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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
#ifndef TextDrawTarget_h
#define TextDrawTarget_h
#include "mozilla/gfx/2D.h"
#include "mozilla/layers/RenderRootStateManager.h"
#include "mozilla/layers/WebRenderLayerManager.h"
#include "mozilla/layers/WebRenderBridgeChild.h"
#include "mozilla/webrender/WebRenderAPI.h"
#include "mozilla/layers/StackingContextHelper.h"
#include "mozilla/layers/IpcResourceUpdateQueue.h"
namespace mozilla {
namespace layout {
using namespace gfx;
// This class is a fake DrawTarget, used to intercept text draw calls, while
// also collecting up the other aspects of text natively.
//
// When using advanced-layers in nsDisplayText's constructor, we construct this
// and run the full painting algorithm with this as the DrawTarget. This is
// done to avoid having to massively refactor gecko's text painting code (which
// has lots of components shared between other rendering algorithms).
//
// In some phases of the painting algorithm, we can grab the relevant values
// and feed them directly into TextDrawTarget. For instance, selections,
// decorations, and shadows are handled in this manner. In those cases we can
// also short-circuit the painting algorithm to save work.
//
// In other phases, the computed values are sufficiently buried in complex
// code that it's best for us to just intercept the final draw calls. This
// is how we handle computing the glyphs of the main text and text-emphasis
// (see our overloaded FillGlyphs implementation).
//
// To be clear: this is a big hack. With time we hope to refactor the codebase
// so that all the elements of text are handled directly by TextDrawTarget,
// which is to say everything is done like we do selections and shadows now.
// This design is a good step for doing this work incrementally.
//
// This is also likely to be a bit buggy (missing or misinterpreted info)
// while we further develop the design.
//
// TextDrawTarget doesn't yet support all features. See mHasUnsupportedFeatures
// for details.
class TextDrawTarget : public DrawTarget {
public:
explicit TextDrawTarget(wr::DisplayListBuilder& aBuilder,
wr::IpcResourceUpdateQueue& aResources,
const layers::StackingContextHelper& aSc,
layers::RenderRootStateManager* aManager,
nsDisplayItem* aItem, nsRect& aBounds,
bool aCallerDoesSaveRestore = false)
: mCallerDoesSaveRestore(aCallerDoesSaveRestore), mBuilder(aBuilder) {
Reinitialize(aResources, aSc, aManager, aItem, aBounds);
}
// Prevent this from being copied
TextDrawTarget(const TextDrawTarget& src) = delete;
TextDrawTarget& operator=(const TextDrawTarget&) = delete;
~TextDrawTarget() { MOZ_ASSERT(mFinished); }
void Reinitialize(wr::IpcResourceUpdateQueue& aResources,
const layers::StackingContextHelper& aSc,
layers::RenderRootStateManager* aManager,
nsDisplayItem* aItem, nsRect& aBounds) {
mResources = &aResources;
mSc = &aSc;
mManager = aManager;
mHasUnsupportedFeatures = false;
mHasShadows = false;
SetPermitSubpixelAA(true);
// Compute clip/bounds
auto appUnitsPerDevPixel =
aItem->Frame()->PresContext()->AppUnitsPerDevPixel();
LayoutDeviceRect layoutBoundsRect =
LayoutDeviceRect::FromAppUnits(aBounds, appUnitsPerDevPixel);
LayoutDeviceRect layoutClipRect = layoutBoundsRect;
mBoundsRect = wr::ToLayoutRect(layoutBoundsRect);
// Add 1 pixel of dirty area around clip rect to allow us to paint
// antialiased pixels beyond the measured text extents.
