void
TileClient::ValidateBackBufferFromFront(const nsIntRegion& aDirtyRegion,
bool aCanRerasterizeValidRegion)
{
if (mBackBuffer && mFrontBuffer) {
const nsIntRect tileRect = nsIntRect(0, 0, TILEDLAYERBUFFER_TILE_SIZE, TILEDLAYERBUFFER_TILE_SIZE);
if (aDirtyRegion.Contains(tileRect)) {
// The dirty region means that we no longer need the front buffer, so
// discard it.
DiscardFrontBuffer();
} else {
// Region that needs copying.
nsIntRegion regionToCopy = mInvalidBack;
regionToCopy.Sub(regionToCopy, aDirtyRegion);
if (regionToCopy.IsEmpty() ||
(aCanRerasterizeValidRegion &&
regionToCopy.Area() < MINIMUM_TILE_COPY_AREA)) {
// Just redraw it all.
return;
}
if (!mFrontBuffer->Lock(OPEN_READ)) {
NS_WARNING("Failed to lock the tile's front buffer");
return;
}
TextureClientAutoUnlock autoFront(mFrontBuffer);
if (!mBackBuffer->Lock(OPEN_WRITE)) {
NS_WARNING("Failed to lock the tile's back buffer");
return;
}
TextureClientAutoUnlock autoBack(mBackBuffer);
// Copy the bounding rect of regionToCopy. As tiles are quite small, it
// is unlikely that we'd save much by copying each individual rect of the
// region, but we can reevaluate this if it becomes an issue.
const nsIntRect rectToCopy = regionToCopy.GetBounds();
gfx::IntRect gfxRectToCopy(rectToCopy.x, rectToCopy.y, rectToCopy.width, rectToCopy.height);
gfx::IntPoint gfxRectToCopyTopLeft = gfxRectToCopy.TopLeft();
mFrontBuffer->CopyToTextureClient(mBackBuffer, &gfxRectToCopy, &gfxRectToCopyTopLeft);
mInvalidBack.SetEmpty();
}
}
}
static Layer*
FindBackgroundLayer(ReadbackLayer* aLayer, nsIntPoint* aOffset)
{
gfx::Matrix transform;
if (!aLayer->GetTransform().Is2D(&transform) ||
transform.HasNonIntegerTranslation())
return nullptr;
nsIntPoint transformOffset(int32_t(transform._31), int32_t(transform._32));
for (Layer* l = aLayer->GetPrevSibling(); l; l = l->GetPrevSibling()) {
gfx::Matrix backgroundTransform;
if (!l->GetTransform().Is2D(&backgroundTransform) ||
gfx::ThebesMatrix(backgroundTransform).HasNonIntegerTranslation())
return nullptr;
nsIntPoint backgroundOffset(int32_t(backgroundTransform._31), int32_t(backgroundTransform._32));
IntRect rectInBackground(transformOffset - backgroundOffset, aLayer->GetSize());
const nsIntRegion visibleRegion = l->GetEffectiveVisibleRegion().ToUnknownRegion();
if (!visibleRegion.Intersects(rectInBackground))
continue;
// Since l is present in the background, from here on we either choose l
// or nothing.
if (!visibleRegion.Contains(rectInBackground))
return nullptr;
if (l->GetEffectiveOpacity() != 1.0 ||
l->HasMaskLayers() ||
!(l->GetContentFlags() & Layer::CONTENT_OPAQUE))
{
return nullptr;
}
// cliprects are post-transform
const Maybe<ParentLayerIntRect>& clipRect = l->GetEffectiveClipRect();
if (clipRect && !clipRect->Contains(ViewAs<ParentLayerPixel>(IntRect(transformOffset, aLayer->GetSize()))))
return nullptr;
Layer::LayerType type = l->GetType();
if (type != Layer::TYPE_COLOR && type != Layer::TYPE_PAINTED)
return nullptr;
*aOffset = backgroundOffset - transformOffset;
return l;
}
return nullptr;
}
bool
HwcComposer2D::PrepareLayerList(Layer* aLayer,
const nsIntRect& aClip,
const Matrix& aParentTransform,
bool aFindSidebandStreams)
{
// NB: we fall off this path whenever there are container layers
// that require intermediate surfaces. That means all the
// GetEffective*() coordinates are relative to the framebuffer.
