SkConfig8888.cpp revision 0c9b1a8d05ea6ec5dfae0ead854304673d94d2c2 
1/*
2 * Copyright 2014 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 "SkBitmap.h"
9#include "SkCanvas.h"
10#include "SkConfig8888.h"
11#include "SkColorPriv.h"
12#include "SkDither.h"
13#include "SkMathPriv.h"
14#include "SkUnPreMultiply.h"
15
16enum AlphaVerb {
17    kNothing_AlphaVerb,
18    kPremul_AlphaVerb,
19    kUnpremul_AlphaVerb,
20};
21
22template <bool doSwapRB, AlphaVerb doAlpha> uint32_t convert32(uint32_t c) {
23    if (doSwapRB) {
24        c = SkSwizzle_RB(c);
25    }
26
27    // Lucky for us, in both RGBA and BGRA, the alpha component is always in the same place, so
28    // we can perform premul or unpremul the same way without knowing the swizzles for RGB.
29    switch (doAlpha) {
30        case kNothing_AlphaVerb:
31            // no change
32            break;
33        case kPremul_AlphaVerb:
34            c = SkPreMultiplyARGB(SkGetPackedA32(c), SkGetPackedR32(c),
35                                  SkGetPackedG32(c), SkGetPackedB32(c));
36            break;
37        case kUnpremul_AlphaVerb:
38            c = SkUnPreMultiply::UnPreMultiplyPreservingByteOrder(c);
39            break;
40    }
41    return c;
42}
43
44template <bool doSwapRB, AlphaVerb doAlpha>
45void convert32_row(uint32_t* dst, const uint32_t* src, int count) {
46    // This has to be correct if src == dst (but not partial overlap)
47    for (int i = 0; i < count; ++i) {
48        dst[i] = convert32<doSwapRB, doAlpha>(src[i]);
49    }
50}
51
52static bool is_32bit_colortype(SkColorType ct) {
53    return kRGBA_8888_SkColorType == ct || kBGRA_8888_SkColorType == ct;
54}
55
56static AlphaVerb compute_AlphaVerb(SkAlphaType src, SkAlphaType dst) {
57    SkASSERT(kUnknown_SkAlphaType != src);
58    SkASSERT(kUnknown_SkAlphaType != dst);
59
60    if (kOpaque_SkAlphaType == src || kOpaque_SkAlphaType == dst || src == dst) {
61        return kNothing_AlphaVerb;
62    }
63    if (kPremul_SkAlphaType == dst) {
64        SkASSERT(kUnpremul_SkAlphaType == src);
65        return kPremul_AlphaVerb;
66    } else {
67        SkASSERT(kPremul_SkAlphaType == src);
68        SkASSERT(kUnpremul_SkAlphaType == dst);
69        return kUnpremul_AlphaVerb;
70    }
71}
72
73static void memcpy32_row(uint32_t* dst, const uint32_t* src, int count) {
74    memcpy(dst, src, count * 4);
75}
76
77bool SkSrcPixelInfo::convertPixelsTo(SkDstPixelInfo* dst, int width, int height) const {
78    if (width <= 0 || height <= 0) {
79        return false;
80    }
81
82    if (!is_32bit_colortype(fColorType) || !is_32bit_colortype(dst->fColorType)) {
83        return false;
84    }
85
86    void (*proc)(uint32_t* dst, const uint32_t* src, int count);
87    AlphaVerb doAlpha = compute_AlphaVerb(fAlphaType, dst->fAlphaType);
88    bool doSwapRB = fColorType != dst->fColorType;
89
90    switch (doAlpha) {
91        case kNothing_AlphaVerb:
92            if (doSwapRB) {
93                proc = convert32_row<true, kNothing_AlphaVerb>;
94            } else {
95                if (fPixels == dst->fPixels) {
96                    return true;
97                }
98                proc = memcpy32_row;
99            }
100            break;
101        case kPremul_AlphaVerb:
102            if (doSwapRB) {
103                proc = convert32_row<true, kPremul_AlphaVerb>;
104            } else {
105                proc = convert32_row<false, kPremul_AlphaVerb>;
106            }
107            break;
108        case kUnpremul_AlphaVerb:
109            if (doSwapRB) {
110                proc = convert32_row<true, kUnpremul_AlphaVerb>;
