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/* libs/graphics/sgl/SkBlitter_ARGB32_Subpixel.cpp
**
** Copyright 2009, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
/* LCD blend functions:
These functions take an alpha pixel of the following form:
red, green, blue -> an alpha value for the given colour component.
alpha -> the max of the red, green and blue alpha values.
These alpha pixels result from subpixel renderering. The R/G/B values have
already been corrected for RGB/BGR element ordering.
The alpha pixel is blended with an original pixel and a source colour,
resulting in a new pixel value.
*/
#include "SkBitmap.h"
#include "SkColorPriv.h"
#include "SkMask.h"
#include "SkRect.h"
namespace skia_blitter_support {
/** Given a clip region which describes the desired location of a glyph and a
bitmap to which an LCD glyph is to be blitted, return a pointer to the
SkBitmap's pixels and output width and height adjusts for the glyph as well
as a pointer into the glyph.
Recall that LCD glyphs have extra rows (vertical mode) or columns
(horizontal mode) at the edges as a result of low-pass filtering. If we
wanted to put a glyph on the hard-left edge of bitmap, we would have to know
to start one pixel into the glyph, as well as to only add 1 to the recorded
glyph width etc. This function encapsulates that behaviour.
@param mask The glyph to be blitted.
@param clip The clip region describing the desired location of the glyph.
@param device The SkBitmap target for the blit.
@param widthAdjustment (output) a number to add to the glyph's nominal width.
@param heightAdjustment (output) a number to add to the glyph's nominal width.
@param alpha32 (output) a pointer into the 32-bit subpixel alpha data for the glyph
*/
uint32_t* adjustForSubpixelClip(const SkMask& mask,
const SkIRect& clip, const SkBitmap& device,
int* widthAdjustment, int* heightAdjustment,
const uint32_t** alpha32) {
const bool lcdMode = mask.fFormat == SkMask::kHorizontalLCD_Format;
const bool verticalLCDMode = mask.fFormat == SkMask::kVerticalLCD_Format;
const int leftOffset = clip.fLeft > 0 ? lcdMode : 0;
const int topOffset = clip.fTop > 0 ? verticalLCDMode : 0;
const int rightOffset = lcdMode && clip.fRight < device.width();
const int bottomOffset = verticalLCDMode && clip.fBottom < device.height();
uint32_t* device32 = device.getAddr32(clip.fLeft - leftOffset, clip.fTop - topOffset);
*alpha32 = mask.getAddrLCD(clip.fLeft + (lcdMode && !leftOffset),
clip.fTop + (verticalLCDMode && !topOffset));
*widthAdjustment = leftOffset + rightOffset;
*heightAdjustment = topOffset + bottomOffset;
return device32;
}
uint32_t BlendLCDPixelWithColor(const uint32_t alphaPixel, const uint32_t originalPixel,
const uint32_t sourcePixel) {
unsigned alphaRed = SkAlpha255To256(SkGetPackedR32(alphaPixel));
unsigned alphaGreen = SkAlpha255To256(SkGetPackedG32(alphaPixel));
unsigned alphaBlue = SkAlpha255To256(SkGetPackedB32(alphaPixel));
unsigned sourceRed = SkGetPackedR32(sourcePixel);
unsigned sourceGreen = SkGetPackedG32(sourcePixel);
unsigned sourceBlue = SkGetPackedB32(sourcePixel);
unsigned sourceAlpha = SkAlpha255To256(SkGetPackedA32(sourcePixel));
alphaRed = (alphaRed * sourceAlpha) >> 8;
alphaGreen = (alphaGreen * sourceAlpha) >> 8;
alphaBlue = (alphaBlue * sourceAlpha) >> 8;
unsigned alphaAlpha = SkMax32(SkMax32(alphaRed, alphaBlue), alphaGreen);
unsigned originalRed = SkGetPackedR32(originalPixel);
unsigned originalGreen = SkGetPackedG32(originalPixel);
unsigned originalBlue = SkGetPackedB32(originalPixel);
unsigned originalAlpha = SkGetPackedA32(originalPixel);
return SkPackARGB32(SkMin32(255u, alphaAlpha + originalAlpha),
((sourceRed * alphaRed) >> 8) + ((originalRed * (256 - alphaRed)) >> 8),
((sourceGreen * alphaGreen) >> 8) + ((originalGreen * (256 - alphaGreen)) >> 8),
((sourceBlue * alphaBlue) >> 8) + ((originalBlue * (256 - alphaBlue)) >> 8));
}
uint32_t BlendLCDPixelWithOpaqueColor(const uint32_t alphaPixel, const uint32_t originalPixel,
const uint32_t sourcePixel) {
unsigned alphaRed = SkAlpha255To256(SkGetPackedR32(alphaPixel));
unsigned alphaGreen = SkAlpha255To256(SkGetPackedG32(alphaPixel));
unsigned alphaBlue = SkAlpha255To256(SkGetPackedB32(alphaPixel));
unsigned alphaAlpha = SkGetPackedA32(alphaPixel);
unsigned sourceRed = SkGetPackedR32(sourcePixel);
unsigned sourceGreen = SkGetPackedG32(sourcePixel);
unsigned sourceBlue = SkGetPackedB32(sourcePixel);
unsigned originalRed = SkGetPackedR32(originalPixel);
unsigned originalGreen = SkGetPackedG32(originalPixel);
unsigned originalBlue = SkGetPackedB32(originalPixel);
unsigned originalAlpha = SkGetPackedA32(originalPixel);
return SkPackARGB32(SkMin32(255u, alphaAlpha + originalAlpha),
((sourceRed * alphaRed) >> 8) + ((originalRed * (256 - alphaRed)) >> 8),
((sourceGreen * alphaGreen) >> 8) + ((originalGreen * (256 - alphaGreen)) >> 8),
((sourceBlue * alphaBlue) >> 8) + ((originalBlue * (256 - alphaBlue)) >> 8));
}
uint32_t BlendLCDPixelWithBlack(const uint32_t alphaPixel, const uint32_t originalPixel) {
unsigned alphaRed = SkAlpha255To256(SkGetPackedR32(alphaPixel));
unsigned alphaGreen = SkAlpha255To256(SkGetPackedG32(alphaPixel));
unsigned alphaBlue = SkAlpha255To256(SkGetPackedB32(alphaPixel));
unsigned alphaAlpha = SkGetPackedA32(alphaPixel);
unsigned originalRed = SkGetPackedR32(originalPixel);
unsigned originalGreen = SkGetPackedG32(originalPixel);
unsigned originalBlue = SkGetPackedB32(originalPixel);
unsigned originalAlpha = SkGetPackedA32(originalPixel);
return SkPackARGB32(SkMin32(255u, alphaAlpha + originalAlpha),
(originalRed * (256 - alphaRed)) >> 8,
(originalGreen * (256 - alphaGreen)) >> 8,
(originalBlue * (256 - alphaBlue)) >> 8);
}
} // namespace skia_blitter_support
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