bool fillColor = false;
const nsIntRegion visibleRegion = aLayer->GetLocalVisibleRegion().ToUnknownRegion();
if (visibleRegion.IsEmpty()) {
return true;
}
uint8_t opacity = std::min(0xFF, (int)(aLayer->GetEffectiveOpacity() * 256.0));
if (opacity == 0) {
LOGD("%s Layer has zero opacity; skipping", aLayer->Name());
return true;
}
if (!mHal->SupportTransparency() && opacity < 0xFF && !aFindSidebandStreams) {
LOGD("%s Layer has planar semitransparency which is unsupported by hwcomposer", aLayer->Name());
return false;
}
if (aLayer->GetMaskLayer() && !aFindSidebandStreams) {
LOGD("%s Layer has MaskLayer which is unsupported by hwcomposer", aLayer->Name());
return false;
}
nsIntRect clip;
nsIntRect layerClip = aLayer->GetLocalClipRect().valueOr(ParentLayerIntRect()).ToUnknownRect();
nsIntRect* layerClipPtr = aLayer->GetLocalClipRect() ? &layerClip : nullptr;
if (!HwcUtils::CalculateClipRect(aParentTransform,
layerClipPtr,
aClip,
&clip))
{
LOGD("%s Clip rect is empty. Skip layer", aLayer->Name());
return true;
}
// HWC supports only the following 2D transformations:
//
// Scaling via the sourceCrop and displayFrame in HwcLayer
// Translation via the sourceCrop and displayFrame in HwcLayer
// Rotation (in square angles only) via the HWC_TRANSFORM_ROT_* flags
// Reflection (horizontal and vertical) via the HWC_TRANSFORM_FLIP_* flags
//
// A 2D transform with PreservesAxisAlignedRectangles() has all the attributes
// above
Matrix layerTransform;
if (!aLayer->GetEffectiveTransform().Is2D(&layerTransform) ||
!layerTransform.PreservesAxisAlignedRectangles()) {
LOGD("Layer EffectiveTransform has a 3D transform or a non-square angle rotation");
return false;
}
Matrix layerBufferTransform;
if (!aLayer->GetEffectiveTransformForBuffer().Is2D(&layerBufferTransform) ||
!layerBufferTransform.PreservesAxisAlignedRectangles()) {
LOGD("Layer EffectiveTransformForBuffer has a 3D transform or a non-square angle rotation");
return false;
}
if (ContainerLayer* container = aLayer->AsContainerLayer()) {
if (container->UseIntermediateSurface() && !aFindSidebandStreams) {
LOGD("Container layer needs intermediate surface");
return false;
}
AutoTArray<Layer*, 12> children;
container->SortChildrenBy3DZOrder(children);
for (uint32_t i = 0; i < children.Length(); i++) {
if (!PrepareLayerList(children[i], clip, layerTransform, aFindSidebandStreams) &&
!aFindSidebandStreams) {
return false;
}
}
return true;
}
LayerRenderState state = aLayer->GetRenderState();
#if ANDROID_VERSION >= 21
if (!state.GetGrallocBuffer() && !state.GetSidebandStream().IsValid()) {
#else
if (!state.GetGrallocBuffer()) {
#endif
if (aLayer->AsColorLayer() && mColorFill) {
fillColor = true;
} else {
LOGD("%s Layer doesn't have a gralloc buffer", aLayer->Name());
return false;
}
}
nsIntRect visibleRect = visibleRegion.GetBounds();
nsIntRect bufferRect;
if (fillColor) {
bufferRect = nsIntRect(visibleRect);
} else {
nsIntRect layerRect;
if (state.mHasOwnOffset) {
bufferRect = nsIntRect(state.mOffset.x, state.mOffset.y,
state.mSize.width, state.mSize.height);
layerRect = bufferRect;
} else {
//Since the buffer doesn't have its own offset, assign the whole
//surface size as its buffer bounds
bufferRect = nsIntRect(0, 0, state.mSize.width, state.mSize.height);
layerRect = bufferRect;
if (aLayer->GetType() == Layer::TYPE_IMAGE) {
ImageLayer* imageLayer = static_cast<ImageLayer*>(aLayer);
if(imageLayer->GetScaleMode() != ScaleMode::SCALE_NONE) {
layerRect = nsIntRect(0, 0, imageLayer->GetScaleToSize().width, imageLayer->GetScaleToSize().height);
}
}
}
// In some cases the visible rect assigned to the layer can be larger
// than the layer's surface, e.g., an ImageLayer with a small Image
// in it.
