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gecko-dev/dom/canvas/CanvasRenderingContext2D.h

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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 "mozilla/Attributes.h"
#include <vector>
#include "nsICanvasRenderingContextInternal.h"
#include "mozilla/RefPtr.h"
#include "nsColor.h"
#include "mozilla/dom/HTMLCanvasElement.h"
#include "mozilla/dom/HTMLVideoElement.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/dom/BasicRenderingContext2D.h"
#include "mozilla/dom/CanvasGradient.h"
#include "mozilla/dom/CanvasRenderingContext2DBinding.h"
#include "mozilla/dom/CanvasPattern.h"
#include "mozilla/gfx/Rect.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/PresShell.h"
#include "mozilla/UniquePtr.h"
#include "gfx2DGlue.h"
#include "imgIEncoder.h"
#include "nsLayoutUtils.h"
#include "mozilla/EnumeratedArray.h"
#include "FilterSupport.h"
#include "SVGObserverUtils.h"
#include "Layers.h"
#include "nsBidi.h"
class gfxFontGroup;
class nsGlobalWindowInner;
class nsXULElement;
namespace mozilla {
namespace gl {
class SourceSurface;
} // namespace gl
namespace dom {
class
HTMLImageElementOrSVGImageElementOrHTMLCanvasElementOrHTMLVideoElementOrImageBitmap;
typedef HTMLImageElementOrSVGImageElementOrHTMLCanvasElementOrHTMLVideoElementOrImageBitmap
CanvasImageSource;
class ImageBitmap;
class ImageData;
class StringOrCanvasGradientOrCanvasPattern;
class OwningStringOrCanvasGradientOrCanvasPattern;
class TextMetrics;
class CanvasPath;
extern const mozilla::gfx::Float SIGMA_MAX;
template <typename T>
class Optional;
struct CanvasBidiProcessor;
class CanvasRenderingContext2DUserData;
class CanvasDrawObserver;
class CanvasShutdownObserver;
/**
** CanvasRenderingContext2D
**/
class CanvasRenderingContext2D final : public nsICanvasRenderingContextInternal,
public nsWrapperCache,
public BasicRenderingContext2D {
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 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;
void SetTransform(double aM11, double aM12, double aM21, double aM22,
double aDx, double aDy,
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(
OwningStringOrCanvasGradientOrCanvasPattern& aValue) override {
GetStyleAsUnion(aValue, Style::STROKE);
}
void SetStrokeStyle(
const StringOrCanvasGradientOrCanvasPattern& aValue) override {
SetStyleFromUnion(aValue, Style::STROKE);
}
void GetFillStyle(
OwningStringOrCanvasGradientOrCanvasPattern& aValue) override {
GetStyleAsUnion(aValue, Style::FILL);
}
void SetFillStyle(
const StringOrCanvasGradientOrCanvasPattern& 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<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(nsAString& aShadowColor) override {
StyleColorToString(CurrentState().shadowColor, aShadowColor);
}
void GetFilter(nsAString& aFilter) { aFilter = CurrentState().filterString; }
void SetShadowColor(const nsAString& aShadowColor) override;
void SetFilter(const nsAString& 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, const CanvasPath& aPath, double aX,
double aY, const CanvasWindingRule& aWinding,
nsIPrincipal&);
bool IsPointInStroke(JSContext* aCx, double aX, double aY,
nsIPrincipal& aSubjectPrincipal);
bool IsPointInStroke(JSContext* aCx, const CanvasPath& aPath, double aX,
double aY, 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 AddHitRegion(const HitRegionOptions& aOptions,
mozilla::ErrorResult& aError);
void RemoveHitRegion(const nsAString& aId);
void ClearHitRegions();
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* aCx, double aSw,
double aSh,
mozilla::ErrorResult& aError);
already_AddRefed<ImageData> CreateImageData(JSContext* aCx,
ImageData& aImagedata,
mozilla::ErrorResult& aError);
