sk_tool_utils.cpp revision c722f79b6c8919e1a8a0df6d4d7735c5a8a1b5e8 
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 "sk_tool_utils.h"
9#include "sk_tool_utils_flags.h"
10
11#include "Resources.h"
12#include "SkBitmap.h"
13#include "SkCanvas.h"
14#include "SkCommonFlags.h"
15#include "SkFontMgr.h"
16#include "SkFontStyle.h"
17#include "SkPixelRef.h"
18#include "SkPoint3.h"
19#include "SkShader.h"
20#include "SkTestScalerContext.h"
21#include "SkTextBlob.h"
22
23DEFINE_bool(portableFonts, false, "Use portable fonts");
24
25namespace sk_tool_utils {
26
27/* these are the default fonts chosen by Chrome for serif, sans-serif, and monospace */
28static const char* gStandardFontNames[][3] = {
29    { "Times", "Helvetica", "Courier" }, // Mac
30    { "Times New Roman", "Helvetica", "Courier" }, // iOS
31    { "Times New Roman", "Arial", "Courier New" }, // Win
32    { "Times New Roman", "Arial", "Monospace" }, // Ubuntu
33    { "serif", "sans-serif", "monospace" }, // Android
34    { "Tinos", "Arimo", "Cousine" } // ChromeOS
35};
36
37const char* platform_font_name(const char* name) {
38    SkString platform = major_platform_os_name();
39    int index;
40    if (!strcmp(name, "serif")) {
41        index = 0;
42    } else if (!strcmp(name, "san-serif")) {
43        index = 1;
44    } else if (!strcmp(name, "monospace")) {
45        index = 2;
46    } else {
47        return name;
48    }
49    if (platform.equals("Mac")) {
50        return gStandardFontNames[0][index];
51    }
52    if (platform.equals("iOS")) {
53        return gStandardFontNames[1][index];
54    }
55    if (platform.equals("Win")) {
56        return gStandardFontNames[2][index];
57    }
58    if (platform.equals("Ubuntu") || platform.equals("Debian")) {
59        return gStandardFontNames[3][index];
60    }
61    if (platform.equals("Android")) {
62        return gStandardFontNames[4][index];
63    }
64    if (platform.equals("ChromeOS")) {
65        return gStandardFontNames[5][index];
66    }
67    return name;
68}
69
70const char* platform_os_emoji() {
71    const char* osName = platform_os_name();
72    if (!strcmp(osName, "Android") || !strcmp(osName, "Ubuntu") || !strcmp(osName, "Debian")) {
73        return "CBDT";
74    }
75    if (!strncmp(osName, "Mac", 3) || !strncmp(osName, "iOS", 3)) {
76        return "SBIX";
77    }
78    if (!strncmp(osName, "Win", 3)) {
79        return "COLR";
80    }
81    return "";
82}
83
84sk_sp<SkTypeface> emoji_typeface() {
85    if (!strcmp(sk_tool_utils::platform_os_emoji(), "CBDT")) {
86        return MakeResourceAsTypeface("/fonts/Funkster.ttf");
87    }
88    if (!strcmp(sk_tool_utils::platform_os_emoji(), "SBIX")) {
89        return SkTypeface::MakeFromName("Apple Color Emoji", SkFontStyle());
90    }
91    if (!strcmp(sk_tool_utils::platform_os_emoji(), "COLR")) {
92        sk_sp<SkFontMgr> fm(SkFontMgr::RefDefault());
93        const char *colorEmojiFontName = "Segoe UI Emoji";
94        sk_sp<SkTypeface> typeface(fm->matchFamilyStyle(colorEmojiFontName, SkFontStyle()));
95        if (typeface) {
96            return typeface;
97        }
98        sk_sp<SkTypeface> fallback(fm->matchFamilyStyleCharacter(
99            colorEmojiFontName, SkFontStyle(), nullptr /* bcp47 */, 0 /* bcp47Count */,
100            0x1f4b0 /* character: �� */));
101        if (fallback) {
102            return fallback;
103        }
104        // If we don't have Segoe UI Emoji and can't find a fallback, try Segoe UI Symbol.
105        // Windows 7 does not have Segoe UI Emoji; Segoe UI Symbol has the (non - color) emoji.
