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gecko-dev/dom/canvas/CanvasRenderingContext2D.h
Lee Salzman 99f83e7841 Bug 1799069 - Preserve buffer provider on same size canvas resets. r=aosmond 
Some canvas users attempt to set .width=.width to have the canvas reset as a
side-effect. When this happens, we throw out the buffer provider on reset. However,
this makes it impossible to do any sort of profiling for accelerated canvas inside
the buffer provider since its state is continually reset every frame in these
sorts of use-cases.

To work around this, we make our best attempt to keep the buffer provider around
so long as the size remains the same. The only caveat is that we still need to
keep the side-effect of clearing the buffer when this happens so that the
behavior is similar regardless.

Differential Revision: https://phabricator.services.mozilla.com/D161615
2022-11-09 04:01:55 +00:00

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/* 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 http://mozilla.org/MPL/2.0/. */
#ifndef CanvasRenderingContext2D_h
#define CanvasRenderingContext2D_h
#include <vector>
#include "mozilla/dom/BasicRenderingContext2D.h"
#include "mozilla/dom/CanvasRenderingContext2DBinding.h"
#include "mozilla/dom/HTMLCanvasElement.h"
#include "mozilla/intl/Bidi.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/EnumeratedArray.h"
#include "mozilla/Maybe.h"
#include "mozilla/RefPtr.h"
#include "mozilla/SurfaceFromElementResult.h"
#include "mozilla/ThreadLocal.h"
#include "mozilla/UniquePtr.h"
#include "FilterDescription.h"
#include "gfx2DGlue.h"
#include "gfxFontConstants.h"
#include "nsICanvasRenderingContextInternal.h"
#include "nsColor.h"
#include "nsIFrame.h"
class gfxFontGroup;
class nsGlobalWindowInner;
class nsXULElement;
namespace mozilla {
class ErrorResult;
class PresShell;
namespace gl {
class SourceSurface;
} // namespace gl
namespace layers {
class PersistentBufferProvider;
enum class LayersBackend : int8_t;
} // namespace layers
namespace dom {
class
HTMLImageElementOrSVGImageElementOrHTMLCanvasElementOrHTMLVideoElementOrOffscreenCanvasOrImageBitmap;
using CanvasImageSource =
HTMLImageElementOrSVGImageElementOrHTMLCanvasElementOrHTMLVideoElementOrOffscreenCanvasOrImageBitmap;
class ImageBitmap;
class ImageData;
class UTF8StringOrCanvasGradientOrCanvasPattern;
class OwningUTF8StringOrCanvasGradientOrCanvasPattern;
class TextMetrics;
class CanvasGradient;
class CanvasPath;
class CanvasPattern;
extern const mozilla::gfx::Float SIGMA_MAX;
template <typename T>
class Optional;
struct CanvasBidiProcessor;
class CanvasDrawObserver;
class CanvasShutdownObserver;
class DOMMatrix;
class DOMMatrixReadOnly;
struct DOMMatrix2DInit;
/**
** CanvasRenderingContext2D
**/
class CanvasRenderingContext2D : public nsICanvasRenderingContextInternal,
public nsWrapperCache,
public BasicRenderingContext2D {
protected:
virtual ~CanvasRenderingContext2D();
public:
explicit CanvasRenderingContext2D(layers::LayersBackend aCompositorBackend);
virtual JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override;
HTMLCanvasElement* GetCanvas() const {
if (!mCanvasElement || mCanvasElement->IsInNativeAnonymousSubtree()) {
return nullptr;
}
// corresponds to changes to the old bindings made in bug 745025
return mCanvasElement->GetOriginalCanvas();
}
void OnMemoryPressure() override;
void OnBeforePaintTransaction() override;
void OnDidPaintTransaction() override;
layers::PersistentBufferProvider* GetBufferProvider() override;
Maybe<layers::SurfaceDescriptor> GetFrontBuffer(
WebGLFramebufferJS*, const bool webvr = false) override;
void Save() override;
void Restore() override;
void Scale(double aX, double aY, mozilla::ErrorResult& aError) override;
void Rotate(double aAngle, mozilla::ErrorResult& aError) override;
void Translate(double aX, double aY, mozilla::ErrorResult& aError) override;
void Transform(double aM11, double aM12, double aM21, double aM22, double aDx,
double aDy, mozilla::ErrorResult& aError) override;
already_AddRefed<DOMMatrix> GetTransform(
