Add a DlStopwatchVisualizer and conditionally use it for Impeller

ci/licenses_golden/excluded_files

@@ -74,6 +74,7 @@
 ../../../flutter/flow/mutators_stack_unittests.cc
 ../../../flutter/flow/raster_cache_unittests.cc
 ../../../flutter/flow/skia_gpu_object_unittests.cc
+../../../flutter/flow/stopwatch_dl_unittests.cc
 ../../../flutter/flow/stopwatch_unittests.cc
 ../../../flutter/flow/surface_frame_unittests.cc
 ../../../flutter/flow/testing

ci/licenses_golden/licenses_flutter

@@ -846,6 +846,8 @@ ORIGIN: ../../../flutter/flow/raster_cache_util.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/skia_gpu_object.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/stopwatch.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/stopwatch.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/flow/stopwatch_dl.cc + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/flow/stopwatch_dl.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/stopwatch_sk.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/stopwatch_sk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/flow/surface.cc + ../../../flutter/LICENSE
@@ -3594,6 +3596,8 @@ FILE: ../../../flutter/flow/raster_cache_util.h
 FILE: ../../../flutter/flow/skia_gpu_object.h
 FILE: ../../../flutter/flow/stopwatch.cc
 FILE: ../../../flutter/flow/stopwatch.h
+FILE: ../../../flutter/flow/stopwatch_dl.cc
+FILE: ../../../flutter/flow/stopwatch_dl.h
 FILE: ../../../flutter/flow/stopwatch_sk.cc
 FILE: ../../../flutter/flow/stopwatch_sk.h
 FILE: ../../../flutter/flow/surface.cc

flow/BUILD.gn

@@ -77,6 +77,8 @@ source_set("flow") {
     "skia_gpu_object.h",
     "stopwatch.cc",
     "stopwatch.h",
+    "stopwatch_dl.cc",
+    "stopwatch_dl.h",
     "stopwatch_sk.cc",
     "stopwatch_sk.h",
     "surface.cc",
@@ -168,6 +170,7 @@ if (enable_unittests) {
       "mutators_stack_unittests.cc",
       "raster_cache_unittests.cc",
       "skia_gpu_object_unittests.cc",
+      "stopwatch_dl_unittests.cc",
       "stopwatch_unittests.cc",
       "surface_frame_unittests.cc",
       "testing/mock_layer_unittests.cc",

flow/layers/performance_overlay_layer.cc

@@ -6,8 +6,11 @@
 
 #include <iomanip>
 #include <iostream>
+#include <memory>
 #include <string>
 
+#include "flow/stopwatch.h"
+#include "flow/stopwatch_dl.h"
 #include "flow/stopwatch_sk.h"
 #include "third_party/skia/include/core/SkFont.h"
 #include "third_party/skia/include/core/SkTextBlob.h"
@@ -16,6 +19,7 @@ namespace flutter {
 namespace {
 
 void VisualizeStopWatch(DlCanvas* canvas,
+                        const bool impeller_enabled,
                         const Stopwatch& stopwatch,
                         SkScalar x,
                         SkScalar y,
@@ -30,11 +34,15 @@ void VisualizeStopWatch(DlCanvas* canvas,
 
   if (show_graph) {
     SkRect visualization_rect = SkRect::MakeXYWH(x, y, width, height);
+    std::unique_ptr<StopwatchVisualizer> visualizer;
 
-    // TODO(matanlurey): Select a visualizer based on the current backend.
-    // https://github.com/flutter/flutter/issues/126009
-    SkStopwatchVisualizer visualizer = SkStopwatchVisualizer(stopwatch);
-    visualizer.Visualize(canvas, visualization_rect);
+    if (impeller_enabled) {
+      visualizer = std::make_unique<DlStopwatchVisualizer>(stopwatch);
+    } else {
+      visualizer = std::make_unique<SkStopwatchVisualizer>(stopwatch);
+    }
+
+    visualizer->Visualize(canvas, visualization_rect);
   }
 
   if (show_labels) {
@@ -105,12 +113,13 @@ void PerformanceOverlayLayer::Paint(PaintContext& context) const {
   auto mutator = context.state_stack.save();
 
   VisualizeStopWatch(
-      context.canvas, context.raster_time, x, y, width, height - padding,
-      options_ & kVisualizeRasterizerStatistics,
+      context.canvas, context.impeller_enabled, context.raster_time, x, y,
+      width, height - padding, options_ & kVisualizeRasterizerStatistics,
       options_ & kDisplayRasterizerStatistics, "Raster", font_path_);
 