106        return SkTypeface::MakeFromName("Segoe UI Symbol", SkFontStyle());
107    }
108    return nullptr;
109}
110
111const char* emoji_sample_text() {
112    if (!strcmp(sk_tool_utils::platform_os_emoji(), "CBDT")) {
113        return "Hamburgefons";
114    }
115    if (!strcmp(sk_tool_utils::platform_os_emoji(), "SBIX") ||
116        !strcmp(sk_tool_utils::platform_os_emoji(), "COLR"))
117    {
118        return "\xF0\x9F\x92\xB0" "\xF0\x9F\x8F\xA1" "\xF0\x9F\x8E\x85"  // ������
119               "\xF0\x9F\x8D\xAA" "\xF0\x9F\x8D\x95" "\xF0\x9F\x9A\x80"  // ������
120               "\xF0\x9F\x9A\xBB" "\xF0\x9F\x92\xA9" "\xF0\x9F\x93\xB7" // ������
121               "\xF0\x9F\x93\xA6" // ��
122               "\xF0\x9F\x87\xBA" "\xF0\x9F\x87\xB8" "\xF0\x9F\x87\xA6"; // ������
123    }
124    return "";
125}
126
127const char* platform_os_name() {
128    for (int index = 0; index < FLAGS_key.count(); index += 2) {
129        if (!strcmp("os", FLAGS_key[index])) {
130            return FLAGS_key[index + 1];
131        }
132    }
133    // when running SampleApp or dm without a --key pair, omit the platform name
134    return "";
135}
136
137// omit version number in returned value
138SkString major_platform_os_name() {
139    SkString name;
140    for (int index = 0; index < FLAGS_key.count(); index += 2) {
141        if (!strcmp("os", FLAGS_key[index])) {
142            const char* platform = FLAGS_key[index + 1];
143            const char* end = platform;
144            while (*end && (*end < '0' || *end > '9')) {
145                ++end;
146            }
147            name.append(platform, end - platform);
148            break;
149        }
150    }
151    return name;
152}
153
154const char* platform_extra_config(const char* config) {
155    for (int index = 0; index < FLAGS_key.count(); index += 2) {
156        if (!strcmp("extra_config", FLAGS_key[index]) && !strcmp(config, FLAGS_key[index + 1])) {
157            return config;
158        }
159    }
160    return "";
161}
162
163const char* colortype_name(SkColorType ct) {
164    switch (ct) {
165        case kUnknown_SkColorType:      return "Unknown";
166        case kAlpha_8_SkColorType:      return "Alpha_8";
167        case kARGB_4444_SkColorType:    return "ARGB_4444";
168        case kRGB_565_SkColorType:      return "RGB_565";
169        case kRGBA_8888_SkColorType:    return "RGBA_8888";
170        case kBGRA_8888_SkColorType:    return "BGRA_8888";
171        case kRGBA_F16_SkColorType:     return "RGBA_F16";
172        default:
173            SkASSERT(false);
174            return "unexpected colortype";
175    }
176}
177
178SkColor color_to_565(SkColor color) {
179    SkPMColor pmColor = SkPreMultiplyColor(color);
180    U16CPU color16 = SkPixel32ToPixel16(pmColor);
181    return SkPixel16ToColor(color16);
182}
183
184sk_sp<SkTypeface> create_portable_typeface(const char* name, SkFontStyle style) {
185    return create_font(name, style);
186}
187
188void set_portable_typeface(SkPaint* paint, const char* name, SkFontStyle style) {
189    paint->setTypeface(create_font(name, style));
190}
191
192void write_pixels(SkCanvas* canvas, const SkBitmap& bitmap, int x, int y,
193                  SkColorType colorType, SkAlphaType alphaType) {
194    SkBitmap tmp(bitmap);
195    const SkImageInfo info = SkImageInfo::Make(tmp.width(), tmp.height(), colorType, alphaType);
196
197    canvas->writePixels(info, tmp.getPixels(), tmp.rowBytes(), x, y);
198}
199
200sk_sp<SkShader> create_checkerboard_shader(SkColor c1, SkColor c2, int size) {
201    SkBitmap bm;
202    bm.allocPixels(SkImageInfo::MakeS32(2 * size, 2 * size, kPremul_SkAlphaType));
203    bm.eraseColor(c1);
204    bm.eraseArea(SkIRect::MakeLTRB(0, 0, size, size), c2);
205    bm.eraseArea(SkIRect::MakeLTRB(size, size, 2 * size, 2 * size), c2);
206    return SkShader::MakeBitmapShader(
207            bm, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode);
208}
209
210SkBitmap create_checkerboard_bitmap(int w, int h, SkColor c1, SkColor c2, int checkSize) {
211    SkBitmap bitmap;
212    bitmap.allocPixels(SkImageInfo::MakeS32(w, h, kPremul_SkAlphaType));
213    SkCanvas canvas(bitmap);
214
215    sk_tool_utils::draw_checkerboard(&canvas, c1, c2, checkSize);
216    return bitmap;
217}
218
219void draw_checkerboard(SkCanvas* canvas, SkColor c1, SkColor c2, int size) {
220    SkPaint paint;
221    paint.setShader(create_checkerboard_shader(c1, c2, size));
222    paint.setBlendMode(SkBlendMode::kSrc);
223    canvas->drawPaint(paint);
224}
225
226SkBitmap create_string_bitmap(int w, int h, SkColor c, int x, int y,
227                              int textSize, const char* str) {
228    SkBitmap bitmap;
229    bitmap.allocN32Pixels(w, h);
230    SkCanvas canvas(bitmap);
231
232    SkPaint paint;
233    paint.setAntiAlias(true);
234    sk_tool_utils::set_portable_typeface(&paint);
235    paint.setColor(c);
236    paint.setTextSize(SkIntToScalar(textSize));
237
238    canvas.clear(0x00000000);
239    canvas.drawString(str, SkIntToScalar(x), SkIntToScalar(y), paint);
240
241    // Tag data as sRGB (without doing any color space conversion). Color-space aware configs
242    // will process this correctly but legacy configs will render as if this returned N32.
