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SkPDF: Support alpha-only images with maskfilters

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- Handle alpha-only images with maskfilters
  - No longer apply color-filter to alpha-only images (it should apply
    to the paint color/shader composed with the alpha image instead).
  - Alpha-only images without maskfilters do sub-pixel clipping.
  - Non-alpha-only drawImages with maskfilters do sub-pixel clipping.

  * Fixes `alpha_image` GM (output now matches GPU backend).
  * Improves GMs `imagemasksubset` and `shadows`.

BUG=skia:6735

Change-Id: I62a82b4133ae0eb42d6315785bc3d2cb834bd352
Reviewed-on: https://skia-review.googlesource.com/24820
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
This commit is contained in:
Hal Canary 2017-07-19 15:48:38 -04:00 committed by Skia Commit-Bot
parent fa486cf4de
commit f0f4c0c6d5
1 changed files with 49 additions and 30 deletions
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79
src/pdf/SkPDFDevice.cpp
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@ -2286,11 +2286,8 @@ void SkPDFDevice::internalDrawImageRect(SkKeyedImage imageSubset,
return;
}
// First, figure out the src->dst transform and subset the image if needed.
SkIRect bounds = imageSubset.image()->bounds();
SkPaint paint = srcPaint;
if (imageSubset.image()->isOpaque()) {
replace_srcmode_on_opaque_paint(&paint);
}
SkRect srcRect = src ? *src : SkRect::Make(bounds);
SkMatrix transform;
transform.setRectToRect(srcRect, dst, SkMatrix::kFill_ScaleToFit);
@ -2309,21 +2306,36 @@ void SkPDFDevice::internalDrawImageRect(SkKeyedImage imageSubset,
}
}
// TODO(halcanary) support isAlphaOnly & getMaskFilter.
bool imageAlphaOnly = imageSubset.image()->isAlphaOnly() && !paint.getMaskFilter();
if (imageAlphaOnly) {
if (SkColorFilter* colorFilter = paint.getColorFilter()) {
sk_sp<SkImage> img = color_filter(imageSubset.image().get(), colorFilter);
paint.setColorFilter(nullptr);
imageSubset = SkKeyedImage(std::move(img));
if (!imageSubset) {
return;
}
imageAlphaOnly = imageSubset.image()->isAlphaOnly();
// The colorfilter can make a alphonly image no longer be alphaonly.
}
// If the image is opaque and the paint's alpha is too, replace
// kSrc blendmode with kSrcOver.
SkPaint paint = srcPaint;
if (imageSubset.image()->isOpaque()) {
replace_srcmode_on_opaque_paint(&paint);
}
if (imageAlphaOnly) {
// Alpha-only images need to get their color from the shader, before
// applying the colorfilter.
if (imageSubset.image()->isAlphaOnly() && paint.getColorFilter()) {
// must blend alpha image and shader before applying colorfilter.
auto surface =
SkSurface::MakeRaster(SkImageInfo::MakeN32Premul(imageSubset.image()->dimensions()));
SkCanvas* canvas = surface->getCanvas();
SkPaint tmpPaint;
// In the case of alpha images with shaders, the shader's coordinate
// system is the image's coordiantes.
tmpPaint.setShader(sk_ref_sp(paint.getShader()));
tmpPaint.setColor(paint.getColor());
canvas->clear(0x00000000);
canvas->drawImage(imageSubset.image().get(), 0, 0, &tmpPaint);
paint.setShader(nullptr);
imageSubset = SkKeyedImage(surface->makeImageSnapshot());
SkASSERT(!imageSubset.image()->isAlphaOnly());
}
if (imageSubset.image()->isAlphaOnly()) {
// The ColorFilter applies to the paint color/shader, not the alpha layer.
SkASSERT(nullptr == paint.getColorFilter());
sk_sp<SkImage> mask = alpha_image_to_greyscale_image(imageSubset.image().get());
if (!mask) {
return;
@ -2333,12 +2345,24 @@ void SkPDFDevice::internalDrawImageRect(SkKeyedImage imageSubset,
sk_sp<SkPDFDevice> maskDevice = this->makeCongruentDevice();
{
SkCanvas canvas(maskDevice.get());
canvas.concat(transform);
canvas.concat(ctm);
// TODO(halcanary): investigate sub-pixel clipping.
canvas.drawImage(mask, 0, 0);
if (paint.getMaskFilter()) {
// This clip prevents the mask image shader from covering
// entire device if unnecessary.
canvas.clipRect(this->cs().bounds(this->bounds()));
canvas.concat(ctm);
SkPaint tmpPaint;
tmpPaint.setShader(mask->makeShader(&transform));
tmpPaint.setMaskFilter(sk_ref_sp(paint.getMaskFilter()));
canvas.drawRect(dst, tmpPaint);
} else {
canvas.concat(ctm);
if (src && !is_integral(*src)) {
canvas.clipRect(dst);
}
canvas.concat(transform);
canvas.drawImage(mask, 0, 0);
}
}
remove_color_filter(&paint);
if (!ctm.isIdentity() && paint.getShader()) {
transform_shader(&paint, ctm); // Since we are using identity matrix.
}
@ -2355,8 +2379,8 @@ void SkPDFDevice::internalDrawImageRect(SkKeyedImage imageSubset,
if (paint.getMaskFilter()) {
paint.setShader(imageSubset.image()->makeShader(&transform));
SkPath path;
path.addRect(SkRect::Make(imageSubset.image()->bounds()));
this->internalDrawPath(this->cs(), this->ctm(), path, paint, &transform, true);
path.addRect(dst); // handles non-integral clipping.
this->internalDrawPath(this->cs(), this->ctm(), path, paint, nullptr, true);
return;
}
transform.postConcat(ctm);
@ -2471,11 +2495,6 @@ void SkPDFDevice::internalDrawImageRect(SkKeyedImage imageSubset,
}
if (SkColorFilter* colorFilter = paint.getColorFilter()) {
// TODO(https://bug.skia.org/4378): implement colorfilter on other
// draw calls. This code here works for all
// drawBitmap*()/drawImage*() calls amd ImageFilters (which
// rasterize a layer on this backend). Fortuanely, this seems
// to be how Chromium impements most color-filters.
sk_sp<SkImage> img = color_filter(imageSubset.image().get(), colorFilter);
imageSubset = SkKeyedImage(std::move(img));
if (!imageSubset) {