void computeDisplacement(Extractor ex, const SkVector& scale, SkBitmap* dst,
const SkBitmap& displ, const SkIPoint& offset,
const SkBitmap& src,
const SkIRect& bounds) {
static const SkScalar Inv8bit = SkScalarInvert(255);
const int srcW = src.width();
const int srcH = src.height();
const SkVector scaleForColor = SkVector::Make(scale.fX * Inv8bit, scale.fY * Inv8bit);
const SkVector scaleAdj = SkVector::Make(SK_ScalarHalf - scale.fX * SK_ScalarHalf,
SK_ScalarHalf - scale.fY * SK_ScalarHalf);
SkPMColor* dstPtr = dst->getAddr32(0, 0);
for (int y = bounds.top(); y < bounds.bottom(); ++y) {
const SkPMColor* displPtr = displ.getAddr32(bounds.left() + offset.fX, y + offset.fY);
for (int x = bounds.left(); x < bounds.right(); ++x, ++displPtr) {
SkPMColor c = unpremul_pm(*displPtr);
SkScalar displX = scaleForColor.fX * ex.getX(c) + scaleAdj.fX;
SkScalar displY = scaleForColor.fY * ex.getY(c) + scaleAdj.fY;
// Truncate the displacement values
const int32_t srcX = Sk32_sat_add(x, SkScalarTruncToInt(displX));
const int32_t srcY = Sk32_sat_add(y, SkScalarTruncToInt(displY));
*dstPtr++ = ((srcX < 0) || (srcX >= srcW) || (srcY < 0) || (srcY >= srcH)) ?
0 : *(src.getAddr32(srcX, srcY));
}
}
}
sk_sp<SkSpecialImage> SkOffsetImageFilter::onFilterImage(SkSpecialImage* source,
const Context& ctx,
SkIPoint* offset) const {
SkIPoint srcOffset = SkIPoint::Make(0, 0);
sk_sp<SkSpecialImage> input(this->filterInput(0, source, ctx, &srcOffset));
if (!input) {
return nullptr;
}
SkIPoint vec = map_offset_vector(ctx.ctm(), fOffset);
if (!this->cropRectIsSet()) {
offset->fX = Sk32_sat_add(srcOffset.fX, vec.fX);
offset->fY = Sk32_sat_add(srcOffset.fY, vec.fY);
return input;
} else {
SkIRect bounds;
SkIRect srcBounds = SkIRect::MakeWH(input->width(), input->height());
srcBounds.offset(srcOffset);
if (!this->applyCropRect(ctx, srcBounds, &bounds)) {
return nullptr;
}
sk_sp<SkSpecialSurface> surf(source->makeSurface(ctx.outputProperties(), bounds.size()));
if (!surf) {
return nullptr;
}
SkCanvas* canvas = surf->getCanvas();
SkASSERT(canvas);
// TODO: it seems like this clear shouldn't be necessary (see skbug.com/5075)
canvas->clear(0x0);
SkPaint paint;
paint.setBlendMode(SkBlendMode::kSrc);
canvas->translate(SkIntToScalar(srcOffset.fX - bounds.fLeft),
SkIntToScalar(srcOffset.fY - bounds.fTop));
input->draw(canvas, vec.fX, vec.fY, &paint);
offset->fX = bounds.fLeft;
offset->fY = bounds.fTop;
return surf->makeImageSnapshot();
}
}