layoutClipRect.Inflate(1);
mSize = IntSize::Ceil(layoutClipRect.Width(), layoutClipRect.Height());
mClipStack.ClearAndRetainStorage();
mClipStack.AppendElement(layoutClipRect);
mBackfaceVisible = !aItem->BackfaceIsHidden();
if (!mCallerDoesSaveRestore) {
mBuilder.Save();
}
}
void FoundUnsupportedFeature() { mHasUnsupportedFeatures = true; }
bool CheckHasUnsupportedFeatures() {
MOZ_ASSERT(mCallerDoesSaveRestore);
#ifdef DEBUG
MOZ_ASSERT(!mFinished);
mFinished = true;
#endif
return mHasUnsupportedFeatures;
}
bool Finish() {
MOZ_ASSERT(!mCallerDoesSaveRestore);
#ifdef DEBUG
mFinished = true;
#endif
if (mHasUnsupportedFeatures) {
mBuilder.Restore();
return false;
}
mBuilder.ClearSave();
return true;
}
wr::FontInstanceFlags GetWRGlyphFlags() const { return mWRGlyphFlags; }
void SetWRGlyphFlags(wr::FontInstanceFlags aFlags) { mWRGlyphFlags = aFlags; }
class AutoRestoreWRGlyphFlags {
public:
~AutoRestoreWRGlyphFlags() {
if (mTarget) {
mTarget->SetWRGlyphFlags(mFlags);
}
}
void Save(TextDrawTarget* aTarget) {
// This allows for recursive saves, in case the flags need to be modified
// under multiple conditions (i.e. transforms and synthetic italics),
// since the flags will be restored to the first saved value in the
// destructor on scope exit.
if (!mTarget) {
// Only record the first save with the original flags that will be
// restored.
mTarget = aTarget;
mFlags = aTarget->GetWRGlyphFlags();
} else {
// Ensure that this is actually a recursive save to the same target
MOZ_ASSERT(
mTarget == aTarget,
"Recursive save of WR glyph flags to different TextDrawTargets");
}
}
private:
TextDrawTarget* mTarget = nullptr;
wr::FontInstanceFlags mFlags = {0};
};
// This overload just stores the glyphs/font/color.
void FillGlyphs(ScaledFont* aFont, const GlyphBuffer& aBuffer,
const Pattern& aPattern,
const DrawOptions& aOptions) override {
// Make sure we're only given boring color patterns
MOZ_RELEASE_ASSERT(aOptions.mCompositionOp == CompositionOp::OP_OVER);
MOZ_RELEASE_ASSERT(aOptions.mAlpha == 1.0f);
MOZ_RELEASE_ASSERT(aPattern.GetType() == PatternType::COLOR);
// Make sure the font exists, and can be serialized
MOZ_RELEASE_ASSERT(aFont);
if (!aFont->CanSerialize()) {
FoundUnsupportedFeature();
return;
}
auto* colorPat = static_cast<const ColorPattern*>(&aPattern);
auto color = wr::ToColorF(colorPat->mColor);
MOZ_ASSERT(aBuffer.mNumGlyphs);
auto glyphs = Range<const wr::GlyphInstance>(
reinterpret_cast<const wr::GlyphInstance*>(aBuffer.mGlyphs),
aBuffer.mNumGlyphs);
// MSVC won't let us use offsetof on the following directly so we give it a
// name with typedef
typedef std::remove_reference<decltype(aBuffer.mGlyphs[0])>::type GlyphType;
// Compare gfx::Glyph and wr::GlyphInstance to make sure that they are
// structurally equivalent to ensure that our cast above was ok
static_assert(
std::is_same<decltype(aBuffer.mGlyphs[0].mIndex),
decltype(glyphs[0].index)>() &&
std::is_same<decltype(aBuffer.mGlyphs[0].mPosition.x.value),
decltype(glyphs[0].point.x)>() &&
std::is_same<decltype(aBuffer.mGlyphs[0].mPosition.y.value),
decltype(glyphs[0].point.y)>() &&
offsetof(GlyphType, mIndex) == offsetof(wr::GlyphInstance, index) &&
offsetof(GlyphType, mPosition) ==
offsetof(wr::GlyphInstance, point) &&
offsetof(decltype(aBuffer.mGlyphs[0].mPosition), x) ==
offsetof(decltype(glyphs[0].point), x) &&
offsetof(decltype(aBuffer.mGlyphs[0].mPosition), y) ==
offsetof(decltype(glyphs[0].point), y) &&
std::is_standard_layout<
std::remove_reference<decltype(aBuffer.mGlyphs[0])>>::value &&
std::is_standard_layout<
std::remove_reference<decltype(glyphs[0])>>::value &&
