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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#include "ClippedImage.h"
#include <algorithm>
#include <cmath>
#include <new> // Workaround for bug in VS10; see bug 981264.
#include <utility>
#include "ImageRegion.h"
#include "Orientation.h"
#include "gfxContext.h"
#include "gfxDrawable.h"
#include "gfxPlatform.h"
#include "gfxUtils.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SVGImageContext.h"
#include "mozilla/gfx/2D.h"
namespace mozilla {
using namespace gfx;
using std::max;
namespace image {
class ClippedImageCachedSurface {
ClippedImageCachedSurface(already_AddRefed<SourceSurface> aSurface,
const nsIntSize& aSize,
const SVGImageContext& aSVGContext, float aFrame,
uint32_t aFlags, ImgDrawResult aDrawResult)
: mSurface(aSurface),
mDrawResult(aDrawResult) {
MOZ_ASSERT(mSurface, "Must have a valid surface");
bool Matches(const nsIntSize& aSize, const SVGImageContext& aSVGContext,
float aFrame, uint32_t aFlags) const {
return mSize == aSize && mSVGContext == aSVGContext && mFrame == aFrame &&
mFlags == aFlags;
already_AddRefed<SourceSurface> Surface() const {
RefPtr<SourceSurface> surf(mSurface);
return surf.forget();
ImgDrawResult GetDrawResult() const { return mDrawResult; }
bool NeedsRedraw() const {
return mDrawResult != ImgDrawResult::SUCCESS &&
mDrawResult != ImgDrawResult::BAD_IMAGE;
RefPtr<SourceSurface> mSurface;
const nsIntSize mSize;
SVGImageContext mSVGContext;
const float mFrame;
const uint32_t mFlags;
const ImgDrawResult mDrawResult;
class DrawSingleTileCallback : public gfxDrawingCallback {
DrawSingleTileCallback(ClippedImage* aImage, const nsIntSize& aSize,
const SVGImageContext& aSVGContext,
uint32_t aWhichFrame, uint32_t aFlags, float aOpacity)
: mImage(aImage),
mOpacity(aOpacity) {
MOZ_ASSERT(mImage, "Must have an image to clip");
virtual bool operator()(gfxContext* aContext, const gfxRect& aFillRect,
const SamplingFilter aSamplingFilter,
const gfxMatrix& aTransform) override {
"Caller is probably CreateSamplingRestrictedDrawable, "
"which should not happen");
// Draw the image. |gfxCallbackDrawable| always calls this function with
// arguments that guarantee we never tile.
mDrawResult = mImage->DrawSingleTile(
aContext, mSize, ImageRegion::Create(aFillRect), mWhichFrame,
aSamplingFilter, mSVGContext, mFlags, mOpacity);
return true;
ImgDrawResult GetDrawResult() { return mDrawResult; }
RefPtr<ClippedImage> mImage;
const nsIntSize mSize;
const SVGImageContext& mSVGContext;
const uint32_t mWhichFrame;
const uint32_t mFlags;
ImgDrawResult mDrawResult;
float mOpacity;
ClippedImage::ClippedImage(Image* aImage, nsIntRect aClip,
const Maybe<nsSize>& aSVGViewportSize)
: ImageWrapper(aImage), mClip(aClip) {
MOZ_ASSERT(aImage != nullptr, "ClippedImage requires an existing Image");
aImage->GetType() == imgIContainer::TYPE_VECTOR);
if (aSVGViewportSize) {
mSVGViewportSize =
ClippedImage::~ClippedImage() {}
bool ClippedImage::ShouldClip() {
// We need to evaluate the clipping region against the image's width and
// height once they're available to determine if it's valid and whether we
// actually need to do any work. We may fail if the image's width and height
// aren't available yet, in which case we'll try again later.
if (mShouldClip.isNothing()) {
int32_t width, height;
RefPtr<ProgressTracker> progressTracker =
if (InnerImage()->HasError()) {
// If there's a problem with the inner image we'll let it handle
// everything.
} else if (mSVGViewportSize && !mSVGViewportSize->IsEmpty()) {
// Clamp the clipping region to the size of the SVG viewport.
nsIntRect svgViewportRect(nsIntPoint(0, 0), *mSVGViewportSize);
mClip = mClip.Intersect(svgViewportRect);
// If the clipping region is the same size as the SVG viewport size
// we don't have to do anything.