visibleRect.IntersectRect(visibleRect, layerRect);
}
// Buffer rotation is not to be confused with the angled rotation done by a transform matrix
// It's a fancy PaintedLayer feature used for scrolling
if (state.BufferRotated()) {
LOGD("%s Layer has a rotated buffer", aLayer->Name());
return false;
}
const bool needsYFlip = state.OriginBottomLeft() ? true
: false;
hwc_rect_t sourceCrop, displayFrame;
if(!HwcUtils::PrepareLayerRects(visibleRect,
layerTransform,
layerBufferTransform,
clip,
bufferRect,
needsYFlip,
&(sourceCrop),
&(displayFrame)))
{
return true;
}
// OK! We can compose this layer with hwc.
int current = mList ? mList->numHwLayers : 0;
// Do not compose any layer below full-screen Opaque layer
// Note: It can be generalized to non-fullscreen Opaque layers.
bool isOpaque = opacity == 0xFF &&
(state.mFlags & LayerRenderStateFlags::OPAQUE);
// Currently we perform opacity calculation using the *bounds* of the layer.
// We can only make this assumption if we're not dealing with a complex visible region.
bool isSimpleVisibleRegion = visibleRegion.Contains(visibleRect);
if (current && isOpaque && isSimpleVisibleRegion) {
nsIntRect displayRect = nsIntRect(displayFrame.left, displayFrame.top,
displayFrame.right - displayFrame.left, displayFrame.bottom - displayFrame.top);
if (displayRect.Contains(mScreenRect)) {
// In z-order, all previous layers are below
// the current layer. We can ignore them now.
mList->numHwLayers = current = 0;
mHwcLayerMap.Clear();
}
}
if (!mList || current >= mMaxLayerCount) {
if (!ReallocLayerList() || current >= mMaxLayerCount) {
LOGE("PrepareLayerList failed! Could not increase the maximum layer count");
return false;
}
}
HwcLayer& hwcLayer = mList->hwLayers[current];
hwcLayer.displayFrame = displayFrame;
mHal->SetCrop(hwcLayer, sourceCrop);
buffer_handle_t handle = nullptr;
#if ANDROID_VERSION >= 21
if (state.GetSidebandStream().IsValid()) {
handle = state.GetSidebandStream().GetRawNativeHandle();
} else if (state.GetGrallocBuffer()) {
handle = state.GetGrallocBuffer()->getNativeBuffer()->handle;
}
#else
if (state.GetGrallocBuffer()) {
handle = state.GetGrallocBuffer()->getNativeBuffer()->handle;
}
#endif
hwcLayer.handle = handle;
hwcLayer.flags = 0;
hwcLayer.hints = 0;
hwcLayer.blending = isOpaque ? HWC_BLENDING_NONE : HWC_BLENDING_PREMULT;
#if ANDROID_VERSION >= 17
hwcLayer.compositionType = HWC_FRAMEBUFFER;
#if ANDROID_VERSION >= 21
if (state.GetSidebandStream().IsValid()) {
hwcLayer.compositionType = HWC_SIDEBAND;
}
#endif
hwcLayer.acquireFenceFd = -1;
hwcLayer.releaseFenceFd = -1;
#if ANDROID_VERSION >= 18
hwcLayer.planeAlpha = opacity;
#endif
#else
hwcLayer.compositionType = HwcUtils::HWC_USE_COPYBIT;
#endif
if (!fillColor) {
if (state.FormatRBSwapped()) {
if (!mRBSwapSupport) {
LOGD("No R/B swap support in H/W Composer");
return false;
}
hwcLayer.flags |= HwcUtils::HWC_FORMAT_RB_SWAP;
}
// Translation and scaling have been addressed in PrepareLayerRects().