already_AddRefed<ImageData> GetImageData(JSContext* aCx, double aSx,
double aSy, double aSw, double aSh,
nsIPrincipal& aSubjectPrincipal,
mozilla::ErrorResult& aError);
void PutImageData(ImageData& aImageData, double aDx, double aDy,
mozilla::ErrorResult& aError);
void PutImageData(ImageData& aImageData, double aDx, double aDy,
double aDirtyX, double aDirtyY, double aDirtyWidth,
double aDirtyHeight, mozilla::ErrorResult& aError);
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(nsAString& aFont) { aFont = GetFont(); }
void SetFont(const nsAString& aFont, mozilla::ErrorResult& aError);
void GetTextAlign(nsAString& aTextAlign);
void SetTextAlign(const nsAString& aTextAlign);
void GetTextBaseline(nsAString& aTextBaseline);
void SetTextBaseline(const nsAString& aTextBaseline);
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 GetMozCurrentTransform(JSContext* aCx,
JS::MutableHandle<JSObject*> aResult,
mozilla::ErrorResult& aError);
void SetMozCurrentTransform(JSContext* aCx,
JS::Handle<JSObject*> aCurrentTransform,
mozilla::ErrorResult& aError);
void GetMozCurrentTransformInverse(JSContext* aCx,
JS::MutableHandle<JSObject*> aResult,
mozilla::ErrorResult& aError);
void SetMozCurrentTransformInverse(JSContext* aCx,
JS::Handle<JSObject*> aCurrentTransform,
mozilla::ErrorResult& aError);
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(nsAString& aMozTextStyle) { GetFont(aMozTextStyle); }
void SetMozTextStyle(const nsAString& 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 nsAString& aBgColor, uint32_t aFlags,
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
*/
nsIPresShell* GetPresShell() final {
if (mCanvasElement) {
return mCanvasElement->OwnerDoc()->GetPresShell();
}
if (mDocShell) {
return mDocShell->GetPresShell();
}
return nullptr;
}
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 char16_t* aEncoderOptions,
nsIInputStream** aStream) override;
already_AddRefed<mozilla::gfx::SourceSurface> GetSurfaceSnapshot(
gfxAlphaType* aOutAlphaType = nullptr) override {
EnsureTarget();
if (aOutAlphaType) {
*aOutAlphaType = (mOpaque ? gfxAlphaType::Opaque : gfxAlphaType::Premult);
}
return mTarget->Snapshot();
}
virtual void SetOpaqueValueFromOpaqueAttr(bool aOpaqueAttrValue) override;
bool GetIsOpaque() override { return mOpaque; }
NS_IMETHOD Reset() override;
already_AddRefed<Layer> GetCanvasLayer(nsDisplayListBuilder* aBuilder,
Layer* aOldLayer,
LayerManager* aManager) override;
bool UpdateWebRenderCanvasData(nsDisplayListBuilder* aBuilder,
WebRenderCanvasData* aCanvasData) override;
bool InitializeCanvasRenderer(nsDisplayListBuilder* aBuilder,
CanvasRenderer* aRenderer) override;
virtual bool ShouldForceInactiveLayer(LayerManager* aManager) override;
void MarkContextClean() override;
void MarkContextCleanForFrameCapture() override;
bool IsContextCleanForFrameCapture() override;
NS_IMETHOD SetIsIPC(bool aIsIPC) override;
// 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_SCRIPT_HOLDER_CLASS(
CanvasRenderingContext2D)
enum class CanvasMultiGetterType : uint8_t {
STRING = 0,
PATTERN = 1,
GRADIENT = 2
};
enum class Style : uint8_t { STROKE = 0, FILL, MAX };
nsINode* GetParentObject() { return mCanvasElement; }
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));
}
}
friend class CanvasRenderingContext2DUserData;
virtual UniquePtr<uint8_t[]> GetImageBuffer(int32_t* aFormat) override;
// Given a point, return hit region ID if it exists
nsString GetHitRegion(const mozilla::gfx::Point& aPoint) override;
// return true and fills in the bound rect if element has a hit region.
bool GetHitRegionRect(Element* aElement, nsRect& aRect) override;
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.