mozilla::ErrorResult& aError) override;
void SetTransform(double aM11, double aM12, double aM21, double aM22,
double aDx, double aDy,
mozilla::ErrorResult& aError) override;
void SetTransform(const DOMMatrix2DInit& aInit,
mozilla::ErrorResult& aError) override;
void ResetTransform(mozilla::ErrorResult& aError) override;
double GlobalAlpha() override { return CurrentState().globalAlpha; }
// Useful for silencing cast warnings
static mozilla::gfx::Float ToFloat(double aValue) {
return mozilla::gfx::Float(aValue);
}
void SetGlobalAlpha(double aGlobalAlpha) override {
if (aGlobalAlpha >= 0.0 && aGlobalAlpha <= 1.0) {
CurrentState().globalAlpha = ToFloat(aGlobalAlpha);
}
}
void GetGlobalCompositeOperation(nsAString& aOp,
mozilla::ErrorResult& aError) override;
void SetGlobalCompositeOperation(const nsAString& aOp,
mozilla::ErrorResult& aError) override;
void GetStrokeStyle(
OwningUTF8StringOrCanvasGradientOrCanvasPattern& aValue) override {
GetStyleAsUnion(aValue, Style::STROKE);
}
void SetStrokeStyle(
const UTF8StringOrCanvasGradientOrCanvasPattern& aValue) override {
SetStyleFromUnion(aValue, Style::STROKE);
}
void GetFillStyle(
OwningUTF8StringOrCanvasGradientOrCanvasPattern& aValue) override {
GetStyleAsUnion(aValue, Style::FILL);
}
void SetFillStyle(
const UTF8StringOrCanvasGradientOrCanvasPattern& aValue) override {
SetStyleFromUnion(aValue, Style::FILL);
}
already_AddRefed<CanvasGradient> CreateLinearGradient(double aX0, double aY0,
double aX1,
double aY1) override;
already_AddRefed<CanvasGradient> CreateRadialGradient(
double aX0, double aY0, double aR0, double aX1, double aY1, double aR1,
ErrorResult& aError) override;
already_AddRefed<CanvasGradient> CreateConicGradient(double aAngle,
double aCx,
double aCy) override;
already_AddRefed<CanvasPattern> CreatePattern(
const CanvasImageSource& aElement, const nsAString& aRepeat,
ErrorResult& aError) override;
double ShadowOffsetX() override { return CurrentState().shadowOffset.x; }
void SetShadowOffsetX(double aShadowOffsetX) override {
CurrentState().shadowOffset.x = ToFloat(aShadowOffsetX);
}
double ShadowOffsetY() override { return CurrentState().shadowOffset.y; }
void SetShadowOffsetY(double aShadowOffsetY) override {
CurrentState().shadowOffset.y = ToFloat(aShadowOffsetY);
}
double ShadowBlur() override { return CurrentState().shadowBlur; }
void SetShadowBlur(double aShadowBlur) override {
if (aShadowBlur >= 0.0) {
CurrentState().shadowBlur = ToFloat(aShadowBlur);
}
}
void GetShadowColor(nsACString& aShadowColor) override {
StyleColorToString(CurrentState().shadowColor, aShadowColor);
}
void GetFilter(nsACString& aFilter) { aFilter = CurrentState().filterString; }
void SetShadowColor(const nsACString& aShadowColor) override;
void SetFilter(const nsACString& aFilter, mozilla::ErrorResult& aError);
void ClearRect(double aX, double aY, double aW, double aH) override;
void FillRect(double aX, double aY, double aW, double aH) override;
void StrokeRect(double aX, double aY, double aW, double aH) override;
void BeginPath();
void Fill(const CanvasWindingRule& aWinding);
void Fill(const CanvasPath& aPath, const CanvasWindingRule& aWinding);
void Stroke();
void Stroke(const CanvasPath& aPath);
void DrawFocusIfNeeded(mozilla::dom::Element& aElement, ErrorResult& aRv);
bool DrawCustomFocusRing(mozilla::dom::Element& aElement);
void Clip(const CanvasWindingRule& aWinding);
void Clip(const CanvasPath& aPath, const CanvasWindingRule& aWinding);
bool IsPointInPath(JSContext* aCx, double aX, double aY,
const CanvasWindingRule& aWinding,
nsIPrincipal& aSubjectPrincipal);
bool IsPointInPath(JSContext* aCx, double aX, double aY,
const CanvasWindingRule& aWinding,
Maybe<nsIPrincipal*> aSubjectPrincipal);
bool IsPointInPath(JSContext* aCx, const CanvasPath& aPath, double aX,
double aY, const CanvasWindingRule& aWinding,
nsIPrincipal&);
bool IsPointInPath(JSContext* aCx, const CanvasPath& aPath, double aX,
double aY, const CanvasWindingRule& aWinding,
Maybe<nsIPrincipal*>);
bool IsPointInStroke(JSContext* aCx, double aX, double aY,
