Move SkPaint mangement for 2D canvas into CanvasRenderingContext2DState

Source/core/html/canvas/CanvasRenderingContext2DState.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2DState.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2DState.cpp b/Source/core/html/canvas/CanvasRenderingContext2DState.cpp
index 5eb0ab5e6835166a51fd77dfa0922ae647fd27b5..7e33d9d40ef0449bcfb44a7adae96a6d30461ea9 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2DState.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2DState.cpp
@@ -10,7 +10,10 @@
 #include "core/html/canvas/CanvasGradient.h"
 #include "core/html/canvas/CanvasPattern.h"
 #include "core/html/canvas/CanvasStyle.h"
+#include "platform/graphics/DrawLooperBuilder.h"
 #include "platform/graphics/skia/SkiaUtils.h"
+#include "third_party/skia/include/effects/SkDashPathEffect.h"
+#include "third_party/skia/include/effects/SkDropShadowImageFilter.h"
 
 static const char defaultFont[] = "10px sans-serif";
 
@@ -18,27 +21,33 @@ namespace blink {
 
 CanvasRenderingContext2DState::CanvasRenderingContext2DState()
     : m_unrealizedSaveCount(0)
-    , m_strokeStyle(CanvasStyle::createFromRGBA(Color::black))
-    , m_fillStyle(CanvasStyle::createFromRGBA(Color::black))
-    , m_lineWidth(1)
-    , m_lineCap(ButtCap)
-    , m_lineJoin(MiterJoin)
-    , m_miterLimit(10)
+    , m_strokeStyle(CanvasStyle::createFromRGBA(SK_ColorBLACK))
+    , m_fillStyle(CanvasStyle::createFromRGBA(SK_ColorBLACK))
     , m_shadowBlur(0)
     , m_shadowColor(Color::transparent)
     , m_globalAlpha(1)
-    , m_globalComposite(SkXfermode::kSrcOver_Mode)
-    , m_isTransformInvertible(true)
     , m_lineDashOffset(0)
-    , m_imageSmoothingEnabled(true)
+    , m_unparsedFont(defaultFont)
     , m_textAlign(StartTextAlign)
     , m_textBaseline(AlphabeticTextBaseline)
     , m_direction(DirectionInherit)
-    , m_unparsedFont(defaultFont)
     , m_realizedFont(false)
+    , m_isTransformInvertible(true)
     , m_hasClip(false)
     , m_hasComplexClip(false)
+    , m_fillStyleDirty(true)
+    , m_strokeStyleDirty(true)
+    , m_lineDashDirty(false)
 {
+    m_fillPaint.setStyle(SkPaint::kFill_Style);
+    m_fillPaint.setAntiAlias(true);
+    m_strokePaint.setStyle(SkPaint::kStroke_Style);
+    m_strokePaint.setStrokeWidth(1);
+    m_strokePaint.setStrokeCap(SkPaint::kButt_Cap);
+    m_strokePaint.setStrokeMiter(10);
+    m_strokePaint.setStrokeJoin(SkPaint::kMiter_Join);
+    m_strokePaint.setAntiAlias(true);
+    setImageSmoothingEnabled(true);
 }
 