// Given the above and that we checked for PreservesAxisAlignedRectangles()
// the only possible transformations left to address are
// square angle rotation and horizontal/vertical reflection.
//
// The rotation and reflection permutations total 16 but can be
// reduced to 8 transformations after eliminating redundancies.
//
// All matrices represented here are in the form
//
// | xx xy |
// | yx yy |
//
// And ignore scaling.
//
// Reflection is applied before rotation
gfx::Matrix rotation = layerTransform;
// Compute fuzzy zero like PreservesAxisAlignedRectangles()
if (fabs(rotation._11) < 1e-6) {
if (rotation._21 < 0) {
if (rotation._12 > 0) {
// 90 degree rotation
//
// | 0 -1 |
// | 1 0 |
//
hwcLayer.transform = HWC_TRANSFORM_ROT_90;
LOGD("Layer rotated 90 degrees");
}
else {
// Horizontal reflection then 90 degree rotation
//
// | 0 -1 | | -1 0 | = | 0 -1 |
// | 1 0 | | 0 1 | | -1 0 |
//
// same as vertical reflection then 270 degree rotation
//
// | 0 1 | | 1 0 | = | 0 -1 |
// | -1 0 | | 0 -1 | | -1 0 |
//
hwcLayer.transform = HWC_TRANSFORM_ROT_90 | HWC_TRANSFORM_FLIP_H;
LOGD("Layer vertically reflected then rotated 270 degrees");
}
} else {
if (rotation._12 < 0) {
// 270 degree rotation
//
// | 0 1 |
// | -1 0 |
//
hwcLayer.transform = HWC_TRANSFORM_ROT_270;
LOGD("Layer rotated 270 degrees");
}
else {
// Vertical reflection then 90 degree rotation
//
// | 0 1 | | -1 0 | = | 0 1 |
// | -1 0 | | 0 1 | | 1 0 |
//
// Same as horizontal reflection then 270 degree rotation
//
// | 0 -1 | | 1 0 | = | 0 1 |
// | 1 0 | | 0 -1 | | 1 0 |
//
hwcLayer.transform = HWC_TRANSFORM_ROT_90 | HWC_TRANSFORM_FLIP_V;
LOGD("Layer horizontally reflected then rotated 270 degrees");
}
}
} else if (rotation._11 < 0) {
if (rotation._22 > 0) {
// Horizontal reflection
//
// | -1 0 |
// | 0 1 |
//
hwcLayer.transform = HWC_TRANSFORM_FLIP_H;
LOGD("Layer rotated 180 degrees");
}
else {
// 180 degree rotation
//
// | -1 0 |
// | 0 -1 |
//
// Same as horizontal and vertical reflection
//
// | -1 0 | | 1 0 | = | -1 0 |
// | 0 1 | | 0 -1 | | 0 -1 |
//
hwcLayer.transform = HWC_TRANSFORM_ROT_180;
LOGD("Layer rotated 180 degrees");
}
} else {
if (rotation._22 < 0) {
// Vertical reflection
//
// | 1 0 |
// | 0 -1 |
//
hwcLayer.transform = HWC_TRANSFORM_FLIP_V;
LOGD("Layer rotated 180 degrees");
}
else {
// No rotation or reflection
//
// | 1 0 |
// | 0 1 |
//
hwcLayer.transform = 0;
}
}
