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* Copyright 2012 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrSWMaskHelper_DEFINED
#define GrSWMaskHelper_DEFINED
#include "GrColor.h"
#include "GrPipelineBuilder.h"
#include "SkBitmap.h"
#include "SkDraw.h"
#include "SkMatrix.h"
#include "SkRasterClip.h"
#include "SkRegion.h"
#include "SkTextureCompressor.h"
#include "SkTypes.h"
class GrContext;
class GrTexture;
class SkPath;
class SkStrokeRec;
class GrDrawTarget;
* The GrSWMaskHelper helps generate clip masks using the software rendering
* path. It is intended to be used as:
* GrSWMaskHelper helper(context);
* helper.init(...);
* draw one or more paths/rects specifying the required boolean ops
* toTexture(); // to get it from the internal bitmap to the GPU
* The result of this process will be the final mask (on the GPU) in the
* upper left hand corner of the texture.
class GrSWMaskHelper : SkNoncopyable {
GrSWMaskHelper(GrContext* context)
: fContext(context)
, fCompressionMode(kNone_CompressionMode) {
// set up the internal state in preparation for draws. Since many masks
// may be accumulated in the helper during creation, "resultBounds"
// allows the caller to specify the region of interest - to limit the
// amount of work. allowCompression should be set to false if you plan on using
// your own texture to draw into, and not a scratch texture via getTexture().
bool init(const SkIRect& resultBounds, const SkMatrix* matrix, bool allowCompression = true);
// Draw a single rect into the accumulation bitmap using the specified op
void draw(const SkRect& rect, SkRegion::Op op,
bool antiAlias, uint8_t alpha);
// Draw a single path into the accumuation bitmap using the specified op
void draw(const SkPath& path, const SkStrokeRec& stroke, SkRegion::Op op,
bool antiAlias, uint8_t alpha);
// Move the mask generation results from the internal bitmap to the gpu.
void toTexture(GrTexture* texture);
// Convert mask generation results to a signed distance field
void toSDF(unsigned char* sdf);
// Reset the internal bitmap
void clear(uint8_t alpha) {
fBM.eraseColor(SkColorSetARGB(alpha, alpha, alpha, alpha));
// Canonical usage utility that draws a single path and uploads it
// to the GPU. The result is returned.
static GrTexture* DrawPathMaskToTexture(GrContext* context,
const SkPath& path,
const SkStrokeRec& stroke,
const SkIRect& resultBounds,
bool antiAlias,
const SkMatrix* matrix);
// This utility routine is used to add a path's mask to some other draw.
// The ClipMaskManager uses it to accumulate clip masks while the
// GrSoftwarePathRenderer uses it to fulfill a drawPath call.
// It draws with "texture" as a path mask into "target" using "rect" as
// geometry and the current drawState. The current drawState is altered to
// accommodate the mask.
// Note that this method assumes that the GrPaint::kTotalStages slot in
// the draw state can be used to hold the mask texture stage.
// This method is really only intended to be used with the
// output of DrawPathMaskToTexture.
static void DrawToTargetWithPathMask(GrTexture* texture,
GrDrawTarget* target,
GrPipelineBuilder* pipelineBuilder,
const SkMatrix& viewMatrix,
const SkIRect& rect);
// Helper function to get a scratch texture suitable for capturing the
// result (i.e., right size & format)
GrTexture* createTexture();
GrContext* fContext;
SkMatrix fMatrix;
SkBitmap fBM;
SkDraw fDraw;
SkRasterClip fRasterClip;
// This enum says whether or not we should compress the mask:
// kNone_CompressionMode: compression is not supported on this device.
// kCompress_CompressionMode: compress the bitmap before it gets sent to the gpu
// kBlitter_CompressionMode: write to the bitmap using a special compressed blitter.
enum CompressionMode {
} fCompressionMode;
// This is the buffer into which we store our compressed data. This buffer is
// only allocated (non-null) if fCompressionMode is kBlitter_CompressionMode
SkAutoMalloc fCompressedBuffer;
// This is the desired format within which to compress the
// texture. This value is only valid if fCompressionMode is not kNone_CompressionMode.
SkTextureCompressor::Format fCompressedFormat;
// Actually sends the texture data to the GPU. This is called from
// toTexture with the data filled in depending on the texture config.
void sendTextureData(GrTexture *texture, const GrSurfaceDesc& desc,
const void *data, size_t rowbytes);
// Compresses the bitmap stored in fBM and sends the compressed data
// to the GPU to be stored in 'texture' using sendTextureData.
void compressTextureData(GrTexture *texture, const GrSurfaceDesc& desc);
typedef SkNoncopyable INHERITED;
#endif // GrSWMaskHelper_DEFINED