 CanvasRenderingContext2DState::CanvasRenderingContext2DState(const CanvasRenderingContext2DState& other, ClipListCopyMode mode)
@@ -48,27 +57,31 @@ CanvasRenderingContext2DState::CanvasRenderingContext2DState(const CanvasRenderi
     , m_unparsedFillColor(other.m_unparsedFillColor)
     , m_strokeStyle(other.m_strokeStyle)
     , m_fillStyle(other.m_fillStyle)
-    , m_lineWidth(other.m_lineWidth)
-    , m_lineCap(other.m_lineCap)
-    , m_lineJoin(other.m_lineJoin)
-    , m_miterLimit(other.m_miterLimit)
+    , m_strokePaint(other.m_strokePaint)
+    , m_fillPaint(other.m_fillPaint)
     , m_shadowOffset(other.m_shadowOffset)
     , m_shadowBlur(other.m_shadowBlur)
     , m_shadowColor(other.m_shadowColor)
+    , m_emptyDrawLooper(other.m_emptyDrawLooper)
+    , m_shadowOnlyDrawLooper(other.m_shadowOnlyDrawLooper)
+    , m_shadowAndForegroundDrawLooper(other.m_shadowAndForegroundDrawLooper)
+    , m_shadowOnlyImageFilter(other.m_shadowOnlyImageFilter)
+    , m_shadowAndForegroundImageFilter(other.m_shadowAndForegroundImageFilter)
     , m_globalAlpha(other.m_globalAlpha)
-    , m_globalComposite(other.m_globalComposite)
     , m_transform(other.m_transform)
-    , m_isTransformInvertible(other.m_isTransformInvertible)
     , m_lineDashOffset(other.m_lineDashOffset)
-    , m_imageSmoothingEnabled(other.m_imageSmoothingEnabled)
+    , m_unparsedFont(other.m_unparsedFont)
+    , m_font(other.m_font)
     , m_textAlign(other.m_textAlign)
     , m_textBaseline(other.m_textBaseline)
     , m_direction(other.m_direction)
-    , m_unparsedFont(other.m_unparsedFont)
-    , m_font(other.m_font)
     , m_realizedFont(other.m_realizedFont)
+    , m_isTransformInvertible(other.m_isTransformInvertible)
     , m_hasClip(other.m_hasClip)
     , m_hasComplexClip(other.m_hasComplexClip)
+    , m_fillStyleDirty(other.m_fillStyleDirty)
+    , m_strokeStyleDirty(other.m_strokeStyleDirty)
+    , m_lineDashDirty(other.m_lineDashDirty)
 {
     if (mode == CopyClipList) {
         m_clipList = other.m_clipList;
@@ -92,26 +105,31 @@ CanvasRenderingContext2DState& CanvasRenderingContext2DState::operator=(const Ca
     m_unparsedFillColor = other.m_unparsedFillColor;
     m_strokeStyle = other.m_strokeStyle;
     m_fillStyle = other.m_fillStyle;
-    m_lineWidth = other.m_lineWidth;
-    m_lineCap = other.m_lineCap;
-    m_lineJoin = other.m_lineJoin;
-    m_miterLimit = other.m_miterLimit;
+    m_strokePaint = other.m_strokePaint;
+    m_fillPaint = other.m_fillPaint;
     m_shadowOffset = other.m_shadowOffset;
     m_shadowBlur = other.m_shadowBlur;
     m_shadowColor = other.m_shadowColor;
+    m_emptyDrawLooper = other.m_emptyDrawLooper;
+    m_shadowOnlyDrawLooper = other.m_shadowOnlyDrawLooper;
+    m_shadowAndForegroundDrawLooper = other.m_shadowAndForegroundDrawLooper;
+    m_shadowOnlyImageFilter = other.m_shadowOnlyImageFilter;
+    m_shadowAndForegroundImageFilter = other.m_shadowAndForegroundImageFilter;
     m_globalAlpha = other.m_globalAlpha;
-    m_globalComposite = other.m_globalComposite;
     m_transform = other.m_transform;
-    m_isTransformInvertible = other.m_isTransformInvertible;
-    m_imageSmoothingEnabled = other.m_imageSmoothingEnabled;
+    m_lineDashOffset = other.m_lineDashOffset;
+    m_unparsedFont = other.m_unparsedFont;
+    m_font = other.m_font;
     m_textAlign = other.m_textAlign;
     m_textBaseline = other.m_textBaseline;
     m_direction = other.m_direction;
-    m_unparsedFont = other.m_unparsedFont;
-    m_font = other.m_font;
     m_realizedFont = other.m_realizedFont;
+    m_isTransformInvertible = other.m_isTransformInvertible;
     m_hasClip = other.m_hasClip;
     m_hasComplexClip = other.m_hasComplexClip;
+    m_fillStyleDirty = other.m_fillStyleDirty;
+    m_strokeStyleDirty = other.m_strokeStyleDirty;
+    m_lineDashDirty = other.m_lineDashDirty;
     m_clipList = other.m_clipList;
 
     if (m_realizedFont)
@@ -143,6 +161,12 @@ DEFINE_TRACE(CanvasRenderingContext2DState)
     CSSFontSelectorClient::trace(visitor);
 }
 
