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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "SVGContextPaint.h"
#include "gfxContext.h"
#include "gfxUtils.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/BasePrincipal.h"
#include "mozilla/dom/Document.h"
#include "mozilla/extensions/WebExtensionPolicy.h"
#include "mozilla/StaticPrefs_svg.h"
#include "mozilla/SVGObserverUtils.h"
#include "mozilla/SVGUtils.h"
#include "SVGPaintServerFrame.h"
using namespace mozilla::gfx;
using namespace mozilla::image;
namespace mozilla {
using image::imgDrawingParams;
/* static */
bool SVGContextPaint::IsAllowedForImageFromURI(nsIURI* aURI) {
if (StaticPrefs::svg_context_properties_content_enabled()) {
return true;
// Context paint is pref'ed off for Web content. Ideally we'd have some
// easy means to determine whether the frame that has linked to the image
// is a frame for a content node that originated from Web content.
// Unfortunately different types of anonymous content, about: documents
// such as about:reader, etc. that are "our" code that we ship are
// sometimes hard to distinguish from real Web content. As a result,
// instead of trying to figure out what content is "ours" we instead let
// any content provide image context paint, but only if the image is
// chrome:// or resource:// do we return true. This should be sufficient
// to stop the image context paint feature being useful to (and therefore
// used by and relied upon by) Web content. (We don't want Web content to
// use this feature because we're not sure that image context paint is a
// good mechanism for wider use, or suitable for specification.)
// Because the default favicon used in the browser UI needs context paint, we
// also allow it for:
// - page-icon:<page-url> (used in history and bookmark items)
// - cached-favicon:<page-url> (used in the awesomebar)
// This allowance does also inadvertently expose context-paint to 3rd-party
// favicons, which is not great, but that hasn't caused trouble as far as we
// know. Also: other places such as the tab bar don't use these protocols to
// load favicons, so they help to ensure that 3rd-party favicons don't grow
// to depend on this feature.
// One case that is not covered by chrome:// or resource:// are WebExtensions,
// specifically ones that are "ours". WebExtensions are moz-extension://
// regardless if the extension is in-tree or not. Since we don't want
// extension developers coming to rely on image context paint either, we only
// enable context-paint for extensions that are owned by Mozilla
// (based on the extension permission "internal:svgContextPropertiesAllowed").
// We also allow this for browser UI icons that are served up from
// Mozilla-controlled domains listed in the
// svg.context-properties.content.allowed-domains pref.
nsAutoCString scheme;
if (NS_SUCCEEDED(aURI->GetScheme(scheme)) &&
(scheme.EqualsLiteral("chrome") || scheme.EqualsLiteral("resource") ||
scheme.EqualsLiteral("page-icon") ||
scheme.EqualsLiteral("cached-favicon"))) {
return true;
RefPtr<BasePrincipal> principal =
BasePrincipal::CreateContentPrincipal(aURI, OriginAttributes());
RefPtr<extensions::WebExtensionPolicy> addonPolicy = principal->AddonPolicy();
if (addonPolicy) {
// Only allowed for extensions that have the
// internal:svgContextPropertiesAllowed permission (added internally from
// to Mozilla-owned extensions, see `isMozillaExtension` function
// defined in Extension.sys.mjs for the exact criteria).
return addonPolicy->HasPermission(
bool isInAllowList = false;
return isInAllowList;
* Stores in |aTargetPaint| information on how to reconstruct the current
* fill or stroke pattern. Will also set the paint opacity to transparent if
* the paint is set to "none".
