) {
+}
+
+bool WaveformRendererSlipMode::init() {
+    m_timer.restart();
+
+    m_pSlipMode.reset(new ControlProxy(
+            m_waveformRenderer->getGroup(), "slip_enabled"));
+
+    return true;
+}
+
+void WaveformRendererSlipMode::setup(const QDomNode& node, const SkinContext& context) {
+    m_color = QColor(224, 224, 224);
+    const QString slipModeOutlineColorName = context.selectString(node, "SlipBorderOutlineColor");
+    if (!slipModeOutlineColorName.isNull()) {
+        m_color = QColor(slipModeOutlineColorName);
+        m_color = WSkinColor::getCorrectColor(m_color);
+    }
+    const float slipBorderTopOutlineSize = context.selectFloat(
+            node, "SlipBorderTopOutlineSize", m_slipBorderTopOutlineSize);
+    if (slipBorderTopOutlineSize >= 0) {
+        m_slipBorderTopOutlineSize = slipBorderTopOutlineSize;
+    }
+    const float slipBorderBottomOutlineSize = context.selectFloat(
+            node, "SlipBorderBottomOutlineSize", m_slipBorderBottomOutlineSize);
+    if (slipBorderBottomOutlineSize >= 0) {
+        m_slipBorderBottomOutlineSize = slipBorderBottomOutlineSize;
+    }
+}
+
+void WaveformRendererSlipMode::initializeGL() {
+    WaveformRenderer::initializeGL();
+    m_shader.init();
+}
+
+void WaveformRendererSlipMode::paintGL() {
+    if (!m_pSlipMode->toBool() || !m_waveformRenderer->isSlipActive()) {
+        return;
+    }
+
+    const int elapsed = m_timer.elapsed().toIntegerMillis() % kBlinkingPeriodMillis;
+
+    const double blinkIntensity = (double)(2 * abs(elapsed - kBlinkingPeriodMillis / 2)) /
+            kBlinkingPeriodMillis;
+
+    const double alpha = 0.25 + 0.5 * blinkIntensity;
+
+    if (alpha != 0.0) {
+        QColor color = m_color;
+        color.setAlphaF(static_cast<float>(alpha));
+
+        glEnable(GL_BLEND);
+        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+        const int colorLocation = m_shader.colorLocation();
+        const int borderLocation = m_shader.boarderLocation();
+        const int positionLocation = m_shader.positionLocation();
+        const int gradientLocation = m_shader.dimensionLocation();
+
+        m_shader.bind();
+        m_shader.enableAttributeArray(positionLocation);
+
+        m_shader.setUniformValue(colorLocation, color);
+        m_shader.setUniformValue(borderLocation,
+                m_slipBorderTopOutlineSize,
+                m_slipBorderBottomOutlineSize);
+
+        m_shader.setAttributeArray(
+                positionLocation, GL_FLOAT, positionArray, 2);
+
+        m_shader.setUniformValue(gradientLocation,
+                (float)m_waveformRenderer->getLength() / 2,
+                (float)m_waveformRenderer->getBreadth() / 2);
+
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+        m_shader.disableAttributeArray(positionLocation);
+        m_shader.release();
+    }
+}
+
+} // namespace allshader
diff --git a/src/waveform/renderers/allshader/waveformrendererslipmode.h b/src/waveform/renderers/allshader/waveformrendererslipmode.h
new file mode 100644
index 00000000000..5e7b189ca57
--- /dev/null
+++ b/src/waveform/renderers/allshader/waveformrendererslipmode.h
@@ -0,0 +1,42 @@
+#pragma once
+
+#include <QColor>
+#include <memory>
+
+#include "shaders/slipmodeshader.h"
+#include "util/class.h"
+#include "util/performancetimer.h"
+#include "waveform/renderers/allshader/waveformrenderer.h"
+
+class ControlProxy;
+class QDomNode;
+class SkinContext;
+
+namespace allshader {
+class WaveformRendererSlipMode;
+}
+
+class allshader::WaveformRendererSlipMode final : public allshader::WaveformRenderer {
+  public:
+    explicit WaveformRendererSlipMode(
+            WaveformWidgetRenderer* waveformWidget);
+
+    void setup(const QDomNode& node, const SkinContext& context) override;
+
+    bool init() override;
+
+    void initializeGL() override;
+    void paintGL() override;
+
+  private:
+    mixxx::SlipModeShader m_shader;
+    std::unique_ptr<ControlProxy> m_pSlipMode;
+
+    float m_slipBorderTopOutlineSize;
+    float m_slipBorderBottomOutlineSize;
+
+    QColor m_color;
+    PerformanceTimer m_timer;
+
+    DISALLOW_COPY_AND_ASSIGN(WaveformRendererSlipMode);
+};
diff --git a/src/waveform/renderers/allshader/waveformrendermark.cpp b/src/waveform/renderers/allshader/waveformrendermark.cpp
index fc5f7004bf9..c510cedc495 100644
--- a/src/waveform/renderers/allshader/waveformrendermark.cpp
+++ b/src/waveform/renderers/allshader/waveformrendermark.cpp
@@ -43,8 +43,11 @@ class TextureGraphics : public WaveformMark::Graphics {
 // The boolean argument for the WaveformRenderMarkBase constructor indicates
 // that updateMarkImages should not be called immediately.
 
