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/*
* Copyright (c) 2008, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "GraphicsContext.h"
#include "ImageBuffer.h"
#include "NativeImageSkia.h"
#include "PlatformContextSkia.h"
#include "SkiaUtils.h"
#include "skia/ext/image_operations.h"
#include "skia/ext/platform_canvas.h"
#include "SkBitmap.h"
#include "SkColorPriv.h"
#include "SkShader.h"
#include "SkDashPathEffect.h"
#include <wtf/MathExtras.h>
#include <wtf/Vector.h>
namespace WebCore
{
extern bool isPathSkiaSafe(const SkMatrix& transform, const SkPath& path);
}
// State -----------------------------------------------------------------------
// Encapsulates the additional painting state information we store for each
// pushed graphics state.
struct PlatformContextSkia::State {
State();
State(const State&);
~State();
// Common shader state.
float m_alpha;
SkXfermode::Mode m_xferMode;
bool m_useAntialiasing;
SkDrawLooper* m_looper;
// Fill.
SkColor m_fillColor;
SkShader* m_fillShader;
// Stroke.
WebCore::StrokeStyle m_strokeStyle;
SkColor m_strokeColor;
SkShader* m_strokeShader;
float m_strokeThickness;
int m_dashRatio; // Ratio of the length of a dash to its width.
float m_miterLimit;
SkPaint::Cap m_lineCap;
SkPaint::Join m_lineJoin;
SkDashPathEffect* m_dash;
// Text. (See cTextFill & friends in GraphicsContext.h.)
int m_textDrawingMode;
// Helper function for applying the state's alpha value to the given input
// color to produce a new output color.
SkColor applyAlpha(SkColor) const;
#if OS(LINUX) || OS(WINDOWS)
// If non-empty, the current State is clipped to this image.
SkBitmap m_imageBufferClip;
// If m_imageBufferClip is non-empty, this is the region the image is clipped to.
WebCore::FloatRect m_clip;
#endif
// This is a list of clipping paths which are currently active, in the
// order in which they were pushed.
WTF::Vector<SkPath> m_antiAliasClipPaths;
private:
// Not supported.
void operator=(const State&);
};
// Note: Keep theses default values in sync with GraphicsContextState.
PlatformContextSkia::State::State()
: m_alpha(1)
, m_xferMode(SkXfermode::kSrcOver_Mode)
, m_useAntialiasing(true)
, m_looper(0)
, m_fillColor(0xFF000000)
, m_fillShader(0)
, m_strokeStyle(WebCore::SolidStroke)
, m_strokeColor(WebCore::Color::black)
, m_strokeShader(0)
, m_strokeThickness(0)
, m_dashRatio(3)
, m_miterLimit(4)
, m_lineCap(SkPaint::kDefault_Cap)
, m_lineJoin(SkPaint::kDefault_Join)
, m_dash(0)
, m_textDrawingMode(WebCore::cTextFill)
{
}
PlatformContextSkia::State::State(const State& other)
: m_alpha(other.m_alpha)
, m_xferMode(other.m_xferMode)
, m_useAntialiasing(other.m_useAntialiasing)
, m_looper(other.m_looper)
, m_fillColor(other.m_fillColor)
, m_fillShader(other.m_fillShader)
, m_strokeStyle(other.m_strokeStyle)
, m_strokeColor(other.m_strokeColor)
, m_strokeShader(other.m_strokeShader)
, m_strokeThickness(other.m_strokeThickness)
, m_dashRatio(other.m_dashRatio)
, m_miterLimit(other.m_miterLimit)
, m_lineCap(other.m_lineCap)
, m_lineJoin(other.m_lineJoin)
, m_dash(other.m_dash)
, m_textDrawingMode(other.m_textDrawingMode)
#if OS(LINUX) || OS(WINDOWS)
, m_imageBufferClip(other.m_imageBufferClip)
, m_clip(other.m_clip)
#endif
{
// Up the ref count of these. saveRef does nothing if 'this' is NULL.