const bool needsYFlip = state.OriginBottomLeft() ? true
: false;
if (needsYFlip) {
// Invert vertical reflection flag if it was already set
hwcLayer.transform ^= HWC_TRANSFORM_FLIP_V;
}
hwc_region_t region;
if (visibleRegion.GetNumRects() > 1) {
mVisibleRegions.push_back(HwcUtils::RectVector());
HwcUtils::RectVector* visibleRects = &(mVisibleRegions.back());
bool isVisible = false;
if(!HwcUtils::PrepareVisibleRegion(visibleRegion,
layerTransform,
layerBufferTransform,
clip,
bufferRect,
visibleRects,
isVisible)) {
LOGD("A region of layer is too small to be rendered by HWC");
return false;
}
if (!isVisible) {
// Layer is not visible, no need to render it
return true;
}
region.numRects = visibleRects->size();
region.rects = &((*visibleRects)[0]);
} else {
region.numRects = 1;
region.rects = &(hwcLayer.displayFrame);
}
hwcLayer.visibleRegionScreen = region;
} else {
hwcLayer.flags |= HwcUtils::HWC_COLOR_FILL;
ColorLayer* colorLayer = aLayer->AsColorLayer();
if (colorLayer->GetColor().a < 1.0) {
LOGD("Color layer has semitransparency which is unsupported");
return false;
}
hwcLayer.transform = colorLayer->GetColor().ToABGR();
}
#if ANDROID_VERSION >= 21
if (aFindSidebandStreams && hwcLayer.compositionType == HWC_SIDEBAND) {
mCachedSidebandLayers.AppendElement(hwcLayer);
}
#endif
mHwcLayerMap.AppendElement(static_cast<LayerComposite*>(aLayer->ImplData()));
mList->numHwLayers++;
return true;
}
#if ANDROID_VERSION >= 17
bool
HwcComposer2D::TryHwComposition(nsScreenGonk* aScreen)
{
DisplaySurface* dispSurface = aScreen->GetDisplaySurface();
if (!(dispSurface && dispSurface->lastHandle)) {
LOGD("H/W Composition failed. DispSurface not initialized.");
return false;
}
// Add FB layer
int idx = mList->numHwLayers++;
if (idx >= mMaxLayerCount) {
if (!ReallocLayerList() || idx >= mMaxLayerCount) {
LOGE("TryHwComposition failed! Could not add FB layer");
return false;
}
}
Prepare(dispSurface->lastHandle, -1, aScreen);
/* Possible composition paths, after hwc prepare:
1. GPU Composition
2. BLIT Composition
3. Full OVERLAY Composition
4. Partial OVERLAY Composition (GPU + OVERLAY) */
bool gpuComposite = false;
bool blitComposite = false;
bool overlayComposite = true;
for (int j=0; j < idx; j++) {
if (mList->hwLayers[j].compositionType == HWC_FRAMEBUFFER ||
mList->hwLayers[j].compositionType == HWC_BLIT) {
// Full OVERLAY composition is not possible on this frame
// It is either GPU / BLIT / partial OVERLAY composition.