nsIPrincipal& aSubjectPrincipal);
bool IsPointInStroke(JSContext* aCx, double aX, double aY,
Maybe<nsIPrincipal*> aSubjectPrincipal);
bool IsPointInStroke(JSContext* aCx, const CanvasPath& aPath, double aX,
double aY, nsIPrincipal&);
bool IsPointInStroke(JSContext* aCx, const CanvasPath& aPath, double aX,
double aY, Maybe<nsIPrincipal*>);
void FillText(const nsAString& aText, double aX, double aY,
const Optional<double>& aMaxWidth,
mozilla::ErrorResult& aError);
void StrokeText(const nsAString& aText, double aX, double aY,
const Optional<double>& aMaxWidth,
mozilla::ErrorResult& aError);
TextMetrics* MeasureText(const nsAString& aRawText,
mozilla::ErrorResult& aError);
void DrawImage(const CanvasImageSource& aImage, double aDx, double aDy,
mozilla::ErrorResult& aError) override {
DrawImage(aImage, 0.0, 0.0, 0.0, 0.0, aDx, aDy, 0.0, 0.0, 0, aError);
}
void DrawImage(const CanvasImageSource& aImage, double aDx, double aDy,
double aDw, double aDh,
mozilla::ErrorResult& aError) override {
DrawImage(aImage, 0.0, 0.0, 0.0, 0.0, aDx, aDy, aDw, aDh, 2, aError);
}
void DrawImage(const CanvasImageSource& aImage, double aSx, double aSy,
double aSw, double aSh, double aDx, double aDy, double aDw,
double aDh, mozilla::ErrorResult& aError) override {
DrawImage(aImage, aSx, aSy, aSw, aSh, aDx, aDy, aDw, aDh, 6, aError);
}
already_AddRefed<ImageData> CreateImageData(JSContext*, int32_t aSw,
int32_t aSh, ErrorResult&);
already_AddRefed<ImageData> CreateImageData(JSContext*, ImageData&,
ErrorResult&);
already_AddRefed<ImageData> GetImageData(JSContext*, int32_t aSx, int32_t aSy,
int32_t aSw, int32_t aSh,
nsIPrincipal& aSubjectPrincipal,
ErrorResult&);
already_AddRefed<ImageData> GetImageData(
JSContext*, int32_t aSx, int32_t aSy, int32_t aSw, int32_t aSh,
Maybe<nsIPrincipal*> aSubjectPrincipal, ErrorResult&);
void PutImageData(ImageData&, int32_t aDx, int32_t aDy, ErrorResult&);
void PutImageData(ImageData&, int32_t aDx, int32_t aDy, int32_t aDirtyX,
int32_t aDirtyY, int32_t aDirtyWidth, int32_t aDirtyHeight,
ErrorResult&);
double LineWidth() override { return CurrentState().lineWidth; }
void SetLineWidth(double aWidth) override {
if (aWidth > 0.0) {
CurrentState().lineWidth = ToFloat(aWidth);
}
}
void GetLineCap(nsAString& aLinecapStyle) override;
void SetLineCap(const nsAString& aLinecapStyle) override;
void GetLineJoin(nsAString& aLinejoinStyle,
mozilla::ErrorResult& aError) override;
void SetLineJoin(const nsAString& aLinejoinStyle) override;
double MiterLimit() override { return CurrentState().miterLimit; }
void SetMiterLimit(double aMiter) override {
if (aMiter > 0.0) {
CurrentState().miterLimit = ToFloat(aMiter);
}
}
void GetFont(nsACString& aFont) { aFont = GetFont(); }
void SetFont(const nsACString& aFont, mozilla::ErrorResult& aError);
void GetTextAlign(nsAString& aTextAlign);
void SetTextAlign(const nsAString& aTextAlign);
void GetTextBaseline(nsAString& aTextBaseline);
void SetTextBaseline(const nsAString& aTextBaseline);
void GetDirection(nsAString& aDirection);
void SetDirection(const nsAString& aDirection);
void GetFontKerning(nsAString& aFontKerning);
void SetFontKerning(const nsAString& aFontKerning);
void ClosePath() override {
EnsureWritablePath();
if (mPathBuilder) {
mPathBuilder->Close();
} else {
mDSPathBuilder->Close();
}
}
void MoveTo(double aX, double aY) override {
EnsureWritablePath();
if (mPathBuilder) {
mPathBuilder->MoveTo(mozilla::gfx::Point(ToFloat(aX), ToFloat(aY)));
} else {
mDSPathBuilder->MoveTo(mTarget->GetTransform().TransformPoint(
mozilla::gfx::Point(ToFloat(aX), ToFloat(aY))));
}
}
void LineTo(double aX, double aY) override {
EnsureWritablePath();
LineTo(mozilla::gfx::Point(ToFloat(aX), ToFloat(aY)));
}
void QuadraticCurveTo(double aCpx, double aCpy, double aX,
double aY) override {
EnsureWritablePath();
if (mPathBuilder) {
mPathBuilder->QuadraticBezierTo(
mozilla::gfx::Point(ToFloat(aCpx), ToFloat(aCpy)),
mozilla::gfx::Point(ToFloat(aX), ToFloat(aY)));
} else {
mozilla::gfx::Matrix transform = mTarget->GetTransform();