m_looper->safeRef();
m_dash->safeRef();
m_fillShader->safeRef();
m_strokeShader->safeRef();
}
PlatformContextSkia::State::~State()
{
m_looper->safeUnref();
m_dash->safeUnref();
m_fillShader->safeUnref();
m_strokeShader->safeUnref();
}
SkColor PlatformContextSkia::State::applyAlpha(SkColor c) const
{
int s = roundf(m_alpha * 256);
if (s >= 256)
return c;
if (s < 0)
return 0;
int a = SkAlphaMul(SkColorGetA(c), s);
return (c & 0x00FFFFFF) | (a << 24);
}
// PlatformContextSkia ---------------------------------------------------------
// Danger: canvas can be NULL.
PlatformContextSkia::PlatformContextSkia(skia::PlatformCanvas* canvas)
: m_canvas(canvas)
#if OS(WINDOWS)
, m_drawingToImageBuffer(false)
#endif
{
m_stateStack.append(State());
m_state = &m_stateStack.last();
}
PlatformContextSkia::~PlatformContextSkia()
{
}
void PlatformContextSkia::setCanvas(skia::PlatformCanvas* canvas)
{
m_canvas = canvas;
}
#if OS(WINDOWS)
void PlatformContextSkia::setDrawingToImageBuffer(bool value)
{
m_drawingToImageBuffer = value;
}
bool PlatformContextSkia::isDrawingToImageBuffer() const
{
return m_drawingToImageBuffer;
}
#endif
void PlatformContextSkia::save()
{
m_stateStack.append(*m_state);
m_state = &m_stateStack.last();
#if OS(LINUX) || OS(WINDOWS)
// The clip image only needs to be applied once. Reset the image so that we
// don't attempt to clip multiple times.
m_state->m_imageBufferClip.reset();
#endif
// Save our native canvas.
canvas()->save();
}
#if OS(LINUX) || OS(WINDOWS)
void PlatformContextSkia::beginLayerClippedToImage(const WebCore::FloatRect& rect,
const WebCore::ImageBuffer* imageBuffer)
{
// Skia doesn't support clipping to an image, so we create a layer. The next
// time restore is invoked the layer and |imageBuffer| are combined to
// create the resulting image.
m_state->m_clip = rect;
SkRect bounds = { SkFloatToScalar(rect.x()), SkFloatToScalar(rect.y()),
SkFloatToScalar(rect.right()), SkFloatToScalar(rect.bottom()) };
canvas()->clipRect(bounds);
canvas()->saveLayerAlpha(&bounds, 255,
static_cast<SkCanvas::SaveFlags>(SkCanvas::kHasAlphaLayer_SaveFlag | SkCanvas::kFullColorLayer_SaveFlag));
// Copy off the image as |imageBuffer| may be deleted before restore is invoked.
const SkBitmap* bitmap = imageBuffer->context()->platformContext()->bitmap();
if (!bitmap->pixelRef()) {
// The bitmap owns it's pixels. This happens when we've allocated the
// pixels in some way and assigned them directly to the bitmap (as
// happens when we allocate a DIB). In this case the assignment operator
// does not copy the pixels, rather the copied bitmap ends up
// referencing the same pixels. As the pixels may not live as long as we
// need it to, we copy the image.
bitmap->copyTo(&m_state->m_imageBufferClip, SkBitmap::kARGB_8888_Config);
} else {
// If there is a pixel ref, we can safely use the assignment operator.
m_state->m_imageBufferClip = *bitmap;
}
}
#endif
void PlatformContextSkia::clipPathAntiAliased(const SkPath& clipPath)
{
// If we are currently tracking any anti-alias clip paths, then we already
// have a layer in place and don't need to add another.
bool haveLayerOutstanding = m_state->m_antiAliasClipPaths.size();
// See comments in applyAntiAliasedClipPaths about how this works.
