skia2/include/core/SkMask.h
2014-11-13 14:39:58 -08:00

149 lines
4.8 KiB
C++

/*
* Copyright 2006 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkMask_DEFINED
#define SkMask_DEFINED
#include "SkRect.h"
/** \class SkMask
SkMask is used to describe alpha bitmaps, either 1bit, 8bit, or
the 3-channel 3D format. These are passed to SkMaskFilter objects.
*/
struct SkMask {
enum Format {
kBW_Format, //!< 1bit per pixel mask (e.g. monochrome)
kA8_Format, //!< 8bits per pixel mask (e.g. antialiasing)
k3D_Format, //!< 3 8bit per pixl planes: alpha, mul, add
kARGB32_Format, //!< SkPMColor
kLCD16_Format, //!< 565 alpha for r/g/b
};
enum {
kCountMaskFormats = kLCD16_Format + 1
};
uint8_t* fImage;
SkIRect fBounds;
uint32_t fRowBytes;
Format fFormat;
/** Returns true if the mask is empty: i.e. it has an empty bounds.
*/
bool isEmpty() const { return fBounds.isEmpty(); }
/** Return the byte size of the mask, assuming only 1 plane.
Does not account for k3D_Format. For that, use computeTotalImageSize().
If there is an overflow of 32bits, then returns 0.
*/
size_t computeImageSize() const;
/** Return the byte size of the mask, taking into account
any extra planes (e.g. k3D_Format).
If there is an overflow of 32bits, then returns 0.
*/
size_t computeTotalImageSize() const;
/** Returns the address of the byte that holds the specified bit.
Asserts that the mask is kBW_Format, and that x,y are in range.
x,y are in the same coordiate space as fBounds.
*/
uint8_t* getAddr1(int x, int y) const {
SkASSERT(kBW_Format == fFormat);
SkASSERT(fBounds.contains(x, y));
SkASSERT(fImage != NULL);
return fImage + ((x - fBounds.fLeft) >> 3) + (y - fBounds.fTop) * fRowBytes;
}
/** Returns the address of the specified byte.
Asserts that the mask is kA8_Format, and that x,y are in range.
x,y are in the same coordiate space as fBounds.
*/
uint8_t* getAddr8(int x, int y) const {
SkASSERT(kA8_Format == fFormat);
SkASSERT(fBounds.contains(x, y));
SkASSERT(fImage != NULL);
return fImage + x - fBounds.fLeft + (y - fBounds.fTop) * fRowBytes;
}
/**
* Return the address of the specified 16bit mask. In the debug build,
* this asserts that the mask's format is kLCD16_Format, and that (x,y)
* are contained in the mask's fBounds.
*/
uint16_t* getAddrLCD16(int x, int y) const {
SkASSERT(kLCD16_Format == fFormat);
SkASSERT(fBounds.contains(x, y));
SkASSERT(fImage != NULL);
uint16_t* row = (uint16_t*)(fImage + (y - fBounds.fTop) * fRowBytes);
return row + (x - fBounds.fLeft);
}
/**
* Return the address of the specified 32bit mask. In the debug build,
* this asserts that the mask's format is 32bits, and that (x,y)
* are contained in the mask's fBounds.
*/
uint32_t* getAddr32(int x, int y) const {
SkASSERT(kARGB32_Format == fFormat);
SkASSERT(fBounds.contains(x, y));
SkASSERT(fImage != NULL);
uint32_t* row = (uint32_t*)(fImage + (y - fBounds.fTop) * fRowBytes);
return row + (x - fBounds.fLeft);
}
/**
* Returns the address of the specified pixel, computing the pixel-size
* at runtime based on the mask format. This will be slightly slower than
* using one of the routines where the format is implied by the name
* e.g. getAddr8 or getAddr32.
*
* x,y must be contained by the mask's bounds (this is asserted in the
* debug build, but not checked in the release build.)
*
* This should not be called with kBW_Format, as it will give unspecified
* results (and assert in the debug build).
*/
void* getAddr(int x, int y) const;
static uint8_t* AllocImage(size_t bytes);
static void FreeImage(void* image);
enum CreateMode {
kJustComputeBounds_CreateMode, //!< compute bounds and return
kJustRenderImage_CreateMode, //!< render into preallocate mask
kComputeBoundsAndRenderImage_CreateMode //!< compute bounds, alloc image and render into it
};
};
///////////////////////////////////////////////////////////////////////////////
/**
* \class SkAutoMaskImage
*
* Stack class used to manage the fImage buffer in a SkMask.
* When this object loses scope, the buffer is freed with SkMask::FreeImage().
*/
class SkAutoMaskFreeImage {
public:
SkAutoMaskFreeImage(uint8_t* maskImage) {
fImage = maskImage;
}
~SkAutoMaskFreeImage() {
SkMask::FreeImage(fImage);
}
private:
uint8_t* fImage;
};
#define SkAutoMaskFreeImage(...) SK_REQUIRE_LOCAL_VAR(SkAutoMaskFreeImage)
#endif