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[web] Fix repaint logic for cullrect,transform changes (flutter/engine#22273)

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This commit is contained in:
Ferhat 2020-11-03 11:31:48 -08:00 committed by GitHub
parent 646894d1bb
commit 2328c882a9
1 changed files with 20 additions and 21 deletions
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41
engine/src/flutter/lib/web_ui/lib/src/engine/html/picture.dart
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@ -91,6 +91,10 @@ class PersistedPicture extends PersistedLeafSurface {
final ui.Rect? localPaintBounds;
final int hints;
double _density = 1.0;
/// Cull rect changes and density changes due to transforms should
/// call applyPaint for picture when retain() or update() is called after
/// preroll is complete.
bool _requiresRepaint = false;
/// Cache for reusing elements such as images across picture updates.
CrossFrameCache<html.HtmlElement>? _elementCache =
@ -114,16 +118,7 @@ class PersistedPicture extends PersistedLeafSurface {
? 1.0 : _computePixelDensity(_transform, paintWidth, paintHeight);
if (newDensity != _density) {
_density = newDensity;
if (_canvas != null) {
// If cull rect and density hasn't changed, this will only repaint.
// If density doesn't match canvas, a new canvas will be created
// and paint queued.
//
// Similar to preroll for transform where transform is updated, for
// picture this means we need to repaint so pixelation doesn't occur
// due to transform changing overall dpi.
applyPaint(_canvas);
}
_requiresRepaint = true;
}
_computeExactCullRects();
}
@ -204,13 +199,14 @@ class PersistedPicture extends PersistedLeafSurface {
}
}
bool _computeOptimalCullRect(PersistedPicture? oldSurface) {
void _computeOptimalCullRect(PersistedPicture? oldSurface) {
assert(_exactLocalCullRect != null);
if (oldSurface == null || !oldSurface.picture.recordingCanvas!.didDraw) {
// First useful paint.
_optimalLocalCullRect = _exactLocalCullRect;
return true;
_requiresRepaint = true;
return;
}
assert(oldSurface._optimalLocalCullRect != null);
@ -224,7 +220,10 @@ class PersistedPicture extends PersistedLeafSurface {
// The clip collapsed into a zero-sized rectangle. If it was already zero,
// no need to signal cull rect change.
_optimalLocalCullRect = ui.Rect.zero;
return oldOptimalLocalCullRect != ui.Rect.zero;
if (oldOptimalLocalCullRect != ui.Rect.zero) {
_requiresRepaint = true;
}
return;
}
if (rectContainsOther(oldOptimalLocalCullRect!, _exactLocalCullRect!)) {
@ -233,7 +232,7 @@ class PersistedPicture extends PersistedLeafSurface {
// a clip when it is scrolled out of the screen. In this case we do not
// repaint the picture. We just let it be shrunk by the outer clip.
_optimalLocalCullRect = oldOptimalLocalCullRect;
return false;
return;
}
// The new cull rect contains area not covered by a previous rect. Perhaps
@ -270,9 +269,8 @@ class PersistedPicture extends PersistedLeafSurface {
_predictTrend(bottomwardDelta, _exactLocalCullRect!.height),
).intersect(localPaintBounds!);
final bool localCullRectChanged = _optimalLocalCullRect != newLocalCullRect;
_requiresRepaint = _optimalLocalCullRect != newLocalCullRect;
_optimalLocalCullRect = newLocalCullRect;
return localCullRectChanged;
}
/// Predicts the delta a particular side of a clip rect will move given the
@ -309,6 +307,7 @@ class PersistedPicture extends PersistedLeafSurface {
void _applyPaint(PersistedPicture? oldSurface) {
final EngineCanvas? oldCanvas = oldSurface?._canvas;
_requiresRepaint = false;
if (!picture.recordingCanvas!.didDraw || _optimalLocalCullRect!.isEmpty) {
// The picture is empty, or it has been completely clipped out. Skip
// painting. This removes all the setup work and scaffolding objects
@ -540,6 +539,7 @@ class PersistedPicture extends PersistedLeafSurface {
@override
void build() {
_computeOptimalCullRect(null);
_requiresRepaint = true;
super.build();
}
@ -556,15 +556,14 @@ class PersistedPicture extends PersistedLeafSurface {
_applyTranslate();
}
final bool cullRectChangeRequiresRepaint =
_computeOptimalCullRect(oldSurface);
_computeOptimalCullRect(oldSurface);
if (identical(picture, oldSurface.picture)) {
bool densityChanged =
(_canvas is BitmapCanvas &&
_density != (_canvas as BitmapCanvas)._density);
// The picture is the same. Attempt to avoid repaint.
if (cullRectChangeRequiresRepaint || densityChanged) {
if (_requiresRepaint || densityChanged) {
// Cull rect changed such that a repaint is still necessary.
_applyPaint(oldSurface);
} else {
@ -581,8 +580,8 @@ class PersistedPicture extends PersistedLeafSurface {
@override
void retain() {
super.retain();
final bool cullRectChangeRequiresRepaint = _computeOptimalCullRect(this);
if (cullRectChangeRequiresRepaint) {
_computeOptimalCullRect(this);
if (_requiresRepaint) {
_applyPaint(this);
}
}