m_state->m_antiAliasClipPaths.append(clipPath);
if (!haveLayerOutstanding) {
SkRect bounds = clipPath.getBounds();
canvas()->saveLayerAlpha(&bounds, 255, static_cast<SkCanvas::SaveFlags>(SkCanvas::kHasAlphaLayer_SaveFlag | SkCanvas::kFullColorLayer_SaveFlag | SkCanvas::kClipToLayer_SaveFlag));
}
}
void PlatformContextSkia::restore()
{
#if OS(LINUX) || OS(WINDOWS)
if (!m_state->m_imageBufferClip.empty()) {
applyClipFromImage(m_state->m_clip, m_state->m_imageBufferClip);
canvas()->restore();
}
#endif
if (!m_state->m_antiAliasClipPaths.isEmpty())
applyAntiAliasedClipPaths(m_state->m_antiAliasClipPaths);
m_stateStack.removeLast();
m_state = &m_stateStack.last();
// Restore our native canvas.
canvas()->restore();
}
void PlatformContextSkia::drawRect(SkRect rect)
{
SkPaint paint;
int fillcolorNotTransparent = m_state->m_fillColor & 0xFF000000;
if (fillcolorNotTransparent) {
setupPaintForFilling(&paint);
canvas()->drawRect(rect, paint);
}
if (m_state->m_strokeStyle != WebCore::NoStroke &&
(m_state->m_strokeColor & 0xFF000000)) {
// We do a fill of four rects to simulate the stroke of a border.
SkColor oldFillColor = m_state->m_fillColor;
// setFillColor() will set the shader to NULL, so save a ref to it now.
SkShader* oldFillShader = m_state->m_fillShader;
oldFillShader->safeRef();
setFillColor(m_state->m_strokeColor);
paint.reset();
setupPaintForFilling(&paint);
SkRect topBorder = { rect.fLeft, rect.fTop, rect.fRight, rect.fTop + 1 };
canvas()->drawRect(topBorder, paint);
SkRect bottomBorder = { rect.fLeft, rect.fBottom - 1, rect.fRight, rect.fBottom };
canvas()->drawRect(bottomBorder, paint);
SkRect leftBorder = { rect.fLeft, rect.fTop + 1, rect.fLeft + 1, rect.fBottom - 1 };
canvas()->drawRect(leftBorder, paint);
SkRect rightBorder = { rect.fRight - 1, rect.fTop + 1, rect.fRight, rect.fBottom - 1 };
canvas()->drawRect(rightBorder, paint);
setFillColor(oldFillColor);
setFillShader(oldFillShader);
oldFillShader->safeUnref();
}
}
void PlatformContextSkia::setupPaintCommon(SkPaint* paint) const
{
#if defined(SK_DEBUG)
{
SkPaint defaultPaint;
SkASSERT(*paint == defaultPaint);
}
#endif
paint->setAntiAlias(m_state->m_useAntialiasing);
paint->setXfermodeMode(m_state->m_xferMode);
paint->setLooper(m_state->m_looper);
}
void PlatformContextSkia::setupPaintForFilling(SkPaint* paint) const
{
setupPaintCommon(paint);
paint->setColor(m_state->applyAlpha(m_state->m_fillColor));
paint->setShader(m_state->m_fillShader);
}
float PlatformContextSkia::setupPaintForStroking(SkPaint* paint, SkRect* rect, int length) const
{
setupPaintCommon(paint);
float width = m_state->m_strokeThickness;
paint->setColor(m_state->applyAlpha(m_state->m_strokeColor));
paint->setShader(m_state->m_strokeShader);
paint->setStyle(SkPaint::kStroke_Style);
paint->setStrokeWidth(SkFloatToScalar(width));
paint->setStrokeCap(m_state->m_lineCap);
paint->setStrokeJoin(m_state->m_lineJoin);
paint->setStrokeMiter(SkFloatToScalar(m_state->m_miterLimit));
if (m_state->m_dash)
paint->setPathEffect(m_state->m_dash);
else {
switch (m_state->m_strokeStyle) {
case WebCore::NoStroke:
case WebCore::SolidStroke:
break;
case WebCore::DashedStroke:
width = m_state->m_dashRatio * width;
// Fall through.