-allshader::WaveformRenderMark::WaveformRenderMark(WaveformWidgetRenderer* waveformWidget)
-        : ::WaveformRenderMarkBase(waveformWidget, false) {
+allshader::WaveformRenderMark::WaveformRenderMark(
+        WaveformWidgetRenderer* waveformWidget,
+        ::WaveformRendererAbstract::Type type)
+        : WaveformRenderMarkBase(waveformWidget, false),
+          m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
 
 void allshader::WaveformRenderMark::initializeGL() {
@@ -153,6 +156,14 @@ void allshader::WaveformRenderMark::drawMark(const QRectF& rect, QColor color) {
 }
 
 void allshader::WaveformRenderMark::paintGL() {
+    if (m_isSlipRenderer && !m_waveformRenderer->isSlipActive()) {
+        return;
+    }
+
+    auto positionType = m_isSlipRenderer ? ::WaveformRendererAbstract::Slip
+                                         : ::WaveformRendererAbstract::Play;
+    bool slipActive = m_waveformRenderer->isSlipActive();
+
     const float devicePixelRatio = m_waveformRenderer->getDevicePixelRatio();
     QList<WaveformWidgetRenderer::WaveformMarkOnScreen> marksOnScreen;
 
@@ -160,6 +171,10 @@ void allshader::WaveformRenderMark::paintGL() {
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
     // Will create textures so requires OpenGL context
+    for (const auto& pMark : std::as_const(m_marks)) {
+        pMark->setBreadth(slipActive ? m_waveformRenderer->getBreadth() / 2
+                                     : m_waveformRenderer->getBreadth());
+    }
     updateMarkImages();
 
     for (const auto& pMark : std::as_const(m_marks)) {
@@ -171,7 +186,7 @@ void allshader::WaveformRenderMark::paintGL() {
         if (samplePosition != Cue::kNoPosition) {
             float currentMarkPoint = static_cast<float>(
                     m_waveformRenderer->transformSamplePositionInRendererWorld(
-                            samplePosition));
+                            samplePosition, positionType));
             const double sampleEndPosition = pMark->getSampleEndPosition();
 
             // Pixmaps are expected to have the mark stroke at the center,
@@ -186,7 +201,11 @@ void allshader::WaveformRenderMark::paintGL() {
             if (currentMarkPoint > -markHalfWidth &&
                     currentMarkPoint < m_waveformRenderer->getLength() +
                                     markHalfWidth) {
-                drawTexture(drawOffset, 0, pTexture);
+                drawTexture(drawOffset,
+                        !m_isSlipRenderer && slipActive
+                                ? m_waveformRenderer->getBreadth() / 2
+                                : 0,
+                        pTexture);
                 visible = true;
             }
 
@@ -197,7 +216,7 @@ void allshader::WaveformRenderMark::paintGL() {
                         float>(
                         m_waveformRenderer
                                 ->transformSamplePositionInRendererWorld(
-                                        sampleEndPosition));
+                                        sampleEndPosition, positionType));
 
                 if (visible || currentMarkEndPoint > 0) {
                     QColor color = pMark->fillColor();
diff --git a/src/waveform/renderers/allshader/waveformrendermark.h b/src/waveform/renderers/allshader/waveformrendermark.h
index a06474cfc07..de8fefd2573 100644
--- a/src/waveform/renderers/allshader/waveformrendermark.h
+++ b/src/waveform/renderers/allshader/waveformrendermark.h
@@ -18,7 +18,9 @@ class WaveformRenderMark;
 class allshader::WaveformRenderMark : public ::WaveformRenderMarkBase,
                                       public allshader::WaveformRendererAbstract {
   public:
-    explicit WaveformRenderMark(WaveformWidgetRenderer* waveformWidget);
+    explicit WaveformRenderMark(WaveformWidgetRenderer* waveformWidget,
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play);
 
     void draw(QPainter* painter, QPaintEvent* event) override {
         Q_UNUSED(painter);
@@ -48,6 +50,8 @@ class allshader::WaveformRenderMark : public ::WaveformRenderMarkBase,
     mixxx::TextureShader m_textureShader;
     std::unique_ptr<QOpenGLTexture> m_pPlayPosMarkTexture;
 
