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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCanvasStateUtils.h"
#include "SkCanvas.h"
#include "SkCanvasStack.h"
#include "SkDevice.h"
#include "SkRasterClip.h"
#include "SkWriter32.h"
/*
* WARNING: The structs below are part of a stable ABI and as such we explicitly
* use unambigious primitives (e.g. int32_t instead of an enum).
*
* ANY CHANGES TO THE STRUCTS BELOW THAT IMPACT THE ABI SHOULD RESULT IN A NEW
* NEW SUBCLASS OF SkCanvasState. SUCH CHANGES SHOULD ONLY BE MADE IF ABSOLUTELY
* NECESSARY!
*
* In order to test changes, run the CanvasState tests. gyp/canvas_state_lib.gyp
* describes how to create a library to pass to the CanvasState tests. The tests
* should succeed when building the library with your changes and passing that to
* the tests running in the unchanged Skia.
*/
enum RasterConfigs {
kUnknown_RasterConfig = 0,
kRGB_565_RasterConfig = 1,
kARGB_8888_RasterConfig = 2
};
typedef int32_t RasterConfig;
enum CanvasBackends {
kUnknown_CanvasBackend = 0,
kRaster_CanvasBackend = 1,
kGPU_CanvasBackend = 2,
kPDF_CanvasBackend = 3
};
typedef int32_t CanvasBackend;
struct ClipRect {
int32_t left, top, right, bottom;
};
struct SkMCState {
float matrix[9];
// NOTE: this only works for non-antialiased clips
int32_t clipRectCount;
ClipRect* clipRects;
};
// NOTE: If you add more members, create a new subclass of SkCanvasState with a
// new CanvasState::version.
struct SkCanvasLayerState {
CanvasBackend type;
int32_t x, y;
int32_t width;
int32_t height;
SkMCState mcState;
union {
struct {
RasterConfig config; // pixel format: a value from RasterConfigs.
uint64_t rowBytes; // Number of bytes from start of one line to next.
void* pixels; // The pixels, all (height * rowBytes) of them.
} raster;
struct {
int32_t textureID;
} gpu;
};
};
class SkCanvasState {
public:
SkCanvasState(int32_t version, SkCanvas* canvas) {
SkASSERT(canvas);
this->version = version;
width = canvas->getBaseLayerSize().width();
height = canvas->getBaseLayerSize().height();
}
/**
* The version this struct was built with. This field must always appear
* first in the struct so that when the versions don't match (and the
* remaining contents and size are potentially different) we can still
* compare the version numbers.
*/
int32_t version;
int32_t width;
int32_t height;
int32_t alignmentPadding;
};
class SkCanvasState_v1 : public SkCanvasState {
public:
static const int32_t kVersion = 1;
SkCanvasState_v1(SkCanvas* canvas)
: INHERITED(kVersion, canvas)
{
layerCount = 0;
layers = nullptr;
mcState.clipRectCount = 0;
mcState.clipRects = nullptr;
originalCanvas = SkRef(canvas);
}
~SkCanvasState_v1() {
// loop through the layers and free the data allocated to the clipRects
for (int i = 0; i < layerCount; ++i) {
sk_free(layers[i].mcState.clipRects);
}
sk_free(mcState.clipRects);
sk_free(layers);
// it is now safe to free the canvas since there should be no remaining
// references to the content that is referenced by this canvas (e.g. pixels)
originalCanvas->unref();
}
SkMCState mcState;
int32_t layerCount;
SkCanvasLayerState* layers;
private:
SkCanvas* originalCanvas;
typedef SkCanvasState INHERITED;
};
////////////////////////////////////////////////////////////////////////////////
class ClipValidator : public SkCanvas::ClipVisitor {
public:
ClipValidator() : fFailed(false) {}
bool failed() { return fFailed; }
// ClipVisitor
void clipRect(const SkRect& rect, SkCanvas::ClipOp op, bool antialias) override {
fFailed |= antialias;
}
void clipRRect(const SkRRect& rrect, SkCanvas::ClipOp op, bool antialias) override {
fFailed |= antialias;
}
void clipPath(const SkPath&, SkCanvas::ClipOp, bool antialias) override {
fFailed |= antialias;
}
private:
bool fFailed;
};
static void setup_MC_state(SkMCState* state, const SkMatrix& matrix, const SkRegion& clip) {
// initialize the struct
state->clipRectCount = 0;
// capture the matrix
for (int i = 0; i < 9; i++) {
state->matrix[i] = matrix.get(i);
}
/*
* capture the clip
*
* storage is allocated on the stack for the first 4 rects. This value was
* chosen somewhat arbitrarily, but does allow us to represent simple clips
* and some more common complex clips (e.g. a clipRect with a sub-rect
* clipped out of its interior) without needing to malloc any additional memory.
*/
SkSWriter32<4*sizeof(ClipRect)> clipWriter;
if (!clip.isEmpty()) {
// only returns the b/w clip so aa clips fail
SkRegion::Iterator clip_iterator(clip);
for (; !clip_iterator.done(); clip_iterator.next()) {
// this assumes the SkIRect is stored in l,t,r,b ordering which
// matches the ordering of our ClipRect struct
clipWriter.writeIRect(clip_iterator.rect());
state->clipRectCount++;
}
}
// allocate memory for the clip then and copy them to the struct
state->clipRects = (ClipRect*) sk_malloc_throw(clipWriter.bytesWritten());
clipWriter.flatten(state->clipRects);
}
SkCanvasState* SkCanvasStateUtils::CaptureCanvasState(SkCanvas* canvas) {
SkASSERT(canvas);
// Check the clip can be decomposed into rectangles (i.e. no soft clips).
