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/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkBitmap.h"
#include "SkRegion.h"
bool SkBitmap::scrollRect(const SkIRect* subset, int dx, int dy,
SkRegion* inval) const
{
if (this->isImmutable() || kUnknown_SkColorType == this->colorType()) {
return false;
}
if (subset) {
SkBitmap tmp;
return this->extractSubset(&tmp, *subset) &&
// now call again with no rectangle
tmp.scrollRect(NULL, dx, dy, inval);
}
int shift = this->bytesPerPixel() >> 1;
int width = this->width();
int height = this->height();
// check if there's nothing to do
if ((dx | dy) == 0 || width <= 0 || height <= 0) {
if (inval) {
inval->setEmpty();
}
return true;
}
// compute the inval region now, before we see if there are any pixels
if (inval) {
SkIRect r;
r.set(0, 0, width, height);
// initial the region with the entire bounds
inval->setRect(r);
// do the "scroll"
r.offset(dx, dy);
// check if we scrolled completely away
if (!SkIRect::Intersects(r, inval->getBounds())) {
// inval has already been updated...
return true;
}
// compute the dirty area
inval->op(r, SkRegion::kDifference_Op);
}
SkAutoLockPixels alp(*this);
// if we have no pixels, just return (inval is already updated)
// don't call readyToDraw(), since we don't require a colortable per se
if (this->getPixels() == NULL) {
return true;
}
char* dst = (char*)this->getPixels();
const char* src = dst;
int rowBytes = (int)this->rowBytes(); // need rowBytes to be signed
if (dy <= 0) {
src -= dy * rowBytes;
height += dy;
} else {
dst += dy * rowBytes;
height -= dy;
// now jump src/dst to the last scanline
src += (height - 1) * rowBytes;
dst += (height - 1) * rowBytes;
// now invert rowbytes so we copy backwards in the loop
rowBytes = -rowBytes;
}
if (dx <= 0) {
src -= dx << shift;
width += dx;
} else {
dst += dx << shift;
width -= dx;
}
// If the X-translation would push it completely beyond the region,
// then there's nothing to draw.
if (width <= 0) {
return true;
}
width <<= shift; // now width is the number of bytes to move per line
while (--height >= 0) {
memmove(dst, src, width);
dst += rowBytes;
src += rowBytes;
}
this->notifyPixelsChanged();
return true;
}
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