SF: Handle buffer scale transforms when calculating layer geometry
In addition to layer transforms, buffer scale transform applied to a layer should be applied to all
its children. This is to ensure WM can treat child surfaces as pixels in the parent surface.
Current bounds calculations is based on the cropped parent bounds in parent layer space and its
effective transform. This breaks because if the parent buffer has a scale transform, the parent
bounds passed on to the child already has the buffer scale transform applied to it.
To fix this, we undo the scale transform on the cropped parent bounds before passing it on to its
children for cropping.
Fixes: 127368943
Test: atest SurfaceFlinger_test
Test: go/wm-smoke
Change-Id: I17966d08b98fbfbf44538cab0a95c9e78b23e11e
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 4add863..d28a484 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -277,14 +277,12 @@
return reduce(mBounds, activeTransparentRegion);
}
-ui::Transform Layer::getTransformWithScale() const {
+ui::Transform Layer::getBufferScaleTransform() const {
// If the layer is not using NATIVE_WINDOW_SCALING_MODE_FREEZE (e.g.
// it isFixedSize) then there may be additional scaling not accounted
- // for in the transform. We need to mirror this scaling to child surfaces
- // or we will break the contract where WM can treat child surfaces as
- // pixels in the parent surface.
+ // for in the layer transform.
if (!isFixedSize() || !mActiveBuffer) {
- return mEffectiveTransform;
+ return {};
}
// If the layer is a buffer state layer, the active width and height
@@ -292,24 +290,40 @@
const uint32_t activeWidth = getActiveWidth(getDrawingState());
const uint32_t activeHeight = getActiveHeight(getDrawingState());
if (activeWidth >= UINT32_MAX && activeHeight >= UINT32_MAX) {
- return mEffectiveTransform;
+ return {};
}
- int bufferWidth;
- int bufferHeight;
- if ((mCurrentTransform & NATIVE_WINDOW_TRANSFORM_ROT_90) == 0) {
- bufferWidth = mActiveBuffer->getWidth();
- bufferHeight = mActiveBuffer->getHeight();
- } else {
- bufferHeight = mActiveBuffer->getWidth();
- bufferWidth = mActiveBuffer->getHeight();
+ int bufferWidth = mActiveBuffer->getWidth();
+ int bufferHeight = mActiveBuffer->getHeight();
+
+ if (mCurrentTransform & NATIVE_WINDOW_TRANSFORM_ROT_90) {
+ std::swap(bufferWidth, bufferHeight);
}
+
float sx = activeWidth / static_cast<float>(bufferWidth);
float sy = activeHeight / static_cast<float>(bufferHeight);
ui::Transform extraParentScaling;
extraParentScaling.set(sx, 0, 0, sy);
- return mEffectiveTransform * extraParentScaling;
+ return extraParentScaling;
+}
+
+ui::Transform Layer::getTransformWithScale(const ui::Transform& bufferScaleTransform) const {
+ // We need to mirror this scaling to child surfaces or we will break the contract where WM can
+ // treat child surfaces as pixels in the parent surface.
+ if (!isFixedSize() || !mActiveBuffer) {
+ return mEffectiveTransform;
+ }
+ return mEffectiveTransform * bufferScaleTransform;
+}
+
+FloatRect Layer::getBoundsPreScaling(const ui::Transform& bufferScaleTransform) const {
+ // We need the pre scaled layer bounds when computing child bounds to make sure the child is
+ // cropped to its parent layer after any buffer transform scaling is applied.
+ if (!isFixedSize() || !mActiveBuffer) {
+ return mBounds;
+ }
+ return bufferScaleTransform.inverse().transform(mBounds);
}
void Layer::computeBounds(FloatRect parentBounds, ui::Transform parentTransform) {
@@ -321,7 +335,7 @@
// Transform parent bounds to layer space
parentBounds = getActiveTransform(s).inverse().transform(parentBounds);
- // Calculate display frame
+ // Calculate source bounds
mSourceBounds = computeSourceBounds(parentBounds);
// Calculate bounds by croping diplay frame with layer crop and parent bounds
@@ -334,13 +348,15 @@
mBounds = bounds;
mScreenBounds = mEffectiveTransform.transform(mBounds);
+
+ // Add any buffer scaling to the layer's children.
+ ui::Transform bufferScaleTransform = getBufferScaleTransform();
for (const sp<Layer>& child : mDrawingChildren) {
- child->computeBounds(mBounds, getTransformWithScale());
+ child->computeBounds(getBoundsPreScaling(bufferScaleTransform),
+ getTransformWithScale(bufferScaleTransform));
}
}
-
-
Rect Layer::getCroppedBufferSize(const State& s) const {
Rect size = getBufferSize(s);
Rect crop = getCrop(s);
@@ -1666,7 +1682,9 @@
void Layer::setChildrenDrawingParent(const sp<Layer>& newParent) {
for (const sp<Layer>& child : mDrawingChildren) {
child->mDrawingParent = newParent;
- child->computeBounds(newParent->mBounds, newParent->getTransformWithScale());
+ child->computeBounds(newParent->mBounds,
+ newParent->getTransformWithScale(
+ newParent->getBufferScaleTransform()));
}
}