// static
bool SkBitmapScaler::Resize(SkBitmap* resultPtr,
const SkBitmap& source,
ResizeMethod method,
float destWidth, float destHeight,
SkBitmap::Allocator* allocator) {
SkConvolutionProcs convolveProcs= { 0, NULL, NULL, NULL, NULL };
PlatformConvolutionProcs(&convolveProcs);
SkRect destSubset = { 0, 0, destWidth, destHeight };
// Ensure that the ResizeMethod enumeration is sound.
SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
(method <= RESIZE_LAST_QUALITY_METHOD)) ||
((RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
(method <= RESIZE_LAST_ALGORITHM_METHOD)));
SkRect dest = { 0, 0, destWidth, destHeight };
if (!dest.contains(destSubset)) {
SkErrorInternals::SetError( kInvalidArgument_SkError,
"Sorry, the destination bitmap scale subset "
"falls outside the full destination bitmap." );
return false;
}
// If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
// return empty.
if (source.width() < 1 || source.height() < 1 ||
destWidth < 1 || destHeight < 1) {
// todo: seems like we could handle negative dstWidth/Height, since that
// is just a negative scale (flip)
return false;
}
method = ResizeMethodToAlgorithmMethod(method);
// Check that we deal with an "algorithm methods" from this point onward.
SkASSERT((SkBitmapScaler::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
(method <= SkBitmapScaler::RESIZE_LAST_ALGORITHM_METHOD));
SkAutoLockPixels locker(source);
if (!source.readyToDraw() ||
source.colorType() != kN32_SkColorType) {
return false;
}
SkResizeFilter filter(method, source.width(), source.height(),
destWidth, destHeight, destSubset, convolveProcs);
// Get a source bitmap encompassing this touched area. We construct the
// offsets and row strides such that it looks like a new bitmap, while
// referring to the old data.
const unsigned char* sourceSubset =
reinterpret_cast<const unsigned char*>(source.getPixels());
// Convolve into the result.
SkBitmap result;
result.setInfo(SkImageInfo::MakeN32(SkScalarCeilToInt(destSubset.width()),
SkScalarCeilToInt(destSubset.height()),
source.alphaType()));
result.allocPixels(allocator, NULL);
if (!result.readyToDraw()) {
return false;
}
BGRAConvolve2D(sourceSubset, static_cast<int>(source.rowBytes()),
!source.isOpaque(), filter.xFilter(), filter.yFilter(),
static_cast<int>(result.rowBytes()),
static_cast<unsigned char*>(result.getPixels()),
convolveProcs, true);
*resultPtr = result;
resultPtr->lockPixels();
SkASSERT(resultPtr->getPixels());
return true;
}
// static
SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source,
ResizeMethod method,
int dest_width, int dest_height,
const SkIRect& dest_subset,
void* dest_pixels /* = nullptr */) {
// Ensure that the ResizeMethod enumeration is sound.
SkASSERT(((RESIZE_FIRST_QUALITY_METHOD <= method) &&
(method <= RESIZE_LAST_QUALITY_METHOD)) ||
((RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
(method <= RESIZE_LAST_ALGORITHM_METHOD)));
// If the size of source or destination is 0, i.e. 0x0, 0xN or Nx0, just
// return empty.
if (source.width() < 1 || source.height() < 1 ||
dest_width < 1 || dest_height < 1)
return SkBitmap();
method = ResizeMethodToAlgorithmMethod(method);
// Check that we deal with an "algorithm methods" from this point onward.
SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD <= method) &&
(method <= ImageOperations::RESIZE_LAST_ALGORITHM_METHOD));
SkAutoLockPixels locker(source);
if (!source.readyToDraw())
return SkBitmap();
ConvolutionFilter1D x_filter;
ConvolutionFilter1D y_filter;
resize::ComputeFilters(method, source.width(), dest_width, dest_subset.fLeft, dest_subset.width(), &x_filter);
resize::ComputeFilters(method, source.height(), dest_height, dest_subset.fTop, dest_subset.height(), &y_filter);
// Get a source bitmap encompassing this touched area. We construct the
// offsets and row strides such that it looks like a new bitmap, while
// referring to the old data.
const uint8_t* source_subset =
reinterpret_cast<const uint8_t*>(source.getPixels());
// Convolve into the result.
SkBitmap result;
SkImageInfo info = SkImageInfo::Make(dest_subset.width(),
dest_subset.height(),
kBGRA_8888_SkColorType,
kPremul_SkAlphaType);
if (dest_pixels) {
result.installPixels(info, dest_pixels, info.minRowBytes());
} else {
result.allocPixels(info);
}
if (!result.readyToDraw())
return SkBitmap();
BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()),
!source.isOpaque(), x_filter, y_filter,
static_cast<int>(result.rowBytes()),
static_cast<unsigned char*>(result.getPixels()));
// Preserve the "opaque" flag for use as an optimization later.
result.setAlphaType(source.alphaType());
return result;
}
// static
SkBitmap ImageOperations::ResizeBasic(const SkBitmap& source,
ResizeMethod method,
int dest_width, int dest_height,
const SkIRect& dest_subset)
{
// 确保枚举值合法.
SkASSERT(((RESIZE_FIRST_QUALITY_METHOD<=method) &&
(method<=RESIZE_LAST_QUALITY_METHOD)) ||
((RESIZE_FIRST_ALGORITHM_METHOD<=method) &&
(method<=RESIZE_LAST_ALGORITHM_METHOD)));
// 用于计算函数执行时间, 方便查看是否有问题.
base::TimeTicks resize_start = base::TimeTicks::Now();
SkIRect dest = { 0, 0, dest_width, dest_height };
DCHECK(dest.contains(dest_subset)) <<
"The supplied subset does not fall within the destination image.";
// 如果源和目的大小都是0(0*0 0*N N*0), 返回一个空位图.
if(source.width()<1 || source.height()<1 ||
dest_width<1 || dest_height<1)
{
return SkBitmap();
}
method = ResizeMethodToAlgorithmMethod(method);
// Check that we deal with an "algorithm methods" from this point onward.
SkASSERT((ImageOperations::RESIZE_FIRST_ALGORITHM_METHOD<=method) &&
(method<=ImageOperations::RESIZE_LAST_ALGORITHM_METHOD));
SkAutoLockPixels locker(source);
ResizeFilter filter(method, source.width(), source.height(),
dest_width, dest_height, dest_subset);
// Get a source bitmap encompassing this touched area. We construct the
// offsets and row strides such that it looks like a new bitmap, while
// referring to the old data.
const uint8* source_subset =
reinterpret_cast<const uint8*>(source.getPixels());
// Convolve into the result.
base::CPU cpu;
SkBitmap result;
result.setConfig(SkBitmap::kARGB_8888_Config,
dest_subset.width(), dest_subset.height());
result.allocPixels();
BGRAConvolve2D(source_subset, static_cast<int>(source.rowBytes()),
!source.isOpaque(), filter.x_filter(), filter.y_filter(),
static_cast<int>(result.rowBytes()),
static_cast<unsigned char*>(result.getPixels()),
cpu.has_sse2());
// Preserve the "opaque" flag for use as an optimization later.
result.setIsOpaque(source.isOpaque());
base::TimeDelta delta = base::TimeTicks::Now() - resize_start;
UMA_HISTOGRAM_TIMES("Image.ResampleMS", delta);
return result;
}