} else if (NS_SUCCEEDED(InnerImage()->GetWidth(&width)) && width > 0 &&
NS_SUCCEEDED(InnerImage()->GetHeight(&height)) && height > 0) {
// Clamp the clipping region to the size of the underlying image.
mClip = mClip.Intersect(nsIntRect(0, 0, width, height));
// If the clipping region is the same size as the underlying image we
// don't have to do anything.
!mClip.IsEqualInterior(nsIntRect(0, 0, width, height)));
} else if (progressTracker &&
!(progressTracker->GetProgress() & FLAG_LOAD_COMPLETE)) {
// The image just hasn't finished loading yet. We don't yet know whether
// clipping with be needed or not for now. Just return without memorizing
// anything.
return false;
} else {
// We have a fully loaded image without a clearly defined width and
// height. This can happen with SVG images.
MOZ_ASSERT(mShouldClip.isSome(), "Should have computed a result");
return *mShouldClip;
ClippedImage::GetWidth(int32_t* aWidth) {
if (!ShouldClip()) {
return InnerImage()->GetWidth(aWidth);
*aWidth = mClip.Width();
return NS_OK;
ClippedImage::GetHeight(int32_t* aHeight) {
if (!ShouldClip()) {
return InnerImage()->GetHeight(aHeight);
*aHeight = mClip.Height();
return NS_OK;
ClippedImage::GetIntrinsicSize(nsSize* aSize) {
if (!ShouldClip()) {
return InnerImage()->GetIntrinsicSize(aSize);
*aSize = nsSize(mClip.Width(), mClip.Height());
return NS_OK;
Maybe<AspectRatio> ClippedImage::GetIntrinsicRatio() {
if (!ShouldClip()) {
return InnerImage()->GetIntrinsicRatio();
return Some(AspectRatio::FromSize(mClip.Width(), mClip.Height()));
ClippedImage::GetFrame(uint32_t aWhichFrame, uint32_t aFlags) {
RefPtr<SourceSurface> surface;
std::tie(std::ignore, surface) = GetFrameInternal(
mClip.Size(), SVGImageContext(), Nothing(), aWhichFrame, aFlags, 1.0);
return surface.forget();
ClippedImage::GetFrameAtSize(const IntSize& aSize, uint32_t aWhichFrame,
uint32_t aFlags) {
// XXX(seth): It'd be nice to support downscale-during-decode for this case,
// but right now we just fall back to the intrinsic size.
return GetFrame(aWhichFrame, aFlags);
std::pair<ImgDrawResult, RefPtr<SourceSurface>> ClippedImage::GetFrameInternal(
const nsIntSize& aSize, const SVGImageContext& aSVGContext,
const Maybe<ImageIntRegion>& aRegion, uint32_t aWhichFrame, uint32_t aFlags,
float aOpacity) {
if (!ShouldClip()) {
RefPtr<SourceSurface> surface = InnerImage()->GetFrame(aWhichFrame, aFlags);
return std::make_pair(
surface ? ImgDrawResult::SUCCESS : ImgDrawResult::NOT_READY,
float frameToDraw = InnerImage()->GetFrameIndex(aWhichFrame);
if (!mCachedSurface ||
!mCachedSurface->Matches(aSize, aSVGContext, frameToDraw, aFlags) ||
mCachedSurface->NeedsRedraw()) {
// Create a surface to draw into.
RefPtr<DrawTarget> target =
IntSize(aSize.width, aSize.height), SurfaceFormat::OS_RGBA);
if (!target || !target->IsValid()) {
NS_ERROR("Could not create a DrawTarget");
return std::make_pair(ImgDrawResult::TEMPORARY_ERROR,
gfxContext ctx(target);
// Create our callback.
RefPtr<DrawSingleTileCallback> drawTileCallback =
new DrawSingleTileCallback(this, aSize, aSVGContext, aWhichFrame,
aFlags, aOpacity);
RefPtr<gfxDrawable> drawable =
new gfxCallbackDrawable(drawTileCallback, aSize);
// Actually draw. The callback will end up invoking DrawSingleTile.
gfxUtils::DrawPixelSnapped(&ctx, drawable, SizeDouble(aSize),
SurfaceFormat::OS_RGBA, SamplingFilter::LINEAR,
// Cache the resulting surface.
