// Draws the given bitmap to the given canvas. The subset of the source bitmap
// identified by src_rect is drawn to the given destination rect. The bitmap
// will be resampled to resample_width * resample_height (this is the size of
// the whole image, not the subset). See shouldResampleBitmap for more.
//
// This does a lot of computation to resample only the portion of the bitmap
// that will only be drawn. This is critical for performance since when we are
// scrolling, for example, we are only drawing a small strip of the image.
// Resampling the whole image every time is very slow, so this speeds up things
// dramatically.
//
// Note: this code is only used when the canvas transformation is limited to
// scaling or translation.
static void drawResampledBitmap(SkCanvas& canvas, SkPaint& paint, const NativeImageSkia& bitmap, const SkIRect& srcIRect, const SkRect& destRect)
{
#if PLATFORM(CHROMIUM)
TRACE_EVENT0("skia", "drawResampledBitmap");
#endif
// Apply forward transform to destRect to estimate required size of
// re-sampled bitmap, and use only in calls required to resize, or that
// check for the required size.
SkRect destRectTransformed;
canvas.getTotalMatrix().mapRect(&destRectTransformed, destRect);
SkIRect destRectTransformedRounded;
destRectTransformed.round(&destRectTransformedRounded);
// Compute the visible portion of our rect.
SkRect destRectVisibleSubset;
ClipRectToCanvas(canvas, destRect, &destRectVisibleSubset);
// ClipRectToCanvas often overshoots, resulting in a larger region than our
// original destRect. Intersecting gets us back inside.
if (!destRectVisibleSubset.intersect(destRect))
return; // Nothing visible in destRect.
// Compute the image-relative (bitmap space) subset.
SkRect destBitmapSubset = destRectVisibleSubset;
destBitmapSubset.offset(-destRect.x(), -destRect.y());
// Scale the subset to the requested size. The canvas scale can be negative,
// but the resampling code is only interested in positive scaling in its normal space.
SkMatrix subsetTransform;
subsetTransform.setScale(SkScalarAbs(canvas.getTotalMatrix().getScaleX()),
SkScalarAbs(canvas.getTotalMatrix().getScaleY()));
SkRect destBitmapSubsetTransformed;
subsetTransform.mapRect(&destBitmapSubsetTransformed, destBitmapSubset);
SkIRect destBitmapSubsetTransformedRounded;
destBitmapSubsetTransformed.round(&destBitmapSubsetTransformedRounded);
// Transforms above plus rounding may cause destBitmapSubsetTransformedRounded
// to go outside the image, so need to clip to avoid problems.
if (!destBitmapSubsetTransformedRounded.intersect(
0, 0, destRectTransformedRounded.width(), destRectTransformedRounded.height()))
return; // Image is not visible.
SkBitmap resampled = bitmap.resizedBitmap(srcIRect,
destRectTransformedRounded.width(),
destRectTransformedRounded.height(),
destBitmapSubsetTransformedRounded);
canvas.drawBitmapRect(resampled, 0, destRectVisibleSubset, &paint);
}
// Draws the given bitmap to the given canvas. The subset of the source bitmap
// identified by src_rect is drawn to the given destination rect. The bitmap
// will be resampled to resample_width * resample_height (this is the size of
// the whole image, not the subset). See shouldResampleBitmap for more.
//
// This does a lot of computation to resample only the portion of the bitmap
// that will only be drawn. This is critical for performance since when we are
// scrolling, for example, we are only drawing a small strip of the image.
// Resampling the whole image every time is very slow, so this speeds up things
// dramatically.
//
// Note: this code is only used when the canvas transformation is limited to
// scaling or translation.
static void drawResampledBitmap(SkCanvas& canvas, SkPaint& paint, const NativeImageSkia& bitmap, const SkIRect& srcIRect, const SkRect& destRect)
{
#if PLATFORM(CHROMIUM)
TRACE_EVENT("drawResampledBitmap", &canvas, 0);
#endif
// Apply forward transform to destRect to estimate required size of
// re-sampled bitmap, and use only in calls required to resize, or that
// check for the required size.
SkRect destRectTransformed;
canvas.getTotalMatrix().mapRect(&destRectTransformed, destRect);
SkIRect destRectTransformedRounded;
destRectTransformed.round(&destRectTransformedRounded);
// Compute the visible portion of our rect.
SkRect destRectVisibleSubset;
ClipRectToCanvas(canvas, destRect, &destRectVisibleSubset);
// ClipRectToCanvas often overshoots, resulting in a larger region than our
// original destRect. Intersecting gets us back inside.
if (!destRectVisibleSubset.intersect(destRect))
return; // Nothing visible in destRect.
// Compute the transformed (screen space) portion of the visible portion for
// use below.
