Add private save-behind and draw-behind methods to canvas.HEADp9.0

The draw-behind  is a variant of drawPaint but is automatically clipped
to the bounds of the most recent saveBehind buffer (axis-aligned bounds).

No public exposure outside of the Android framework.

Impl is pretty simple (its a variant of drawPaint)
- find the most recent saveBehind device bounds
- if there is none, draw nothing, else
  - temporarily intersect the device's clip with that bounds
  - drawPaint
  - restore the clip

This patches did not apply cleanly and have been updated to compile
with a previous version of Skia. It was cherry-picked from the
following 3 Skia commits:
148b7fd3ad9c29dec0052de624c26ff291ef8f0a
d567408362bf7847d6000f6786f9a7b2c9d0b88b
9adc82c73df0ef25b708cae8aa48ef9c39ed4c67

Bug: 129117085
Test: None
Change-Id: I291f57885de6e95f749bf5cdb70ac16a5781ffb1

1 files changed, 29 insertions, 0 deletions

diff --git a/src/core/SkPictureRecord.cpp b/src/core/SkPictureRecord.cpp
index 6268584aa0..c62c4077cd 100644
--- a/src/core/SkPictureRecord.cpp
+++ b/src/core/SkPictureRecord.cpp
@@ -82,6 +82,26 @@ SkCanvas::SaveLayerStrategy SkPictureRecord::getSaveLayerStrategy(const SaveLaye
     return kNoLayer_SaveLayerStrategy;
 }
 
+bool SkPictureRecord::onDoSaveBehind(const SkRect* subset) {
+    fRestoreOffsetStack.push(-(int32_t)fWriter.bytesWritten());
+
+    size_t size = sizeof(kUInt32Size) + sizeof(uint32_t); // op + flags
+    uint32_t flags = 0;
+    if (subset) {
+        flags |= SAVEBEHIND_HAS_SUBSET;
+        size += sizeof(*subset);
+    }
+
+    size_t initialOffset = this->addDraw(SAVE_BEHIND, &size);
+    this->addInt(flags);
+    if (subset) {
+        this->addRect(*subset);
+    }
+
+    this->validate(initialOffset, size);
+    return false;
+}
+
 void SkPictureRecord::recordSaveLayer(const SaveLayerRec& rec) {
     // op + flatflags
     size_t size = 2 * kUInt32Size;
@@ -409,6 +429,15 @@ void SkPictureRecord::onDrawPaint(const SkPaint& paint) {
     this->validate(initialOffset, size);
 }
 
+void SkPictureRecord::onDrawBehind(const SkPaint& paint) {
+    // logically the same as drawPaint, but with a diff enum
+    // op + paint index
+    size_t size = 2 * kUInt32Size;
+    size_t initialOffset = this->addDraw(DRAW_BEHIND_PAINT, &size);
+    this->addPaint(paint);
+    this->validate(initialOffset, size);
+}
+
 void SkPictureRecord::onDrawPoints(PointMode mode, size_t count, const SkPoint pts[],
                                    const SkPaint& paint) {
     // op + paint index + mode + count + point data