+    bool m_isSlipRenderer;
+
     void drawMark(const QRectF& rect, QColor color);
     void drawTexture(float x, float y, QOpenGLTexture* texture);
 
diff --git a/src/waveform/renderers/waveformrendererabstract.h b/src/waveform/renderers/waveformrendererabstract.h
index a4687986884..b17ec9b70ce 100644
--- a/src/waveform/renderers/waveformrendererabstract.h
+++ b/src/waveform/renderers/waveformrendererabstract.h
@@ -15,6 +15,13 @@ class WaveformRendererAbstract;
 
 class WaveformRendererAbstract {
   public:
+    /// The type of cursor for which the waveform is rendered
+    ///  Play: the play cursor is the area of focus for the renderer
+    ///  Slip: the slip cursor is the area of focus for the renderer
+    enum Type {
+        Play,
+        Slip
+    };
     explicit WaveformRendererAbstract(
             WaveformWidgetRenderer* waveformWidgetRenderer);
     virtual ~WaveformRendererAbstract();
diff --git a/src/waveform/renderers/waveformwidgetrenderer.cpp b/src/waveform/renderers/waveformwidgetrenderer.cpp
index 86dc06f6591..3b328f68c7f 100644
--- a/src/waveform/renderers/waveformwidgetrenderer.cpp
+++ b/src/waveform/renderers/waveformwidgetrenderer.cpp
@@ -17,6 +17,7 @@ const double WaveformWidgetRenderer::s_defaultPlayMarkerPosition = 0.5;
 
 namespace {
 constexpr int kDefaultDimBrightThreshold = 127;
+constexpr int kWaveformRendererAbstractTypeEnd = ::WaveformRendererAbstract::Slip + 1;
 } // namespace
 
 WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
@@ -27,8 +28,6 @@ WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
           m_width(-1),
           m_devicePixelRatio(1.0f),
 
-          m_firstDisplayedPosition(0.0),
-          m_lastDisplayedPosition(0.0),
           m_trackPixelCount(0.0),
 
           m_zoomFactor(1.0),
@@ -37,7 +36,6 @@ WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
           m_alphaBeatGrid(90),
           // Really create some to manage those;
           m_visualPlayPosition(nullptr),
-          m_playPosVSample(0),
           m_totalVSamples(0),
           m_pRateRatioCO(nullptr),
           m_pGainControlObject(nullptr),
@@ -46,10 +44,17 @@ WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
           m_trackSamples(0),
           m_scaleFactor(1.0),
           m_playMarkerPosition(s_defaultPlayMarkerPosition),
-          m_passthroughEnabled(false),
-          m_playPos(-1.0),
-          m_truePosSample(-1.0) {
+          m_passthroughEnabled(false) {
     //qDebug() << "WaveformWidgetRenderer";
+    for (int type = ::WaveformRendererAbstract::Play;
+            type < kWaveformRendererAbstractTypeEnd;
+            type++) {
+        m_firstDisplayedPosition[type] = 0.0;
+        m_lastDisplayedPosition[type] = 0.0;
+        m_posVSample[type] = 0.0;
+        m_pos[type] = -1.0; // disable renderers
+        m_truePosSample[type] = -1.0;
+    }
 
 #ifdef WAVEFORMWIDGETRENDERER_DEBUG
     m_timer = new QTime();
@@ -103,7 +108,13 @@ bool WaveformWidgetRenderer::init() {
 
 void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
     if (m_passthroughEnabled) {
-        m_playPos = -1; // disables renderers in draw()
+        // disables renderers in draw()
+        for (int type = ::WaveformRendererAbstract::Play;
+                type < kWaveformRendererAbstractTypeEnd;
+                type++) {
+            m_pos[type] = -1.0;
+            m_truePosSample[type] = -1.0;
+        }
         return;
     }
 
@@ -133,19 +144,15 @@ void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
         }
     }
 
-    double truePlayPos = m_visualPlayPosition->getAtNextVSync(vsyncThread);
+    double truePos[2]{0};
+    m_visualPlayPosition->getPlaySlipAtNextVSync(vsyncThread,
+            truePos + ::WaveformRendererAbstract::Play,
+            truePos + ::WaveformRendererAbstract::Slip);
     // truePlayPos = -1 happens, when a new track is in buffer but m_visualPlayPosition was not updated
 
-    if (m_audioSamplePerPixel > 0 && truePlayPos != -1) {
+    if (m_audioSamplePerPixel > 0) {
         // Track length in pixels.
         m_trackPixelCount = m_trackSamples / 2.0 / m_audioSamplePerPixel;
-
-        // Avoid pixel jitter in play position by rounding to the nearest track
-        // pixel.
-        m_playPos = round(truePlayPos * m_trackPixelCount) / m_trackPixelCount;
-        m_totalVSamples = static_cast<int>(m_trackPixelCount * m_visualSamplePerPixel);
-        m_playPosVSample = static_cast<int>(m_playPos * m_totalVSamples);
-        m_truePosSample = truePlayPos * static_cast<double>(m_trackSamples);
         double leftOffset = m_playMarkerPosition;
         double rightOffset = 1.0 - m_playMarkerPosition;
 
@@ -159,11 +166,26 @@ void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
         //        "displayedLengthLeft=" << displayedLengthLeft <<
         //        "displayedLengthRight=" << displayedLengthRight;
 
