src/third_party/skia/src/utils/SkCanvasStateUtils.cpp

   1 /*
   2  * Copyright 2013 Google Inc.
   3  *
   4  * Use of this source code is governed by a BSD-style license that can be
   5  * found in the LICENSE file.
   6  */
   7
   8 #include "SkCanvasStateUtils.h"
   9
  10 #include "SkBitmapDevice.h"
  11 #include "SkCanvas.h"
  12 #include "SkCanvasStack.h"
  13 #include "SkErrorInternals.h"
  14 #include "SkWriter32.h"
  15
  16 /*
  17  * WARNING: The structs below are part of a stable ABI and as such we explicitly
  18  * use unambigious primitives (e.g. int32_t instead of an enum).
  19  *
  20  * ANY CHANGES TO THE STRUCTS BELOW THAT IMPACT THE ABI SHOULD RESULT IN A NEW
  21  * NEW SUBCLASS OF SkCanvasState. SUCH CHANGES SHOULD ONLY BE MADE IF ABSOLUTELY
  22  * NECESSARY!
  23  */
  24 enum RasterConfigs {
  25   kUnknown_RasterConfig   = 0,
  26   kRGB_565_RasterConfig   = 1,
  27   kARGB_8888_RasterConfig = 2
  28 };
  29 typedef int32_t RasterConfig;
  30
  31 enum CanvasBackends {
  32     kUnknown_CanvasBackend = 0,
  33     kRaster_CanvasBackend  = 1,
  34     kGPU_CanvasBackend     = 2,
  35     kPDF_CanvasBackend     = 3
  36 };
  37 typedef int32_t CanvasBackend;
  38
  39 struct ClipRect {
  40     int32_t left, top, right, bottom;
  41 };
  42
  43 struct SkMCState {
  44     float matrix[9];
  45     // NOTE: this only works for non-antialiased clips
  46     int32_t clipRectCount;
  47     ClipRect* clipRects;
  48 };
  49
  50 // NOTE: If you add more members, create a new subclass of SkCanvasState with a
  51 // new CanvasState::version.
  52 struct SkCanvasLayerState {
  53     CanvasBackend type;
  54     int32_t x, y;
  55     int32_t width;
  56     int32_t height;
  57
  58     SkMCState mcState;
  59
  60     union {
  61         struct {
  62             RasterConfig config; // pixel format: a value from RasterConfigs.
  63             uint64_t rowBytes;   // Number of bytes from start of one line to next.
  64             void* pixels;        // The pixels, all (height * rowBytes) of them.
  65         } raster;
  66         struct {
  67             int32_t textureID;
  68         } gpu;
  69     };
  70 };
  71
  72 class SkCanvasState {
  73 public:
  74     SkCanvasState(int32_t version, SkCanvas* canvas) {
  75         SkASSERT(canvas);
  76         this->version = version;
  77         width = canvas->getBaseLayerSize().width();
  78         height = canvas->getBaseLayerSize().height();
  79
  80     }
  81
  82     /**
  83      * The version this struct was built with.  This field must always appear
  84      * first in the struct so that when the versions don't match (and the
  85      * remaining contents and size are potentially different) we can still
  86      * compare the version numbers.
  87      */
  88     int32_t version;
  89     int32_t width;
  90     int32_t height;
  91     int32_t alignmentPadding;
  92 };
  93
  94 class SkCanvasState_v1 : public SkCanvasState {
  95 public:
  96     static const int32_t kVersion = 1;
  97
  98     SkCanvasState_v1(SkCanvas* canvas)
  99     : INHERITED(kVersion, canvas)
 100     {
 101         layerCount = 0;
 102         layers = NULL;
 103         mcState.clipRectCount = 0;
 104         mcState.clipRects = NULL;
 105         originalCanvas = SkRef(canvas);
 106     }
 107
 108     ~SkCanvasState_v1() {
 109         // loop through the layers and free the data allocated to the clipRects
 110         for (int i = 0; i < layerCount; ++i) {
 111             sk_free(layers[i].mcState.clipRects);
 112         }
 113
 114         sk_free(mcState.clipRects);
 115         sk_free(layers);
 116
 117         // it is now safe to free the canvas since there should be no remaining
 118         // references to the content that is referenced by this canvas (e.g. pixels)
 119         originalCanvas->unref();
 120     }
 121
 122     SkMCState mcState;
 123
 124     int32_t layerCount;
 125     SkCanvasLayerState* layers;
 126 private:
 127     SkCanvas* originalCanvas;
 128     typedef SkCanvasState INHERITED;
 129 };
 130
 131 ////////////////////////////////////////////////////////////////////////////////
 132
 133 class ClipValidator : public SkCanvas::ClipVisitor {
 134 public:
 135     ClipValidator() : fFailed(false) {}
 136     bool failed() { return fFailed; }
 137
 138     // ClipVisitor
 139     virtual void clipRect(const SkRect& rect, SkRegion::Op op, bool antialias) SK_OVERRIDE {
 140         fFailed |= antialias;
 141     }
 142
 143     virtual void clipRRect(const SkRRect& rrect, SkRegion::Op op, bool antialias) SK_OVERRIDE {
 144         fFailed |= antialias;
 145     }
 146
 147     virtual void clipPath(const SkPath&, SkRegion::Op, bool antialias) SK_OVERRIDE {
 148         fFailed |= antialias;
 149     }
 150
 151 private:
 152     bool fFailed;
 153 };
 154
 155 static void setup_MC_state(SkMCState* state, const SkMatrix& matrix, const SkRegion& clip) {
 156     // initialize the struct
 157     state->clipRectCount = 0;
 158
 159     // capture the matrix
 160     for (int i = 0; i < 9; i++) {
 161         state->matrix[i] = matrix.get(i);
 162     }
 163
 164     /*
 165      * capture the clip
 166      *
 167      * storage is allocated on the stack for the first 4 rects. This value was
 168      * chosen somewhat arbitrarily, but does allow us to represent simple clips
 169      * and some more common complex clips (e.g. a clipRect with a sub-rect
 170      * clipped out of its interior) without needing to malloc any additional memory.