case WebCore::DottedStroke:
// Truncate the width, since we don't want fuzzy dots or dashes.
int dashLength = static_cast<int>(width);
// Subtract off the endcaps, since they're rendered separately.
int distance = length - 2 * static_cast<int>(m_state->m_strokeThickness);
int phase = 1;
if (dashLength > 1) {
// Determine how many dashes or dots we should have.
int numDashes = distance / dashLength;
int remainder = distance % dashLength;
// Adjust the phase to center the dashes within the line.
if (numDashes % 2 == 0) {
// Even: shift right half a dash, minus half the remainder
phase = (dashLength - remainder) / 2;
} else {
// Odd: shift right a full dash, minus half the remainder
phase = dashLength - remainder / 2;
}
}
SkScalar dashLengthSk = SkIntToScalar(dashLength);
SkScalar intervals[2] = { dashLengthSk, dashLengthSk };
paint->setPathEffect(new SkDashPathEffect(intervals, 2, SkIntToScalar(phase)))->unref();
}
}
return width;
}
void PlatformContextSkia::setDrawLooper(SkDrawLooper* dl)
{
SkRefCnt_SafeAssign(m_state->m_looper, dl);
}
void PlatformContextSkia::setMiterLimit(float ml)
{
m_state->m_miterLimit = ml;
}
void PlatformContextSkia::setAlpha(float alpha)
{
m_state->m_alpha = alpha;
}
void PlatformContextSkia::setLineCap(SkPaint::Cap lc)
{
m_state->m_lineCap = lc;
}
void PlatformContextSkia::setLineJoin(SkPaint::Join lj)
{
m_state->m_lineJoin = lj;
}
void PlatformContextSkia::setXfermodeMode(SkXfermode::Mode pdm)
{
m_state->m_xferMode = pdm;
}
void PlatformContextSkia::setFillColor(SkColor color)
{
m_state->m_fillColor = color;
setFillShader(NULL);
}
SkDrawLooper* PlatformContextSkia::getDrawLooper() const
{
return m_state->m_looper;
}
WebCore::StrokeStyle PlatformContextSkia::getStrokeStyle() const
{
return m_state->m_strokeStyle;
}
void PlatformContextSkia::setStrokeStyle(WebCore::StrokeStyle strokeStyle)
{
m_state->m_strokeStyle = strokeStyle;
}
void PlatformContextSkia::setStrokeColor(SkColor strokeColor)
{
m_state->m_strokeColor = strokeColor;
setStrokeShader(NULL);
}
float PlatformContextSkia::getStrokeThickness() const
{
return m_state->m_strokeThickness;
}
void PlatformContextSkia::setStrokeThickness(float thickness)
{
m_state->m_strokeThickness = thickness;
}
void PlatformContextSkia::setStrokeShader(SkShader* strokeShader)
{
if (strokeShader != m_state->m_strokeShader) {
m_state->m_strokeShader->safeUnref();
m_state->m_strokeShader = strokeShader;
m_state->m_strokeShader->safeRef();
}
}
int PlatformContextSkia::getTextDrawingMode() const
{
return m_state->m_textDrawingMode;
}
float PlatformContextSkia::getAlpha() const
{
return m_state->m_alpha;
}
void PlatformContextSkia::setTextDrawingMode(int mode)
{
// cTextClip is never used, so we assert that it isn't set:
// https://bugs.webkit.org/show_bug.cgi?id=21898
ASSERT((mode & WebCore::cTextClip) == 0);
m_state->m_textDrawingMode = mode;
}
void PlatformContextSkia::setUseAntialiasing(bool enable)
{
m_state->m_useAntialiasing = enable;
}
SkColor PlatformContextSkia::effectiveFillColor() const
{
return m_state->applyAlpha(m_state->m_fillColor);
}
SkColor PlatformContextSkia::effectiveStrokeColor() const
{
return m_state->applyAlpha(m_state->m_strokeColor);
}
void PlatformContextSkia::beginPath()
{
m_path.reset();
}
