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Add solid stroke coverage override (flutter#127)
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@bdero @dnfield
bdero authored and dnfield committed Apr 27, 2022
1 parent 0ed6d4c commit 1a055b0
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Showing 3 changed files with 136 additions and 53 deletions.
24 changes: 24 additions & 0 deletions impeller/entity/contents/solid_stroke_contents.cc
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Expand Up @@ -4,6 +4,8 @@

#include "solid_stroke_contents.h"

#include <optional>

#include "impeller/entity/contents/clip_contents.h"
#include "impeller/entity/contents/content_context.h"
#include "impeller/entity/entity.h"
Expand All @@ -27,6 +29,28 @@ const Color& SolidStrokeContents::GetColor() const {
return color_;
}

std::optional<Rect> SolidStrokeContents::GetCoverage(
const Entity& entity) const {
auto path_coverage = entity.GetPathCoverage();
if (!path_coverage.has_value()) {
return std::nullopt;
}

Scalar max_radius = 0.5;
if (cap_ == Cap::kSquare) {
max_radius = max_radius * kSqrt2;
}
if (join_ == Join::kMiter) {
max_radius = std::max(max_radius, miter_limit_ * 0.5f);
}
Vector2 max_radius_xy = entity.GetTransformation().TransformDirection(
Vector2(max_radius, max_radius) * stroke_size_);

return Rect(path_coverage->origin - max_radius_xy,
Size(path_coverage->size.width + max_radius_xy.x * 2,
path_coverage->size.height + max_radius_xy.y * 2));
}

static VertexBuffer CreateSolidStrokeVertices(
const Path& path,
HostBuffer& buffer,
Expand Down
3 changes: 3 additions & 0 deletions impeller/entity/contents/solid_stroke_contents.h
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Expand Up @@ -68,6 +68,9 @@ class SolidStrokeContents final : public Contents {

Join GetStrokeJoin();

// |Contents|
std::optional<Rect> GetCoverage(const Entity& entity) const override;

// |Contents|
bool Render(const ContentContext& renderer,
const Entity& entity,
Expand Down
162 changes: 109 additions & 53 deletions impeller/entity/entity_unittests.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
#include "impeller/entity/contents/solid_stroke_contents.h"
#include "impeller/entity/entity.h"
#include "impeller/entity/entity_playground.h"
#include "impeller/geometry/geometry_unittests.h"
#include "impeller/geometry/path_builder.h"
#include "impeller/playground/playground.h"
#include "impeller/playground/widgets.h"
Expand Down Expand Up @@ -100,76 +101,89 @@ TEST_F(EntityTest, StrokeCapAndJoinTest) {
ImGui::SetNextWindowPos(
{0 * padding.x + margin.x, 1.7f * padding.y + margin.y});
}
ImGui::Begin("Controls");

// Slightly above sqrt(2) by default, so that right angles are just below
// the limit and acute angles are over the limit (causing them to get
// beveled).
static Scalar miter_limit = 1.41421357;
static Scalar width = 30;
ImGui::SliderFloat("Miter limit", &miter_limit, 0, 30);
ImGui::SliderFloat("Stroke width", &width, 0, 100);
if (ImGui::Button("Reset")) {
miter_limit = 1.41421357;
width = 30;

ImGui::Begin("Controls");
{
ImGui::SliderFloat("Miter limit", &miter_limit, 0, 30);
ImGui::SliderFloat("Stroke width", &width, 0, 100);
if (ImGui::Button("Reset")) {
miter_limit = 1.41421357;
width = 30;
}
}
ImGui::End();

auto create_contents = [width = width](SolidStrokeContents::Cap cap,
SolidStrokeContents::Join join) {
auto render_path = [width = width, &context, &pass](
Path path, SolidStrokeContents::Cap cap,
SolidStrokeContents::Join join) {
auto contents = std::make_unique<SolidStrokeContents>();
contents->SetColor(Color::Red().Premultiply());
contents->SetStrokeSize(width);
contents->SetStrokeCap(cap);
contents->SetStrokeJoin(join);
contents->SetStrokeMiter(miter_limit);
return contents;
};

Entity entity;
Entity entity;
entity.SetPath(path);
entity.SetContents(std::move(contents));

auto coverage = entity.GetCoverage();
if (coverage.has_value()) {
auto bounds_contents = std::make_unique<SolidColorContents>();
bounds_contents->SetColor(Color::Green().WithAlpha(0.5));
Entity bounds_entity;
bounds_entity.SetPath(
PathBuilder{}.AddRect(entity.GetCoverage().value()).TakePath());
bounds_entity.SetContents(std::move(bounds_contents));
bounds_entity.Render(context, pass);
}

entity.Render(context, pass);
};

const Point a_def(0, 0), b_def(0, 100), c_def(150, 0), d_def(150, -100),
e_def(75, 75);
const Scalar r = 30;
// Cap::kButt demo.
{
Point off = Point(0, 0) * padding + margin;
Point a, b, c, d;
std::tie(a, b) = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
std::tie(c, d) = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
entity.SetPath(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kButt,
SolidStrokeContents::Join::kBevel));
entity.Render(context, pass);
auto [a, b] = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
auto [c, d] = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
render_path(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath(),
SolidStrokeContents::Cap::kButt,
SolidStrokeContents::Join::kBevel);
}

// Cap::kSquare demo.
{
Point off = Point(1, 0) * padding + margin;
Point a, b, c, d;
std::tie(a, b) = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
std::tie(c, d) = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
entity.SetPath(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kSquare,
SolidStrokeContents::Join::kBevel));
entity.Render(context, pass);
auto [a, b] = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
auto [c, d] = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
render_path(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath(),
SolidStrokeContents::Cap::kSquare,
SolidStrokeContents::Join::kBevel);
}

