[Impeller] Adds the ability to specify a golden threshold

impeller/aiks/aiks_playground.cc

@@ -14,7 +14,8 @@ AiksPlayground::AiksPlayground() = default;
 
 AiksPlayground::~AiksPlayground() = default;
 
-bool AiksPlayground::OpenPlaygroundHere(const Picture& picture) {
+bool AiksPlayground::OpenPlaygroundHere(const Picture& picture,
+                                        double threshold) {
   return OpenPlaygroundHere(
       [&picture](AiksContext& renderer, RenderTarget& render_target) -> bool {
         return renderer.Render(picture, render_target);

impeller/aiks/aiks_playground.h

@@ -20,7 +20,7 @@ class AiksPlayground : public PlaygroundTest {
 
   ~AiksPlayground();
 
-  bool OpenPlaygroundHere(const Picture& picture);
+  bool OpenPlaygroundHere(const Picture& picture, double threshold = 0.01);
 
   bool OpenPlaygroundHere(AiksPlaygroundCallback callback);
 

impeller/aiks/aiks_unittests.cc

@@ -1317,9 +1317,6 @@ TEST_P(AiksTest, CanRenderTextOutsideBoundaries) {
 }
 
 TEST_P(AiksTest, TextRotated) {
-#ifdef IMPELLER_GOLDEN_TESTS
-  GTEST_SKIP() << "Test has small differences on different mac hosts";
-#endif
   Canvas canvas;
   canvas.Transform(Matrix(0.5, -0.3, 0, -0.002,  //
                           0, 1, 0, 0,            //
@@ -1330,7 +1327,8 @@ TEST_P(AiksTest, TextRotated) {
       GetContext(), canvas, "the quick brown fox jumped over the lazy dog!.?",
       "Roboto-Regular.ttf"));
 
-  ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
+  ASSERT_TRUE(
+      OpenPlaygroundHere(canvas.EndRecordingAsPicture(), /*threshold=*/0.1));
 }
 
 TEST_P(AiksTest, CanDrawPaint) {

impeller/golden_tests/golden_digest.cc

@@ -23,8 +23,9 @@ GoldenDigest::GoldenDigest() {}
 void GoldenDigest::AddImage(const std::string& test_name,
                             const std::string& filename,
                             int32_t width,
-                            int32_t height) {
-  entries_.push_back({test_name, filename, width, height});
+                            int32_t height,
+                            double threshold) {
+  entries_.push_back({test_name, filename, width, height, threshold});
 }
 
 bool GoldenDigest::Write(WorkingDirectory* working_directory) {
@@ -46,8 +47,15 @@ bool GoldenDigest::Write(WorkingDirectory* working_directory) {
          << "\"testName\" : \"" << entry.test_name << "\", "
          << "\"filename\" : \"" << entry.filename << "\", "
          << "\"width\" : " << entry.width << ", "
-         << "\"height\" : " << entry.height << " "
-         << "}";
+         << "\"height\" : " << entry.height << ", ";
+
+    if (entry.threshold == static_cast<int64_t>(entry.threshold)) {
+      fout << "\"threshold\" : " << entry.threshold << ".0 ";
+    } else {
+      fout << "\"threshold\" : " << entry.threshold << " ";
+    }
+
+    fout << "}";
   }
   fout << std::endl << "]" << std::endl;
 

impeller/golden_tests/golden_digest.h

@@ -21,7 +21,8 @@ class GoldenDigest {
   void AddImage(const std::string& test_name,
                 const std::string& filename,
                 int32_t width,
-                int32_t height);
+                int32_t height,
+                double threshold);
 
   /// Writes a "digest.json" file to `working_directory`.
   ///
@@ -36,6 +37,7 @@ class GoldenDigest {
     std::string filename;
     int32_t width;
     int32_t height;
+    double threshold;
   };
 
   static GoldenDigest* instance_;

impeller/golden_tests/golden_playground_test.h

@@ -26,7 +26,7 @@ class GoldenPlaygroundTest
 
   PlaygroundBackend GetBackend() const;
 
-  bool OpenPlaygroundHere(const Picture& picture);
+  bool OpenPlaygroundHere(const Picture& picture, double threshold = 0.01);
 
   bool OpenPlaygroundHere(const AiksPlaygroundCallback& callback);
 

impeller/golden_tests/golden_playground_test_mac.cc

@@ -28,14 +28,16 @@ std::string GetGoldenFilename() {
   return GetTestName() + ".png";
 }
 