*/
void UpdateFilter();
protected:
nsresult GetImageDataArray(JSContext* aCx, int32_t aX, int32_t aY,
uint32_t aWidth, uint32_t aHeight,
nsIPrincipal& aSubjectPrincipal,
JSObject** aRetval);
nsresult PutImageData_explicit(int32_t aX, int32_t aY, uint32_t aW,
uint32_t aH, dom::Uint8ClampedArray* aArray,
bool aHasDirtyRect, int32_t aDirtyX,
int32_t aDirtyY, int32_t aDirtyWidth,
int32_t aDirtyHeight);
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 uintptr_t sNumLivingContexts;
static mozilla::gfx::DrawTarget* sErrorTarget;
void SetTransformInternal(const mozilla::gfx::Matrix& aTransform);
// Some helpers. Doesn't modify a color on failure.
void SetStyleFromUnion(const StringOrCanvasGradientOrCanvasPattern& aValue,
Style aWhichStyle);
void SetStyleFromString(const nsAString& 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(OwningStringOrCanvasGradientOrCanvasPattern& aValue,
Style aWhichStyle);
// Returns whether a color was successfully parsed.
bool ParseColor(const nsAString& aString, nscolor* aColor);
static void StyleColorToString(const nscolor& aColor, nsAString& aStr);
// Returns whether a filter was successfully parsed.
bool ParseFilter(const nsAString& aString,
nsTArray<nsStyleFilter>& aFilterChain, ErrorResult& aError);
// Returns whether the font was successfully updated.
bool SetFontInternal(const nsAString& 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 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; }
/**
* 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;
nsLayoutUtils::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 nsLayoutUtils::DirectDrawInfo& aImage,
mozilla::gfx::Rect* aBounds,
mozilla::gfx::Rect aDest, mozilla::gfx::Rect aSrc,
gfx::IntSize aImgSize);
nsString& 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;
nsTArray<CanvasRenderingContext2DUserData*> mUserDatas;
// 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;
RefPtr<CanvasShutdownObserver> mShutdownObserver;
void RemoveShutdownObserver();
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.
*/
bool mIsCapturedFrameInvalid;
/**
* 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;
/**
* State information for hit regions
*/
struct RegionInfo {
nsString mId;
// fallback element for a11y
RefPtr<Element> mElement;
// Path of the hit region in the 2d context coordinate space (not user
// space)
RefPtr<gfx::Path> mPath;
};
nsTArray<RegionInfo> mHitRegionsOptions;
nsBidi 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();
}
mozilla::gfx::CompositionOp UsedOperation() {
if (NeedToDrawShadow() || NeedToApplyFilter()) {
// In this case the shadow or filter rendering will use the operator.
return mozilla::gfx::CompositionOp::OP_OVER;
}
return CurrentState().op;
}
// 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 };
protected:
gfxFontGroup* GetCurrentFontStyle();
/**
* Implementation of the fillText, strokeText, and measure functions with
* the operation abstracted to a flag.
*/
nsresult DrawOrMeasureText(const nsAString& aText, float aX, float aY,
const Optional<double>& aMaxWidth,
TextDrawOperation aOp, float* aWidth);
// 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) {
colorStyles[aWhichStyle] = aColor;
gradientStyles[aWhichStyle] = nullptr;
patternStyles[aWhichStyle] = nullptr;
}
void SetPatternStyle(Style aWhichStyle, CanvasPattern* aPat) {
gradientStyles[aWhichStyle] = nullptr;
patternStyles[aWhichStyle] = aPat;
}
void SetGradientStyle(Style aWhichStyle, CanvasGradient* aGrad) {
gradientStyles[aWhichStyle] = aGrad;
patternStyles[aWhichStyle] = nullptr;
}
/**
* 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;
nsString font;
TextAlign textAlign = TextAlign::START;
TextBaseline textBaseline = TextBaseline::ALPHABETIC;
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;
nsString filterString = nsString(u"none");
nsTArray<nsStyleFilter> 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) {
// If we don't have a canvas element, we just return something generic.
int32_t devPixel = 60;
int32_t cssPixel = 60;
nsIPresShell* ps = GetPresShell();
nsPresContext* pc;
if (!ps) goto FINISH;
pc = ps->GetPresContext();
if (!pc) goto FINISH;
devPixel = pc->AppUnitsPerDevPixel();
cssPixel = AppUnitsPerCSSPixel();
FINISH:
if (aPerDevPixel) *aPerDevPixel = devPixel;
if (aPerCSSPixel) *aPerCSSPixel = cssPixel;
}
friend struct CanvasBidiProcessor;
friend class CanvasDrawObserver;
friend class ImageBitmap;
void SetWriteOnly();
bool IsWriteOnly() const { return mWriteOnly; }
bool mWriteOnly;
};
size_t BindingJSObjectMallocBytes(CanvasRenderingContext2D* aContext);
} // namespace dom
} // namespace mozilla
#endif /* CanvasRenderingContext2D_h */
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