skia/images/SkCreateRLEPixelRef.cpp

   1 #include "SkChunkAlloc.h"
   2 #include "SkPackBits.h"
   3 #include "SkBitmap.h"
   4 #include "SkPixelRef.h"
   5
   6 class RLEPixelRef : public SkPixelRef {
   7 public:
   8     RLEPixelRef(SkBitmap::RLEPixels* rlep, SkColorTable* ctable);
   9     virtual ~RLEPixelRef();
  10
  11 protected:
  12     // overrides from SkPixelRef
  13     virtual void* onLockPixels(SkColorTable**);
  14     virtual void onUnlockPixels();
  15
  16 private:
  17     SkBitmap::RLEPixels* fRLEPixels;
  18     SkColorTable*        fCTable;
  19 };
  20
  21 RLEPixelRef::RLEPixelRef(SkBitmap::RLEPixels* rlep, SkColorTable* ctable)
  22         : SkPixelRef(NULL) {
  23     fRLEPixels = rlep;  // we now own this ptr
  24     fCTable = ctable;
  25     ctable->safeRef();
  26 }
  27
  28 RLEPixelRef::~RLEPixelRef() {
  29     SkDELETE(fRLEPixels);
  30     fCTable->safeUnref();
  31 }
  32
  33 void* RLEPixelRef::onLockPixels(SkColorTable** ct) {
  34     *ct = fCTable;
  35     return fRLEPixels;
  36 }
  37
  38 void RLEPixelRef::onUnlockPixels() {
  39     // nothing to do
  40 }
  41
  42 /////////////////////////////////////////////////////////////////////////////
  43
  44 class ChunkRLEPixels : public SkBitmap::RLEPixels {
  45 public:
  46     ChunkRLEPixels(int width, int height, size_t chunkSize)
  47         : SkBitmap::RLEPixels(width, height), fStorage(chunkSize) {
  48     }
  49
  50     SkChunkAlloc fStorage;
  51 };
  52
  53 SkPixelRef* SkCreateRLEPixelRef(const SkBitmap& src);
  54 SkPixelRef* SkCreateRLEPixelRef(const SkBitmap& src) {
  55
  56     if (SkBitmap::kIndex8_Config != src.config() &&
  57             SkBitmap::kA8_Config != src.config()) {
  58         return NULL;
  59     }
  60
  61     size_t maxPacked = SkPackBits::ComputeMaxSize8(src.width());
  62
  63     // estimate the rle size based on the original size
  64     size_t size = src.getSize() >> 3;
  65     if (size < maxPacked) {
  66         size = maxPacked;
  67     }
  68
  69     ChunkRLEPixels* rlePixels = SkNEW_ARGS(ChunkRLEPixels,
  70                                            (src.width(), src.height(), size));
  71
  72     uint8_t* dstRow = NULL;
  73     size_t free = 0;
  74     size_t totalPacked = 0;
  75
  76     for (int y = 0; y < src.height(); y++) {
  77         const uint8_t* srcRow = src.getAddr8(0, y);
  78
  79         if (free < maxPacked) {
  80             dstRow = (uint8_t*)rlePixels->fStorage.allocThrow(size);
  81             free = size;
  82         }
  83         size_t packedSize = SkPackBits::Pack8(srcRow, src.width(), dstRow);
  84         SkASSERT(packedSize <= free);
  85         rlePixels->setPackedAtY(y, dstRow);
  86
  87         dstRow += packedSize;
  88         free -= packedSize;
  89
  90         totalPacked += packedSize;
  91     }
  92
  93 //#ifdef SK_DEBUG
  94 #if 0
  95     // test
  96     uint8_t* buffer = new uint8_t[src.width()];
  97     for (int y = 0; y < src.height(); y++) {
  98         const uint8_t* srcRow = src.getAddr8(0, y);
  99         SkPackBits::Unpack8(buffer, 0, src.width(), rlePixels->packedAtY(y));
 100         int n = memcmp(buffer, srcRow, src.width());
 101         if (n) {
 102             SkDebugf("----- memcmp returned %d on line %d\n", n, y);
 103         }
 104         SkASSERT(n == 0);
 105     }
 106     delete[] buffer;
 107
 108     size_t totalAlloc = src.height() * sizeof(uint8_t*) + totalPacked;
 109
 110     SkDebugf("--- RLE: orig [%d %d] %d, rle %d %d savings %g\n",
 111              src.width(), src.height(), src.getSize(),
 112              src.height() * sizeof(uint8_t*), totalPacked,
 113              (float)totalAlloc / src.getSize());
 114
 115 #endif
 116
 117     // transfer ownership of rlePixels to our pixelref
 118     return SkNEW_ARGS(RLEPixelRef, (rlePixels, src.getColorTable()));
 119 }
 120