243    SkBitmap result;
244    result.setInfo(SkImageInfo::MakeS32(w, h, kPremul_SkAlphaType));
245    result.setPixelRef(sk_ref_sp(bitmap.pixelRef()), 0, 0);
246    return result;
247}
248
249void add_to_text_blob(SkTextBlobBuilder* builder, const char* text, const SkPaint& origPaint,
250                      SkScalar x, SkScalar y) {
251    SkPaint paint(origPaint);
252    SkTDArray<uint16_t> glyphs;
253
254    size_t len = strlen(text);
255    glyphs.append(paint.textToGlyphs(text, len, nullptr));
256    paint.textToGlyphs(text, len, glyphs.begin());
257
258    paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
259    const SkTextBlobBuilder::RunBuffer& run = builder->allocRun(paint, glyphs.count(), x, y,
260                                                                nullptr);
261    memcpy(run.glyphs, glyphs.begin(), glyphs.count() * sizeof(uint16_t));
262}
263
264static inline void norm_to_rgb(SkBitmap* bm, int x, int y, const SkVector3& norm) {
265    SkASSERT(SkScalarNearlyEqual(norm.length(), 1.0f));
266    unsigned char r = static_cast<unsigned char>((0.5f * norm.fX + 0.5f) * 255);
267    unsigned char g = static_cast<unsigned char>((-0.5f * norm.fY + 0.5f) * 255);
268    unsigned char b = static_cast<unsigned char>((0.5f * norm.fZ + 0.5f) * 255);
269    *bm->getAddr32(x, y) = SkPackARGB32(0xFF, r, g, b);
270}
271
272void create_hemi_normal_map(SkBitmap* bm, const SkIRect& dst) {
273    const SkPoint center = SkPoint::Make(dst.fLeft + (dst.width() / 2.0f),
274                                         dst.fTop + (dst.height() / 2.0f));
275    const SkPoint halfSize = SkPoint::Make(dst.width() / 2.0f, dst.height() / 2.0f);
276
277    SkVector3 norm;
278
279    for (int y = dst.fTop; y < dst.fBottom; ++y) {
280        for (int x = dst.fLeft; x < dst.fRight; ++x) {
281            norm.fX = (x + 0.5f - center.fX) / halfSize.fX;
282            norm.fY = (y + 0.5f - center.fY) / halfSize.fY;
283
284            SkScalar tmp = norm.fX * norm.fX + norm.fY * norm.fY;
285            if (tmp >= 1.0f) {
286                norm.set(0.0f, 0.0f, 1.0f);
287            } else {
288                norm.fZ = sqrtf(1.0f - tmp);
289            }
290
291            norm_to_rgb(bm, x, y, norm);
292        }
293    }
294}
295
296void create_frustum_normal_map(SkBitmap* bm, const SkIRect& dst) {
297    const SkPoint center = SkPoint::Make(dst.fLeft + (dst.width() / 2.0f),
298                                         dst.fTop + (dst.height() / 2.0f));
299
300    SkIRect inner = dst;
301    inner.inset(dst.width()/4, dst.height()/4);
302
303    SkPoint3 norm;
304    const SkPoint3 left =  SkPoint3::Make(-SK_ScalarRoot2Over2, 0.0f, SK_ScalarRoot2Over2);
305    const SkPoint3 up =    SkPoint3::Make(0.0f, -SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
306    const SkPoint3 right = SkPoint3::Make(SK_ScalarRoot2Over2,  0.0f, SK_ScalarRoot2Over2);
307    const SkPoint3 down =  SkPoint3::Make(0.0f,  SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
308
309    for (int y = dst.fTop; y < dst.fBottom; ++y) {
310        for (int x = dst.fLeft; x < dst.fRight; ++x) {
311            if (inner.contains(x, y)) {
312                norm.set(0.0f, 0.0f, 1.0f);
313            } else {
314                SkScalar locX = x + 0.5f - center.fX;
315                SkScalar locY = y + 0.5f - center.fY;
316
317                if (locX >= 0.0f) {
318                    if (locY > 0.0f) {