-  VisualizeStopWatch(context.canvas, context.ui_time, x, y + height, width,
-                     height - padding, options_ & kVisualizeEngineStatistics,
+  VisualizeStopWatch(context.canvas, context.impeller_enabled, context.ui_time,
+                     x, y + height, width, height - padding,
+                     options_ & kVisualizeEngineStatistics,
                      options_ & kDisplayEngineStatistics, "UI", font_path_);
 }
 

flow/stopwatch.cc

@@ -48,6 +48,10 @@ const fml::TimeDelta& Stopwatch::GetLap(size_t index) const {
   return laps_[index];
 }
 
+size_t Stopwatch::GetLapsCount() const {
+  return laps_.size();
+}
+
 size_t Stopwatch::GetCurrentSample() const {
   return current_sample_;
 }

flow/stopwatch.h

@@ -32,6 +32,9 @@ class Stopwatch {
 
   const fml::TimeDelta& GetLap(size_t index) const;
 
+  /// Return a reference to all the laps.
+  size_t GetLapsCount() const;
+
   size_t GetCurrentSample() const;
 
   const fml::TimeDelta& LastLap() const;

flow/stopwatch_dl.cc

@@ -0,0 +1,149 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/flow/stopwatch_dl.h"
+#include <memory>
+#include <vector>
+#include "display_list/dl_blend_mode.h"
+#include "display_list/dl_canvas.h"
+#include "display_list/dl_color.h"
+#include "display_list/dl_paint.h"
+#include "display_list/dl_vertices.h"
+#include "include/core/SkRect.h"
+
+namespace flutter {
+
+static const size_t kMaxSamples = 120;
+static const size_t kMaxFrameMarkers = 8;
+
+void DlStopwatchVisualizer::Visualize(DlCanvas* canvas,
+                                      const SkRect& rect) const {
+  auto painter = DlVertexPainter();
+  DlPaint paint;
+
+  // Establish the graph position.
+  auto const x = rect.x();
+  auto const y = rect.y();
+  auto const width = rect.width();
+  auto const height = rect.height();
+  auto const bottom = rect.bottom();
+
+  // Scale the graph to show time frames up to those that are 3x the frame time.
+  auto const one_frame_ms = stopwatch_.GetFrameBudget().count();
+  auto const max_interval = one_frame_ms * 3.0;
+  auto const max_unit_interval = UnitFrameInterval(max_interval);
+  auto const sample_unit_width = (1.0 / kMaxSamples);
+
+  // Provide a semi-transparent background for the graph.
+  painter.DrawRect(rect, 0x99FFFFFF);
+
+  // Prepare a path for the data; we start at the height of the last point so
+  // it looks like we wrap around.
+  {
+    for (auto i = size_t(0); i < stopwatch_.GetLapsCount(); i++) {
+      auto const sample_unit_height =
+          (1.0 - UnitHeight(stopwatch_.GetLap(i).ToMillisecondsF(),
+                            max_unit_interval));
+
+      auto const bar_width = width * sample_unit_width;
+      auto const bar_height = height * sample_unit_height;
+      auto const bar_left = x + width * sample_unit_width * i;
+
+      painter.DrawRect(SkRect::MakeLTRB(/*left=*/bar_left,
+                                        /*top=*/y + bar_height,
+                                        /*right=*/bar_left + bar_width,
+                                        /*bottom=*/bottom),
+                       0xAA0000FF);
+    }
+  }
+
+  // Draw horizontal frame markers.
+  {
+    if (max_interval > one_frame_ms) {
+      // Paint the horizontal markers.
+      auto count = static_cast<size_t>(max_interval / one_frame_ms);
+
+      // Limit the number of markers to a reasonable amount.
+      if (count > kMaxFrameMarkers) {
+        count = 1;
+      }
+
+      for (auto i = size_t(0); i < count; i++) {
+        auto const frame_height =
+            height * (1.0 - (UnitFrameInterval(i + 1) * one_frame_ms) /
+                                max_unit_interval);
+
+        // Draw a skinny rectangle (i.e. a line).
+        painter.DrawRect(SkRect::MakeLTRB(/*left=*/x,
+                                          /*top=*/y + frame_height,
+                                          /*right=*/width,
+                                          /*bottom=*/y + frame_height + 1),
+                         0xCC000000);
+      }
+    }
+  }
+
+  // Paint the vertical marker for the current frame.
+  {
+    DlColor color = DlColor::kGreen();
+    if (UnitFrameInterval(stopwatch_.LastLap().ToMillisecondsF()) > 1.0) {
+      // budget exceeded.
+      color = DlColor::kRed();
+    }
+    auto const l =
+        x + width * (static_cast<double>(stopwatch_.GetCurrentSample()) /
+                     kMaxSamples);
+    auto const t = y;
+    auto const r = l + width * sample_unit_width;
+    auto const b = rect.bottom();
+    painter.DrawRect(SkRect::MakeLTRB(l, t, r, b), color);
+  }
+
+  // Actually draw.
+  // Note we use kSrcOver, because some of the colors above have opacity < 1.0.
+  canvas->DrawVertices(painter.IntoVertices(), DlBlendMode::kSrcOver, paint);
+}
+
+void DlVertexPainter::DrawRect(const SkRect& rect, const DlColor& color) {
+  // Draw 6 vertices representing 2 triangles.
+  auto const left = rect.x();
+  auto const top = rect.y();
+  auto const right = rect.right();
+  auto const bottom = rect.bottom();
+
+  auto const vertices = std::array<SkPoint, 6>{
+      SkPoint::Make(left, top),      // tl tr
+      SkPoint::Make(right, top),     //    br
+      SkPoint::Make(right, bottom),  //
+      SkPoint::Make(right, bottom),  // tl
+      SkPoint::Make(left, bottom),   // bl br
+      SkPoint::Make(left, top)       //
+  };
+
+  auto const colors = std::array<DlColor, 6>{
+      color,  // tl tr
+      color,  //    br
+      color,  //
+      color,  // tl
+      color,  // bl br
+      color   //
+  };
+
+  vertices_.insert(vertices_.end(), vertices.begin(), vertices.end());
+  colors_.insert(colors_.end(), colors.begin(), colors.end());
+}
+
+std::shared_ptr<DlVertices> DlVertexPainter::IntoVertices() {
+  auto const result = DlVertices::Make(
+      /*mode=*/DlVertexMode::kTriangles,
+      /*vertex_count=*/vertices_.size(),
+      /*vertices=*/vertices_.data(),
+      /*texture_coordinates=*/nullptr,
+      /*colors=*/colors_.data());
+  vertices_.clear();
+  colors_.clear();
+  return result;
+}
+
+}  // namespace flutter