 171      */
 172     SkSWriter32<4*sizeof(ClipRect)> clipWriter;
 173
 174     if (!clip.isEmpty()) {
 175         // only returns the b/w clip so aa clips fail
 176         SkRegion::Iterator clip_iterator(clip);
 177         for (; !clip_iterator.done(); clip_iterator.next()) {
 178             // this assumes the SkIRect is stored in l,t,r,b ordering which
 179             // matches the ordering of our ClipRect struct
 180             clipWriter.writeIRect(clip_iterator.rect());
 181             state->clipRectCount++;
 182         }
 183     }
 184
 185     // allocate memory for the clip then and copy them to the struct
 186     state->clipRects = (ClipRect*) sk_malloc_throw(clipWriter.bytesWritten());
 187     clipWriter.flatten(state->clipRects);
 188 }
 189
 190
 191
 192 SkCanvasState* SkCanvasStateUtils::CaptureCanvasState(SkCanvas* canvas) {
 193     SkASSERT(canvas);
 194
 195     // Check the clip can be decomposed into rectangles (i.e. no soft clips).
 196     ClipValidator validator;
 197     canvas->replayClips(&validator);
 198     if (validator.failed()) {
 199         SkErrorInternals::SetError(kInvalidOperation_SkError,
 200                 "CaptureCanvasState does not support canvases with antialiased clips.\n");
 201         return NULL;
 202     }
 203
 204     SkAutoTDelete<SkCanvasState_v1> canvasState(SkNEW_ARGS(SkCanvasState_v1, (canvas)));
 205
 206     // decompose the total matrix and clip
 207     setup_MC_state(&canvasState->mcState, canvas->getTotalMatrix(),
 208                    canvas->internal_private_getTotalClip());
 209
 210     /*
 211      * decompose the layers
 212      *
 213      * storage is allocated on the stack for the first 3 layers. It is common in
 214      * some view systems (e.g. Android) that a few non-clipped layers are present
 215      * and we will not need to malloc any additional memory in those cases.
 216      */
 217     SkSWriter32<3*sizeof(SkCanvasLayerState)> layerWriter;
 218     int layerCount = 0;
 219     for (SkCanvas::LayerIter layer(canvas, true/*skipEmptyClips*/); !layer.done(); layer.next()) {
 220
 221         // we currently only work for bitmap backed devices
 222         const SkBitmap& bitmap = layer.device()->accessBitmap(true/*changePixels*/);
 223         if (bitmap.empty() || bitmap.isNull() || !bitmap.lockPixelsAreWritable()) {
 224             return NULL;
 225         }
 226
 227         SkCanvasLayerState* layerState =
 228                 (SkCanvasLayerState*) layerWriter.reserve(sizeof(SkCanvasLayerState));
 229         layerState->type = kRaster_CanvasBackend;
 230         layerState->x = layer.x();
 231         layerState->y = layer.y();
 232         layerState->width = bitmap.width();
 233         layerState->height = bitmap.height();
 234
 235         switch (bitmap.colorType()) {
 236             case kN32_SkColorType:
 237                 layerState->raster.config = kARGB_8888_RasterConfig;
 238                 break;
 239             case kRGB_565_SkColorType:
 240                 layerState->raster.config = kRGB_565_RasterConfig;
 241                 break;
 242             default:
 243                 return NULL;
 244         }
 245         layerState->raster.rowBytes = bitmap.rowBytes();
 246         layerState->raster.pixels = bitmap.getPixels();
 247
 248         setup_MC_state(&layerState->mcState, layer.matrix(), layer.clip());
 249         layerCount++;
 250     }
 251
 252     // allocate memory for the layers and then and copy them to the struct
 253     SkASSERT(layerWriter.bytesWritten() == layerCount * sizeof(SkCanvasLayerState));
 254     canvasState->layerCount = layerCount;
 255     canvasState->layers = (SkCanvasLayerState*) sk_malloc_throw(layerWriter.bytesWritten());
 256     layerWriter.flatten(canvasState->layers);
 257
 258     // for now, just ignore any client supplied DrawFilter.
