Add SkiaCanvas::captureCanvasState()

Test: Verified bug is fixed.  Wrote unit test.

Bug: 37268771

Change-Id: I9deb7db353cd2129ad245e7f65419670463bb717

libs/hwui/SkiaCanvas.cpp

@@ -23,6 +23,7 @@
 #include "hwui/MinikinUtils.h"
 #include "pipeline/skia/AnimatedDrawables.h"
 
+#include <SkCanvasStateUtils.h>
 #include <SkColorSpaceXformCanvas.h>
 #include <SkDrawable.h>
 #include <SkDeque.h>
@@ -410,6 +411,30 @@ void SkiaCanvas::setDrawFilter(SkDrawFilter* drawFilter) {
     mCanvas->setDrawFilter(drawFilter);
 }
 
+// ----------------------------------------------------------------------------
+// Canvas state operations: Capture
+// ----------------------------------------------------------------------------
+
+SkCanvasState* SkiaCanvas::captureCanvasState() const {
+    SkCanvas* canvas = mCanvas;
+    if (mCanvasOwned) {
+        // Important to use the underlying SkCanvas, not the wrapper.
+        canvas = mCanvasOwned.get();
+    }
+
+    // Workarounds for http://crbug.com/271096: SW draw only supports
+    // translate & scale transforms, and a simple rectangular clip.
+    // (This also avoids significant wasted time in calling
+    // SkCanvasStateUtils::CaptureCanvasState when the clip is complex).
+    if (!canvas->isClipRect() ||
+        (canvas->getTotalMatrix().getType() &
+                  ~(SkMatrix::kTranslate_Mask | SkMatrix::kScale_Mask))) {
+      return nullptr;
+    }
+
+    return SkCanvasStateUtils::CaptureCanvasState(canvas);
+}
+
 // ----------------------------------------------------------------------------
 // Canvas draw operations
 // ----------------------------------------------------------------------------

libs/hwui/SkiaCanvas.h

@@ -102,6 +102,8 @@ public:
     virtual SkDrawFilter* getDrawFilter() override;
     virtual void setDrawFilter(SkDrawFilter* drawFilter) override;
 
+    virtual SkCanvasState* captureCanvasState() const override;
+
     virtual void drawColor(int color, SkBlendMode mode) override;
     virtual void drawPaint(const SkPaint& paint) override;
 

libs/hwui/hwui/Canvas.h

@@ -27,6 +27,7 @@
 #include <SkCanvas.h>
 #include <SkMatrix.h>
 
+class SkCanvasState;
 class SkVertices;
 
 namespace minikin {
@@ -204,6 +205,9 @@ public:
     virtual SkDrawFilter* getDrawFilter() = 0;
     virtual void setDrawFilter(SkDrawFilter* drawFilter) = 0;
 
+    // WebView only
+    virtual SkCanvasState* captureCanvasState() const { return nullptr; }
+
 // ----------------------------------------------------------------------------
 // Canvas draw operations
 // ----------------------------------------------------------------------------

libs/hwui/tests/unit/SkiaCanvasTests.cpp

@@ -19,6 +19,7 @@
 #include <gtest/gtest.h>
 #include <RecordingCanvas.h>
 #include <SkBlurDrawLooper.h>
+#include <SkCanvasStateUtils.h>
 #include <SkPicture.h>
 #include <SkPictureRecorder.h>
 
@@ -128,3 +129,32 @@ TEST(SkiaCanvas, colorSpaceXform) {
     canvas.asSkCanvas()->drawPicture(picture);
     ASSERT_EQ(0xFF0000FF, *skBitmap.getAddr32(0, 0));
 }
+
+TEST(SkiaCanvas, captureCanvasState) {
+    // Create a software canvas.
+    SkImageInfo info = SkImageInfo::Make(1, 1, kN32_SkColorType, kOpaque_SkAlphaType);
+    sk_sp<Bitmap> bitmap = Bitmap::allocateHeapBitmap(info);
+    SkBitmap skBitmap;
+    bitmap->getSkBitmap(&skBitmap);
+    skBitmap.eraseColor(0);
+    SkiaCanvas canvas(skBitmap);
+
+    // Translate, then capture and verify the CanvasState.
+    canvas.translate(1.0f, 1.0f);
+    SkCanvasState* state = canvas.captureCanvasState();
+    ASSERT_NE(state, nullptr);
+    std::unique_ptr<SkCanvas> newCanvas = SkCanvasStateUtils::MakeFromCanvasState(state);
+    ASSERT_NE(newCanvas.get(), nullptr);
+    newCanvas->translate(-1.0f, -1.0f);
+    ASSERT_TRUE(newCanvas->getTotalMatrix().isIdentity());
+    SkCanvasStateUtils::ReleaseCanvasState(state);
+
+    // Create a picture canvas.
+    SkPictureRecorder recorder;
+    SkCanvas* skPicCanvas = recorder.beginRecording(1, 1, NULL, 0);
+    SkiaCanvas picCanvas(skPicCanvas, Canvas::XformToSRGB::kDefer);
+    state = picCanvas.captureCanvasState();
+
+    // Verify that we cannot get the CanvasState.
+    ASSERT_EQ(state, nullptr);
+}