SkRect destRectVisibleSubsetTransformed;
canvas.getTotalMatrix().mapRect(&destRectVisibleSubsetTransformed, destRectVisibleSubset);
SkRect destBitmapSubsetTransformed = destRectVisibleSubsetTransformed;
destBitmapSubsetTransformed.offset(-destRectTransformed.fLeft,
-destRectTransformed.fTop);
SkIRect destBitmapSubsetTransformedRounded;
destBitmapSubsetTransformed.round(&destBitmapSubsetTransformedRounded);
// Transforms above plus rounding may cause destBitmapSubsetTransformedRounded
// to go outside the image, so need to clip to avoid problems.
if (!destBitmapSubsetTransformedRounded.intersect(
0, 0, destRectTransformedRounded.width(), destRectTransformedRounded.height()))
return; // Image is not visible.
SkBitmap resampled = bitmap.resizedBitmap(srcIRect,
destRectTransformedRounded.width(),
destRectTransformedRounded.height(),
destBitmapSubsetTransformedRounded);
canvas.drawBitmapRect(resampled, 0, destRectVisibleSubset, &paint);
}
// This function is used to scale an image and extract a scaled fragment.
//
// ALGORITHM
//
// Because the scaled image size has to be integers, we approximate the real
// scale with the following formula (only X direction is shown):
//
// scaledImageWidth = round(scaleX * imageRect.width())
// approximateScaleX = scaledImageWidth / imageRect.width()
//
// With this method we maintain a constant scale factor among fragments in
// the scaled image. This allows fragments to stitch together to form the
// full scaled image. The downside is there will be a small difference
// between |scaleX| and |approximateScaleX|.
//
// A scaled image fragment is identified by:
//
// - Scaled image size
// - Scaled image fragment rectangle (IntRect)
//
// Scaled image size has been determined and the next step is to compute the
// rectangle for the scaled image fragment which needs to be an IntRect.
//
// scaledSrcRect = srcRect * (approximateScaleX, approximateScaleY)
// enclosingScaledSrcRect = enclosingIntRect(scaledSrcRect)
//
// Finally we extract the scaled image fragment using
// (scaledImageSize, enclosingScaledSrcRect).
//
static SkBitmap extractScaledImageFragment(const NativeImageSkia& bitmap, const SkRect& srcRect, float scaleX, float scaleY, SkRect* scaledSrcRect, SkIRect* enclosingScaledSrcRect)
{
SkISize imageSize = SkISize::Make(bitmap.bitmap().width(), bitmap.bitmap().height());
SkISize scaledImageSize = SkISize::Make(clampToInteger(roundf(imageSize.width() * scaleX)),
clampToInteger(roundf(imageSize.height() * scaleY)));
SkRect imageRect = SkRect::MakeWH(imageSize.width(), imageSize.height());
SkRect scaledImageRect = SkRect::MakeWH(scaledImageSize.width(), scaledImageSize.height());
SkMatrix scaleTransform;
scaleTransform.setRectToRect(imageRect, scaledImageRect, SkMatrix::kFill_ScaleToFit);
scaleTransform.mapRect(scaledSrcRect, srcRect);
scaledSrcRect->intersect(scaledImageRect);
*enclosingScaledSrcRect = enclosingIntRect(*scaledSrcRect);
// |enclosingScaledSrcRect| can be larger than |scaledImageSize| because
// of float inaccuracy so clip to get inside.
enclosingScaledSrcRect->intersect(SkIRect::MakeSize(scaledImageSize));
return bitmap.resizedBitmap(scaledImageSize, *enclosingScaledSrcRect);
}
void Image::drawPattern(GraphicsContext* context,
const FloatRect& floatSrcRect,
const AffineTransform& patternTransform,
const FloatPoint& phase,
ColorSpace styleColorSpace,
CompositeOperator compositeOp,
const FloatRect& destRect)
{
FloatRect normSrcRect = normalizeRect(floatSrcRect);
if (destRect.isEmpty() || normSrcRect.isEmpty())
return; // nothing to draw
NativeImageSkia* bitmap = nativeImageForCurrentFrame();
if (!bitmap)
return;
SkIRect srcRect = enclosingIntRect(normSrcRect);
// Figure out what size the bitmap will be in the destination. The
// destination rect is the bounds of the pattern, we need to use the
// matrix to see how big it will be.
float destBitmapWidth, destBitmapHeight;
TransformDimensions(patternTransform, srcRect.width(), srcRect.height(),
&destBitmapWidth, &destBitmapHeight);
// Compute the resampling mode.