111            } else {
112                proc = convert32_row<false, kUnpremul_AlphaVerb>;
113            }
114            break;
115    }
116
117    uint32_t* dstP = static_cast<uint32_t*>(dst->fPixels);
118    const uint32_t* srcP = static_cast<const uint32_t*>(fPixels);
119    size_t srcInc = fRowBytes >> 2;
120    size_t dstInc = dst->fRowBytes >> 2;
121    for (int y = 0; y < height; ++y) {
122        proc(dstP, srcP, width);
123        dstP += dstInc;
124        srcP += srcInc;
125    }
126    return true;
127}
128
129static void rect_memcpy(void* dst, size_t dstRB, const void* src, size_t srcRB, size_t bytesPerRow,
130                        int rowCount) {
131    SkASSERT(bytesPerRow <= srcRB);
132    SkASSERT(bytesPerRow <= dstRB);
133    for (int i = 0; i < rowCount; ++i) {
134        memcpy(dst, src, bytesPerRow);
135        dst = (char*)dst + dstRB;
136        src = (const char*)src + srcRB;
137    }
138}
139
140static void copy_g8_to_32(void* dst, size_t dstRB, const void* src, size_t srcRB, int w, int h) {
141    uint32_t* dst32 = (uint32_t*)dst;
142    const uint8_t* src8 = (const uint8_t*)src;
143
144    for (int y = 0; y < h; ++y) {
145        for (int x = 0; x < w; ++x) {
146            dst32[x] = SkPackARGB32(0xFF, src8[x], src8[x], src8[x]);
147        }
148        dst32 = (uint32_t*)((char*)dst32 + dstRB);
149        src8 += srcRB;
150    }
151}
152
153static void copy_32_to_g8(void* dst, size_t dstRB, const void* src, size_t srcRB,
154                          const SkImageInfo& srcInfo) {
155    uint8_t* dst8 = (uint8_t*)dst;
156    const uint32_t* src32 = (const uint32_t*)src;
157
158    const int w = srcInfo.width();
159    const int h = srcInfo.height();
160    const bool isBGRA = (kBGRA_8888_SkColorType == srcInfo.colorType());
161
162    for (int y = 0; y < h; ++y) {
163        if (isBGRA) {
164            // BGRA
165            for (int x = 0; x < w; ++x) {
166                uint32_t s = src32[x];
167                dst8[x] = SkComputeLuminance((s >> 16) & 0xFF, (s >> 8) & 0xFF, s & 0xFF);
168            }
169        } else {
170            // RGBA
171            for (int x = 0; x < w; ++x) {
172                uint32_t s = src32[x];
173                dst8[x] = SkComputeLuminance(s & 0xFF, (s >> 8) & 0xFF, (s >> 16) & 0xFF);
174            }
175        }
176        src32 = (const uint32_t*)((const char*)src32 + srcRB);
177        dst8 += dstRB;
178    }
179}
180
181bool SkPixelInfo::CopyPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRB,
182                             const SkImageInfo& srcInfo, const void* srcPixels, size_t srcRB,
183                             SkColorTable* ctable) {
184    if (srcInfo.dimensions() != dstInfo.dimensions()) {
185        return false;
186    }
187
188    const int width = srcInfo.width();
189    const int height = srcInfo.height();
190
191    // Handle fancy alpha swizzling if both are ARGB32
192    if (4 == srcInfo.bytesPerPixel() && 4 == dstInfo.bytesPerPixel()) {
193        SkDstPixelInfo dstPI;
194        dstPI.fColorType = dstInfo.colorType();
195        dstPI.fAlphaType = dstInfo.alphaType();
196        dstPI.fPixels = dstPixels;
197        dstPI.fRowBytes = dstRB;
198
199        SkSrcPixelInfo srcPI;
200        srcPI.fColorType = srcInfo.colorType();
201        srcPI.fAlphaType = srcInfo.alphaType();
202        srcPI.fPixels = srcPixels;
203        srcPI.fRowBytes = srcRB;
204
205        return srcPI.convertPixelsTo(&dstPI, width, height);
206    }
207
208    // If they agree on colorType and the alphaTypes are compatible, then we just memcpy.