mDSPathBuilder->QuadraticBezierTo(
transform.TransformPoint(
mozilla::gfx::Point(ToFloat(aCpx), ToFloat(aCpy))),
transform.TransformPoint(
mozilla::gfx::Point(ToFloat(aX), ToFloat(aY))));
}
}
void BezierCurveTo(double aCp1x, double aCp1y, double aCp2x, double aCp2y,
double aX, double aY) override {
EnsureWritablePath();
BezierTo(mozilla::gfx::Point(ToFloat(aCp1x), ToFloat(aCp1y)),
mozilla::gfx::Point(ToFloat(aCp2x), ToFloat(aCp2y)),
mozilla::gfx::Point(ToFloat(aX), ToFloat(aY)));
}
void ArcTo(double aX1, double aY1, double aX2, double aY2, double aRadius,
mozilla::ErrorResult& aError) override;
void Rect(double aX, double aY, double aW, double aH) override;
void Arc(double aX, double aY, double aRadius, double aStartAngle,
double aEndAngle, bool aAnticlockwise,
mozilla::ErrorResult& aError) override;
void Ellipse(double aX, double aY, double aRadiusX, double aRadiusY,
double aRotation, double aStartAngle, double aEndAngle,
bool aAnticlockwise, ErrorResult& aError) override;
void GetFillRule(nsAString& aFillRule);
void SetFillRule(const nsAString& aFillRule);
void SetLineDash(const Sequence<double>& aSegments,
mozilla::ErrorResult& aRv) override;
void GetLineDash(nsTArray<double>& aSegments) const override;
void SetLineDashOffset(double aOffset) override;
double LineDashOffset() const override;
void GetMozTextStyle(nsACString& aMozTextStyle) { GetFont(aMozTextStyle); }
void SetMozTextStyle(const nsACString& aMozTextStyle,
mozilla::ErrorResult& aError) {
SetFont(aMozTextStyle, aError);
}
bool ImageSmoothingEnabled() override {
return CurrentState().imageSmoothingEnabled;
}
void SetImageSmoothingEnabled(bool aImageSmoothingEnabled) override {
if (aImageSmoothingEnabled != CurrentState().imageSmoothingEnabled) {
CurrentState().imageSmoothingEnabled = aImageSmoothingEnabled;
}
}
void DrawWindow(nsGlobalWindowInner& aWindow, double aX, double aY, double aW,
double aH, const nsACString& aBgColor, uint32_t aFlags,
nsIPrincipal& aSubjectPrincipal,
mozilla::ErrorResult& aError);
// Eventually this should be deprecated. Keeping for now to keep the binding
// functional.
void Demote();
nsresult Redraw();
gfx::IntSize GetSize() const { return gfx::IntSize(mWidth, mHeight); }
virtual int32_t GetWidth() override { return GetSize().width; }
virtual int32_t GetHeight() override { return GetSize().height; }
// nsICanvasRenderingContextInternal
/**
* Gets the pres shell from either the canvas element or the doc shell
*/
PresShell* GetPresShell() final;
void Initialize() override;
NS_IMETHOD SetDimensions(int32_t aWidth, int32_t aHeight) override;
NS_IMETHOD InitializeWithDrawTarget(
nsIDocShell* aShell, NotNull<gfx::DrawTarget*> aTarget) override;
NS_IMETHOD GetInputStream(const char* aMimeType,
const nsAString& aEncoderOptions,
nsIInputStream** aStream) override;
already_AddRefed<mozilla::gfx::SourceSurface> GetSurfaceSnapshot(
gfxAlphaType* aOutAlphaType = nullptr) override;
virtual void SetOpaqueValueFromOpaqueAttr(bool aOpaqueAttrValue) override;
bool GetIsOpaque() override { return mOpaque; }
void ResetBitmap(bool aFreeBuffer);
void ResetBitmap() override { ResetBitmap(true); }
bool UpdateWebRenderCanvasData(nsDisplayListBuilder* aBuilder,
WebRenderCanvasData* aCanvasData) override;
bool InitializeCanvasRenderer(nsDisplayListBuilder* aBuilder,
CanvasRenderer* aRenderer) override;
void MarkContextClean() override;
void MarkContextCleanForFrameCapture() override {
mFrameCaptureState = FrameCaptureState::CLEAN;
}
Watchable<FrameCaptureState>* GetFrameCaptureState() override {
return &mFrameCaptureState;
}
// this rect is in canvas device space
void Redraw(const mozilla::gfx::Rect& aR);
NS_IMETHOD Redraw(const gfxRect& aR) override {
Redraw(ToRect(aR));
return NS_OK;
}
NS_IMETHOD SetContextOptions(JSContext* aCx, JS::Handle<JS::Value> aOptions,
ErrorResult& aRvForDictionaryInit) override;
/**
* An abstract base class to be implemented by callers wanting to be notified
* that a refresh has occurred. Callers must ensure an observer is removed
* before it is destroyed.
