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, 26 insertions, 0 deletions

diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 9b5a5a9338..0cf4a9a08b 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -1264,6 +1264,32 @@ sk_sp<SkSpecialImage> SkGpuDevice::snapSpecial() {
                                                &this->surfaceProps());
 }
 
+sk_sp<SkSpecialImage> SkGpuDevice::snapBackImage(const SkIRect& subset) {
+    GrRenderTargetContext* rtc = this->accessRenderTargetContext();
+    if (!rtc) {
+        return nullptr;
+    }
+
+    GrContext* ctx = this->context();
+    if (!rtc->asSurfaceProxy()) {
+        return nullptr;
+    }
+
+    auto srcProxy = GrSurfaceProxy::Copy(ctx, rtc->asSurfaceProxy(), rtc->mipMapped(), subset,
+                                         rtc->asSurfaceProxy()->isBudgeted());
+    if (!srcProxy) {
+        return nullptr;
+    }
+
+    // Note, can't move srcProxy since we also refer to this in the 2nd parameter
+    return SkSpecialImage::MakeDeferredFromGpu(fContext.get(),
+                                               SkIRect::MakeWH(srcProxy->width(), srcProxy->height()),
+                                               kNeedNewImageUniqueID_SpecialImage,
+                                               srcProxy,
+                                               this->imageInfo().refColorSpace(),
+                                               &this->surfaceProps());
+}
+
 void SkGpuDevice::drawDevice(SkBaseDevice* device,
                              int left, int top, const SkPaint& paint) {
     SkASSERT(!paint.getImageFilter());