* @param aOuterContextPaint pattern information from the outer text context
* @param aTargetPaint where to store the current pattern information
* @param aFillOrStroke member pointer to the paint we are setting up
static void SetupInheritablePaint(const DrawTarget* aDrawTarget,
const gfxMatrix& aContextMatrix,
nsIFrame* aFrame, float& aOpacity,
SVGContextPaint* aOuterContextPaint,
SVGContextPaintImpl::Paint& aTargetPaint,
StyleSVGPaint nsStyleSVG::*aFillOrStroke,
nscolor aDefaultFallbackColor,
imgDrawingParams& aImgParams) {
const nsStyleSVG* style = aFrame->StyleSVG();
SVGPaintServerFrame* ps =
SVGObserverUtils::GetAndObservePaintServer(aFrame, aFillOrStroke);
if (ps) {
RefPtr<gfxPattern> pattern =
ps->GetPaintServerPattern(aFrame, aDrawTarget, aContextMatrix,
aFillOrStroke, aOpacity, aImgParams);
if (pattern) {
aTargetPaint.SetPaintServer(aFrame, aContextMatrix, ps);
if (aOuterContextPaint) {
RefPtr<gfxPattern> pattern;
auto tag = SVGContextPaintImpl::Paint::Tag::None;
switch ((style->*aFillOrStroke).kind.tag) {
case StyleSVGPaintKind::Tag::ContextFill:
tag = SVGContextPaintImpl::Paint::Tag::ContextFill;
pattern = aOuterContextPaint->GetFillPattern(
aDrawTarget, aOpacity, aContextMatrix, aImgParams);
case StyleSVGPaintKind::Tag::ContextStroke:
tag = SVGContextPaintImpl::Paint::Tag::ContextStroke;
pattern = aOuterContextPaint->GetStrokePattern(
aDrawTarget, aOpacity, aContextMatrix, aImgParams);
if (pattern) {
aTargetPaint.SetContextPaint(aOuterContextPaint, tag);
nscolor color = SVGUtils::GetFallbackOrPaintColor(
*aFrame->Style(), aFillOrStroke, aDefaultFallbackColor);
DrawMode SVGContextPaintImpl::Init(const DrawTarget* aDrawTarget,
const gfxMatrix& aContextMatrix,
nsIFrame* aFrame,
SVGContextPaint* aOuterContextPaint,
imgDrawingParams& aImgParams) {
DrawMode toDraw = DrawMode(0);
const nsStyleSVG* style = aFrame->StyleSVG();
// fill:
if (style->mFill.kind.IsNone()) {
} else {
float opacity =
SVGUtils::GetOpacity(style->mFillOpacity, aOuterContextPaint);
SetupInheritablePaint(aDrawTarget, aContextMatrix, aFrame, opacity,
aOuterContextPaint, mFillPaint, &nsStyleSVG::mFill,
NS_RGB(0, 0, 0), aImgParams);
toDraw |= DrawMode::GLYPH_FILL;
// stroke:
if (style->mStroke.kind.IsNone()) {
} else {
float opacity =
SVGUtils::GetOpacity(style->mStrokeOpacity, aOuterContextPaint);
aDrawTarget, aContextMatrix, aFrame, opacity, aOuterContextPaint,
mStrokePaint, &nsStyleSVG::mStroke, NS_RGBA(0, 0, 0, 0), aImgParams);
toDraw |= DrawMode::GLYPH_STROKE;
return toDraw;
void SVGContextPaint::InitStrokeGeometry(gfxContext* aContext,
float devUnitsPerSVGUnit) {
mStrokeWidth = aContext->CurrentLineWidth() / devUnitsPerSVGUnit;
aContext->CurrentDash(mDashes, &mDashOffset);
for (uint32_t i = 0; i < mDashes.Length(); i++) {
mDashes[i] /= devUnitsPerSVGUnit;
mDashOffset /= devUnitsPerSVGUnit;
SVGContextPaint* SVGContextPaint::GetContextPaint(nsIContent* aContent) {
dom::Document* ownerDoc = aContent->OwnerDoc();
const auto* contextPaint = ownerDoc->GetCurrentContextPaint();
// XXX The SVGContextPaint that Document keeps around is const. We could
// and should keep that constness to the SVGContextPaint that we get here
// (SVGImageContext is never changed after it is initialized).
// Unfortunately lazy initialization of SVGContextPaint (which is a member of
// SVGImageContext, and also conceptually never changes after construction)
// prevents some of SVGContextPaint's conceptually const methods from being
// const. Trying to fix SVGContextPaint (perhaps by using |mutable|) is a
// bit of a headache so for now we punt on that, don't reapply the constness
// to the SVGContextPaint here, and trust that no one will add code that
// actually modifies the object.
return const_cast<SVGContextPaint*>(contextPaint);
already_AddRefed<gfxPattern> SVGContextPaintImpl::GetFillPattern(
const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
imgDrawingParams& aImgParams) {
return mFillPaint.GetPattern(aDrawTarget, aOpacity, &nsStyleSVG::mFill, aCTM,
already_AddRefed<gfxPattern> SVGContextPaintImpl::GetStrokePattern(
const DrawTarget* aDrawTarget, float aOpacity, const gfxMatrix& aCTM,
imgDrawingParams& aImgParams) {
return mStrokePaint.GetPattern(aDrawTarget, aOpacity, &nsStyleSVG::mStroke,
aCTM, aImgParams);
already_AddRefed<gfxPattern> SVGContextPaintImpl::Paint::GetPattern(
const DrawTarget* aDrawTarget, float aOpacity,
StyleSVGPaint nsStyleSVG::*aFillOrStroke, const gfxMatrix& aCTM,
imgDrawingParams& aImgParams) {
RefPtr<gfxPattern> pattern;
if (mPatternCache.Get(aOpacity, getter_AddRefs(pattern))) {
// Set the pattern matrix just in case it was messed with by a previous
// caller. We should get the same matrix each time a pattern is constructed
// so this should be fine.