-        m_firstDisplayedPosition = m_playPos - displayedLengthLeft;
-        m_lastDisplayedPosition = m_playPos + displayedLengthRight;
+        m_totalVSamples = static_cast<int>(m_trackPixelCount * m_visualSamplePerPixel);
+        for (int type = ::WaveformRendererAbstract::Play;
+                type < kWaveformRendererAbstractTypeEnd;
+                type++) {
+            // Avoid pixel jitter in play position by rounding to the nearest track
+            // pixel.
+            m_pos[type] = round(truePos[type] * m_trackPixelCount) / m_trackPixelCount;
+            m_posVSample[type] = static_cast<int>(m_pos[type] * m_totalVSamples);
+            m_truePosSample[type] = truePos[type] * static_cast<double>(m_trackSamples);
+            m_firstDisplayedPosition[type] = m_pos[type] - displayedLengthLeft;
+            m_lastDisplayedPosition[type] = m_pos[type] + displayedLengthRight;
+        }
+
     } else {
-        m_playPos = -1.0; // disable renderers
-        m_truePosSample = -1.0;
+        for (int type = ::WaveformRendererAbstract::Play;
+                type < kWaveformRendererAbstractTypeEnd;
+                type++) {
+            m_pos[type] = -1.0; // disable renderers
+            m_truePosSample[type] = -1.0;
+        }
     }
 
     // qDebug() << "WaveformWidgetRenderer::onPreRender" <<
diff --git a/src/waveform/renderers/waveformwidgetrenderer.h b/src/waveform/renderers/waveformwidgetrenderer.h
index 5570ed8fc08..893705a680b 100644
--- a/src/waveform/renderers/waveformwidgetrenderer.h
+++ b/src/waveform/renderers/waveformwidgetrenderer.h
@@ -3,6 +3,7 @@
 #include "track/track_decl.h"
 #include "util/class.h"
 #include "waveform/renderers/waveformmark.h"
+#include "waveform/renderers/waveformrendererabstract.h"
 #include "waveform/renderers/waveformsignalcolors.h"
 #include "waveform/waveform.h"
 
@@ -45,6 +46,10 @@ class WaveformWidgetRenderer {
         return m_pTrack;
     }
 
+    bool isSlipActive() const {
+        return m_pos[::WaveformRendererAbstract::Play] != m_pos[::WaveformRendererAbstract::Slip];
+    }
+
     ConstWaveformPointer getWaveform() const;
 
     /// Get cue mark at a point on the waveform widget.
@@ -52,11 +57,15 @@ class WaveformWidgetRenderer {
 
     CuePointer getCuePointerFromIndex(int cueIndex) const;
 
-    double getFirstDisplayedPosition() const {
-        return m_firstDisplayedPosition;
+    double getFirstDisplayedPosition(
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play) const {
+        return m_firstDisplayedPosition[type];
     }
-    double getLastDisplayedPosition() const {
-        return m_lastDisplayedPosition;
+    double getLastDisplayedPosition(
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play) const {
+        return m_lastDisplayedPosition[type];
     }
 
     void setZoom(double zoom);
@@ -74,20 +83,23 @@ class WaveformWidgetRenderer {
     // this "regulate" against visual sampling to make the position in widget
     // stable and deterministic
     // Transform sample index to pixel in track.
-    inline double transformSamplePositionInRendererWorld(double samplePosition) const {
-        if (std::abs(samplePosition - m_truePosSample) < 1.f) {
+    inline double transformSamplePositionInRendererWorld(double samplePosition,
+            ::WaveformRendererAbstract::Type type =
+                    ::WaveformRendererAbstract::Play) const {
+        if (std::abs(samplePosition - m_truePosSample[type]) < 1.f) {
             // When asked for the sample position that corresponds with the play
             // marker, return the play market pixel position. This avoids a rare
             // rounding issue where a marker at that sample position would be
             // 1 pixel off.
             return m_playMarkerPosition * getLength();
         }
-        return (samplePosition - m_firstDisplayedPosition * m_trackSamples) /
+        return (samplePosition - m_firstDisplayedPosition[type] * m_trackSamples) /
                 2 / m_audioSamplePerPixel;
     }
 
-    int getPlayPosVSample() const {
-        return m_playPosVSample;
+    int getPlayPosVSample(::WaveformRendererAbstract::Type type =
+                                  ::WaveformRendererAbstract::Play) const {
+        return m_posVSample[type];
     }
     int getTotalVSample() const {
         return m_totalVSamples;
@@ -146,9 +158,9 @@ class WaveformWidgetRenderer {
         return m_dimBrightThreshold;
     }
 
