Implement canvas2d direction attribute

Source/core/html/canvas/CanvasRenderingContext2D.cpp

Index: Source/core/html/canvas/CanvasRenderingContext2D.cpp
diff --git a/Source/core/html/canvas/CanvasRenderingContext2D.cpp b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
index 68441e75ec978269515f7c29620e4b80a70b64b0..0e6857286b4b217fb400483bc274f61c0b4d8bce 100644
--- a/Source/core/html/canvas/CanvasRenderingContext2D.cpp
+++ b/Source/core/html/canvas/CanvasRenderingContext2D.cpp
@@ -75,6 +75,9 @@ namespace blink {
 static const int defaultFontSize = 10;
 static const char defaultFontFamily[] = "sans-serif";
 static const char defaultFont[] = "10px sans-serif";
+static const char inherit[] = "inherit";
+static const char rtl[] = "rtl";
+static const char ltr[] = "ltr";
 static const double TryRestoreContextInterval = 0.5;
 static const unsigned MaxTryRestoreContextAttempts = 4;
 
@@ -257,6 +260,7 @@ CanvasRenderingContext2D::State::State()
     , m_imageSmoothingEnabled(true)
     , m_textAlign(StartTextAlign)
     , m_textBaseline(AlphabeticTextBaseline)
+    , m_direction(DirectionInherit)
     , m_unparsedFont(defaultFont)
     , m_realizedFont(false)
     , m_hasClip(false)
@@ -286,6 +290,7 @@ CanvasRenderingContext2D::State::State(const State& other)
     , m_imageSmoothingEnabled(other.m_imageSmoothingEnabled)
     , 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)
@@ -325,6 +330,7 @@ CanvasRenderingContext2D::State& CanvasRenderingContext2D::State::operator=(cons
     m_imageSmoothingEnabled = other.m_imageSmoothingEnabled;
     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;
@@ -2017,6 +2023,49 @@ void CanvasRenderingContext2D::setTextBaseline(const String& s)
     modifiableState().m_textBaseline = baseline;
 }
 
+inline TextDirection CanvasRenderingContext2D::toTextDirection(Direction direction, RenderStyle** computedStyle) const
+{
+    RenderStyle* style = (computedStyle || direction == DirectionInherit) ? canvas()->computedStyle() : nullptr;
+    if (computedStyle)
+        *computedStyle = style;
+    switch (direction) {
+    case DirectionInherit:
+        return style ? style->direction() : LTR;
+    case DirectionRTL:
+        return RTL;
+    case DirectionLTR:
+        return LTR;
+    }
+    ASSERT_NOT_REACHED();
+    return LTR;
+}
+
+String CanvasRenderingContext2D::direction() const
+{
+    if (state().m_direction == DirectionInherit)
+        canvas()->document().updateRenderTreeIfNeeded();
+    return toTextDirection(state().m_direction) == RTL ? rtl : ltr;
+}
+
+void CanvasRenderingContext2D::setDirection(const String& directionString)
+{
+    Direction direction;
+    if (directionString == inherit)
+        direction = DirectionInherit;
+    else if (directionString == rtl)
+        direction = DirectionRTL;
+    else if (directionString == ltr)
+        direction = DirectionLTR;
+    else
+        return;
+
+    if (state().m_direction == direction)
+        return;
+
+    realizeSaves();
+    modifiableState().m_direction = direction;
+}
+
 void CanvasRenderingContext2D::fillText(const String& text, float x, float y)
 {
     drawTextInternal(text, x, y, true);
@@ -2143,8 +2192,8 @@ void CanvasRenderingContext2D::drawTextInternal(const String& text, float x, flo
 
     // FIXME: Need to turn off font smoothing.
 
-    RenderStyle* computedStyle = canvas()->computedStyle();
-    TextDirection direction = computedStyle ? computedStyle->direction() : LTR;
+    RenderStyle* computedStyle;
+    TextDirection direction = toTextDirection(state().m_direction, &computedStyle);
     bool isRTL = direction == RTL;
     bool override = computedStyle ? isOverride(computedStyle->unicodeBidi()) : false;