sizeof(aBuffer.mGlyphs[0]) == sizeof(glyphs[0]) &&
sizeof(aBuffer.mGlyphs[0].mPosition) == sizeof(glyphs[0].point),
"glyph buf types don't match");
wr::GlyphOptions glyphOptions;
glyphOptions.render_mode =
wr::ToFontRenderMode(aOptions.mAntialiasMode, GetPermitSubpixelAA());
glyphOptions.flags = mWRGlyphFlags;
mManager->WrBridge()->PushGlyphs(mBuilder, *mResources, glyphs, aFont,
color, *mSc, mBoundsRect, ClipRect(),
mBackfaceVisible, &glyphOptions);
}
void PushClipRect(const Rect& aRect) override {
LayoutDeviceRect rect = LayoutDeviceRect::FromUnknownRect(aRect);
rect = rect.Intersect(mClipStack.LastElement());
mClipStack.AppendElement(rect);
}
void PopClip() override { mClipStack.RemoveLastElement(); }
IntSize GetSize() const override { return mSize; }
void AppendShadow(const wr::Shadow& aShadow, bool aInflate) {
mBuilder.PushShadow(mBoundsRect, ClipRect(), mBackfaceVisible, aShadow,
aInflate);
mHasShadows = true;
}
void TerminateShadows() {
if (mHasShadows) {
mBuilder.PopAllShadows();
mHasShadows = false;
}
}
void AppendSelectionRect(const LayoutDeviceRect& aRect,
const DeviceColor& aColor) {
auto rect = wr::ToLayoutRect(aRect);
auto color = wr::ToColorF(aColor);
mBuilder.PushRect(rect, ClipRect(), mBackfaceVisible, false, false, color);
}
// This function is basically designed to slide into the decoration drawing
// code of nsCSSRendering with minimum disruption, to minimize the
// chances of implementation drift. As such, it mostly looks like a call
// to a skia-style StrokeLine method: two end-points, with a thickness
// and style. Notably the end-points are *centered* in the block direction,
// even though webrender wants a rect-like representation, where the points
// are on corners.
//
// So we mangle the format here in a single centralized place, where neither
// webrender nor nsCSSRendering has to care about this mismatch.
//
// NOTE: we assume the points are axis-aligned, and aStart should be used
// as the top-left corner of the rect.
void AppendDecoration(const Point& aStart, const Point& aEnd,
const float aThickness, const bool aVertical,
const DeviceColor& aColor,
const StyleTextDecorationStyle aStyle) {
auto pos = LayoutDevicePoint::FromUnknownPoint(aStart);
LayoutDeviceSize size;
if (aVertical) {
pos.x -= aThickness / 2; // adjust from center to corner
size = LayoutDeviceSize(aThickness,
ViewAs<LayoutDevicePixel>(aEnd.y - aStart.y));
} else {
pos.y -= aThickness / 2; // adjust from center to corner
size = LayoutDeviceSize(ViewAs<LayoutDevicePixel>(aEnd.x - aStart.x),
aThickness);
}
wr::Line decoration;
decoration.bounds = wr::ToLayoutRect(LayoutDeviceRect(pos, size));
decoration.wavyLineThickness = 0; // dummy value, unused
decoration.color = wr::ToColorF(aColor);
decoration.orientation = aVertical ? wr::LineOrientation::Vertical
: wr::LineOrientation::Horizontal;
switch (aStyle) {
case StyleTextDecorationStyle::Solid:
decoration.style = wr::LineStyle::Solid;
break;
case StyleTextDecorationStyle::Dotted:
decoration.style = wr::LineStyle::Dotted;
break;
case StyleTextDecorationStyle::Dashed:
decoration.style = wr::LineStyle::Dashed;
break;
// Wavy lines should go through AppendWavyDecoration
case StyleTextDecorationStyle::Wavy:
// Double lines should be lowered to two solid lines
case StyleTextDecorationStyle::Double:
default:
MOZ_CRASH("TextDrawTarget received unsupported line style");
}
mBuilder.PushLine(ClipRect(), mBackfaceVisible, decoration);
}
// Seperated out from AppendDecoration because Wavy Lines are completely
// different, and trying to merge the concept is more of a mess than it's
// worth.