-    template< class T_Renderer>
-    inline T_Renderer* addRenderer() {
-        T_Renderer* renderer = new T_Renderer(this);
+    template<class T_Renderer, typename... Args>
+    inline T_Renderer* addRenderer(Args&&... args) {
+        T_Renderer* renderer = new T_Renderer(this, std::forward<Args>(args)...);
         m_rendererStack.push_back(renderer);
         return renderer;
     }
@@ -158,7 +170,7 @@ class WaveformWidgetRenderer {
         m_markPositions = markPositions;
     }
 
-    double getPlayMarkerPosition() {
+    double getPlayMarkerPosition() const {
         return m_playMarkerPosition;
     }
 
@@ -172,7 +184,7 @@ class WaveformWidgetRenderer {
     void setPassThroughEnabled(bool enabled);
 
     bool shouldOnlyDrawBackground() const {
-        return m_trackSamples <= 0.0 || m_playPos == -1;
+        return m_trackSamples <= 0.0 || m_pos[::WaveformRendererAbstract::Play] == -1;
     }
 
   protected:
@@ -187,8 +199,8 @@ class WaveformWidgetRenderer {
     WaveformSignalColors m_colors;
     QColor m_passthroughLabelColor;
 
-    double m_firstDisplayedPosition;
-    double m_lastDisplayedPosition;
+    double m_firstDisplayedPosition[2];
+    double m_lastDisplayedPosition[2];
     double m_trackPixelCount;
 
     double m_zoomFactor;
@@ -200,7 +212,7 @@ class WaveformWidgetRenderer {
     //TODO: vRince create some class to manage control/value
     //ControlConnection
     QSharedPointer<VisualPlayPosition> m_visualPlayPosition;
-    int m_playPosVSample;
+    int m_posVSample[2];
     int m_totalVSamples;
     ControlProxy* m_pRateRatioCO;
     ControlProxy* m_pGainControlObject;
@@ -233,6 +245,6 @@ class WaveformWidgetRenderer {
     void drawPassthroughLabel(QPainter* painter);
 
     bool m_passthroughEnabled;
-    double m_playPos;
-    double m_truePosSample;
+    double m_pos[2];
+    double m_truePosSample[2];
 };
diff --git a/src/waveform/widgets/allshader/rgbwaveformwidget.cpp b/src/waveform/widgets/allshader/rgbwaveformwidget.cpp
index 605dbe37629..b6571435a79 100644
--- a/src/waveform/widgets/allshader/rgbwaveformwidget.cpp
+++ b/src/waveform/widgets/allshader/rgbwaveformwidget.cpp
@@ -5,6 +5,7 @@
 #include "waveform/renderers/allshader/waveformrendererendoftrack.h"
 #include "waveform/renderers/allshader/waveformrendererpreroll.h"
 #include "waveform/renderers/allshader/waveformrendererrgb.h"
+#include "waveform/renderers/allshader/waveformrendererslipmode.h"
 #include "waveform/renderers/allshader/waveformrendermark.h"
 #include "waveform/renderers/allshader/waveformrendermarkrange.h"
 #include "waveform/widgets/allshader/moc_rgbwaveformwidget.cpp"
@@ -20,6 +21,12 @@ RGBWaveformWidget::RGBWaveformWidget(const QString& group, QWidget* parent)
     addRenderer<WaveformRendererRGB>();
     addRenderer<WaveformRenderBeat>();
     addRenderer<WaveformRenderMark>();
+    // The following renderer will add an overlay waveform if a slip is in progress
+    addRenderer<WaveformRendererSlipMode>();
+    addRenderer<WaveformRendererPreroll>(::WaveformRendererAbstract::Slip);
+    addRenderer<WaveformRendererRGB>(::WaveformRendererAbstract::Slip);
+    addRenderer<WaveformRenderBeat>(::WaveformRendererAbstract::Slip);
+    addRenderer<WaveformRenderMark>(::WaveformRendererAbstract::Slip);
 
     m_initSuccess = init();
 }

From 50e070a65927c4bdea22357175032876487bbe50 Mon Sep 17 00:00:00 2001
From: Antoine C <mixxx@acolombier.dev>
Date: Mon, 8 Apr 2024 15:05:05 +0100
Subject: [PATCH 2/2] code style feedback

---
 src/shaders/slipmodeshader.cpp                |  4 ++--
 .../allshader/waveformrenderbeat.cpp          |  2 +-
 .../renderers/allshader/waveformrenderbeat.h  |  2 +-
 .../allshader/waveformrendererpreroll.cpp     |  2 +-
 .../allshader/waveformrendererpreroll.h       |  2 +-
 .../allshader/waveformrendererrgb.cpp         |  2 +-
 .../renderers/allshader/waveformrendererrgb.h |  2 +-
 .../allshader/waveformrendererslipmode.cpp    | 22 +++++++++++--------
 .../allshader/waveformrendermark.cpp          |  2 +-
 .../renderers/allshader/waveformrendermark.h  |  2 +-
 .../renderers/waveformrendererabstract.h      |  2 +-
 .../renderers/waveformwidgetrenderer.cpp      |  9 ++++----
 .../renderers/waveformwidgetrenderer.h        |  8 +++----
 13 files changed, 32 insertions(+), 29 deletions(-)

diff --git a/src/shaders/slipmodeshader.cpp b/src/shaders/slipmodeshader.cpp
index b176e217840..352d61c9ea9 100644
--- a/src/shaders/slipmodeshader.cpp
+++ b/src/shaders/slipmodeshader.cpp
@@ -27,8 +27,8 @@ in highp vec4 vposition;
 void main()
 {
 
