GlyphOverflow visualOverflowForDecorations(const RenderStyle& lineStyle, const InlineTextBox* inlineTextBox)
{
ASSERT(!inlineTextBox || inlineTextBox->lineStyle() == lineStyle);
TextDecoration decoration = lineStyle.textDecorationsInEffect();
if (decoration == TextDecorationNone)
return GlyphOverflow();
float strokeThickness = textDecorationStrokeThickness(lineStyle.fontSize());
float controlPointDistance;
float step;
float wavyOffset;
TextDecorationStyle decorationStyle = lineStyle.textDecorationStyle();
float height = lineStyle.fontCascade().fontMetrics().floatHeight();
GlyphOverflow overflowResult;
if (decorationStyle == TextDecorationStyleWavy) {
getWavyStrokeParameters(strokeThickness, controlPointDistance, step);
wavyOffset = wavyOffsetFromDecoration();
overflowResult.left = strokeThickness;
overflowResult.right = strokeThickness;
}
// These metrics must match where underlines get drawn.
if (decoration & TextDecorationUnderline) {
// Compensate for the integral ceiling in GraphicsContext::computeLineBoundsAndAntialiasingModeForText()
int underlineOffset = 1;
underlineOffset += computeUnderlineOffset(lineStyle.textUnderlinePosition(), lineStyle.fontMetrics(), inlineTextBox, strokeThickness);
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, underlineOffset + wavyOffset + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(underlineOffset + wavyOffset - controlPointDistance - strokeThickness));
} else {
extendIntToFloat(overflowResult.bottom, underlineOffset + strokeThickness - height);
extendIntToFloat(overflowResult.top, -underlineOffset);
}
}
if (decoration & TextDecorationOverline) {
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, -wavyOffset + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, wavyOffset + controlPointDistance + strokeThickness);
} else {
extendIntToFloat(overflowResult.bottom, strokeThickness - height);
// top is untouched
}
}
if (decoration & TextDecorationLineThrough) {
float baseline = lineStyle.fontMetrics().floatAscent();
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, 2 * baseline / 3 + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(2 * baseline / 3 - controlPointDistance - strokeThickness));
} else {
extendIntToFloat(overflowResult.bottom, 2 * baseline / 3 + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(2 * baseline / 3));
}
}
return overflowResult;
}
/*
* Draw one cubic Bezier curve and repeat the same pattern long the the decoration's axis.
* The start point (p1), controlPoint1, controlPoint2 and end point (p2) of the Bezier curve
* form a diamond shape:
*
* step
* |-----------|
*
* controlPoint1
* +
*
*
* . .
* . .
* . .
* (x1, y1) p1 + . + p2 (x2, y2) - <--- Decoration's axis
* . . |
* . . |
* . . | controlPointDistance
* |
* |
* + -
* controlPoint2
*
* |-----------|
* step
*/
static void strokeWavyTextDecoration(GraphicsContext& context, const FloatPoint& start, const FloatPoint& end, float strokeThickness)
{
FloatPoint p1 = start;
FloatPoint p2 = end;
context.adjustLineToPixelBoundaries(p1, p2, strokeThickness, context.strokeStyle());
Path path;
path.moveTo(p1);
float controlPointDistance;
float step;
getWavyStrokeParameters(strokeThickness, controlPointDistance, step);
bool isVerticalLine = (p1.x() == p2.x());
if (isVerticalLine) {
ASSERT(p1.x() == p2.x());
float xAxis = p1.x();
float y1;
float y2;
if (p1.y() < p2.y()) {
y1 = p1.y();
y2 = p2.y();
} else {
y1 = p2.y();
y2 = p1.y();
}
adjustStepToDecorationLength(step, controlPointDistance, y2 - y1);
FloatPoint controlPoint1(xAxis + controlPointDistance, 0);
FloatPoint controlPoint2(xAxis - controlPointDistance, 0);
for (float y = y1; y + 2 * step <= y2;) {
controlPoint1.setY(y + step);
controlPoint2.setY(y + step);
y += 2 * step;
path.addBezierCurveTo(controlPoint1, controlPoint2, FloatPoint(xAxis, y));
}
} else {
ASSERT(p1.y() == p2.y());
float yAxis = p1.y();
float x1;
float x2;
if (p1.x() < p2.x()) {
x1 = p1.x();
x2 = p2.x();
} else {
x1 = p2.x();
x2 = p1.x();
}
adjustStepToDecorationLength(step, controlPointDistance, x2 - x1);
FloatPoint controlPoint1(0, yAxis + controlPointDistance);
FloatPoint controlPoint2(0, yAxis - controlPointDistance);
for (float x = x1; x + 2 * step <= x2;) {
controlPoint1.setX(x + step);
controlPoint2.setX(x + step);
x += 2 * step;
path.addBezierCurveTo(controlPoint1, controlPoint2, FloatPoint(x, yAxis));
}
}
context.setShouldAntialias(true);
context.strokePath(path);
}
