michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "SkMipMap.h"
michael@0: #include "SkBitmap.h"
michael@0: #include "SkColorPriv.h"
michael@0: 
michael@0: static void downsampleby2_proc32(SkBitmap* dst, int x, int y,
michael@0:                                  const SkBitmap& src) {
michael@0:     x <<= 1;
michael@0:     y <<= 1;
michael@0:     const SkPMColor* p = src.getAddr32(x, y);
michael@0:     const SkPMColor* baseP = p;
michael@0:     SkPMColor c, ag, rb;
michael@0: 
michael@0:     c = *p; ag = (c >> 8) & 0xFF00FF; rb = c & 0xFF00FF;
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c = *p; ag += (c >> 8) & 0xFF00FF; rb += c & 0xFF00FF;
michael@0: 
michael@0:     p = baseP;
michael@0:     if (y < src.height() - 1) {
michael@0:         p += src.rowBytes() >> 2;
michael@0:     }
michael@0:     c = *p; ag += (c >> 8) & 0xFF00FF; rb += c & 0xFF00FF;
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c = *p; ag += (c >> 8) & 0xFF00FF; rb += c & 0xFF00FF;
michael@0: 
michael@0:     *dst->getAddr32(x >> 1, y >> 1) =
michael@0:     ((rb >> 2) & 0xFF00FF) | ((ag << 6) & 0xFF00FF00);
michael@0: }
michael@0: 
michael@0: static inline uint32_t expand16(U16CPU c) {
michael@0:     return (c & ~SK_G16_MASK_IN_PLACE) | ((c & SK_G16_MASK_IN_PLACE) << 16);
michael@0: }
michael@0: 
michael@0: // returns dirt in the top 16bits, but we don't care, since we only
michael@0: // store the low 16bits.
michael@0: static inline U16CPU pack16(uint32_t c) {
michael@0:     return (c & ~SK_G16_MASK_IN_PLACE) | ((c >> 16) & SK_G16_MASK_IN_PLACE);
michael@0: }
michael@0: 
michael@0: static void downsampleby2_proc16(SkBitmap* dst, int x, int y,
michael@0:                                  const SkBitmap& src) {
michael@0:     x <<= 1;
michael@0:     y <<= 1;
michael@0:     const uint16_t* p = src.getAddr16(x, y);
michael@0:     const uint16_t* baseP = p;
michael@0:     SkPMColor       c;
michael@0: 
michael@0:     c = expand16(*p);
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c += expand16(*p);
michael@0: 
michael@0:     p = baseP;
michael@0:     if (y < src.height() - 1) {
michael@0:         p += src.rowBytes() >> 1;
michael@0:     }
michael@0:     c += expand16(*p);
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c += expand16(*p);
michael@0: 
michael@0:     *dst->getAddr16(x >> 1, y >> 1) = (uint16_t)pack16(c >> 2);
michael@0: }
michael@0: 
michael@0: static uint32_t expand4444(U16CPU c) {
michael@0:     return (c & 0xF0F) | ((c & ~0xF0F) << 12);
michael@0: }
michael@0: 
michael@0: static U16CPU collaps4444(uint32_t c) {
michael@0:     return (c & 0xF0F) | ((c >> 12) & ~0xF0F);
michael@0: }
michael@0: 
michael@0: static void downsampleby2_proc4444(SkBitmap* dst, int x, int y,
michael@0:                                    const SkBitmap& src) {
michael@0:     x <<= 1;
michael@0:     y <<= 1;
michael@0:     const uint16_t* p = src.getAddr16(x, y);
michael@0:     const uint16_t* baseP = p;
michael@0:     uint32_t        c;
michael@0: 
michael@0:     c = expand4444(*p);
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c += expand4444(*p);
michael@0: 
michael@0:     p = baseP;
michael@0:     if (y < src.height() - 1) {
michael@0:         p += src.rowBytes() >> 1;
michael@0:     }
michael@0:     c += expand4444(*p);
michael@0:     if (x < src.width() - 1) {
michael@0:         p += 1;
michael@0:     }
michael@0:     c += expand4444(*p);
michael@0: 
michael@0:     *dst->getAddr16(x >> 1, y >> 1) = (uint16_t)collaps4444(c >> 2);
michael@0: }
michael@0: 
michael@0: SkMipMap::Level* SkMipMap::AllocLevels(int levelCount, size_t pixelSize) {
michael@0:     if (levelCount < 0) {
michael@0:         return NULL;
michael@0:     }
michael@0:     int64_t size = sk_64_mul(levelCount + 1, sizeof(Level)) + pixelSize;
michael@0:     if (!sk_64_isS32(size)) {
michael@0:         return NULL;
michael@0:     }
michael@0:     return (Level*)sk_malloc_throw(sk_64_asS32(size));
michael@0: }
michael@0: 
michael@0: SkMipMap* SkMipMap::Build(const SkBitmap& src) {
michael@0:     void (*proc)(SkBitmap* dst, int x, int y, const SkBitmap& src);
michael@0: 
michael@0:     const SkBitmap::Config config = src.config();
michael@0:     switch (config) {
michael@0:         case SkBitmap::kARGB_8888_Config:
michael@0:             proc = downsampleby2_proc32;
michael@0:             break;
michael@0:         case SkBitmap::kRGB_565_Config:
michael@0:             proc = downsampleby2_proc16;