-    float xBorder = abs(dimension.x*vposition.x);
-    float yBorder = dimension.y*vposition.y;
+    float xBorder = abs(dimension.x * vposition.x);
+    float yBorder = dimension.y * vposition.y;
     float upperBoard = borders.x;
     float lowerBoard = borders.y;
 
diff --git a/src/waveform/renderers/allshader/waveformrenderbeat.cpp b/src/waveform/renderers/allshader/waveformrenderbeat.cpp
index efc04efb6ae..3f793efd706 100644
--- a/src/waveform/renderers/allshader/waveformrenderbeat.cpp
+++ b/src/waveform/renderers/allshader/waveformrenderbeat.cpp
@@ -11,7 +11,7 @@
 namespace allshader {
 
 WaveformRenderBeat::WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget,
-        ::WaveformRendererAbstract::Type type)
+        ::WaveformRendererAbstract::PositionSource type)
         : WaveformRenderer(waveformWidget),
           m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
diff --git a/src/waveform/renderers/allshader/waveformrenderbeat.h b/src/waveform/renderers/allshader/waveformrenderbeat.h
index 01912ae9083..d3b2b79d1bc 100644
--- a/src/waveform/renderers/allshader/waveformrenderbeat.h
+++ b/src/waveform/renderers/allshader/waveformrenderbeat.h
@@ -17,7 +17,7 @@ class WaveformRenderBeat;
 class allshader::WaveformRenderBeat final : public allshader::WaveformRenderer {
   public:
     explicit WaveformRenderBeat(WaveformWidgetRenderer* waveformWidget,
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play);
 
     void setup(const QDomNode& node, const SkinContext& context) override;
diff --git a/src/waveform/renderers/allshader/waveformrendererpreroll.cpp b/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
index 60beca4ee9e..3fa00e6bd86 100644
--- a/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
+++ b/src/waveform/renderers/allshader/waveformrendererpreroll.cpp
@@ -62,7 +62,7 @@ namespace allshader {
 
 WaveformRendererPreroll::WaveformRendererPreroll(
         WaveformWidgetRenderer* waveformWidget,
-        ::WaveformRendererAbstract::Type type)
+        ::WaveformRendererAbstract::PositionSource type)
         : WaveformRenderer(waveformWidget),
           m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
diff --git a/src/waveform/renderers/allshader/waveformrendererpreroll.h b/src/waveform/renderers/allshader/waveformrendererpreroll.h
index ec54b17c8c5..c764d68b338 100644
--- a/src/waveform/renderers/allshader/waveformrendererpreroll.h
+++ b/src/waveform/renderers/allshader/waveformrendererpreroll.h
@@ -22,7 +22,7 @@ class allshader::WaveformRendererPreroll : public allshader::WaveformRenderer {
   public:
     explicit WaveformRendererPreroll(
             WaveformWidgetRenderer* waveformWidgetRenderer,
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play);
     ~WaveformRendererPreroll() override;
 
diff --git a/src/waveform/renderers/allshader/waveformrendererrgb.cpp b/src/waveform/renderers/allshader/waveformrendererrgb.cpp
index f83044b9e53..20c4d12a484 100644
--- a/src/waveform/renderers/allshader/waveformrendererrgb.cpp
+++ b/src/waveform/renderers/allshader/waveformrendererrgb.cpp
@@ -15,7 +15,7 @@ inline float math_pow2(float x) {
 } // namespace
 
 WaveformRendererRGB::WaveformRendererRGB(WaveformWidgetRenderer* waveformWidget,
-        ::WaveformRendererAbstract::Type type)
+        ::WaveformRendererAbstract::PositionSource type)
         : WaveformRendererSignalBase(waveformWidget),
           m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
diff --git a/src/waveform/renderers/allshader/waveformrendererrgb.h b/src/waveform/renderers/allshader/waveformrendererrgb.h
index a7c1a1983fb..d9b2d5a65d2 100644
--- a/src/waveform/renderers/allshader/waveformrendererrgb.h
+++ b/src/waveform/renderers/allshader/waveformrendererrgb.h
@@ -13,7 +13,7 @@ class WaveformRendererRGB;
 class allshader::WaveformRendererRGB final : public allshader::WaveformRendererSignalBase {
   public:
     explicit WaveformRendererRGB(WaveformWidgetRenderer* waveformWidget,
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play);
 