ResamplingMode resampling;
if (context->platformContext()->isAccelerated() || context->platformContext()->printing())
resampling = RESAMPLE_LINEAR;
else
resampling = computeResamplingMode(context->platformContext(), *bitmap, srcRect.width(), srcRect.height(), destBitmapWidth, destBitmapHeight);
// Load the transform WebKit requested.
SkMatrix matrix(patternTransform);
SkShader* shader;
if (resampling == RESAMPLE_AWESOME) {
// Do nice resampling.
int width = static_cast<int>(destBitmapWidth);
int height = static_cast<int>(destBitmapHeight);
SkBitmap resampled = bitmap->resizedBitmap(srcRect, width, height);
shader = SkShader::CreateBitmapShader(resampled, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
// Since we just resized the bitmap, we need to undo the scale set in
// the image transform.
matrix.setScaleX(SkIntToScalar(1));
matrix.setScaleY(SkIntToScalar(1));
} else {
// No need to do nice resampling.
SkBitmap srcSubset;
bitmap->bitmap().extractSubset(&srcSubset, srcRect);
shader = SkShader::CreateBitmapShader(srcSubset, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
}
// We also need to translate it such that the origin of the pattern is the
// origin of the destination rect, which is what WebKit expects. Skia uses
// the coordinate system origin as the base for the patter. If WebKit wants
// a shifted image, it will shift it from there using the patternTransform.
float adjustedX = phase.x() + normSrcRect.x() *
narrowPrecisionToFloat(patternTransform.a());
float adjustedY = phase.y() + normSrcRect.y() *
narrowPrecisionToFloat(patternTransform.d());
matrix.postTranslate(SkFloatToScalar(adjustedX),
SkFloatToScalar(adjustedY));
shader->setLocalMatrix(matrix);
SkPaint paint;
paint.setShader(shader)->unref();
paint.setXfermodeMode(WebCoreCompositeToSkiaComposite(compositeOp));
paint.setFilterBitmap(resampling == RESAMPLE_LINEAR);
context->platformContext()->paintSkPaint(destRect, paint);
}
// Draws the given bitmap to the given canvas. The subset of the source bitmap
// identified by src_rect is drawn to the given destination rect. The bitmap
// will be resampled to resample_width * resample_height (this is the size of
// the whole image, not the subset). See shouldResampleBitmap for more.
//
// This does a lot of computation to resample only the portion of the bitmap
// that will only be drawn. This is critical for performance since when we are
// scrolling, for example, we are only drawing a small strip of the image.
// Resampling the whole image every time is very slow, so this speeds up things
// dramatically.
static void drawResampledBitmap(SkCanvas& canvas, SkPaint& paint, const NativeImageSkia& bitmap, const SkIRect& srcIRect, const SkRect& destRect)
{
// First get the subset we need. This is efficient and does not copy pixels.
SkBitmap subset;
bitmap.extractSubset(&subset, srcIRect);
SkRect srcRect;
srcRect.set(srcIRect);
// Whether we're doing a subset or using the full source image.
bool srcIsFull = srcIRect.fLeft == 0 && srcIRect.fTop == 0
&& srcIRect.width() == bitmap.width()
&& srcIRect.height() == bitmap.height();
// We will always draw in integer sizes, so round the destination rect.
SkIRect destRectRounded;
destRect.round(&destRectRounded);
SkIRect resizedImageRect = // Represents the size of the resized image.
{ 0, 0, destRectRounded.width(), destRectRounded.height() };
if (srcIsFull && bitmap.hasResizedBitmap(destRectRounded.width(), destRectRounded.height())) {
// Yay, this bitmap frame already has a resized version.
SkBitmap resampled = bitmap.resizedBitmap(destRectRounded.width(), destRectRounded.height());
canvas.drawBitmapRect(resampled, 0, destRect, &paint);
return;
}
// Compute the visible portion of our rect.
SkRect destBitmapSubsetSk;
ClipRectToCanvas(canvas, destRect, &destBitmapSubsetSk);
destBitmapSubsetSk.offset(-destRect.fLeft, -destRect.fTop);
// The matrix inverting, etc. could have introduced rounding error which
// causes the bounds to be outside of the resized bitmap. We round outward
// so we always lean toward it being larger rather than smaller than we
// need, and then clamp to the bitmap bounds so we don't get any invalid
// data.
SkIRect destBitmapSubsetSkI;
destBitmapSubsetSk.roundOut(&destBitmapSubsetSkI);
if (!destBitmapSubsetSkI.intersect(resizedImageRect))
return; // Resized image does not intersect.
if (srcIsFull && bitmap.shouldCacheResampling(
resizedImageRect.width(),
resizedImageRect.height(),
destBitmapSubsetSkI.width(),
destBitmapSubsetSkI.height())) {
// We're supposed to resize the entire image and cache it, even though
// we don't need all of it.