overlayComposite = false;
break;
}
}
if (!overlayComposite) {
for (int k=0; k < idx; k++) {
switch (mList->hwLayers[k].compositionType) {
case HWC_FRAMEBUFFER:
gpuComposite = true;
break;
case HWC_BLIT:
blitComposite = true;
break;
#if ANDROID_VERSION >= 21
case HWC_SIDEBAND:
#endif
case HWC_OVERLAY: {
// HWC will compose HWC_OVERLAY layers in partial
// Overlay Composition, set layer composition flag
// on mapped LayerComposite to skip GPU composition
mHwcLayerMap[k]->SetLayerComposited(true);
uint8_t opacity = std::min(0xFF, (int)(mHwcLayerMap[k]->GetLayer()->GetEffectiveOpacity() * 256.0));
if ((mList->hwLayers[k].hints & HWC_HINT_CLEAR_FB) &&
(opacity == 0xFF)) {
// Clear visible rect on FB with transparent pixels.
hwc_rect_t r = mList->hwLayers[k].displayFrame;
mHwcLayerMap[k]->SetClearRect(nsIntRect(r.left, r.top,
r.right - r.left,
r.bottom - r.top));
}
break;
}
default:
break;
}
}
if (gpuComposite) {
// GPU or partial OVERLAY Composition
return false;
} else if (blitComposite) {
// BLIT Composition, flip DispSurface target
GetGonkDisplay()->UpdateDispSurface(aScreen->GetEGLDisplay(), aScreen->GetEGLSurface());
DisplaySurface* dispSurface = aScreen->GetDisplaySurface();
if (!dispSurface) {
LOGE("H/W Composition failed. NULL DispSurface.");
return false;
}
mList->hwLayers[idx].handle = dispSurface->lastHandle;
mList->hwLayers[idx].acquireFenceFd = dispSurface->GetPrevDispAcquireFd();
}
}
// BLIT or full OVERLAY Composition
return Commit(aScreen);
}
bool
ClientTiledLayerBuffer::ComputeProgressiveUpdateRegion(const nsIntRegion& aInvalidRegion,
const nsIntRegion& aOldValidRegion,
nsIntRegion& aRegionToPaint,
BasicTiledLayerPaintData* aPaintData,
bool aIsRepeated)
{
aRegionToPaint = aInvalidRegion;
// If the composition bounds rect is empty, we can't make any sensible
// decision about how to update coherently. In this case, just update
// everything in one transaction.
if (aPaintData->mCompositionBounds.IsEmpty()) {
aPaintData->mPaintFinished = true;
return false;
}
// If this is a low precision buffer, we force progressive updates. The
// assumption is that the contents is less important, so visual coherency
// is lower priority than speed.
bool drawingLowPrecision = IsLowPrecision();
// Find out if we have any non-stale content to update.
nsIntRegion staleRegion;
staleRegion.And(aInvalidRegion, aOldValidRegion);
// Find out the current view transform to determine which tiles to draw
// first, and see if we should just abort this paint. Aborting is usually
// caused by there being an incoming, more relevant paint.
ParentLayerRect compositionBounds;
CSSToParentLayerScale zoom;
#if defined(MOZ_WIDGET_ANDROID)
bool abortPaint = mManager->ProgressiveUpdateCallback(!staleRegion.Contains(aInvalidRegion),
compositionBounds, zoom,
!drawingLowPrecision);
#else
MOZ_ASSERT(mSharedFrameMetricsHelper);
ContainerLayer* parent = mThebesLayer->AsLayer()->GetParent();
bool abortPaint =
mSharedFrameMetricsHelper->UpdateFromCompositorFrameMetrics(
parent,
!staleRegion.Contains(aInvalidRegion),
drawingLowPrecision,
compositionBounds,
zoom);
#endif
if (abortPaint) {
// We ignore if front-end wants to abort if this is the first,
// non-low-precision paint, as in that situation, we're about to override
// front-end's page/viewport metrics.
if (!aPaintData->mFirstPaint || drawingLowPrecision) {
PROFILER_LABEL("ContentClient", "Abort painting");
aRegionToPaint.SetEmpty();
return aIsRepeated;
}
}
// Transform the screen coordinates into transformed layout device coordinates.