     // override ::WaveformRendererSignalBase
diff --git a/src/waveform/renderers/allshader/waveformrendererslipmode.cpp b/src/waveform/renderers/allshader/waveformrendererslipmode.cpp
index 2f16f579b15..79061fb53f4 100644
--- a/src/waveform/renderers/allshader/waveformrendererslipmode.cpp
+++ b/src/waveform/renderers/allshader/waveformrendererslipmode.cpp
@@ -11,8 +11,12 @@
 namespace {
 
 constexpr int kBlinkingPeriodMillis = 1600;
+// Position matrix passed to OpenGL when drawing the shader
 constexpr float positionArray[] = {-1.f, -1.f, 1.f, -1.f, -1.f, 1.f, 1.f, 1.f};
 
+// Used as default outline color in case no value is provided in the theme
+constexpr QColor kDefaultColor = QColor(224, 224, 224);
+
 } // anonymous namespace
 
 namespace allshader {
@@ -20,7 +24,6 @@ namespace allshader {
 WaveformRendererSlipMode::WaveformRendererSlipMode(
         WaveformWidgetRenderer* waveformWidget)
         : WaveformRenderer(waveformWidget),
-          m_pSlipMode(nullptr),
           m_slipBorderTopOutlineSize(10.f),
           m_slipBorderBottomOutlineSize(10.f) {
 }
@@ -28,18 +31,18 @@ WaveformRendererSlipMode::WaveformRendererSlipMode(
 bool WaveformRendererSlipMode::init() {
     m_timer.restart();
 
-    m_pSlipMode.reset(new ControlProxy(
-            m_waveformRenderer->getGroup(), "slip_enabled"));
+    m_pSlipMode = std::make_unique<ControlProxy>(
+            m_waveformRenderer->getGroup(), "slip_enabled");
 
     return true;
 }
 
 void WaveformRendererSlipMode::setup(const QDomNode& node, const SkinContext& context) {
-    m_color = QColor(224, 224, 224);
     const QString slipModeOutlineColorName = context.selectString(node, "SlipBorderOutlineColor");
     if (!slipModeOutlineColorName.isNull()) {
-        m_color = QColor(slipModeOutlineColorName);
-        m_color = WSkinColor::getCorrectColor(m_color);
+        m_color = WSkinColor::getCorrectColor(QColor(slipModeOutlineColorName));
+    } else {
+        m_color = kDefaultColor;
     }
     const float slipBorderTopOutlineSize = context.selectFloat(
             node, "SlipBorderTopOutlineSize", m_slipBorderTopOutlineSize);
@@ -65,7 +68,8 @@ void WaveformRendererSlipMode::paintGL() {
 
     const int elapsed = m_timer.elapsed().toIntegerMillis() % kBlinkingPeriodMillis;
 
-    const double blinkIntensity = (double)(2 * abs(elapsed - kBlinkingPeriodMillis / 2)) /
+    const double blinkIntensity =
+            static_cast<double>(2 * abs(elapsed - kBlinkingPeriodMillis / 2)) /
             kBlinkingPeriodMillis;
 
     const double alpha = 0.25 + 0.5 * blinkIntensity;
@@ -94,8 +98,8 @@ void WaveformRendererSlipMode::paintGL() {
                 positionLocation, GL_FLOAT, positionArray, 2);
 
         m_shader.setUniformValue(gradientLocation,
-                (float)m_waveformRenderer->getLength() / 2,
-                (float)m_waveformRenderer->getBreadth() / 2);
+                static_cast<float>(m_waveformRenderer->getLength()) / 2,
+                static_cast<float>(m_waveformRenderer->getBreadth()) / 2);
 
         glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 
diff --git a/src/waveform/renderers/allshader/waveformrendermark.cpp b/src/waveform/renderers/allshader/waveformrendermark.cpp
index c510cedc495..064905ffe8f 100644
--- a/src/waveform/renderers/allshader/waveformrendermark.cpp
+++ b/src/waveform/renderers/allshader/waveformrendermark.cpp
@@ -45,7 +45,7 @@ class TextureGraphics : public WaveformMark::Graphics {
 
 allshader::WaveformRenderMark::WaveformRenderMark(
         WaveformWidgetRenderer* waveformWidget,
-        ::WaveformRendererAbstract::Type type)
+        ::WaveformRendererAbstract::PositionSource type)
         : WaveformRenderMarkBase(waveformWidget, false),
           m_isSlipRenderer(type == ::WaveformRendererAbstract::Slip) {
 }
diff --git a/src/waveform/renderers/allshader/waveformrendermark.h b/src/waveform/renderers/allshader/waveformrendermark.h
index de8fefd2573..60580f1e34c 100644
--- a/src/waveform/renderers/allshader/waveformrendermark.h
+++ b/src/waveform/renderers/allshader/waveformrendermark.h
@@ -19,7 +19,7 @@ class allshader::WaveformRenderMark : public ::WaveformRenderMarkBase,
                                       public allshader::WaveformRendererAbstract {
   public:
     explicit WaveformRenderMark(WaveformWidgetRenderer* waveformWidget,
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play);
 