void PlatformContextSkia::addPath(const SkPath& path)
{
m_path.addPath(path, m_canvas->getTotalMatrix());
}
SkPath PlatformContextSkia::currentPathInLocalCoordinates() const
{
SkPath localPath = m_path;
const SkMatrix& matrix = m_canvas->getTotalMatrix();
SkMatrix inverseMatrix;
if (!matrix.invert(&inverseMatrix))
return SkPath();
localPath.transform(inverseMatrix);
return localPath;
}
void PlatformContextSkia::setFillRule(SkPath::FillType fr)
{
m_path.setFillType(fr);
}
void PlatformContextSkia::setFillShader(SkShader* fillShader)
{
if (fillShader != m_state->m_fillShader) {
m_state->m_fillShader->safeUnref();
m_state->m_fillShader = fillShader;
m_state->m_fillShader->safeRef();
}
}
void PlatformContextSkia::setDashPathEffect(SkDashPathEffect* dash)
{
if (dash != m_state->m_dash) {
m_state->m_dash->safeUnref();
m_state->m_dash = dash;
}
}
void PlatformContextSkia::paintSkPaint(const SkRect& rect,
const SkPaint& paint)
{
m_canvas->drawRect(rect, paint);
}
const SkBitmap* PlatformContextSkia::bitmap() const
{
return &m_canvas->getDevice()->accessBitmap(false);
}
bool PlatformContextSkia::isPrinting()
{
return m_canvas->getTopPlatformDevice().IsVectorial();
}
#if OS(LINUX) || OS(WINDOWS)
void PlatformContextSkia::applyClipFromImage(const WebCore::FloatRect& rect, const SkBitmap& imageBuffer)
{
// NOTE: this assumes the image mask contains opaque black for the portions that are to be shown, as such we
// only look at the alpha when compositing. I'm not 100% sure this is what WebKit expects for image clipping.
SkPaint paint;
paint.setXfermodeMode(SkXfermode::kDstIn_Mode);
m_canvas->drawBitmap(imageBuffer, SkFloatToScalar(rect.x()), SkFloatToScalar(rect.y()), &paint);
}
#endif
void PlatformContextSkia::applyAntiAliasedClipPaths(WTF::Vector<SkPath>& paths)
{
// Anti-aliased clipping:
//
// Skia's clipping is 1-bit only. Consider what would happen if it were 8-bit:
// We have a square canvas, filled with white and we declare a circular
// clipping path. Then we fill twice with a black rectangle. The fractional
// pixels would first get the correct color (white * alpha + black * (1 -
// alpha)), but the second fill would apply the alpha to the already
// modified color and the result would be too dark.
//
// This, anti-aliased clipping needs to be performed after the drawing has
// been done. In order to do this, we create a new layer of the canvas in
// clipPathAntiAliased and store the clipping path. All drawing is done to
// the layer's bitmap while it's in effect. When WebKit calls restore() to
// undo the clipping, this function is called.
//
// Here, we walk the list of clipping paths backwards and, for each, we
// clear outside of the clipping path. We only need a single extra layer
// for any number of clipping paths.
//
// When we call restore on the SkCanvas, the layer's bitmap is composed
// into the layer below and we end up with correct, anti-aliased clipping.
SkPaint paint;
paint.setXfermodeMode(SkXfermode::kClear_Mode);
paint.setAntiAlias(true);
paint.setStyle(SkPaint::kFill_Style);
for (size_t i = paths.size() - 1; i < paths.size(); --i) {
paths[i].setFillType(SkPath::kInverseWinding_FillType);
m_canvas->drawPath(paths[i], paint);
}
m_canvas->restore();
}
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