*/
virtual void DidRefresh() override;
// this rect is in mTarget's current user space
void RedrawUser(const gfxRect& aR);
// nsISupports interface + CC
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SKIPPABLE_WRAPPERCACHE_CLASS(
CanvasRenderingContext2D)
enum class CanvasMultiGetterType : uint8_t {
STRING = 0,
PATTERN = 1,
GRADIENT = 2
};
enum class Style : uint8_t { STROKE = 0, FILL, MAX };
void LineTo(const mozilla::gfx::Point& aPoint) {
if (mPathBuilder) {
mPathBuilder->LineTo(aPoint);
} else {
mDSPathBuilder->LineTo(mTarget->GetTransform().TransformPoint(aPoint));
}
}
void BezierTo(const mozilla::gfx::Point& aCP1,
const mozilla::gfx::Point& aCP2,
const mozilla::gfx::Point& aCP3) {
if (mPathBuilder) {
mPathBuilder->BezierTo(aCP1, aCP2, aCP3);
} else {
mozilla::gfx::Matrix transform = mTarget->GetTransform();
mDSPathBuilder->BezierTo(transform.TransformPoint(aCP1),
transform.TransformPoint(aCP2),
transform.TransformPoint(aCP3));
}
}
virtual UniquePtr<uint8_t[]> GetImageBuffer(int32_t* aFormat) override;
virtual void OnShutdown();
/**
* Update CurrentState().filter with the filter description for
* CurrentState().filterChain.
* Flushes the PresShell, so the world can change if you call this function.
*/
MOZ_CAN_RUN_SCRIPT_BOUNDARY void UpdateFilter();
protected:
nsresult GetImageDataArray(JSContext* aCx, int32_t aX, int32_t aY,
uint32_t aWidth, uint32_t aHeight,
Maybe<nsIPrincipal*> aSubjectPrincipal,
JSObject** aRetval);
void PutImageData_explicit(int32_t aX, int32_t aY, ImageData&,
bool aHasDirtyRect, int32_t aDirtyX,
int32_t aDirtyY, int32_t aDirtyWidth,
int32_t aDirtyHeight, ErrorResult&);
bool CopyBufferProvider(layers::PersistentBufferProvider& aOld,
gfx::DrawTarget& aTarget, gfx::IntRect aCopyRect);
/**
* Internal method to complete initialisation, expects mTarget to have been
* set
*/
nsresult Initialize(int32_t aWidth, int32_t aHeight);
nsresult InitializeWithTarget(mozilla::gfx::DrawTarget* aSurface,
int32_t aWidth, int32_t aHeight);
/**
* The number of living nsCanvasRenderingContexts. When this goes down to
* 0, we free the premultiply and unpremultiply tables, if they exist.
*/
static MOZ_THREAD_LOCAL(uintptr_t) sNumLivingContexts;
static MOZ_THREAD_LOCAL(mozilla::gfx::DrawTarget*) sErrorTarget;
void SetTransformInternal(const mozilla::gfx::Matrix& aTransform);
// Some helpers. Doesn't modify a color on failure.
void SetStyleFromUnion(
const UTF8StringOrCanvasGradientOrCanvasPattern& aValue,
Style aWhichStyle);
void SetStyleFromString(const nsACString& aStr, Style aWhichStyle);
void SetStyleFromGradient(CanvasGradient& aGradient, Style aWhichStyle) {
CurrentState().SetGradientStyle(aWhichStyle, &aGradient);
}
void SetStyleFromPattern(CanvasPattern& aPattern, Style aWhichStyle) {
CurrentState().SetPatternStyle(aWhichStyle, &aPattern);
}
void GetStyleAsUnion(OwningUTF8StringOrCanvasGradientOrCanvasPattern& aValue,
Style aWhichStyle);
// Returns whether a color was successfully parsed.
bool ParseColor(const nsACString& aString, nscolor* aColor);
static void StyleColorToString(const nscolor& aColor, nsACString& aStr);
// Returns whether a filter was successfully parsed.
bool ParseFilter(const nsACString& aString,
StyleOwnedSlice<StyleFilter>& aFilterChain,
ErrorResult& aError);
// Returns whether the font was successfully updated.
bool SetFontInternal(const nsACString& aFont, mozilla::ErrorResult& aError);
// Helper for SetFontInternal in the case where we have no PresShell.
bool SetFontInternalDisconnected(const nsACString& aFont,
mozilla::ErrorResult& aError);
// Clears the target and updates mOpaque based on mOpaqueAttrValue and
// mContextAttributesHasAlpha.
void UpdateIsOpaque();
/**
* Creates the error target, if it doesn't exist
*/
static void EnsureErrorTarget();
/* This function ensures there is a writable pathbuilder available, this
* pathbuilder may be working in user space or in device space or
* device space.
* After calling this function mPathTransformWillUpdate will be false
*/
void EnsureWritablePath();
// Ensures a path in UserSpace is available.
void EnsureUserSpacePath(
const CanvasWindingRule& aWinding = CanvasWindingRule::Nonzero);
/**
* Needs to be called before updating the transform. This makes a call to
* EnsureTarget() so you don't have to.
