diff --git a/src/gifcodec.c b/src/gifcodec.c index e1a0697..e645c6e 100644 --- a/src/gifcodec.c +++ b/src/gifcodec.c @@ -39,4 +39,291 @@ GUID gdip_gif_image_format_guid = {0xb96b3cb0U, 0x0728U, 0x11d3U, {0x9d, 0x7b, 0 #include "gifcodec.h" +#define COLOR_ARRAY_SIZE 32768 +#define BITS_PER_PRIM_COLOR 5 +#define MAX_PRIM_COLOR 0x1f + +static int SortRGBAxis; + +typedef struct QuantizedColorType { + GifByteType RGB[3]; + GifByteType NewColorIndex; + long Count; + struct QuantizedColorType *Pnext; +} QuantizedColorType; + +typedef struct NewColorMapType { + GifByteType RGBMin[3], RGBWidth[3]; + unsigned int NumEntries; /* # of QuantizedColorType in linked list below */ + unsigned long Count; /* Total number of pixels in all the entries */ + QuantizedColorType *QuantizedColors; +} NewColorMapType; + + +/**************************************************************************** + * Routine called by qsort to compare two entries. + ****************************************************************************/ +static int +SortCmpRtn(const void *Entry1, + const void *Entry2) { + + return (*((QuantizedColorType **) Entry1))->RGB[SortRGBAxis] - + (*((QuantizedColorType **) Entry2))->RGB[SortRGBAxis]; +} + +/****************************************************************************** + * Routine to subdivide the RGB space recursively using median cut in each + * axes alternatingly until ColorMapSize different cubes exists. + * The biggest cube in one dimension is subdivide unless it has only one entry. + * Returns GIF_ERROR if failed, otherwise GIF_OK. + ******************************************************************************/ +static int +SubdivColorMap(NewColorMapType * NewColorSubdiv, + unsigned int ColorMapSize, + unsigned int *NewColorMapSize) { + + int MaxSize; + unsigned int i, j, Index = 0, NumEntries, MinColor, MaxColor; + long Sum, Count; + QuantizedColorType *QuantizedColor, **SortArray; + + while (ColorMapSize > *NewColorMapSize) { + /* Find candidate for subdivision: */ + MaxSize = -1; + for (i = 0; i < *NewColorMapSize; i++) { + for (j = 0; j < 3; j++) { + if ((((int)NewColorSubdiv[i].RGBWidth[j]) > MaxSize) && + (NewColorSubdiv[i].NumEntries > 1)) { + MaxSize = NewColorSubdiv[i].RGBWidth[j]; + Index = i; + SortRGBAxis = j; + } + } + } + + if (MaxSize == -1) + return GIF_OK; + + /* Split the entry Index into two along the axis SortRGBAxis: */ + + /* Sort all elements in that entry along the given axis and split at + * the median. */ + SortArray = (QuantizedColorType **)malloc( + sizeof(QuantizedColorType *) * + NewColorSubdiv[Index].NumEntries); + if (SortArray == NULL) + return GIF_ERROR; + for (j = 0, QuantizedColor = NewColorSubdiv[Index].QuantizedColors; + j < NewColorSubdiv[Index].NumEntries && QuantizedColor != NULL; + j++, QuantizedColor = QuantizedColor->Pnext) + SortArray[j] = QuantizedColor; + + qsort(SortArray, NewColorSubdiv[Index].NumEntries, + sizeof(QuantizedColorType *), SortCmpRtn); + + /* Relink the sorted list into one: */ + for (j = 0; j < NewColorSubdiv[Index].NumEntries - 1; j++) + SortArray[j]->Pnext = SortArray[j + 1]; + SortArray[NewColorSubdiv[Index].NumEntries - 1]->Pnext = NULL; + NewColorSubdiv[Index].QuantizedColors = QuantizedColor = SortArray[0]; + free((char *)SortArray); + + /* Now simply add the Counts until we have half of the Count: */ + Sum = NewColorSubdiv[Index].Count / 2 - QuantizedColor->Count; + NumEntries = 1; + Count = QuantizedColor->Count; + while (QuantizedColor->Pnext != NULL && + (Sum -= QuantizedColor->Pnext->Count) >= 0 && + QuantizedColor->Pnext->Pnext != NULL) { + QuantizedColor = QuantizedColor->Pnext; + NumEntries++; + Count += QuantizedColor->Count; + } + /* Save the values of the last color of the first half, and first + * of the second half so we can update the Bounding Boxes later. + * Also as the colors are quantized and the BBoxes are full 0..255, + * they need to be rescaled. + */ + MaxColor = QuantizedColor->RGB[SortRGBAxis]; /* Max. of first half */ + /* coverity[var_deref_op] */ + MinColor = QuantizedColor->Pnext->RGB[SortRGBAxis]; /* of second */ + MaxColor <<= (8 - BITS_PER_PRIM_COLOR); + MinColor <<= (8 - BITS_PER_PRIM_COLOR); + + /* Partition right here: */ + NewColorSubdiv[*NewColorMapSize].QuantizedColors = + QuantizedColor->Pnext; + QuantizedColor->Pnext = NULL; + NewColorSubdiv[*NewColorMapSize].Count = Count; + NewColorSubdiv[Index].Count -= Count; + NewColorSubdiv[*NewColorMapSize].NumEntries = + NewColorSubdiv[Index].NumEntries - NumEntries; + NewColorSubdiv[Index].NumEntries = NumEntries; + for (j = 0; j < 3; j++) { + NewColorSubdiv[*NewColorMapSize].RGBMin[j] = + NewColorSubdiv[Index].RGBMin[j]; + NewColorSubdiv[*NewColorMapSize].RGBWidth[j] = + NewColorSubdiv[Index].RGBWidth[j]; + } + NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] = + NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] + + NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] - MinColor; + NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] = MinColor; + + NewColorSubdiv[Index].RGBWidth[SortRGBAxis] = + MaxColor - NewColorSubdiv[Index].RGBMin[SortRGBAxis]; + + (*NewColorMapSize)++; + } + + return GIF_OK; +} + +/****************************************************************************** + * Quantize high resolution image into lower one. Input image consists of a + * 2D array for each of the RGB colors with size Width by Height. There is no + * Color map for the input. Output is a quantized image with 2D array of + * indexes into the output color map. + * Note input image can be 24 bits at the most (8 for red/green/blue) and + * the output has 256 colors at the most (256 entries in the color map.). + * ColorMapSize specifies size of color map up to 256 and will be updated to + * real size before returning. + * Also non of the parameter are allocated by this routine. + * This function returns GIF_OK if succesfull, GIF_ERROR otherwise. + ******************************************************************************/ +static int +QuantizeBuffer(unsigned int Width, + unsigned int Height, + int *ColorMapSize, + GifByteType * RedInput, + GifByteType * GreenInput, + GifByteType * BlueInput, + GifByteType * OutputBuffer, + GifColorType * OutputColorMap) { + + unsigned int Index, NumOfEntries; + int i, j, MaxRGBError[3]; + unsigned int NewColorMapSize; + long Red, Green, Blue; + NewColorMapType NewColorSubdiv[256]; + QuantizedColorType *ColorArrayEntries, *QuantizedColor; + + ColorArrayEntries = (QuantizedColorType *)malloc( + sizeof(QuantizedColorType) * COLOR_ARRAY_SIZE); + if (ColorArrayEntries == NULL) { + return GIF_ERROR; + } + + for (i = 0; i < COLOR_ARRAY_SIZE; i++) { + ColorArrayEntries[i].RGB[0] = i >> (2 * BITS_PER_PRIM_COLOR); + ColorArrayEntries[i].RGB[1] = (i >> BITS_PER_PRIM_COLOR) & + MAX_PRIM_COLOR; + ColorArrayEntries[i].RGB[2] = i & MAX_PRIM_COLOR; + ColorArrayEntries[i].Count = 0; + } + + /* Sample the colors and their distribution: */ + for (i = 0; i < (int)(Width * Height); i++) { + Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << + (2 * BITS_PER_PRIM_COLOR)) + + ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << + BITS_PER_PRIM_COLOR) + + (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR)); + ColorArrayEntries[Index].Count++; + } + + /* Put all the colors in the first entry of the color map, and call the + * recursive subdivision process. */ + for (i = 0; i < 256; i++) { + NewColorSubdiv[i].QuantizedColors = NULL; + NewColorSubdiv[i].Count = NewColorSubdiv[i].NumEntries = 0; + for (j = 0; j < 3; j++) { + NewColorSubdiv[i].RGBMin[j] = 0; + NewColorSubdiv[i].RGBWidth[j] = 255; + } + } + + /* Find the non empty entries in the color table and chain them: */ + for (i = 0; i < COLOR_ARRAY_SIZE; i++) + if (ColorArrayEntries[i].Count > 0) + break; + QuantizedColor = NewColorSubdiv[0].QuantizedColors = &ColorArrayEntries[i]; + NumOfEntries = 1; + while (++i < COLOR_ARRAY_SIZE) + if (ColorArrayEntries[i].Count > 0) { + QuantizedColor->Pnext = &ColorArrayEntries[i]; + QuantizedColor = &ColorArrayEntries[i]; + NumOfEntries++; + } + QuantizedColor->Pnext = NULL; + + NewColorSubdiv[0].NumEntries = NumOfEntries; /* Different sampled colors */ + NewColorSubdiv[0].Count = ((long)Width) * Height; /* Pixels */ + NewColorMapSize = 1; + if (SubdivColorMap(NewColorSubdiv, *ColorMapSize, &NewColorMapSize) != + GIF_OK) { + free((char *)ColorArrayEntries); + return GIF_ERROR; + } + if (NewColorMapSize < *ColorMapSize) { + /* And clear rest of color map: */ + for (i = NewColorMapSize; i < *ColorMapSize; i++) + OutputColorMap[i].Red = OutputColorMap[i].Green = + OutputColorMap[i].Blue = 0; + } + + /* Average the colors in each entry to be the color to be used in the + * output color map, and plug it into the output color map itself. */ + for (i = 0; i < NewColorMapSize; i++) { + if ((j = NewColorSubdiv[i].NumEntries) > 0) { + QuantizedColor = NewColorSubdiv[i].QuantizedColors; + Red = Green = Blue = 0; + while (QuantizedColor) { + QuantizedColor->NewColorIndex = i; + Red += QuantizedColor->RGB[0]; + Green += QuantizedColor->RGB[1]; + Blue += QuantizedColor->RGB[2]; + QuantizedColor = QuantizedColor->Pnext; + } + OutputColorMap[i].Red = (Red << (8 - BITS_PER_PRIM_COLOR)) / j; + OutputColorMap[i].Green = (Green << (8 - BITS_PER_PRIM_COLOR)) / j; + OutputColorMap[i].Blue = (Blue << (8 - BITS_PER_PRIM_COLOR)) / j; + } else + fprintf(stderr, + "\n%s: Null entry in quantized color map - that's weird.\n", + "libgdiplus"); + } + + /* Finally scan the input buffer again and put the mapped index in the + * output buffer. */ + MaxRGBError[0] = MaxRGBError[1] = MaxRGBError[2] = 0; + for (i = 0; i < (int)(Width * Height); i++) { + Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << + (2 * BITS_PER_PRIM_COLOR)) + + ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) << + BITS_PER_PRIM_COLOR) + + (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR)); + Index = ColorArrayEntries[Index].NewColorIndex; + OutputBuffer[i] = Index; + if (MaxRGBError[0] < ABS(OutputColorMap[Index].Red - RedInput[i])) + MaxRGBError[0] = ABS(OutputColorMap[Index].Red - RedInput[i]); + if (MaxRGBError[1] < ABS(OutputColorMap[Index].Green - GreenInput[i])) + MaxRGBError[1] = ABS(OutputColorMap[Index].Green - GreenInput[i]); + if (MaxRGBError[2] < ABS(OutputColorMap[Index].Blue - BlueInput[i])) + MaxRGBError[2] = ABS(OutputColorMap[Index].Blue - BlueInput[i]); + } + +#ifdef DEBUG + fprintf(stderr, + "Quantization L(0) errors: Red = %d, Green = %d, Blue = %d.\n", + MaxRGBError[0], MaxRGBError[1], MaxRGBError[2]); +#endif /* DEBUG */ + + free((char *)ColorArrayEntries); + + *ColorMapSize = NewColorMapSize; + + return GIF_OK; +} + /* Data structure used for callback */