void AppendWavyDecoration(const Rect& aBounds, const float aThickness,
const bool aVertical, const DeviceColor& aColor) {
wr::Line decoration;
decoration.bounds =
wr::ToLayoutRect(LayoutDeviceRect::FromUnknownRect(aBounds));
decoration.wavyLineThickness = aThickness;
decoration.color = wr::ToColorF(aColor);
decoration.orientation = aVertical ? wr::LineOrientation::Vertical
: wr::LineOrientation::Horizontal;
decoration.style = wr::LineStyle::Wavy;
mBuilder.PushLine(ClipRect(), mBackfaceVisible, decoration);
}
layers::WebRenderBridgeChild* WrBridge() { return mManager->WrBridge(); }
layers::WebRenderLayerManager* WrLayerManager() {
return mManager->LayerManager();
}
Maybe<wr::ImageKey> DefineImage(const IntSize& aSize, uint32_t aStride,
SurfaceFormat aFormat, const uint8_t* aData) {
wr::ImageKey key = mManager->WrBridge()->GetNextImageKey();
wr::ImageDescriptor desc(aSize, aStride, aFormat);
Range<uint8_t> bytes(const_cast<uint8_t*>(aData), aStride * aSize.height);
if (mResources->AddImage(key, desc, bytes)) {
return Some(key);
}
return Nothing();
}
void PushImage(wr::ImageKey aKey, const Rect& aBounds, const Rect& aClip,
wr::ImageRendering aFilter, const wr::ColorF& aColor) {
if (!aClip.Intersects(GeckoClipRect().ToUnknownRect())) {
return;
}
mBuilder.PushImage(wr::ToLayoutRect(aBounds), wr::ToLayoutRect(aClip), true,
false, aFilter, aKey, true, aColor);
}
LayoutDeviceRect GeckoClipRect() { return mClipStack.LastElement(); }
private:
wr::LayoutRect ClipRect() {
return wr::ToLayoutRect(mClipStack.LastElement());
}
// Whether anything unsupported was encountered. This will result in this
// text being emitted as a blob, which means subpixel-AA can't be used and
// that performance will probably be a bit worse. At this point, we've
// properly implemented everything that shows up a lot, so you can assume
// that the remaining things we don't implement are fairly rare. The complete
// set of things that we don't implement are as follows:
//
// * Unserializable Fonts: WR lives across an IPC boundary
// * Text-Combine-Upright Squishing: no one's really bothered to impl it yet
// * Text-Stroke: not a real standard (exists for webcompat)
// * SVG Glyphs: not a real standard (we got overzealous with svg)
// * Color Glyphs (Emoji) With Transparency: requires us to apply transparency
// with a composited layer (a single emoji can be many single-color glyphs)
//
// The transparent colored-glyphs issue is probably the most valuable to fix,
// since ideally it would also result in us fixing transparency for all
// intersecting glyphs (which currently look bad with or without webrender,
// so there's no fallback like with emoji). Specifically, transparency
// looks bad for "cursive" fonts where glyphs overlap at the seams. Since
// this is more common for non-latin scripts (e.g. मनीष), this amounts to us
// treating non-latin scripts poorly... unless they're emoji. Yikes!
bool mHasUnsupportedFeatures = false;
// The caller promises to call Save/Restore on the builder as needed.
bool mCallerDoesSaveRestore = false;
#ifdef DEBUG
bool mFinished = false;
#endif
// Whether PopAllShadows needs to be called
bool mHasShadows = false;
// Things used to push to webrender
wr::DisplayListBuilder& mBuilder;
wr::IpcResourceUpdateQueue* mResources;
const layers::StackingContextHelper* mSc;
layers::RenderRootStateManager* mManager;
// Computed facts
IntSize mSize;
wr::LayoutRect mBoundsRect;
AutoTArray<LayoutDeviceRect, 3> mClipStack;
bool mBackfaceVisible;
wr::FontInstanceFlags mWRGlyphFlags = {0};
// The rest of this is dummy implementations of DrawTarget's API
public:
DrawTargetType GetType() const override {
return DrawTargetType::SOFTWARE_RASTER;
}
BackendType GetBackendType() const override {
return BackendType::WEBRENDER_TEXT;
}
bool IsRecording() const override { return true; }
already_AddRefed<SourceSurface> Snapshot() override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<SourceSurface> IntoLuminanceSource(
LuminanceType aLuminanceType, float aOpacity) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
void Flush() override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void DrawSurface(SourceSurface* aSurface, const Rect& aDest,
const Rect& aSource, const DrawSurfaceOptions& aSurfOptions,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void DrawFilter(FilterNode* aNode, const Rect& aSourceRect,
const Point& aDestPoint,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void DrawSurfaceWithShadow(SourceSurface* aSurface, const Point& aDest,
const ShadowOptions& aShadow,