+void CanvasRenderingContext2DState::setLineDashOffset(float offset)
+{
+    m_lineDashOffset = offset;
+    m_lineDashDirty = true;
+}
+
 void CanvasRenderingContext2DState::setLineDash(const Vector<float>& dash)
 {
     m_lineDash = dash;
@@ -150,6 +174,65 @@ void CanvasRenderingContext2DState::setLineDash(const Vector<float>& dash)
     // number of elements is odd
     if (dash.size() % 2)
         m_lineDash.appendVector(dash);
+
+    m_lineDashDirty = true;
+}
+
+void CanvasRenderingContext2DState::updateLineDash() const
+{
+    if (!m_lineDashDirty)
+        return;
+
+    if (m_lineDash.size() == 0) {
+        m_strokePaint.setPathEffect(0);
+    } else {
+        m_strokePaint.setPathEffect(SkDashPathEffect::Create(m_lineDash.data(), m_lineDash.size(), m_lineDashOffset));
+    }
+
+    m_lineDashDirty = false;
+}
+
+void CanvasRenderingContext2DState::setStrokeStyle(PassRefPtrWillBeRawPtr<CanvasStyle> style)
+{
+    m_strokeStyle = style;
+    m_strokeStyleDirty = true;
+}
+
+void CanvasRenderingContext2DState::setFillStyle(PassRefPtrWillBeRawPtr<CanvasStyle> style)
+{
+    m_fillStyle = style;
+    m_fillStyleDirty = true;
+}
+
+void CanvasRenderingContext2DState::updateStrokeStyle() const
+{
+    if (!m_strokeStyleDirty)
+        return;
+
+    int clampedAlpha = clampedAlphaForBlending(m_globalAlpha);
+    ASSERT(m_strokeStyle);
+    m_strokePaint.setShader(m_strokeStyle->shader());
+    m_strokePaint.setColor(scaleAlpha(m_strokeStyle->paintColor(), clampedAlpha));
+    m_strokeStyleDirty = false;
+}
+
+void CanvasRenderingContext2DState::updateFillStyle() const
+{
+    if (!m_fillStyleDirty)
+        return;
+
+    int clampedAlpha = clampedAlphaForBlending(m_globalAlpha);
+    ASSERT(m_fillStyle);
+    m_fillPaint.setShader(m_fillStyle->shader());
+    m_fillPaint.setColor(scaleAlpha(m_fillStyle->paintColor(), clampedAlpha));
+    m_fillStyleDirty = false;
+}
+
+void CanvasRenderingContext2DState::setGlobalAlpha(float alpha)
+{
+    m_globalAlpha = alpha;
+    m_strokeStyleDirty = true;
+    m_fillStyleDirty = true;
 }
 
 void CanvasRenderingContext2DState::clipPath(const SkPath& path, AntiAliasingMode antiAliasingMode)
@@ -190,4 +273,163 @@ void CanvasRenderingContext2DState::resetTransform()
     m_isTransformInvertible = true;
 }
 
+SkDrawLooper* CanvasRenderingContext2DState::emptyDrawLooper() const
+{
+    if (!m_emptyDrawLooper) {
+        OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
+        m_emptyDrawLooper = drawLooperBuilder->detachDrawLooper();
+    }
+    return m_emptyDrawLooper.get();
+}
+
+SkDrawLooper* CanvasRenderingContext2DState::shadowOnlyDrawLooper() const
+{
+    if (!m_shadowOnlyDrawLooper) {
+        OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
+        drawLooperBuilder->addShadow(m_shadowOffset, m_shadowBlur, m_shadowColor, DrawLooperBuilder::ShadowIgnoresTransforms, DrawLooperBuilder::ShadowRespectsAlpha);
+        m_shadowOnlyDrawLooper = drawLooperBuilder->detachDrawLooper();
+    }
+    return m_shadowOnlyDrawLooper.get();
+}
+
+SkDrawLooper* CanvasRenderingContext2DState::shadowAndForegroundDrawLooper() const
+{
+    if (!m_shadowAndForegroundDrawLooper) {
+        OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
+        drawLooperBuilder->addShadow(m_shadowOffset, m_shadowBlur, m_shadowColor, DrawLooperBuilder::ShadowIgnoresTransforms, DrawLooperBuilder::ShadowRespectsAlpha);
+        drawLooperBuilder->addUnmodifiedContent();
+        m_shadowAndForegroundDrawLooper = drawLooperBuilder->detachDrawLooper();
+    }
+    return m_shadowAndForegroundDrawLooper.get();
+}
+
+SkImageFilter* CanvasRenderingContext2DState::shadowOnlyImageFilter() const
+{
+    if (!m_shadowOnlyImageFilter) {
+        float sigma = skBlurRadiusToSigma(m_shadowBlur);
+        m_shadowOnlyImageFilter = adoptRef(SkDropShadowImageFilter::Create(m_shadowOffset.width(), m_shadowOffset.height(), sigma, sigma, m_shadowColor, SkDropShadowImageFilter::kDrawShadowOnly_ShadowMode));

[Stephen White, 2015/03/19 20:35:17]

Suggestion: refactor the Create() call into a helper function that takes a mode
and gets the rest from member vars.

[Justin Novosad, 2015/03/19 21:03:36]

Tried it out and backtracked because it adds a dependency on
SkDropShadowImageFilter.h in CanvasRenderingContext2DState.h (for the ShadowMode
enum). The helper has to be a member function to access the member vars.

[Stephen White, 2015/03/19 22:47:54]

Acknowledged.