mCachedSurface = MakeUnique<ClippedImageCachedSurface>(
target->Snapshot(), aSize, aSVGContext, frameToDraw, aFlags,
MOZ_ASSERT(mCachedSurface, "Should have a cached surface now");
RefPtr<SourceSurface> surface = mCachedSurface->Surface();
return std::make_pair(mCachedSurface->GetDrawResult(), std::move(surface));
ClippedImage::IsImageContainerAvailable(WindowRenderer* aRenderer,
uint32_t aFlags) {
if (!ShouldClip()) {
return InnerImage()->IsImageContainerAvailable(aRenderer, aFlags);
return false;
ClippedImage::GetImageProvider(WindowRenderer* aRenderer,
const gfx::IntSize& aSize,
const SVGImageContext& aSVGContext,
const Maybe<ImageIntRegion>& aRegion,
uint32_t aFlags,
WebRenderImageProvider** aProvider) {
// XXX(seth): We currently don't have a way of clipping the result of
// GetImageContainer. We work around this by always returning null, but if it
// ever turns out that ClippedImage is widely used on codepaths that can
// actually benefit from GetImageContainer, it would be a good idea to fix
// that method for performance reasons.
if (!ShouldClip()) {
return InnerImage()->GetImageProvider(aRenderer, aSize, aSVGContext,
aRegion, aFlags, aProvider);
return ImgDrawResult::NOT_SUPPORTED;
static bool MustCreateSurface(gfxContext* aContext, const nsIntSize& aSize,
const ImageRegion& aRegion,
const uint32_t aFlags) {
gfxRect imageRect(0, 0, aSize.width, aSize.height);
bool willTile = !imageRect.Contains(aRegion.Rect()) &&
!(aFlags & imgIContainer::FLAG_CLAMP);
bool willResample = aContext->CurrentMatrix().HasNonIntegerTranslation() &&
(willTile || !aRegion.RestrictionContains(imageRect));
return willTile || willResample;
ClippedImage::Draw(gfxContext* aContext, const nsIntSize& aSize,
const ImageRegion& aRegion, uint32_t aWhichFrame,
SamplingFilter aSamplingFilter,
const SVGImageContext& aSVGContext, uint32_t aFlags,
float aOpacity) {
if (!ShouldClip()) {
return InnerImage()->Draw(aContext, aSize, aRegion, aWhichFrame,
aSamplingFilter, aSVGContext, aFlags, aOpacity);
// Check for tiling. If we need to tile then we need to create a
// gfxCallbackDrawable to handle drawing for us.
if (MustCreateSurface(aContext, aSize, aRegion, aFlags)) {
// Create a temporary surface containing a single tile of this image.
// GetFrame will call DrawSingleTile internally.
auto [result, surface] = GetFrameInternal(aSize, aSVGContext, Nothing(),
aWhichFrame, aFlags, aOpacity);
if (!surface) {
MOZ_ASSERT(result != ImgDrawResult::SUCCESS);
return result;
// Create a drawable from that surface.
RefPtr<gfxSurfaceDrawable> drawable =
new gfxSurfaceDrawable(surface, aSize);
// Draw.
gfxUtils::DrawPixelSnapped(aContext, drawable, SizeDouble(aSize), aRegion,
SurfaceFormat::OS_RGBA, aSamplingFilter,
return result;
return DrawSingleTile(aContext, aSize, aRegion, aWhichFrame, aSamplingFilter,
aSVGContext, aFlags, aOpacity);
ImgDrawResult ClippedImage::DrawSingleTile(
gfxContext* aContext, const nsIntSize& aSize, const ImageRegion& aRegion,
uint32_t aWhichFrame, SamplingFilter aSamplingFilter,
const SVGImageContext& aSVGContext, uint32_t aFlags, float aOpacity) {
MOZ_ASSERT(!MustCreateSurface(aContext, aSize, aRegion, aFlags),
"Shouldn't need to create a surface");
gfxRect clip(mClip.X(), mClip.Y(), mClip.Width(), mClip.Height());
nsIntSize size(aSize), innerSize(aSize);
bool needScale = false;
if (mSVGViewportSize && !mSVGViewportSize->IsEmpty()) {
innerSize = *mSVGViewportSize;
needScale = true;
} else if (NS_SUCCEEDED(InnerImage()->GetWidth(&innerSize.width)) &&
NS_SUCCEEDED(InnerImage()->GetHeight(&innerSize.height))) {
needScale = true;
} else {
"If ShouldClip() led us to draw then we should never get here");
if (needScale) {
double scaleX = aSize.width / clip.Width();
double scaleY = aSize.height / clip.Height();
// Map the clip and size to the scale requested by the caller.
clip.Scale(scaleX, scaleY);
size = innerSize;
size.Scale(scaleX, scaleY);
// We restrict our drawing to only the clipping region, and translate so that
// the clipping region is placed at the position the caller expects.