*/
void TransformWillUpdate();
// Report the fillRule has changed.
void FillRuleChanged();
/**
* Create the backing surfacing, if it doesn't exist. If there is an error
* in creating the target then it will put sErrorTarget in place. If there
* is in turn an error in creating the sErrorTarget then they would both
* be null so IsTargetValid() would still return null.
*
* Returns true on success.
*/
bool EnsureTarget(const gfx::Rect* aCoveredRect = nullptr,
bool aWillClear = false);
void RestoreClipsAndTransformToTarget();
bool TryAcceleratedTarget(
RefPtr<gfx::DrawTarget>& aOutDT,
RefPtr<layers::PersistentBufferProvider>& aOutProvider);
bool TrySharedTarget(RefPtr<gfx::DrawTarget>& aOutDT,
RefPtr<layers::PersistentBufferProvider>& aOutProvider);
bool TryBasicTarget(RefPtr<gfx::DrawTarget>& aOutDT,
RefPtr<layers::PersistentBufferProvider>& aOutProvider);
void RegisterAllocation();
void SetInitialState();
void SetErrorState();
/**
* This method is run at the end of the event-loop spin where
* ScheduleStableStateCallback was called.
*
* We use it to unlock resources that need to be locked while drawing.
*/
void OnStableState();
/**
* Cf. OnStableState.
*/
void ScheduleStableStateCallback();
/**
* Disposes an old target and prepares to lazily create a new target.
*
* Parameters are the new dimensions to be used, or if either is negative,
* existing dimensions will be left unchanged.
*/
void ClearTarget(int32_t aWidth = -1, int32_t aHeight = -1);
/*
* Returns the target to the buffer provider. i.e. this will queue a frame for
* rendering.
*/
void ReturnTarget(bool aForceReset = false);
/**
* Check if the target is valid after calling EnsureTarget.
*/
bool IsTargetValid() const {
return !!mTarget && mTarget != sErrorTarget.get();
}
/**
* Returns the surface format this canvas should be allocated using. Takes
* into account mOpaque, platform requirements, etc.
*/
mozilla::gfx::SurfaceFormat GetSurfaceFormat() const;
/**
* Returns true if we know for sure that the pattern for a given style is
* opaque. Usefull to know if we can discard the content below in certain
* situations. Optionally checks if the pattern is a color pattern.
*/
bool PatternIsOpaque(Style aStyle, bool* aIsColor = nullptr) const;
SurfaceFromElementResult CachedSurfaceFromElement(Element* aElement);
void DrawImage(const CanvasImageSource& aImgElt, double aSx, double aSy,
double aSw, double aSh, double aDx, double aDy, double aDw,
double aDh, uint8_t aOptional_argc,
mozilla::ErrorResult& aError);
void DrawDirectlyToCanvas(const DirectDrawInfo& aImage,
mozilla::gfx::Rect* aBounds,
mozilla::gfx::Rect aDest, mozilla::gfx::Rect aSrc,
gfx::IntSize aImgSize);
nsCString& GetFont() {
/* will initilize the value if not set, else does nothing */
GetCurrentFontStyle();
return CurrentState().font;
}
// Member vars
int32_t mWidth, mHeight;
// This is true when the canvas is valid, but of zero size, this requires
// specific behavior on some operations.
bool mZero;
// The two ways to set the opaqueness of the canvas.
// mOpaqueAttrValue: Whether the <canvas> element has the moz-opaque attribute
// set. Can change during the lifetime of the context. Non-standard, should
// hopefully go away soon.
// mContextAttributesHasAlpha: The standard way of setting canvas opaqueness.
// Set at context initialization time and never changes.
bool mOpaqueAttrValue;
bool mContextAttributesHasAlpha;
// Determines the context's opaqueness. Is computed from mOpaqueAttrValue and
// mContextAttributesHasAlpha in UpdateIsOpaque().
bool mOpaque;
// This is true when the next time our layer is retrieved we need to
// recreate it (i.e. our backing surface changed)
bool mResetLayer;
// This is needed for drawing in drawAsyncXULElement
bool mIPC;
bool mHasPendingStableStateCallback;
// If mCanvasElement is not provided, then a docshell is
nsCOMPtr<nsIDocShell> mDocShell;
// This is created lazily so it is necessary to call EnsureTarget before
// accessing it. In the event of an error it will be equal to
// sErrorTarget.
RefPtr<mozilla::gfx::DrawTarget> mTarget;
RefPtr<mozilla::layers::PersistentBufferProvider> mBufferProvider;
bool mBufferNeedsClear = false;
// Whether we should try to create an accelerated buffer provider.
bool mAllowAcceleration = true;
RefPtr<CanvasShutdownObserver> mShutdownObserver;
virtual void AddShutdownObserver();
virtual void RemoveShutdownObserver();
virtual bool AlreadyShutDown() const { return !mShutdownObserver; }
/**
* Flag to avoid duplicate calls to InvalidateFrame. Set to true whenever
* Redraw is called, reset to false when Render is called.
