The Tor Browser / file revision

 /*

  * 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 "SkBitmapDevice.h"

 #include "SkCanvas.h"

 #include "SkCanvasStack.h"

 #include "SkErrorInternals.h"

 #include "SkWriter32.h"

 #define CANVAS_STATE_VERSION 1

 /*

  * 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 AN

  * UPDATE OF THE CANVAS_STATE_VERSION. SUCH CHANGES SHOULD ONLY BE MADE IF

  * ABSOLUTELY NECESSARY!

  */

 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, bump 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.

             size_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(SkCanvas* canvas) {

         SkASSERT(canvas);

         version = CANVAS_STATE_VERSION;

         width = canvas->getDeviceSize().width();

         height = canvas->getDeviceSize().height();

         layerCount = 0;

         layers = NULL;

         originalCanvas = SkRef(canvas);

         mcState.clipRectCount = 0;

         mcState.clipRects = NULL;

     }

     ~SkCanvasState() {

         // 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();

     }

     /**

      * 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;

     SkMCState mcState;

     int32_t layerCount;

     SkCanvasLayerState* layers;

 private:

     SkCanvas* originalCanvas;

 };

 ////////////////////////////////////////////////////////////////////////////////

 class ClipValidator : public SkCanvas::ClipVisitor {

 public:

     ClipValidator() : fFailed(false) {}

     bool failed() { return fFailed; }

     // ClipVisitor

     virtual void clipRect(const SkRect& rect, SkRegion::Op op, bool antialias) SK_OVERRIDE {

         fFailed |= antialias;

     }

     virtual void clipRRect(const SkRRect& rrect, SkRegion::Op op, bool antialias) SK_OVERRIDE {

         fFailed |= antialias;

     }

     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) SK_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()) {

         SkErrorInternals::SetError(kInvalidOperation_SkError,

                 "CaptureCanvasState does not support canvases with antialiased clips.\n");

         return NULL;

     }

     SkAutoTDelete<SkCanvasState> canvasState(SkNEW_ARGS(SkCanvasState, (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, true/*skipEmptyClips*/); !layer.done(); layer.next()) {

         // we currently only work for bitmap backed devices

         const SkBitmap& bitmap = layer.device()->accessBitmap(true/*changePixels*/);

         if (bitmap.empty() || bitmap.isNull() || !bitmap.lockPixelsAreWritable()) {

             return NULL;

         }

         SkCanvasLayerState* layerState =

                 (SkCanvasLayerState*) layerWriter.reserve(sizeof(SkCanvasLayerState));

         layerState->type = kRaster_CanvasBackend;

         layerState->x = layer.x();

         layerState->y = layer.y();

         layerState->width = bitmap.width();

         layerState->height = bitmap.height();

         switch (bitmap.colorType()) {

             case kPMColor_SkColorType:

                 layerState->raster.config = kARGB_8888_RasterConfig;

                 break;

             case kRGB_565_SkColorType:

                 layerState->raster.config = kRGB_565_RasterConfig;

                 break;

             default:

                 return NULL;

         }

         layerState->raster.rowBytes = bitmap.rowBytes();

         layerState->raster.pixels = bitmap.getPixels();

         setup_MC_state(&layerState->mcState, layer.matrix(), layer.clip());

         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);

     // for now, just ignore any client supplied DrawFilter.

     if (canvas->getDrawFilter()) {

 //        SkDEBUGF(("CaptureCanvasState will ignore the canvases draw filter.\n"));

     }

     return canvasState.detach();

 }

 ////////////////////////////////////////////////////////////////////////////////

 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->setClipRegion(clip);

 }

 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 ? kPMColor_SkColorType :

         layerState.raster.config == kRGB_565_RasterConfig ? kRGB_565_SkColorType :

         kUnknown_SkColorType;

     if (colorType == kUnknown_SkColorType) {

         return NULL;

     }

     bitmap.installPixels(SkImageInfo::Make(layerState.width, layerState.height,

                                            colorType, kPremul_SkAlphaType),

                          layerState.raster.pixels, layerState.raster.rowBytes,

                          NULL, NULL);

     SkASSERT(!bitmap.empty());

     SkASSERT(!bitmap.isNull());

     SkAutoTUnref<SkCanvas> canvas(SkNEW_ARGS(SkCanvas, (bitmap)));

     // setup the matrix and clip

     setup_canvas_from_MC_state(layerState.mcState, canvas.get());

     return canvas.detach();

 }

 SkCanvas* SkCanvasStateUtils::CreateFromCanvasState(const SkCanvasState* state) {

     SkASSERT(state);

     // check that the versions match

     if (CANVAS_STATE_VERSION != state->version) {

         SkDebugf("CreateFromCanvasState version does not match the one use to create the input");

         return NULL;

     }

     if (state->layerCount < 1) {

         return NULL;

     }

     SkAutoTUnref<SkCanvasStack> canvas(SkNEW_ARGS(SkCanvasStack, (state->width, state->height)));

     // setup the matrix and clip on the n-way canvas

     setup_canvas_from_MC_state(state->mcState, canvas);

     // Iterate over the layers and add them to the n-way canvas

     for (int i = state->layerCount - 1; i >= 0; --i) {

         SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state->layers[i]));

         if (!canvasLayer.get()) {

             return NULL;

         }

         canvas->pushCanvas(canvasLayer.get(), SkIPoint::Make(state->layers[i].x,

                                                              state->layers[i].y));

     }

     return canvas.detach();

 }

 ////////////////////////////////////////////////////////////////////////////////

 void SkCanvasStateUtils::ReleaseCanvasState(SkCanvasState* state) {

     SkDELETE(state);

 }