ImageRegion region(aRegion);
region.MoveBy(clip.X(), clip.Y());
region = region.Intersect(clip);
gfxContextMatrixAutoSaveRestore saveMatrix(aContext);
aContext->Multiply(gfxMatrix::Translation(-clip.X(), -clip.Y()));
auto unclipViewport = [&](const SVGImageContext& aOldContext) {
// Map the viewport to the inner image. Note that we don't take the aSize
// parameter of imgIContainer::Draw into account, just the clipping region.
// The size in pixels at which the output will ultimately be drawn is
// irrelevant here since the purpose of the SVG viewport size is to
// determine what *region* of the SVG document will be drawn.
SVGImageContext context(aOldContext);
auto oldViewport = aOldContext.GetViewportSize();
if (oldViewport) {
CSSIntSize newViewport;
newViewport.width =
ceil(oldViewport->width * double(innerSize.width) / mClip.Width());
newViewport.height =
ceil(oldViewport->height * double(innerSize.height) / mClip.Height());
return context;
return InnerImage()->Draw(aContext, size, region, aWhichFrame,
aSamplingFilter, unclipViewport(aSVGContext),
aFlags, aOpacity);
ClippedImage::RequestDiscard() {
// We're very aggressive about discarding.
mCachedSurface = nullptr;
return InnerImage()->RequestDiscard();
ClippedImage::GetOrientation() {
// XXX(seth): This should not actually be here; this is just to work around a
// what appears to be a bug in MSVC's linker.
return InnerImage()->GetOrientation();
nsIntSize ClippedImage::OptimalImageSizeForDest(const gfxSize& aDest,
uint32_t aWhichFrame,
SamplingFilter aSamplingFilter,
uint32_t aFlags) {
if (!ShouldClip()) {
return InnerImage()->OptimalImageSizeForDest(aDest, aWhichFrame,
aSamplingFilter, aFlags);
int32_t imgWidth, imgHeight;
bool needScale = false;
bool forceUniformScaling = false;
if (mSVGViewportSize && !mSVGViewportSize->IsEmpty()) {
imgWidth = mSVGViewportSize->width;
imgHeight = mSVGViewportSize->height;
needScale = true;
forceUniformScaling = (aFlags & imgIContainer::FLAG_FORCE_UNIFORM_SCALING);
} else if (NS_SUCCEEDED(InnerImage()->GetWidth(&imgWidth)) &&
NS_SUCCEEDED(InnerImage()->GetHeight(&imgHeight))) {
needScale = true;
if (needScale) {
// To avoid ugly sampling artifacts, ClippedImage needs the image size to
// be chosen such that the clipping region lies on pixel boundaries.
// First, we select a scale that's good for ClippedImage. An integer
// multiple of the size of the clipping region is always fine.
IntSize scale = IntSize::Ceil(aDest.width / mClip.Width(),
aDest.height / mClip.Height());
if (forceUniformScaling) {
scale.width = scale.height = max(scale.height, scale.width);
// Determine the size we'd prefer to render the inner image at, and ask the
// inner image what size we should actually use.
gfxSize desiredSize(double(imgWidth) * scale.width,
double(imgHeight) * scale.height);
nsIntSize innerDesiredSize = InnerImage()->OptimalImageSizeForDest(
desiredSize, aWhichFrame, aSamplingFilter, aFlags);
// To get our final result, we take the inner image's desired size and
// determine how large the clipped region would be at that scale. (Again, we
// ensure an integer multiple of the size of the clipping region.)
IntSize finalScale =
IntSize::Ceil(double(innerDesiredSize.width) / imgWidth,
double(innerDesiredSize.height) / imgHeight);
return mClip.Size() * finalScale;
"If ShouldClip() led us to draw then we should never get here");
return InnerImage()->OptimalImageSizeForDest(aDest, aWhichFrame,
aSamplingFilter, aFlags);
ClippedImage::GetImageSpaceInvalidationRect(const nsIntRect& aRect) {
if (!ShouldClip()) {
return InnerImage()->GetImageSpaceInvalidationRect(aRect);
nsIntRect rect(InnerImage()->GetImageSpaceInvalidationRect(aRect));
rect = rect.Intersect(mClip);
rect.MoveBy(-mClip.X(), -mClip.Y());
return rect;
} // namespace image
} // namespace mozilla