CompositionOp aOperator) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void ClearRect(const Rect& aRect) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void CopySurface(SourceSurface* aSurface, const IntRect& aSourceRect,
const IntPoint& aDestination) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void FillRect(const Rect& aRect, const Pattern& aPattern,
const DrawOptions& aOptions = DrawOptions()) override {
MOZ_RELEASE_ASSERT(aPattern.GetType() == PatternType::COLOR);
if (!aRect.Intersects(GeckoClipRect().ToUnknownRect())) {
return;
}
auto rect = wr::ToLayoutRect(LayoutDeviceRect::FromUnknownRect(aRect));
auto color =
wr::ToColorF(static_cast<const ColorPattern&>(aPattern).mColor);
mBuilder.PushRect(rect, ClipRect(), mBackfaceVisible, false, false, color);
}
void StrokeRect(const Rect& aRect, const Pattern& aPattern,
const StrokeOptions& aStrokeOptions,
const DrawOptions& aOptions) override {
MOZ_RELEASE_ASSERT(aPattern.GetType() == PatternType::COLOR &&
aStrokeOptions.mDashLength == 0);
wr::LayoutSideOffsets widths = {
aStrokeOptions.mLineWidth, aStrokeOptions.mLineWidth,
aStrokeOptions.mLineWidth, aStrokeOptions.mLineWidth};
wr::ColorF color =
wr::ToColorF(static_cast<const ColorPattern&>(aPattern).mColor);
wr::BorderSide sides[4] = {{color, wr::BorderStyle::Solid},
{color, wr::BorderStyle::Solid},
{color, wr::BorderStyle::Solid},
{color, wr::BorderStyle::Solid}};
wr::BorderRadius radius = {{0, 0}, {0, 0}, {0, 0}, {0, 0}};
LayoutDeviceRect rect = LayoutDeviceRect::FromUnknownRect(aRect);
rect.Inflate(aStrokeOptions.mLineWidth / 2);
if (!rect.Intersects(GeckoClipRect())) {
return;
}
wr::LayoutRect bounds = wr::ToLayoutRect(rect);
mBuilder.PushBorder(bounds, ClipRect(), true, widths,
Range<const wr::BorderSide>(sides, 4), radius);
}
void StrokeLine(const Point& aStart, const Point& aEnd,
const Pattern& aPattern, const StrokeOptions& aStrokeOptions,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void Stroke(const Path* aPath, const Pattern& aPattern,
const StrokeOptions& aStrokeOptions,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void Fill(const Path* aPath, const Pattern& aPattern,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void StrokeGlyphs(ScaledFont* aFont, const GlyphBuffer& aBuffer,
const Pattern& aPattern,
const StrokeOptions& aStrokeOptions,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void Mask(const Pattern& aSource, const Pattern& aMask,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void MaskSurface(const Pattern& aSource, SourceSurface* aMask, Point aOffset,
const DrawOptions& aOptions) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
bool Draw3DTransformedSurface(SourceSurface* aSurface,
const Matrix4x4& aMatrix) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void PushClip(const Path* aPath) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void PushDeviceSpaceClipRects(const IntRect* aRects,
uint32_t aCount) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
void PushLayer(bool aOpaque, Float aOpacity, SourceSurface* aMask,
const Matrix& aMaskTransform, const IntRect& aBounds,
bool aCopyBackground) override {
// Fine to pretend we do this
}
void PopLayer() override {
// Fine to pretend we do this
}
already_AddRefed<SourceSurface> CreateSourceSurfaceFromData(
unsigned char* aData, const IntSize& aSize, int32_t aStride,
SurfaceFormat aFormat) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<SourceSurface> OptimizeSourceSurface(
SourceSurface* aSurface) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<SourceSurface> CreateSourceSurfaceFromNativeSurface(
const NativeSurface& aSurface) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<DrawTarget> CreateSimilarDrawTarget(
const IntSize& aSize, SurfaceFormat aFormat) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
bool CanCreateSimilarDrawTarget(const IntSize& aSize,
SurfaceFormat aFormat) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return false;
}
virtual RefPtr<DrawTarget> CreateClippedDrawTarget(
const Rect& aBounds, SurfaceFormat aFormat) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<PathBuilder> CreatePathBuilder(
FillRule aFillRule) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<FilterNode> CreateFilter(FilterType aType) override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
already_AddRefed<GradientStops> CreateGradientStops(
GradientStop* aStops, uint32_t aNumStops,
ExtendMode aExtendMode) const override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
return nullptr;
}
void DetachAllSnapshots() override {
MOZ_CRASH("TextDrawTarget: Method shouldn't be called");
}
};
} // namespace layout
} // namespace mozilla
#endif