// Cap::kRound demo.
{
Point off = Point(2, 0) * padding + margin;
Point a, b, c, d;
std::tie(a, b) = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
std::tie(c, d) = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
entity.SetPath(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kRound,
SolidStrokeContents::Join::kBevel));
entity.Render(context, pass);
auto [a, b] = IMPELLER_PLAYGROUND_LINE(off + a_def, off + b_def, r,
Color::Black(), Color::White());
auto [c, d] = IMPELLER_PLAYGROUND_LINE(off + c_def, off + d_def, r,
Color::Black(), Color::White());
render_path(PathBuilder{}.AddCubicCurve(a, b, d, c).TakePath(),
SolidStrokeContents::Cap::kRound,
SolidStrokeContents::Join::kBevel);
}

// Join::kBevel demo.
Expand All @@ -178,11 +192,9 @@ TEST_F(EntityTest, StrokeCapAndJoinTest) {
Point a = IMPELLER_PLAYGROUND_POINT(off + a_def, r, Color::White());
Point b = IMPELLER_PLAYGROUND_POINT(off + e_def, r, Color::White());
Point c = IMPELLER_PLAYGROUND_POINT(off + c_def, r, Color::White());
entity.SetPath(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kButt,
SolidStrokeContents::Join::kBevel));
entity.Render(context, pass);
render_path(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath(),
SolidStrokeContents::Cap::kButt, SolidStrokeContents::Join::kBevel);
}

// Join::kMiter demo.
Expand All @@ -191,11 +203,9 @@ TEST_F(EntityTest, StrokeCapAndJoinTest) {
Point a = IMPELLER_PLAYGROUND_POINT(off + a_def, r, Color::White());
Point b = IMPELLER_PLAYGROUND_POINT(off + e_def, r, Color::White());
Point c = IMPELLER_PLAYGROUND_POINT(off + c_def, r, Color::White());
entity.SetPath(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kButt,
SolidStrokeContents::Join::kMiter));
entity.Render(context, pass);
render_path(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath(),
SolidStrokeContents::Cap::kButt, SolidStrokeContents::Join::kMiter);
}

// Join::kRound demo.
Expand All @@ -204,11 +214,9 @@ TEST_F(EntityTest, StrokeCapAndJoinTest) {
Point a = IMPELLER_PLAYGROUND_POINT(off + a_def, r, Color::White());
Point b = IMPELLER_PLAYGROUND_POINT(off + e_def, r, Color::White());
Point c = IMPELLER_PLAYGROUND_POINT(off + c_def, r, Color::White());
entity.SetPath(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath());
entity.SetContents(create_contents(SolidStrokeContents::Cap::kButt,
SolidStrokeContents::Join::kRound));
entity.Render(context, pass);
render_path(
PathBuilder{}.MoveTo(a).LineTo(b).LineTo(c).Close().TakePath(),
SolidStrokeContents::Cap::kButt, SolidStrokeContents::Join::kRound);
}

return true;
Expand Down Expand Up @@ -789,5 +797,53 @@ TEST_F(EntityTest, ContentsGetBoundsForEmptyPathReturnsNullopt) {
ASSERT_FALSE(entity.GetPathCoverage().has_value());
}

TEST_F(EntityTest, SolidStrokeCoverageIsCorrect) {
{
Entity entity;
auto contents = std::make_unique<SolidStrokeContents>();
contents->SetStrokeCap(SolidStrokeContents::Cap::kButt);
contents->SetStrokeJoin(SolidStrokeContents::Join::kBevel);
contents->SetStrokeSize(4);
entity.SetPath(PathBuilder{}.AddLine({0, 0}, {10, 10}).TakePath());
entity.SetContents(std::move(contents));
auto actual = entity.GetCoverage();
auto expected = Rect::MakeLTRB(-2, -2, 12, 12);
ASSERT_TRUE(actual.has_value());
ASSERT_RECT_NEAR(actual.value(), expected);
}

// Cover the Cap::kSquare case.
{
Entity entity;
auto contents = std::make_unique<SolidStrokeContents>();
contents->SetStrokeCap(SolidStrokeContents::Cap::kSquare);
contents->SetStrokeJoin(SolidStrokeContents::Join::kBevel);
contents->SetStrokeSize(4);
entity.SetPath(PathBuilder{}.AddLine({0, 0}, {10, 10}).TakePath());
entity.SetContents(std::move(contents));
auto actual = entity.GetCoverage();
auto expected =
Rect::MakeLTRB(-sqrt(8), -sqrt(8), 10 + sqrt(8), 10 + sqrt(8));
ASSERT_TRUE(actual.has_value());
ASSERT_RECT_NEAR(actual.value(), expected);
}

// Cover the Join::kMiter case.
{
Entity entity;
auto contents = std::make_unique<SolidStrokeContents>();
contents->SetStrokeCap(SolidStrokeContents::Cap::kSquare);
contents->SetStrokeJoin(SolidStrokeContents::Join::kMiter);
contents->SetStrokeSize(4);
contents->SetStrokeMiter(2);
entity.SetPath(PathBuilder{}.AddLine({0, 0}, {10, 10}).TakePath());
entity.SetContents(std::move(contents));
auto actual = entity.GetCoverage();
auto expected = Rect::MakeLTRB(-4, -4, 14, 14);
ASSERT_TRUE(actual.has_value());
ASSERT_RECT_NEAR(actual.value(), expected);
}
}

} // namespace testing
} // namespace impeller

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