Fix fading edge effect from impacting neighboring pixels

Bug: 129117085
Test: skia unit tests and test cases described in the bug
Change-Id: Ieaa7c831dd6298ac0565e6f1837b1c1dbd4545da
diff --git a/libs/hwui/RecordingCanvas.cpp b/libs/hwui/RecordingCanvas.cpp
index 8594766..e58fbbe 100644
--- a/libs/hwui/RecordingCanvas.cpp
+++ b/libs/hwui/RecordingCanvas.cpp
@@ -20,6 +20,7 @@
 
 #include "SkAndroidFrameworkUtils.h"
 #include "SkCanvas.h"
+#include "SkCanvasPriv.h"
 #include "SkData.h"
 #include "SkDrawShadowInfo.h"
 #include "SkImage.h"
@@ -187,6 +188,12 @@
     SkPaint paint;
     void draw(SkCanvas* c, const SkMatrix&) const { c->drawPaint(paint); }
 };
+struct DrawBehind final : Op {
+    static const auto kType = Type::DrawBehind;
+    DrawBehind(const SkPaint& paint) : paint(paint) {}
+    SkPaint paint;
+    void draw(SkCanvas* c, const SkMatrix&) const { SkCanvasPriv::DrawBehind(c, paint); }
+};
 struct DrawPath final : Op {
     static const auto kType = Type::DrawPath;
     DrawPath(const SkPath& path, const SkPaint& paint) : path(path), paint(paint) {}
@@ -565,6 +572,9 @@
 void DisplayListData::drawPaint(const SkPaint& paint) {
     this->push<DrawPaint>(0, paint);
 }
+void DisplayListData::drawBehind(const SkPaint& paint) {
+    this->push<DrawBehind>(0, paint);
+}
 void DisplayListData::drawPath(const SkPath& path, const SkPaint& paint) {
     this->push<DrawPath>(0, path, paint);
 }
@@ -834,6 +844,9 @@
 void RecordingCanvas::onDrawPaint(const SkPaint& paint) {
     fDL->drawPaint(paint);
 }
+void RecordingCanvas::onDrawBehind(const SkPaint& paint) {
+    fDL->drawBehind(paint);
+}
 void RecordingCanvas::onDrawPath(const SkPath& path, const SkPaint& paint) {
     fDL->drawPath(path, paint);
 }