209    // Note: we've already taken care of 32bit colortypes above.
210    if (srcInfo.colorType() == dstInfo.colorType()) {
211        switch (srcInfo.colorType()) {
212            case kRGB_565_SkColorType:
213            case kAlpha_8_SkColorType:
214            case kGray_8_SkColorType:
215                break;
216            case kIndex_8_SkColorType:
217            case kARGB_4444_SkColorType:
218                if (srcInfo.alphaType() != dstInfo.alphaType()) {
219                    return false;
220                }
221                break;
222            default:
223                return false;
224        }
225        rect_memcpy(dstPixels, dstRB, srcPixels, srcRB, width * srcInfo.bytesPerPixel(), height);
226        return true;
227    }
228
229    /*
230     *  Begin section where we try to change colorTypes along the way. Not all combinations
231     *  are supported.
232     */
233
234    if (kGray_8_SkColorType == srcInfo.colorType() && 4 == dstInfo.bytesPerPixel()) {
235        copy_g8_to_32(dstPixels, dstRB, srcPixels, srcRB, width, height);
236        return true;
237    }
238    if (kGray_8_SkColorType == dstInfo.colorType() && 4 == srcInfo.bytesPerPixel()) {
239        copy_32_to_g8(dstPixels, dstRB, srcPixels, srcRB, srcInfo);
240        return true;
241    }
242
243    // Can no longer draw directly into 4444, but we can manually whack it for a few combinations
244    if (kARGB_4444_SkColorType == dstInfo.colorType() &&
245        (kN32_SkColorType == srcInfo.colorType() || kIndex_8_SkColorType == srcInfo.colorType())) {
246        if (srcInfo.alphaType() == kUnpremul_SkAlphaType) {
247            // Our method for converting to 4444 assumes premultiplied.
248            return false;
249        }
250
251        const SkPMColor* table = NULL;
252        if (kIndex_8_SkColorType == srcInfo.colorType()) {
253            if (NULL == ctable) {
254                return false;
255            }
256            table = ctable->readColors();
257        }
258
259        for (int y = 0; y < height; ++y) {
260            DITHER_4444_SCAN(y);
261            SkPMColor16* SK_RESTRICT dstRow = (SkPMColor16*)dstPixels;
262            if (table) {
263                const uint8_t* SK_RESTRICT srcRow = (const uint8_t*)srcPixels;
264                for (int x = 0; x < width; ++x) {
265                    dstRow[x] = SkDitherARGB32To4444(table[srcRow[x]], DITHER_VALUE(x));
266                }
267            } else {
268                const SkPMColor* SK_RESTRICT srcRow = (const SkPMColor*)srcPixels;
269                for (int x = 0; x < width; ++x) {
270                    dstRow[x] = SkDitherARGB32To4444(srcRow[x], DITHER_VALUE(x));
271                }
272            }
273            dstPixels = (char*)dstPixels + dstRB;
274            srcPixels = (const char*)srcPixels + srcRB;
275        }
276        return true;
277    }
278
279    if (dstInfo.alphaType() == kUnpremul_SkAlphaType) {
280        // We do not support drawing to unpremultiplied bitmaps.
281        return false;
282    }
283
284    // Final fall-back, draw with a canvas
285    //
286    // Always clear the dest in case one of the blitters accesses it
287    // TODO: switch the allocation of tmpDst to call sk_calloc_throw
288    {
289        SkBitmap bm;
290        if (!bm.installPixels(srcInfo, const_cast<void*>(srcPixels), srcRB, ctable, NULL, NULL)) {
291            return false;
292        }
293        SkAutoTUnref<SkCanvas> canvas(SkCanvas::NewRasterDirect(dstInfo, dstPixels, dstRB));
294        if (NULL == canvas.get()) {
295            return false;
296        }
297
298        SkPaint  paint;
299        paint.setDither(true);
300
301        canvas->clear(0);
302        canvas->drawBitmap(bm, 0, 0, &paint);
303        return true;
304    }
305}
306
307