Fixed transform control example

include/ignition/rendering/Utils.hh

@@ -34,6 +34,11 @@ namespace ignition
     /// \return The screen scaling factor.
     IGNITION_RENDERING_VISIBLE
     float screenScalingFactor();
+    /// \brief Get the screen scaling factor.
+    /// \param[out] _xScale The X screen scaling factor.
+    /// \param[out] _yScale The Y screen scaling factor.
+    IGNITION_RENDERING_VISIBLE
+    void screenScalingFactor(float &_xScale, float &_yScale);
     }
   }
 }

ogre/src/OgreCamera.cc

@@ -216,10 +216,11 @@ VisualPtr OgreCamera::VisualAt(const ignition::math::Vector2i
     }
   }
 
-  float ratio = screenScalingFactor();
+  float xScale, yScale;
+  screenScalingFactor(xScale, yScale);
   ignition::math::Vector2i mousePos(
-      static_cast<int>(std::rint(ratio * _mousePos.X())),
-      static_cast<int>(std::rint(ratio * _mousePos.Y())));
+      static_cast<int>(std::rint(xScale * _mousePos.X())),
+      static_cast<int>(std::rint(yScale * _mousePos.Y())));
 
   Ogre::Entity *entity = this->selectionBuffer->OnSelectionClick(
       mousePos.X(), mousePos.Y());

ogre2/src/Ogre2Camera.cc

@@ -201,10 +201,11 @@ VisualPtr Ogre2Camera::VisualAt(const ignition::math::Vector2i &_mousePos)
     }
   }
 
-  float ratio = screenScalingFactor();
+  float xScale, yScale;
+  screenScalingFactor(xScale, yScale);
   ignition::math::Vector2i mousePos(
-      static_cast<int>(std::rint(ratio * _mousePos.X())),
-      static_cast<int>(std::rint(ratio * _mousePos.Y())));
+      static_cast<int>(std::rint(xScale * _mousePos.X())),
+      static_cast<int>(std::rint(yScale * _mousePos.Y())));
 
   Ogre::Item *ogreItem = this->selectionBuffer->OnSelectionClick(
       mousePos.X(), mousePos.Y());

src/Utils.cc

@@ -31,11 +31,30 @@ inline namespace IGNITION_RENDERING_VERSION_NAMESPACE {
 /////////////////////////////////////////////////
 float screenScalingFactor()
 {
-  // todo(anyone) set device pixel ratio for high dpi displays on Windows
-  float ratio = 1.0;
+  float x{1.0f};
+  float y{1.0f};
+  screenScalingFactor(x, y);
+  return y;
+}
+
+/////////////////////////////////////////////////
+void screenScalingFactor(float &_xScale, float &_yScale)
+{
+  _xScale = 1.0f;
+  _yScale = 1.0f;
+
+  // todo(anyone) set device pixel ratio for high dpi displays on other
+  // platforms
 #ifdef __linux__
-  Display *disp = XOpenDisplay(nullptr);
-  char *resourceString = XResourceManagerString(disp);
+  auto closeDisplay = [](Display * display)
+  {
+    if (display)
+      XCloseDisplay(display);
+  };
+  auto display =
+    std::unique_ptr<Display, decltype(closeDisplay)>(
+      XOpenDisplay(nullptr), closeDisplay);
+  char *resourceString = XResourceManagerString(display.get());
 
   if (resourceString)
   {
@@ -65,21 +84,34 @@ float screenScalingFactor()
     //        = N pixels / (M inch / 25.4)
     //        = (N * 25.4 pixels) / M inch
     //
-    // We can use either the width or height in the following line. The zero
-    // values in DisplayHeight and DisplayHeightMM is the screen number. A
-    // value of zero uses the default screen.
-    float yDpiRes = (DisplayHeight(disp, 0) * 25.4) /
-      DisplayHeightMM(disp, 0);
+    // The zero values in DisplayHeight and DisplayHeightMM is the screen
+    // number. A value of zero uses the default screen.
+    auto xPixels = DisplayWidth(display.get(), 0);
+    auto yPixels = DisplayHeight(display.get(), 0);
+
+    auto xMM = DisplayWidthMM(display.get(), 0);
+    auto yMM = DisplayHeightMM(display.get(), 0);
+
+    auto xIn = xMM / 25.4;
+    auto yIn = yMM / 25.4;
+
+    float xDpiRes = xPixels / xIn;
+    float yDpiRes = yPixels / yIn;
+
+    if (!math::equal(dpiDesktop, 0.0f) && !math::equal(xDpiRes, 0.0f))
+      _xScale = xDpiRes / dpiDesktop;
 
     if (!math::equal(dpiDesktop, 0.0f) && !math::equal(yDpiRes, 0.0f))
-      ratio = dpiDesktop / yDpiRes;
+      _yScale = yDpiRes / dpiDesktop;
+
+    if (_xScale < 1) _xScale = 1;
+    if (_yScale < 1) _yScale = 1;
 
     // Debug:
-    // printf("DPI Desktop: %f, DPI XY: [%f, %f], Ratio XY: [%f, %f]\n",
-    // dpiDesktop, xDpiRes, yDpiRes, xRatio, yRatio);
+    // printf("DPI Desktop: %f, DPI XY: [%f, %f], Scale XY: [%f, %f]\n",
+    //   dpiDesktop, xDpiRes, yDpiRes, _xScale, _yScale);
   }
 #endif
-  return ratio;
 }
 }
 }