michael@0:             break;
michael@0:         case SkBitmap::kARGB_4444_Config:
michael@0:             proc = downsampleby2_proc4444;
michael@0:             break;
michael@0:         case SkBitmap::kIndex8_Config:
michael@0:         case SkBitmap::kA8_Config:
michael@0:         default:
michael@0:             return NULL; // don't build mipmaps for these configs
michael@0:     }
michael@0: 
michael@0:     SkAutoLockPixels alp(src);
michael@0:     if (!src.readyToDraw()) {
michael@0:         return NULL;
michael@0:     }
michael@0: 
michael@0:     // whip through our loop to compute the exact size needed
michael@0:     size_t  size = 0;
michael@0:     int     countLevels = 0;
michael@0:     {
michael@0:         int width = src.width();
michael@0:         int height = src.height();
michael@0:         for (;;) {
michael@0:             width >>= 1;
michael@0:             height >>= 1;
michael@0:             if (0 == width || 0 == height) {
michael@0:                 break;
michael@0:             }
michael@0:             size += SkBitmap::ComputeRowBytes(config, width) * height;
michael@0:             countLevels += 1;
michael@0:         }
michael@0:     }
michael@0:     if (0 == countLevels) {
michael@0:         return NULL;
michael@0:     }
michael@0: 
michael@0:     Level* levels = SkMipMap::AllocLevels(countLevels, size);
michael@0:     if (NULL == levels) {
michael@0:         return NULL;
michael@0:     }
michael@0: 
michael@0:     uint8_t*    baseAddr = (uint8_t*)&levels[countLevels];
michael@0:     uint8_t*    addr = baseAddr;
michael@0:     int         width = src.width();
michael@0:     int         height = src.height();
michael@0:     uint32_t    rowBytes;
michael@0:     SkBitmap    srcBM(src);
michael@0: 
michael@0:     for (int i = 0; i < countLevels; ++i) {
michael@0:         width >>= 1;
michael@0:         height >>= 1;
michael@0:         rowBytes = SkToU32(SkBitmap::ComputeRowBytes(config, width));
michael@0: 
michael@0:         levels[i].fPixels   = addr;
michael@0:         levels[i].fWidth    = width;
michael@0:         levels[i].fHeight   = height;
michael@0:         levels[i].fRowBytes = rowBytes;
michael@0:         levels[i].fScale    = (float)width / src.width();
michael@0: 
michael@0:         SkBitmap dstBM;
michael@0:         dstBM.setConfig(config, width, height, rowBytes);
michael@0:         dstBM.setPixels(addr);
michael@0: 
michael@0:         srcBM.lockPixels();
michael@0:         for (int y = 0; y < height; y++) {
michael@0:             for (int x = 0; x < width; x++) {
michael@0:                 proc(&dstBM, x, y, srcBM);
michael@0:             }
michael@0:         }
michael@0:         srcBM.unlockPixels();
michael@0: 
michael@0:         srcBM = dstBM;
michael@0:         addr += height * rowBytes;
michael@0:     }
michael@0:     SkASSERT(addr == baseAddr + size);
michael@0: 
michael@0:     return SkNEW_ARGS(SkMipMap, (levels, countLevels, size));
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: //static int gCounter;
michael@0: 
michael@0: SkMipMap::SkMipMap(Level* levels, int count, size_t size)
michael@0:     : fSize(size), fLevels(levels), fCount(count) {
michael@0:     SkASSERT(levels);
michael@0:     SkASSERT(count > 0);
michael@0: //    SkDebugf("mips %d\n", ++gCounter);
michael@0: }
michael@0: 
michael@0: SkMipMap::~SkMipMap() {
michael@0:     sk_free(fLevels);
michael@0: //    SkDebugf("mips %d\n", --gCounter);
michael@0: }
michael@0: 
michael@0: static SkFixed compute_level(SkScalar scale) {
michael@0:     SkFixed s = SkAbs32(SkScalarToFixed(SkScalarInvert(scale)));
michael@0: 
michael@0:     if (s < SK_Fixed1) {
michael@0:         return 0;
michael@0:     }
michael@0:     int clz = SkCLZ(s);
michael@0:     SkASSERT(clz >= 1 && clz <= 15);
michael@0:     return SkIntToFixed(15 - clz) + ((unsigned)(s << (clz + 1)) >> 16);
michael@0: }
michael@0: 
michael@0: bool SkMipMap::extractLevel(SkScalar scale, Level* levelPtr) const {
michael@0:     if (scale >= SK_Scalar1) {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     int level = compute_level(scale) >> 16;
michael@0:     SkASSERT(level >= 0);
michael@0:     if (level <= 0) {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     if (level > fCount) {
michael@0:         level = fCount;
michael@0:     }
michael@0:     if (levelPtr) {
michael@0:         *levelPtr = fLevels[level - 1];
michael@0:     }
michael@0:     return true;
michael@0: }