flow/stopwatch_dl.h

@@ -0,0 +1,56 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_FLOW_STOPWATCH_DL_H_
+#define FLUTTER_FLOW_STOPWATCH_DL_H_
+
+#include "flow/stopwatch.h"
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// A stopwatch visualizer that uses DisplayList (|DlCanvas|) to draw.
+///
+/// @note This is the newer non-backend specific version, that works in both
+///       Skia and Impeller. The older Skia-specific version is
+///       |SkStopwatchVisualizer|, which still should be used for Skia-specific
+///       optimizations.
+class DlStopwatchVisualizer : public StopwatchVisualizer {
+ public:
+  explicit DlStopwatchVisualizer(const Stopwatch& stopwatch)
+      : StopwatchVisualizer(stopwatch) {}
+
+  void Visualize(DlCanvas* canvas, const SkRect& rect) const override;
+};
+
+/// @brief Provides canvas-like painting methods that actually build vertices.
+///
+/// The goal is minimally invasive rendering for the performance monitor.
+///
+/// The methods in this class are intended to be used by |DlStopwatchVisualizer|
+/// only. The rationale is the creating lines, rectangles, and paths (while OK
+/// for general apps) would cause non-trivial work for the performance monitor
+/// due to tessellation per-frame.
+///
+/// @note A goal of this class was to make updating the performance monitor
+/// (and keeping it in sync with the |SkStopwatchVisualizer|) as easy as
+/// possible (i.e. not having to do triangle-math).
+class DlVertexPainter final {
+ public:
+  /// Draws a rectangle with the given color to a buffer.
+  void DrawRect(const SkRect& rect, const DlColor& color);
+
+  /// Converts the buffered vertices into a |DlVertices| object.
+  ///
+  /// @note This method clears the buffer.
+  std::shared_ptr<DlVertices> IntoVertices();
+
+ private:
+  std::vector<SkPoint> vertices_;
+  std::vector<DlColor> colors_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_FLOW_STOPWATCH_DL_H_