ClipValidator validator;
canvas->replayClips(&validator);
if (validator.failed()) {
return nullptr;
}
SkAutoTDelete<SkCanvasState_v1> canvasState(new SkCanvasState_v1(canvas));
// decompose the total matrix and clip
setup_MC_state(&canvasState->mcState, canvas->getTotalMatrix(),
canvas->internal_private_getTotalClip());
/*
* decompose the layers
*
* storage is allocated on the stack for the first 3 layers. It is common in
* some view systems (e.g. Android) that a few non-clipped layers are present
* and we will not need to malloc any additional memory in those cases.
*/
SkSWriter32<3*sizeof(SkCanvasLayerState)> layerWriter;
int layerCount = 0;
for (SkCanvas::LayerIter layer(canvas); !layer.done(); layer.next()) {
// we currently only work for bitmap backed devices
SkPixmap pmap;
if (!layer.device()->accessPixels(&pmap) || 0 == pmap.width() || 0 == pmap.height()) {
return nullptr;
}
SkCanvasLayerState* layerState =
(SkCanvasLayerState*) layerWriter.reserve(sizeof(SkCanvasLayerState));
layerState->type = kRaster_CanvasBackend;
layerState->x = layer.x();
layerState->y = layer.y();
layerState->width = pmap.width();
layerState->height = pmap.height();
switch (pmap.colorType()) {
case kN32_SkColorType:
layerState->raster.config = kARGB_8888_RasterConfig;
break;
case kRGB_565_SkColorType:
layerState->raster.config = kRGB_565_RasterConfig;
break;
default:
return nullptr;
}
layerState->raster.rowBytes = pmap.rowBytes();
layerState->raster.pixels = pmap.writable_addr();
setup_MC_state(&layerState->mcState, layer.matrix(), layer.clip().bwRgn());
layerCount++;
}
// allocate memory for the layers and then and copy them to the struct
SkASSERT(layerWriter.bytesWritten() == layerCount * sizeof(SkCanvasLayerState));
canvasState->layerCount = layerCount;
canvasState->layers = (SkCanvasLayerState*) sk_malloc_throw(layerWriter.bytesWritten());
layerWriter.flatten(canvasState->layers);
return canvasState.release();
}
////////////////////////////////////////////////////////////////////////////////
static void setup_canvas_from_MC_state(const SkMCState& state, SkCanvas* canvas) {
// reconstruct the matrix
SkMatrix matrix;
for (int i = 0; i < 9; i++) {
matrix.set(i, state.matrix[i]);
}
// reconstruct the clip
SkRegion clip;
for (int i = 0; i < state.clipRectCount; ++i) {
clip.op(SkIRect::MakeLTRB(state.clipRects[i].left,
state.clipRects[i].top,
state.clipRects[i].right,
state.clipRects[i].bottom),
SkRegion::kUnion_Op);
}
canvas->setMatrix(matrix);
canvas->clipRegion(clip, SkCanvas::kReplace_Op);
}
static SkCanvas* create_canvas_from_canvas_layer(const SkCanvasLayerState& layerState) {
SkASSERT(kRaster_CanvasBackend == layerState.type);
SkBitmap bitmap;
SkColorType colorType =
layerState.raster.config == kARGB_8888_RasterConfig ? kN32_SkColorType :
layerState.raster.config == kRGB_565_RasterConfig ? kRGB_565_SkColorType :
kUnknown_SkColorType;
if (colorType == kUnknown_SkColorType) {
return nullptr;
}
bitmap.installPixels(SkImageInfo::Make(layerState.width, layerState.height,
colorType, kPremul_SkAlphaType),
layerState.raster.pixels, (size_t) layerState.raster.rowBytes);
SkASSERT(!bitmap.empty());
SkASSERT(!bitmap.isNull());
SkAutoTUnref<SkCanvas> canvas(new SkCanvas(bitmap));
// setup the matrix and clip
setup_canvas_from_MC_state(layerState.mcState, canvas.get());
return canvas.release();
}
SkCanvas* SkCanvasStateUtils::CreateFromCanvasState(const SkCanvasState* state) {
SkASSERT(state);
// Currently there is only one possible version.
SkASSERT(SkCanvasState_v1::kVersion == state->version);
const SkCanvasState_v1* state_v1 = static_cast<const SkCanvasState_v1*>(state);
if (state_v1->layerCount < 1) {
return nullptr;
}
SkAutoTUnref<SkCanvasStack> canvas(new SkCanvasStack(state->width, state->height));
// setup the matrix and clip on the n-way canvas
setup_canvas_from_MC_state(state_v1->mcState, canvas);
// Iterate over the layers and add them to the n-way canvas
for (int i = state_v1->layerCount - 1; i >= 0; --i) {
SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state_v1->layers[i]));
if (!canvasLayer.get()) {
return nullptr;
}
canvas->pushCanvas(canvasLayer.get(), SkIPoint::Make(state_v1->layers[i].x,
state_v1->layers[i].y));
}
return canvas.release();
}
////////////////////////////////////////////////////////////////////////////////
void SkCanvasStateUtils::ReleaseCanvasState(SkCanvasState* state) {
SkASSERT(!state || SkCanvasState_v1::kVersion == state->version);
// Upcast to the correct version of SkCanvasState. This avoids having a virtual destructor on
// SkCanvasState. That would be strange since SkCanvasState has no other virtual functions, and
// instead uses the field "version" to determine how to behave.
delete static_cast<SkCanvasState_v1*>(state);
}