*/
bool mIsEntireFrameInvalid;
/**
* When this is set, the first call to Redraw(gfxRect) should set
* mIsEntireFrameInvalid since we expect it will be followed by
* many more Redraw calls.
*/
bool mPredictManyRedrawCalls;
/**
* Flag to avoid unnecessary surface copies to FrameCaptureListeners in the
* case when the canvas is not currently being drawn into and not rendered
* but canvas capturing is still ongoing.
*/
Watchable<FrameCaptureState> mFrameCaptureState;
/**
* We also have a device space pathbuilder. The reason for this is as
* follows, when a path is being built, but the transform changes, we
* can no longer keep a single path in userspace, considering there's
* several 'user spaces' now. We therefore transform the current path
* into device space, and add all operations to this path in device
* space.
*
* When then finally executing a render, the Azure drawing API expects
* the path to be in userspace. We could then set an identity transform
* on the DrawTarget and do all drawing in device space. This is
* undesirable because it requires transforming patterns, gradients,
* clips, etc. into device space and it would not work for stroking.
* What we do instead is convert the path back to user space when it is
* drawn, and draw it with the current transform. This makes all drawing
* occur correctly.
*
* There's never both a device space path builder and a user space path
* builder present at the same time. There is also never a path and a
* path builder present at the same time. When writing proceeds on an
* existing path the Path is cleared and a new builder is created.
*
* mPath is always in user-space.
*/
RefPtr<mozilla::gfx::Path> mPath;
RefPtr<mozilla::gfx::PathBuilder> mDSPathBuilder;
RefPtr<mozilla::gfx::PathBuilder> mPathBuilder;
bool mPathTransformWillUpdate;
mozilla::gfx::Matrix mPathToDS;
/**
* Number of times we've invalidated before calling redraw
*/
uint32_t mInvalidateCount;
static const uint32_t kCanvasMaxInvalidateCount = 100;
mozilla::intl::Bidi mBidiEngine;
/**
* Returns true if a shadow should be drawn along with a
* drawing operation.
*/
bool NeedToDrawShadow() {
const ContextState& state = CurrentState();
// The spec says we should not draw shadows if the operator is OVER.
// If it's over and the alpha value is zero, nothing needs to be drawn.
return NS_GET_A(state.shadowColor) != 0 &&
(state.shadowBlur != 0.f || state.shadowOffset.x != 0.f ||
state.shadowOffset.y != 0.f);
}
/**
* Returns true if the result of a drawing operation should be
* drawn with a filter.
*/
bool NeedToApplyFilter() {
return EnsureUpdatedFilter().mPrimitives.Length() > 0;
}
/**
* Calls UpdateFilter if the canvas's WriteOnly state has changed between the
* last call to UpdateFilter and now.
*/
const gfx::FilterDescription& EnsureUpdatedFilter() {
bool isWriteOnly = mCanvasElement && mCanvasElement->IsWriteOnly();
if (CurrentState().filterSourceGraphicTainted != isWriteOnly) {
UpdateFilter();
EnsureTarget();
}
MOZ_ASSERT(CurrentState().filterSourceGraphicTainted == isWriteOnly);
return CurrentState().filter;
}
bool NeedToCalculateBounds() {
return NeedToDrawShadow() || NeedToApplyFilter();
}
// text
protected:
enum class TextAlign : uint8_t { START, END, LEFT, RIGHT, CENTER };
enum class TextBaseline : uint8_t {
TOP,
HANGING,
MIDDLE,
ALPHABETIC,
IDEOGRAPHIC,
BOTTOM
};
enum class TextDrawOperation : uint8_t { FILL, STROKE, MEASURE };
enum class TextDirection : uint8_t { LTR, RTL, INHERIT };
// Match values from the style system, so we don't have to bother mapping
// between them when setting up an nsFont.
enum class FontKerning : uint8_t {
AUTO = NS_FONT_KERNING_AUTO,
NORMAL = NS_FONT_KERNING_NORMAL,
NONE = NS_FONT_KERNING_NONE
};
protected:
gfxFontGroup* GetCurrentFontStyle();
/**
* Implementation of the fillText, strokeText, and measure functions with
* the operation abstracted to a flag.
* Returns a TextMetrics object _only_ if the operation is measure;
* drawing operations (fill or stroke) always return nullptr.
*/
TextMetrics* DrawOrMeasureText(const nsAString& aText, float aX, float aY,
const Optional<double>& aMaxWidth,
TextDrawOperation aOp, ErrorResult& aError);
// A clip or a transform, recorded and restored in order.
struct ClipState {
explicit ClipState(mozilla::gfx::Path* aClip) : clip(aClip) {}
explicit ClipState(const mozilla::gfx::Matrix& aTransform)
: transform(aTransform) {}
bool IsClip() const { return !!clip; }
RefPtr<mozilla::gfx::Path> clip;
mozilla::gfx::Matrix transform;
};
// state stack handling
class ContextState {
public:
ContextState();
ContextState(const ContextState& aOther);
~ContextState();
void SetColorStyle(Style aWhichStyle, nscolor aColor);
void SetPatternStyle(Style aWhichStyle, CanvasPattern* aPat);
void SetGradientStyle(Style aWhichStyle, CanvasGradient* aGrad);
/**
* returns true iff the given style is a solid color.