+    }
+    return m_shadowOnlyImageFilter.get();
+}
+
+SkImageFilter* CanvasRenderingContext2DState::shadowAndForegroundImageFilter() const
+{
+    if (!m_shadowAndForegroundImageFilter) {
+        float sigma = skBlurRadiusToSigma(m_shadowBlur);
+        m_shadowAndForegroundImageFilter = adoptRef(SkDropShadowImageFilter::Create(m_shadowOffset.width(), m_shadowOffset.height(), sigma, sigma, m_shadowColor, SkDropShadowImageFilter::kDrawShadowAndForeground_ShadowMode));
+    }
+    return m_shadowAndForegroundImageFilter.get();
+}
+
+void CanvasRenderingContext2DState::shadowParameterChanged()
+{
+    m_shadowOnlyDrawLooper.clear();
+    m_shadowAndForegroundDrawLooper.clear();
+    m_shadowOnlyImageFilter.clear();
+    m_shadowAndForegroundImageFilter.clear();
+}
+
+void CanvasRenderingContext2DState::setShadowOffsetX(float x)
+{
+    m_shadowOffset.setWidth(x);
+    shadowParameterChanged();
+}
+
+void CanvasRenderingContext2DState::setShadowOffsetY(float y)
+{
+    m_shadowOffset.setHeight(y);
+    shadowParameterChanged();
+}
+
+void CanvasRenderingContext2DState::setShadowBlur(float shadowBlur)
+{
+    m_shadowBlur = shadowBlur;
+    shadowParameterChanged();
+}
+
+void CanvasRenderingContext2DState::setShadowColor(SkColor shadowColor)
+{
+    m_shadowColor = shadowColor;
+    shadowParameterChanged();
+}
+
+void CanvasRenderingContext2DState::setGlobalComposite(SkXfermode::Mode mode)
+{
+    m_strokePaint.setXfermodeMode(mode);
+    m_fillPaint.setXfermodeMode(mode);
+}
+
+SkXfermode::Mode CanvasRenderingContext2DState::globalComposite() const
+{
+    SkXfermode* xferMode = m_strokePaint.getXfermode();
+    SkXfermode::Mode mode;
+    if (!xferMode || !xferMode->asMode(&mode))
+        return SkXfermode::kSrcOver_Mode;
+    return mode;
+}
+
+void CanvasRenderingContext2DState::setImageSmoothingEnabled(bool enabled)
+{
+    SkFilterQuality filterQuality = enabled ? kLow_SkFilterQuality : kNone_SkFilterQuality;
+    m_strokePaint.setFilterQuality(filterQuality);
+    m_fillPaint.setFilterQuality(filterQuality);
+}
+
+bool CanvasRenderingContext2DState::imageSmoothingEnabled() const
+{
+    return m_strokePaint.getFilterQuality() == kLow_SkFilterQuality;
+}
+
+bool CanvasRenderingContext2DState::shouldDrawShadows() const
+{
+    return alphaChannel(m_shadowColor) && (m_shadowBlur || !m_shadowOffset.isZero());
+}
+
+const SkPaint* CanvasRenderingContext2DState::getPaint(CanvasPaintType paintType, ShadowMode shadowMode, CanvasShadowStrategy shadowStrategy) const
+{
+    SkPaint* paint;
+    if (paintType == StrokePaintType) {
+        updateLineDash();
+        updateStrokeStyle();
+        paint = &m_strokePaint;
+    } else {
+        updateFillStyle();
+        paint = &m_fillPaint;
+    }
+
+    if ((!shouldDrawShadows() && shadowMode == DrawShadowAndForeground) || shadowMode == DrawForegroundOnly) {
+        paint->setLooper(0);
+        paint->setImageFilter(0);
+        return paint;
+    }
+
+    if (!shouldDrawShadows() && shadowMode == DrawShadowOnly) {
+        paint->setLooper(emptyDrawLooper()); // draw nothing
+        paint->setImageFilter(0);
+        return paint;
+    }
+
+    if (shadowMode == DrawShadowOnly) {
+        if (shadowStrategy == DrawLooperShadowStrategy) {
+            paint->setLooper(shadowOnlyDrawLooper());
+            paint->setImageFilter(0);
+            return paint;
+        }
+        paint->setLooper(0);
+        paint->setImageFilter(shadowOnlyImageFilter());
+        return paint;
+    }
+
+    ASSERT(shadowMode == DrawShadowAndForeground);
+    if (shadowStrategy == DrawLooperShadowStrategy) {
+        paint->setLooper(shadowAndForegroundDrawLooper());
+        paint->setImageFilter(0);
+        return paint;
+    }
+
+    paint->setLooper(0);
+    paint->setImageFilter(shadowAndForegroundImageFilter());
+    return paint;
+}
+
 } // blink