add saveBehind to canvas
Bug: skia:
Change-Id: I62e48b116b2d7efef585d4f465441f24ae4d2b29
Reviewed-on: https://skia-review.googlesource.com/c/177892
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/src/core/SkCanvas.cpp b/src/core/SkCanvas.cpp
index bdd330e..59511c7 100644
--- a/src/core/SkCanvas.cpp
+++ b/src/core/SkCanvas.cpp
@@ -208,6 +208,14 @@
}
};
+namespace {
+// Encapsulate state needed to restore from saveBehind()
+struct BackImage {
+ sk_sp<SkSpecialImage> fImage;
+ SkIPoint fLoc;
+};
+}
+
/* This is the record we keep for each save/restore level in the stack.
Since a level optionally copies the matrix and/or stack, we have pointers
for these fields. If the value is copied for this level, the copy is
@@ -217,17 +225,18 @@
*/
class SkCanvas::MCRec {
public:
- DeviceCM* fLayer;
+ DeviceCM* fLayer;
/* If there are any layers in the stack, this points to the top-most
one that is at or below this level in the stack (so we know what
bitmap/device to draw into from this level. This value is NOT
reference counted, since the real owner is either our fLayer field,
or a previous one in a lower level.)
*/
- DeviceCM* fTopLayer;
- SkConservativeClip fRasterClip;
- SkMatrix fMatrix;
- int fDeferredSaveCount;
+ DeviceCM* fTopLayer;
+ std::unique_ptr<BackImage> fBackImage;
+ SkConservativeClip fRasterClip;
+ SkMatrix fMatrix;
+ int fDeferredSaveCount;
MCRec() {
fLayer = nullptr;
@@ -919,6 +928,22 @@
return this->getSaveCount() - 1;
}
+int SkCanvas::only_axis_aligned_saveBehind(const SkRect* bounds) {
+ if (bounds && !this->getLocalClipBounds().intersects(*bounds)) {
+ // Assuming clips never expand, if the request bounds is outside of the current clip
+ // there is no need to copy/restore the area, so just devolve back to a regular save.
+ this->save();
+ } else {
+ bool doTheWork = this->onDoSaveBehind(bounds);
+ fSaveCount += 1;
+ this->internalSave();
+ if (doTheWork) {
+ this->internalSaveBehind(bounds);
+ }
+ }
+ return this->getSaveCount() - 1;
+}
+
void SkCanvas::DrawDeviceWithFilter(SkBaseDevice* src, const SkImageFilter* filter,
SkBaseDevice* dst, const SkIPoint& dstOrigin,
const SkMatrix& ctm) {
@@ -1090,6 +1115,48 @@
}
}
+void SkCanvas::internalSaveBehind(const SkRect* localBounds) {
+ SkIRect devBounds;
+ if (localBounds) {
+ SkRect tmp;
+ fMCRec->fMatrix.mapRect(&tmp, *localBounds);
+ if (!devBounds.intersect(tmp.round(), this->getDeviceClipBounds())) {
+ devBounds.setEmpty();
+ }
+ } else {
+ devBounds = this->getDeviceClipBounds();
+ }
+ if (devBounds.isEmpty()) {
+ return;
+ }
+
+ SkBaseDevice* device = this->getTopDevice();
+ if (nullptr == device) { // Do we still need this check???
+ return;
+ }
+
+ // need the bounds relative to the device itself
+ devBounds.offset(-device->fOrigin.fX, -device->fOrigin.fY);
+
+ auto backImage = device->snapBackImage(devBounds);
+ if (!backImage) {
+ return;
+ }
+
+ // we really need the save, so we can wack the fMCRec
+ this->checkForDeferredSave();
+
+ fMCRec->fBackImage.reset(new BackImage{std::move(backImage), devBounds.topLeft()});
+
+ SkPaint paint;
+ paint.setBlendMode(SkBlendMode::kClear);
+ if (localBounds) {
+ this->drawRect(*localBounds, paint);
+ } else {
+ this->drawPaint(paint);
+ }
+}
+
void SkCanvas::internalRestore() {
SkASSERT(fMCStack.count() != 0);
@@ -1098,6 +1165,9 @@
// now detach it from fMCRec so we can pop(). Gets freed after its drawn
fMCRec->fLayer = nullptr;
+ // move this out before we do the actual restore
+ auto backImage = std::move(fMCRec->fBackImage);
+
// now do the normal restore()
fMCRec->~MCRec(); // balanced in save()
fMCStack.pop_back();
@@ -1107,6 +1177,15 @@
FOR_EACH_TOP_DEVICE(device->restore(fMCRec->fMatrix));
}
+ if (backImage) {
+ SkPaint paint;
+ paint.setBlendMode(SkBlendMode::kDstOver);
+ const int x = backImage->fLoc.x();
+ const int y = backImage->fLoc.y();
+ this->getTopDevice()->drawSpecial(backImage->fImage.get(), x, y, paint,
+ nullptr, SkMatrix::I());
+ }
+
/* Time to draw the layer's offscreen. We can't call the public drawSprite,
since if we're being recorded, we don't want to record this (the
recorder will have already recorded the restore).
@@ -2828,6 +2907,10 @@
return kNoLayer_SaveLayerStrategy;
}
+bool SkNoDrawCanvas::onDoSaveBehind(const SkRect*) {
+ return false;
+}
+
///////////////////////////////////////////////////////////////////////////////
static_assert((int)SkRegion::kDifference_Op == (int)kDifference_SkClipOp, "");