*/
bool StyleIsColor(Style aWhichStyle) const {
return !(patternStyles[aWhichStyle] || gradientStyles[aWhichStyle]);
}
int32_t ShadowBlurRadius() const {
static const gfxFloat GAUSSIAN_SCALE_FACTOR =
(3 * sqrt(2 * M_PI) / 4) * 1.5;
return (int32_t)floor(ShadowBlurSigma() * GAUSSIAN_SCALE_FACTOR + 0.5);
}
mozilla::gfx::Float ShadowBlurSigma() const {
return std::min(SIGMA_MAX, shadowBlur / 2.0f);
}
nsTArray<ClipState> clipsAndTransforms;
RefPtr<gfxFontGroup> fontGroup;
RefPtr<nsAtom> fontLanguage;
nsFont fontFont;
EnumeratedArray<Style, Style::MAX, RefPtr<CanvasGradient>> gradientStyles;
EnumeratedArray<Style, Style::MAX, RefPtr<CanvasPattern>> patternStyles;
EnumeratedArray<Style, Style::MAX, nscolor> colorStyles;
nsCString font;
TextAlign textAlign = TextAlign::START;
TextBaseline textBaseline = TextBaseline::ALPHABETIC;
TextDirection textDirection = TextDirection::INHERIT;
FontKerning fontKerning = FontKerning::AUTO;
nscolor shadowColor = 0;
mozilla::gfx::Matrix transform;
mozilla::gfx::Point shadowOffset;
mozilla::gfx::Float lineWidth = 1.0f;
mozilla::gfx::Float miterLimit = 10.0f;
mozilla::gfx::Float globalAlpha = 1.0f;
mozilla::gfx::Float shadowBlur = 0.0f;
nsTArray<mozilla::gfx::Float> dash;
mozilla::gfx::Float dashOffset = 0.0f;
mozilla::gfx::CompositionOp op = mozilla::gfx::CompositionOp::OP_OVER;
mozilla::gfx::FillRule fillRule = mozilla::gfx::FillRule::FILL_WINDING;
mozilla::gfx::CapStyle lineCap = mozilla::gfx::CapStyle::BUTT;
mozilla::gfx::JoinStyle lineJoin = mozilla::gfx::JoinStyle::MITER_OR_BEVEL;
nsCString filterString{"none"};
StyleOwnedSlice<StyleFilter> filterChain;
// RAII object that we obtain when we start to observer SVG filter elements
// for rendering changes. When released we stop observing the SVG elements.
nsCOMPtr<nsISupports> autoSVGFiltersObserver;
mozilla::gfx::FilterDescription filter;
nsTArray<RefPtr<mozilla::gfx::SourceSurface>> filterAdditionalImages;
// This keeps track of whether the canvas was "tainted" or not when
// we last used a filter. This is a security measure, whereby the
// canvas is flipped to write-only if a cross-origin image is drawn to it.
// This is to stop bad actors from reading back data they shouldn't have
// access to.
//
// This also limits what filters we can apply to the context; in particular
// feDisplacementMap is restricted.
//
// We keep track of this to ensure that if this gets out of sync with the
// tainted state of the canvas itself, we update our filters accordingly.
bool filterSourceGraphicTainted = false;
bool imageSmoothingEnabled = true;
bool fontExplicitLanguage = false;
};
AutoTArray<ContextState, 3> mStyleStack;
inline ContextState& CurrentState() {
return mStyleStack[mStyleStack.Length() - 1];
}
inline const ContextState& CurrentState() const {
return mStyleStack[mStyleStack.Length() - 1];
}
friend class CanvasGeneralPattern;
friend class AdjustedTarget;
friend class AdjustedTargetForShadow;
friend class AdjustedTargetForFilter;
// other helpers
void GetAppUnitsValues(int32_t* aPerDevPixel, int32_t* aPerCSSPixel);
friend struct CanvasBidiProcessor;
friend class CanvasDrawObserver;
friend class ImageBitmap;
void SetWriteOnly();
bool IsWriteOnly() const { return mWriteOnly; }
bool mWriteOnly;
bool mClipsNeedConverting = false;
virtual void AddZoneWaitingForGC();
virtual void AddAssociatedMemory();
virtual void RemoveAssociatedMemory();
};
size_t BindingJSObjectMallocBytes(CanvasRenderingContext2D* aContext);
} // namespace dom
} // namespace mozilla
#endif /* CanvasRenderingContext2D_h */
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