SkBitmap resampled = bitmap.resizedBitmap(destRectRounded.width(),
destRectRounded.height());
canvas.drawBitmapRect(resampled, 0, destRect, &paint);
} else {
// We should only resize the exposed part of the bitmap to do the
// minimal possible work.
// Resample the needed part of the image.
SkBitmap resampled = skia::ImageOperations::Resize(subset,
skia::ImageOperations::RESIZE_LANCZOS3,
destRectRounded.width(), destRectRounded.height(),
destBitmapSubsetSkI);
// Compute where the new bitmap should be drawn. Since our new bitmap
// may be smaller than the original, we have to shift it over by the
// same amount that we cut off the top and left.
destBitmapSubsetSkI.offset(destRect.fLeft, destRect.fTop);
SkRect offsetDestRect;
offsetDestRect.set(destBitmapSubsetSkI);
canvas.drawBitmapRect(resampled, 0, offsetDestRect, &paint);
}
}
void Image::drawPattern(GraphicsContext* context,
const FloatRect& floatSrcRect,
const AffineTransform& patternTransform,
const FloatPoint& phase,
ColorSpace styleColorSpace,
CompositeOperator compositeOp,
const FloatRect& destRect)
{
#if PLATFORM(CHROMIUM)
TRACE_EVENT0("skia", "Image::drawPattern");
#endif
FloatRect normSrcRect = normalizeRect(floatSrcRect);
if (destRect.isEmpty() || normSrcRect.isEmpty())
return; // nothing to draw
NativeImageSkia* bitmap = nativeImageForCurrentFrame();
if (!bitmap)
return;
SkIRect srcRect = enclosingIntRect(normSrcRect);
SkMatrix ctm = context->platformContext()->canvas()->getTotalMatrix();
SkMatrix totalMatrix;
totalMatrix.setConcat(ctm, patternTransform);
// Figure out what size the bitmap will be in the destination. The
// destination rect is the bounds of the pattern, we need to use the
// matrix to see how big it will be.
SkRect destRectTarget;
totalMatrix.mapRect(&destRectTarget, normSrcRect);
float destBitmapWidth = SkScalarToFloat(destRectTarget.width());
float destBitmapHeight = SkScalarToFloat(destRectTarget.height());
// Compute the resampling mode.
ResamplingMode resampling;
if (context->platformContext()->isAccelerated() || context->platformContext()->printing())
resampling = RESAMPLE_LINEAR;
else
resampling = computeResamplingMode(totalMatrix, *bitmap, srcRect.width(), srcRect.height(), destBitmapWidth, destBitmapHeight);
resampling = limitResamplingMode(context->platformContext(), resampling);
// Load the transform WebKit requested.
SkMatrix matrix(patternTransform);
SkShader* shader;
if (resampling == RESAMPLE_AWESOME) {
// Do nice resampling.
int width = static_cast<int>(destBitmapWidth);
int height = static_cast<int>(destBitmapHeight);
SkBitmap resampled = bitmap->resizedBitmap(srcRect, width, height);
shader = SkShader::CreateBitmapShader(resampled, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
// Since we just resized the bitmap, we need to remove the scale
// applied to the pixels in the bitmap shader. This means we need
// CTM * patternTransform to have identity scale. Since we
// can't modify CTM (or the rectangle will be drawn in the wrong
// place), we must set patternTransform's scale to the inverse of
// CTM scale.
matrix.setScaleX(ctm.getScaleX() ? 1 / ctm.getScaleX() : 1);
matrix.setScaleY(ctm.getScaleY() ? 1 / ctm.getScaleY() : 1);
} else {
// No need to do nice resampling.
SkBitmap srcSubset;
bitmap->bitmap().extractSubset(&srcSubset, srcRect);
shader = SkShader::CreateBitmapShader(srcSubset, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
}
// We also need to translate it such that the origin of the pattern is the
// origin of the destination rect, which is what WebKit expects. Skia uses
// the coordinate system origin as the base for the patter. If WebKit wants
// a shifted image, it will shift it from there using the patternTransform.
float adjustedX = phase.x() + normSrcRect.x() *
narrowPrecisionToFloat(patternTransform.a());
float adjustedY = phase.y() + normSrcRect.y() *
narrowPrecisionToFloat(patternTransform.d());
matrix.postTranslate(SkFloatToScalar(adjustedX),
SkFloatToScalar(adjustedY));
shader->setLocalMatrix(matrix);
SkPaint paint;
paint.setShader(shader)->unref();
paint.setXfermodeMode(WebCoreCompositeToSkiaComposite(compositeOp));
paint.setFilterBitmap(resampling == RESAMPLE_LINEAR);
context->platformContext()->paintSkPaint(destRect, paint);
}