LayoutDeviceRect transformedCompositionBounds =
TransformCompositionBounds(compositionBounds, zoom, aPaintData->mScrollOffset,
aPaintData->mResolution, aPaintData->mTransformParentLayerToLayout);
// Paint tiles that have stale content or that intersected with the screen
// at the time of issuing the draw command in a single transaction first.
// This is to avoid rendering glitches on animated page content, and when
// layers change size/shape.
LayoutDeviceRect coherentUpdateRect =
transformedCompositionBounds.Intersect(aPaintData->mCompositionBounds);
nsIntRect roundedCoherentUpdateRect =
LayoutDeviceIntRect::ToUntyped(RoundedOut(coherentUpdateRect));
aRegionToPaint.And(aInvalidRegion, roundedCoherentUpdateRect);
aRegionToPaint.Or(aRegionToPaint, staleRegion);
bool drawingStale = !aRegionToPaint.IsEmpty();
if (!drawingStale) {
aRegionToPaint = aInvalidRegion;
}
// Prioritise tiles that are currently visible on the screen.
bool paintVisible = false;
if (aRegionToPaint.Intersects(roundedCoherentUpdateRect)) {
aRegionToPaint.And(aRegionToPaint, roundedCoherentUpdateRect);
paintVisible = true;
}
// Paint area that's visible and overlaps previously valid content to avoid
// visible glitches in animated elements, such as gifs.
bool paintInSingleTransaction = paintVisible && (drawingStale || aPaintData->mFirstPaint);
// The following code decides what order to draw tiles in, based on the
// current scroll direction of the primary scrollable layer.
NS_ASSERTION(!aRegionToPaint.IsEmpty(), "Unexpectedly empty paint region!");
nsIntRect paintBounds = aRegionToPaint.GetBounds();
int startX, incX, startY, incY;
int tileLength = GetScaledTileLength();
if (aPaintData->mScrollOffset.x >= aPaintData->mLastScrollOffset.x) {
startX = RoundDownToTileEdge(paintBounds.x);
incX = tileLength;
} else {
startX = RoundDownToTileEdge(paintBounds.XMost() - 1);
incX = -tileLength;
}
if (aPaintData->mScrollOffset.y >= aPaintData->mLastScrollOffset.y) {
startY = RoundDownToTileEdge(paintBounds.y);
incY = tileLength;
} else {
startY = RoundDownToTileEdge(paintBounds.YMost() - 1);
incY = -tileLength;
}
// Find a tile to draw.
nsIntRect tileBounds(startX, startY, tileLength, tileLength);
int32_t scrollDiffX = aPaintData->mScrollOffset.x - aPaintData->mLastScrollOffset.x;
int32_t scrollDiffY = aPaintData->mScrollOffset.y - aPaintData->mLastScrollOffset.y;
// This loop will always terminate, as there is at least one tile area
// along the first/last row/column intersecting with regionToPaint, or its
// bounds would have been smaller.
while (true) {
aRegionToPaint.And(aInvalidRegion, tileBounds);
if (!aRegionToPaint.IsEmpty()) {
break;
}
if (Abs(scrollDiffY) >= Abs(scrollDiffX)) {
tileBounds.x += incX;
} else {
tileBounds.y += incY;
}
}
if (!aRegionToPaint.Contains(aInvalidRegion)) {
// The region needed to paint is larger then our progressive chunk size
// therefore update what we want to paint and ask for a new paint transaction.
// If we need to draw more than one tile to maintain coherency, make
// sure it happens in the same transaction by requesting this work be
// repeated immediately.
// If this is unnecessary, the remaining work will be done tile-by-tile in
// subsequent transactions.
if (!drawingLowPrecision && paintInSingleTransaction) {
return true;
}
mManager->SetRepeatTransaction();
return false;
}
// We're not repeating painting and we've not requested a repeat transaction,
// so the paint is finished. If there's still a separate low precision
// paint to do, it will get marked as unfinished later.
aPaintData->mPaintFinished = true;
return false;
}