     void draw(QPainter* painter, QPaintEvent* event) override {
diff --git a/src/waveform/renderers/waveformrendererabstract.h b/src/waveform/renderers/waveformrendererabstract.h
index b17ec9b70ce..6c15dd523d5 100644
--- a/src/waveform/renderers/waveformrendererabstract.h
+++ b/src/waveform/renderers/waveformrendererabstract.h
@@ -18,7 +18,7 @@ class WaveformRendererAbstract {
     /// The type of cursor for which the waveform is rendered
     ///  Play: the play cursor is the area of focus for the renderer
     ///  Slip: the slip cursor is the area of focus for the renderer
-    enum Type {
+    enum PositionSource {
         Play,
         Slip
     };
diff --git a/src/waveform/renderers/waveformwidgetrenderer.cpp b/src/waveform/renderers/waveformwidgetrenderer.cpp
index 3b328f68c7f..ffefe5d6d45 100644
--- a/src/waveform/renderers/waveformwidgetrenderer.cpp
+++ b/src/waveform/renderers/waveformwidgetrenderer.cpp
@@ -17,7 +17,6 @@ const double WaveformWidgetRenderer::s_defaultPlayMarkerPosition = 0.5;
 
 namespace {
 constexpr int kDefaultDimBrightThreshold = 127;
-constexpr int kWaveformRendererAbstractTypeEnd = ::WaveformRendererAbstract::Slip + 1;
 } // namespace
 
 WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
@@ -47,7 +46,7 @@ WaveformWidgetRenderer::WaveformWidgetRenderer(const QString& group)
           m_passthroughEnabled(false) {
     //qDebug() << "WaveformWidgetRenderer";
     for (int type = ::WaveformRendererAbstract::Play;
-            type < kWaveformRendererAbstractTypeEnd;
+            type <= ::WaveformRendererAbstract::Slip;
             type++) {
         m_firstDisplayedPosition[type] = 0.0;
         m_lastDisplayedPosition[type] = 0.0;
@@ -110,7 +109,7 @@ void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
     if (m_passthroughEnabled) {
         // disables renderers in draw()
         for (int type = ::WaveformRendererAbstract::Play;
-                type < kWaveformRendererAbstractTypeEnd;
+                type <= ::WaveformRendererAbstract::Slip;
                 type++) {
             m_pos[type] = -1.0;
             m_truePosSample[type] = -1.0;
@@ -168,7 +167,7 @@ void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
 
         m_totalVSamples = static_cast<int>(m_trackPixelCount * m_visualSamplePerPixel);
         for (int type = ::WaveformRendererAbstract::Play;
-                type < kWaveformRendererAbstractTypeEnd;
+                type <= ::WaveformRendererAbstract::Slip;
                 type++) {
             // Avoid pixel jitter in play position by rounding to the nearest track
             // pixel.
@@ -181,7 +180,7 @@ void WaveformWidgetRenderer::onPreRender(VSyncThread* vsyncThread) {
 
     } else {
         for (int type = ::WaveformRendererAbstract::Play;
-                type < kWaveformRendererAbstractTypeEnd;
+                type <= ::WaveformRendererAbstract::Slip;
                 type++) {
             m_pos[type] = -1.0; // disable renderers
             m_truePosSample[type] = -1.0;
diff --git a/src/waveform/renderers/waveformwidgetrenderer.h b/src/waveform/renderers/waveformwidgetrenderer.h
index 893705a680b..a2b82dd5e53 100644
--- a/src/waveform/renderers/waveformwidgetrenderer.h
+++ b/src/waveform/renderers/waveformwidgetrenderer.h
@@ -58,12 +58,12 @@ class WaveformWidgetRenderer {
     CuePointer getCuePointerFromIndex(int cueIndex) const;
 
     double getFirstDisplayedPosition(
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play) const {
         return m_firstDisplayedPosition[type];
     }
     double getLastDisplayedPosition(
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play) const {
         return m_lastDisplayedPosition[type];
     }
@@ -84,7 +84,7 @@ class WaveformWidgetRenderer {
     // stable and deterministic
     // Transform sample index to pixel in track.
     inline double transformSamplePositionInRendererWorld(double samplePosition,
-            ::WaveformRendererAbstract::Type type =
+            ::WaveformRendererAbstract::PositionSource type =
                     ::WaveformRendererAbstract::Play) const {
         if (std::abs(samplePosition - m_truePosSample[type]) < 1.f) {
             // When asked for the sample position that corresponds with the play
@@ -97,7 +97,7 @@ class WaveformWidgetRenderer {
                 2 / m_audioSamplePerPixel;
     }
 
-    int getPlayPosVSample(::WaveformRendererAbstract::Type type =
+    int getPlayPosVSample(::WaveformRendererAbstract::PositionSource type =
                                   ::WaveformRendererAbstract::Play) const {
         return m_posVSample[type];
     }