-bool SaveScreenshot(std::unique_ptr<testing::MetalScreenshot> screenshot) {
+bool SaveScreenshot(std::unique_ptr<testing::MetalScreenshot> screenshot,
+                    double threshold) {
   if (!screenshot || !screenshot->GetBytes()) {
     return false;
   }
   std::string test_name = GetTestName();
   std::string filename = GetGoldenFilename();
   testing::GoldenDigest::Instance()->AddImage(
-      test_name, filename, screenshot->GetWidth(), screenshot->GetHeight());
+      test_name, filename, screenshot->GetWidth(), screenshot->GetHeight(),
+      threshold);
   return screenshot->WriteToPNG(
       testing::WorkingDirectory::Instance()->GetFilenamePath(filename));
 }
@@ -96,10 +98,11 @@ PlaygroundBackend GoldenPlaygroundTest::GetBackend() const {
   return GetParam();
 }
 
-bool GoldenPlaygroundTest::OpenPlaygroundHere(const Picture& picture) {
+bool GoldenPlaygroundTest::OpenPlaygroundHere(const Picture& picture,
+                                              double threshold) {
   auto screenshot =
       pimpl_->screenshoter_->MakeScreenshot(picture, pimpl_->window_size_);
-  return SaveScreenshot(std::move(screenshot));
+  return SaveScreenshot(std::move(screenshot), threshold);
 }
 
 bool GoldenPlaygroundTest::OpenPlaygroundHere(

impeller/golden_tests/golden_playground_test_stub.cc

@@ -16,7 +16,8 @@ PlaygroundBackend GoldenPlaygroundTest::GetBackend() const {
   return GetParam();
 }
 
-bool GoldenPlaygroundTest::OpenPlaygroundHere(const Picture& picture) {
+bool GoldenPlaygroundTest::OpenPlaygroundHere(const Picture& picture,
+                                              double threshold) {
   return false;
 }
 

impeller/golden_tests/golden_tests.cc

@@ -32,14 +32,16 @@ std::string GetGoldenFilename() {
   return GetTestName() + ".png";
 }
 
-bool SaveScreenshot(std::unique_ptr<MetalScreenshot> screenshot) {
+bool SaveScreenshot(std::unique_ptr<MetalScreenshot> screenshot,
+                    double threshold) {
   if (!screenshot || !screenshot->GetBytes()) {
     return false;
   }
   std::string test_name = GetTestName();
   std::string filename = GetGoldenFilename();
-  GoldenDigest::Instance()->AddImage(
-      test_name, filename, screenshot->GetWidth(), screenshot->GetHeight());
+  GoldenDigest::Instance()->AddImage(test_name, filename,
+                                     screenshot->GetWidth(),
+                                     screenshot->GetHeight(), threshold);
   return screenshot->WriteToPNG(
       WorkingDirectory::Instance()->GetFilenamePath(filename));
 }
@@ -73,7 +75,7 @@ TEST_F(GoldenTests, ConicalGradient) {
   canvas.DrawRect(Rect(10, 10, 250, 250), paint);
   Picture picture = canvas.EndRecordingAsPicture();
   auto screenshot = Screenshoter().MakeScreenshot(picture);
-  ASSERT_TRUE(SaveScreenshot(std::move(screenshot)));
+  ASSERT_TRUE(SaveScreenshot(std::move(screenshot), 0.01));
 }
 }  // namespace testing
 }  // namespace impeller

impeller/golden_tests_harvester/bin/golden_tests_harvester.dart

@@ -23,7 +23,7 @@ class FakeSkiaGoldClient implements SkiaGoldClient {
       {double differentPixelsRate = 0.01,
       int pixelColorDelta = 0,
       required int screenshotSize}) async {
-    Logger.instance.log('addImg $testName ${goldenFile.path} $screenshotSize');
+    Logger.instance.log('addImg testName:$testName goldenFile:${goldenFile.path} screenshotSize:$screenshotSize differentPixelsRate:$differentPixelsRate');
   }
 
   @override

impeller/golden_tests_harvester/lib/golden_tests_harvester.dart

@@ -32,9 +32,11 @@ Future<void> harvest(
     final String filename = (map['filename'] as String?)!;
     final int width = (map['width'] as int?)!;
     final int height = (map['height'] as int?)!;
+    final double threshold = (map['threshold'] as double?)!;
     final File goldenImage = File(p.join(workDirectory.path, filename));
     final Future<void> future = skiaGoldClient
-        .addImg(filename, goldenImage, screenshotSize: width * height)
+        .addImg(filename, goldenImage,
+            screenshotSize: width * height, differentPixelsRate: threshold)
         .catchError((dynamic err) {
       Logger.instance.log('skia gold comparison failed: $err');
       throw Exception('Failed comparison: $filename');