michael@0: /*
michael@0:  * Copyright 2007 The Android Open Source Project
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "SkMask.h"
michael@0: 
michael@0: /** returns the product if it is positive and fits in 31 bits. Otherwise this
michael@0:     returns 0.
michael@0:  */
michael@0: static int32_t safeMul32(int32_t a, int32_t b) {
michael@0:     int64_t size = sk_64_mul(a, b);
michael@0:     if (size > 0 && sk_64_isS32(size)) {
michael@0:         return sk_64_asS32(size);
michael@0:     }
michael@0:     return 0;
michael@0: }
michael@0: 
michael@0: size_t SkMask::computeImageSize() const {
michael@0:     return safeMul32(fBounds.height(), fRowBytes);
michael@0: }
michael@0: 
michael@0: size_t SkMask::computeTotalImageSize() const {
michael@0:     size_t size = this->computeImageSize();
michael@0:     if (fFormat == SkMask::k3D_Format) {
michael@0:         size = safeMul32(SkToS32(size), 3);
michael@0:     }
michael@0:     return size;
michael@0: }
michael@0: 
michael@0: /** We explicitly use this allocator for SkBimap pixels, so that we can
michael@0:     freely assign memory allocated by one class to the other.
michael@0: */
michael@0: uint8_t* SkMask::AllocImage(size_t size) {
michael@0:     return (uint8_t*)sk_malloc_throw(SkAlign4(size));
michael@0: }
michael@0: 
michael@0: /** We explicitly use this allocator for SkBimap pixels, so that we can
michael@0:     freely assign memory allocated by one class to the other.
michael@0: */
michael@0: void SkMask::FreeImage(void* image) {
michael@0:     sk_free(image);
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: static const int gMaskFormatToShift[] = {
michael@0:     ~0, // BW -- not supported
michael@0:     0,  // A8
michael@0:     0,  // 3D
michael@0:     2,  // ARGB32
michael@0:     1,  // LCD16
michael@0:     2   // LCD32
michael@0: };
michael@0: 
michael@0: static int maskFormatToShift(SkMask::Format format) {
michael@0:     SkASSERT((unsigned)format < SK_ARRAY_COUNT(gMaskFormatToShift));
michael@0:     SkASSERT(SkMask::kBW_Format != format);
michael@0:     return gMaskFormatToShift[format];
michael@0: }
michael@0: 
michael@0: void* SkMask::getAddr(int x, int y) const {
michael@0:     SkASSERT(kBW_Format != fFormat);
michael@0:     SkASSERT(fBounds.contains(x, y));
michael@0:     SkASSERT(fImage);
michael@0: 
michael@0:     char* addr = (char*)fImage;
michael@0:     addr += (y - fBounds.fTop) * fRowBytes;
michael@0:     addr += (x - fBounds.fLeft) << maskFormatToShift(fFormat);
michael@0:     return addr;
michael@0: }