 259     if (canvas->getDrawFilter()) {
 260 //        SkDEBUGF(("CaptureCanvasState will ignore the canvas's draw filter.\n"));
 261     }
 262
 263     return canvasState.detach();
 264 }
 265
 266 ////////////////////////////////////////////////////////////////////////////////
 267
 268 static void setup_canvas_from_MC_state(const SkMCState& state, SkCanvas* canvas) {
 269     // reconstruct the matrix
 270     SkMatrix matrix;
 271     for (int i = 0; i < 9; i++) {
 272         matrix.set(i, state.matrix[i]);
 273     }
 274
 275     // reconstruct the clip
 276     SkRegion clip;
 277     for (int i = 0; i < state.clipRectCount; ++i) {
 278         clip.op(SkIRect::MakeLTRB(state.clipRects[i].left,
 279                                   state.clipRects[i].top,
 280                                   state.clipRects[i].right,
 281                                   state.clipRects[i].bottom),
 282                 SkRegion::kUnion_Op);
 283     }
 284
 285     canvas->setMatrix(matrix);
 286     canvas->setClipRegion(clip);
 287 }
 288
 289 static SkCanvas* create_canvas_from_canvas_layer(const SkCanvasLayerState& layerState) {
 290     SkASSERT(kRaster_CanvasBackend == layerState.type);
 291
 292     SkBitmap bitmap;
 293     SkColorType colorType =
 294         layerState.raster.config == kARGB_8888_RasterConfig ? kN32_SkColorType :
 295         layerState.raster.config == kRGB_565_RasterConfig ? kRGB_565_SkColorType :
 296         kUnknown_SkColorType;
 297
 298     if (colorType == kUnknown_SkColorType) {
 299         return NULL;
 300     }
 301
 302     bitmap.installPixels(SkImageInfo::Make(layerState.width, layerState.height,
 303                                            colorType, kPremul_SkAlphaType),
 304                          layerState.raster.pixels, (size_t) layerState.raster.rowBytes);
 305
 306     SkASSERT(!bitmap.empty());
 307     SkASSERT(!bitmap.isNull());
 308
 309     SkAutoTUnref<SkCanvas> canvas(SkNEW_ARGS(SkCanvas, (bitmap)));
 310
 311     // setup the matrix and clip
 312     setup_canvas_from_MC_state(layerState.mcState, canvas.get());
 313
 314     return canvas.detach();
 315 }
 316
 317 SkCanvas* SkCanvasStateUtils::CreateFromCanvasState(const SkCanvasState* state) {
 318     SkASSERT(state);
 319     // Currently there is only one possible version.
 320     SkASSERT(SkCanvasState_v1::kVersion == state->version);
 321
 322     const SkCanvasState_v1* state_v1 = static_cast<const SkCanvasState_v1*>(state);
 323
 324     if (state_v1->layerCount < 1) {
 325         return NULL;
 326     }
 327
 328     SkAutoTUnref<SkCanvasStack> canvas(SkNEW_ARGS(SkCanvasStack, (state->width, state->height)));
 329
 330     // setup the matrix and clip on the n-way canvas
 331     setup_canvas_from_MC_state(state_v1->mcState, canvas);
 332
 333     // Iterate over the layers and add them to the n-way canvas
 334     for (int i = state_v1->layerCount - 1; i >= 0; --i) {
 335         SkAutoTUnref<SkCanvas> canvasLayer(create_canvas_from_canvas_layer(state_v1->layers[i]));
 336         if (!canvasLayer.get()) {
 337             return NULL;
 338         }
 339         canvas->pushCanvas(canvasLayer.get(), SkIPoint::Make(state_v1->layers[i].x,
 340                                                              state_v1->layers[i].y));
 341     }
 342
 343     return canvas.detach();
 344 }
 345
 346 ////////////////////////////////////////////////////////////////////////////////
 347
 348 void SkCanvasStateUtils::ReleaseCanvasState(SkCanvasState* state) {
 349     SkASSERT(!state || SkCanvasState_v1::kVersion == state->version);
 350     // Upcast to the correct version of SkCanvasState. This avoids having a virtual destructor on
 351     // SkCanvasState. That would be strange since SkCanvasState has no other virtual functions, and
 352     // instead uses the field "version" to determine how to behave.
 353     SkDELETE(static_cast<SkCanvasState_v1*>(state));
 354 }