pattern->SetMatrix(aCTM * mPatternMatrix);
return pattern.forget();
switch (mPaintType) {
case Tag::None:
pattern = new gfxPattern(DeviceColor());
mPatternMatrix = gfxMatrix();
case Tag::Color: {
DeviceColor color = ToDeviceColor(mPaintDefinition.mColor);
color.a *= aOpacity;
pattern = new gfxPattern(color);
mPatternMatrix = gfxMatrix();
case Tag::PaintServer:
pattern = mPaintDefinition.mPaintServerFrame->GetPaintServerPattern(
mFrame, aDrawTarget, mContextMatrix, aFillOrStroke, aOpacity,
if (!pattern) {
return nullptr;
// m maps original-user-space to pattern space
gfxMatrix m = pattern->GetMatrix();
gfxMatrix deviceToOriginalUserSpace = mContextMatrix;
if (!deviceToOriginalUserSpace.Invert()) {
return nullptr;
// mPatternMatrix maps device space to pattern space via original user
// space
mPatternMatrix = deviceToOriginalUserSpace * m;
pattern->SetMatrix(aCTM * mPatternMatrix);
case Tag::ContextFill:
pattern = mPaintDefinition.mContextPaint->GetFillPattern(
aDrawTarget, aOpacity, aCTM, aImgParams);
// Don't cache this. mContextPaint will have cached it anyway. If we
// cache it, we'll have to compute mPatternMatrix, which is annoying.
return pattern.forget();
case Tag::ContextStroke:
pattern = mPaintDefinition.mContextPaint->GetStrokePattern(
aDrawTarget, aOpacity, aCTM, aImgParams);
// Don't cache this. mContextPaint will have cached it anyway. If we
// cache it, we'll have to compute mPatternMatrix, which is annoying.
return pattern.forget();
MOZ_ASSERT(false, "invalid paint type");
return nullptr;
mPatternCache.InsertOrUpdate(aOpacity, RefPtr{pattern});
return pattern.forget();
const SVGContextPaint* aContextPaint, dom::Document* aDocument)
: mDocument(aDocument),
mOuterContextPaint(aDocument->GetCurrentContextPaint()) {
AutoSetRestoreSVGContextPaint::~AutoSetRestoreSVGContextPaint() {
// SVGEmbeddingContextPaint
already_AddRefed<gfxPattern> SVGEmbeddingContextPaint::GetFillPattern(
const DrawTarget* aDrawTarget, float aFillOpacity, const gfxMatrix& aCTM,
imgDrawingParams& aImgParams) {
if (!mFill) {
return nullptr;
// The gfxPattern that we create below depends on aFillOpacity, and since
// different elements in the SVG image may pass in different values for
// fill opacities we don't try to cache the gfxPattern that we create.
DeviceColor fill = *mFill;
fill.a *= aFillOpacity;
return do_AddRef(new gfxPattern(fill));
already_AddRefed<gfxPattern> SVGEmbeddingContextPaint::GetStrokePattern(
const DrawTarget* aDrawTarget, float aStrokeOpacity, const gfxMatrix& aCTM,
imgDrawingParams& aImgParams) {
if (!mStroke) {
return nullptr;
DeviceColor stroke = *mStroke;
stroke.a *= aStrokeOpacity;
return do_AddRef(new gfxPattern(stroke));
uint32_t SVGEmbeddingContextPaint::Hash() const {
uint32_t hash = 0;
if (mFill) {
hash = HashGeneric(hash, mFill->ToABGR());
} else {
// Arbitrary number, just to avoid trivial hash collisions between pairs of
// instances where one embedding context has fill set to the same value as
// another context has stroke set to.
hash = 1;
if (mStroke) {
hash = HashGeneric(hash, mStroke->ToABGR());
if (mFillOpacity != 1.0f) {
hash = HashGeneric(hash, mFillOpacity);
if (mStrokeOpacity != 1.0f) {
hash = HashGeneric(hash, mStrokeOpacity);
return hash;
} // namespace mozilla