Wire up stroke cap/join/miter limit display list ops (flutter#105)

Author: bdero

impeller/aiks/paint.cc

@@ -23,6 +23,9 @@ std::shared_ptr<Contents> Paint::CreateContentsForEntity() const {
       auto solid_stroke = std::make_shared<SolidStrokeContents>();
       solid_stroke->SetColor(color.Premultiply());
       solid_stroke->SetStrokeSize(stroke_width);
+      solid_stroke->SetStrokeMiter(stroke_miter);
+      solid_stroke->SetStrokeCap(stroke_cap);
+      solid_stroke->SetStrokeJoin(stroke_join);
       return solid_stroke;
     }
   }

impeller/aiks/paint.h

@@ -8,6 +8,7 @@
 
 #include "flutter/fml/macros.h"
 #include "impeller/entity/contents/contents.h"
+#include "impeller/entity/contents/solid_stroke_contents.h"
 #include "impeller/entity/entity.h"
 #include "impeller/geometry/color.h"
 
@@ -21,6 +22,9 @@ struct Paint {
 
   Color color = Color::Black();
   Scalar stroke_width = 0.0;
+  SolidStrokeContents::Cap stroke_cap = SolidStrokeContents::Cap::kButt;
+  SolidStrokeContents::Join stroke_join = SolidStrokeContents::Join::kMiter;
+  Scalar stroke_miter = 4.0;
   Style style = Style::kFill;
   Entity::BlendMode blend_mode = Entity::BlendMode::kSourceOver;
   std::shared_ptr<Contents> contents;

impeller/display_list/display_list_dispatcher.cc

@@ -8,6 +8,7 @@
 
 #include "flutter/fml/trace_event.h"
 #include "impeller/entity/contents/linear_gradient_contents.h"
+#include "impeller/entity/contents/solid_stroke_contents.h"
 #include "impeller/entity/entity.h"
 #include "impeller/geometry/path_builder.h"
 #include "impeller/typographer/backends/skia/text_frame_skia.h"
@@ -65,17 +66,37 @@ void DisplayListDispatcher::setStrokeWidth(SkScalar width) {
 
 // |flutter::Dispatcher|
 void DisplayListDispatcher::setStrokeMiter(SkScalar limit) {
-  UNIMPLEMENTED;
+  paint_.stroke_miter = limit;
 }
 
 // |flutter::Dispatcher|
 void DisplayListDispatcher::setStrokeCap(SkPaint::Cap cap) {
-  UNIMPLEMENTED;
+  switch (cap) {
+    case SkPaint::kButt_Cap:
+      paint_.stroke_cap = SolidStrokeContents::Cap::kButt;
+      break;
+    case SkPaint::kRound_Cap:
+      paint_.stroke_cap = SolidStrokeContents::Cap::kRound;
+      break;
+    case SkPaint::kSquare_Cap:
+      paint_.stroke_cap = SolidStrokeContents::Cap::kSquare;
+      break;
+  }
 }
 
 // |flutter::Dispatcher|
 void DisplayListDispatcher::setStrokeJoin(SkPaint::Join join) {
-  UNIMPLEMENTED;
+  switch (join) {
+    case SkPaint::kMiter_Join:
+      paint_.stroke_join = SolidStrokeContents::Join::kMiter;
+      break;
+    case SkPaint::kRound_Join:
+      paint_.stroke_join = SolidStrokeContents::Join::kRound;
+      break;
+    case SkPaint::kBevel_Join:
+      paint_.stroke_join = SolidStrokeContents::Join::kBevel;
+      break;
+  }
 }
 
 static Point ToPoint(const SkPoint& point) {
@@ -397,11 +418,9 @@ static Path ToPath(const SkPath& path) {
         builder.MoveTo(ToPoint(data.points[0]));
         break;
       case SkPath::kLine_Verb:
-        builder.LineTo(ToPoint(data.points[0]));
         builder.LineTo(ToPoint(data.points[1]));
         break;
       case SkPath::kQuad_Verb:
-        builder.LineTo(ToPoint(data.points[0]));
         builder.QuadraticCurveTo(ToPoint(data.points[1]),
                                  ToPoint(data.points[2]));
         break;
@@ -422,13 +441,11 @@ static Path ToPath(const SkPath& path) {
              curve_index < curve_count;             //
              curve_index++, point_index += 2        //
         ) {
-          builder.LineTo(ToPoint(points[point_index + 0]));
           builder.QuadraticCurveTo(ToPoint(points[point_index + 1]),
                                    ToPoint(points[point_index + 2]));
         }
       } break;
       case SkPath::kCubic_Verb:
-        builder.LineTo(ToPoint(data.points[0]));
         builder.CubicCurveTo(ToPoint(data.points[1]), ToPoint(data.points[2]),
                              ToPoint(data.points[3]));
         break;

impeller/display_list/display_list_unittests.cc

@@ -5,6 +5,7 @@
 #include "flutter/display_list/display_list_builder.h"
 #include "flutter/testing/testing.h"
 #include "impeller/display_list/display_list_playground.h"
+#include "third_party/skia/include/core/SkPathBuilder.h"
 
 namespace impeller {
 namespace testing {
@@ -26,5 +27,50 @@ TEST_F(DisplayListTest, CanDrawTextBlob) {
   ASSERT_TRUE(OpenPlaygroundHere(builder.Build()));
 }
 
+TEST_F(DisplayListTest, CapsAndJoins) {
+  flutter::DisplayListBuilder builder;
+
+  builder.setStyle(SkPaint::Style::kStroke_Style);
+  builder.setStrokeWidth(30);
+  builder.setColor(SK_ColorRED);
+
+  auto path =
+      SkPathBuilder{}.moveTo(-50, 0).lineTo(0, -50).lineTo(50, 0).snapshot();
+
+  builder.translate(100, 100);
+  {
+    builder.setStrokeCap(SkPaint::Cap::kButt_Cap);
+    builder.setStrokeJoin(SkPaint::Join::kMiter_Join);
+    builder.setStrokeMiter(4);
+    builder.drawPath(path);
+  }
+
+  {
+    builder.save();
+    builder.translate(0, 100);
+    // The joint in the path is 45 degrees. A miter length of 1 convert to a
+    // bevel in this case.
+    builder.setStrokeMiter(1);
+    builder.drawPath(path);
+    builder.restore();
+  }
+
+  builder.translate(150, 0);
+  {
+    builder.setStrokeCap(SkPaint::Cap::kSquare_Cap);
+    builder.setStrokeJoin(SkPaint::Join::kBevel_Join);
+    builder.drawPath(path);
+  }
+
+  builder.translate(150, 0);
+  {
+    builder.setStrokeCap(SkPaint::Cap::kRound_Cap);
+    builder.setStrokeJoin(SkPaint::Join::kRound_Join);
+    builder.drawPath(path);
+  }
+
+  ASSERT_TRUE(OpenPlaygroundHere(builder.Build()));
+}
+
 }  // namespace testing
 }  // namespace impeller