319                        norm = locX >= locY ? right : down;   // LR corner
320                    } else {
321                        norm = locX > -locY ? right : up;     // UR corner
322                    }
323                } else {
324                    if (locY > 0.0f) {
325                        norm = -locX > locY ? left : down;    // LL corner
326                    } else {
327                        norm = locX > locY ? up : left;       // UL corner
328                    }
329                }
330            }
331
332            norm_to_rgb(bm, x, y, norm);
333        }
334    }
335}
336
337void create_tetra_normal_map(SkBitmap* bm, const SkIRect& dst) {
338    const SkPoint center = SkPoint::Make(dst.fLeft + (dst.width() / 2.0f),
339                                         dst.fTop + (dst.height() / 2.0f));
340
341    static const SkScalar k1OverRoot3 = 0.5773502692f;
342
343    SkPoint3 norm;
344    const SkPoint3 leftUp =  SkPoint3::Make(-k1OverRoot3, -k1OverRoot3, k1OverRoot3);
345    const SkPoint3 rightUp = SkPoint3::Make(k1OverRoot3,  -k1OverRoot3, k1OverRoot3);
346    const SkPoint3 down =  SkPoint3::Make(0.0f,  SK_ScalarRoot2Over2, SK_ScalarRoot2Over2);
347
348    for (int y = dst.fTop; y < dst.fBottom; ++y) {
349        for (int x = dst.fLeft; x < dst.fRight; ++x) {
350            SkScalar locX = x + 0.5f - center.fX;
351            SkScalar locY = y + 0.5f - center.fY;
352
353            if (locX >= 0.0f) {
354                if (locY > 0.0f) {
355                    norm = locX >= locY ? rightUp : down;   // LR corner
356                } else {
357                    norm = rightUp;
358                }
359            } else {
360                if (locY > 0.0f) {
361                    norm = -locX > locY ? leftUp : down;    // LL corner
362                } else {
363                    norm = leftUp;
364                }
365            }
366
367            norm_to_rgb(bm, x, y, norm);
368        }
369    }
370}
371
372#if !defined(__clang__) && defined(_MSC_VER)
373    // MSVC takes ~2 minutes to compile this function with optimization.
374    // We don't really care to wait that long for this function.
375    #pragma optimize("", off)
376#endif
377void make_big_path(SkPath& path) {
378    #include "BigPathBench.inc"
379}
380
381static float gaussian2d_value(int x, int y, float sigma) {
382    // don't bother with the scale term since we're just going to normalize the
383    // kernel anyways
384    float temp = expf(-(x*x + y*y)/(2*sigma*sigma));
385    return temp;
386}
387
388static float* create_2d_kernel(float sigma, int* filterSize) {
389    // We will actually take 2*halfFilterSize+1 samples (i.e., our filter kernel
390    // sizes are always odd)
391    int halfFilterSize = SkScalarCeilToInt(6*sigma)/2;
392    int wh = *filterSize = 2*halfFilterSize + 1;
393
394    float* temp = new float[wh*wh];
395
396    float filterTot = 0.0f;
397    for (int yOff = 0; yOff < wh; ++yOff) {
398        for (int xOff = 0; xOff < wh; ++xOff) {
399            temp[yOff*wh+xOff] = gaussian2d_value(xOff-halfFilterSize, yOff-halfFilterSize, sigma);
400
401            filterTot += temp[yOff*wh+xOff];
402        }
403    }
404
405    // normalize the kernel
406    for (int yOff = 0; yOff < wh; ++yOff) {
407        for (int xOff = 0; xOff < wh; ++xOff) {
408            temp[yOff*wh+xOff] /= filterTot;
409        }
410    }
411
412    return temp;
413}
414
415static SkPMColor blur_pixel(const SkBitmap& bm, int x, int y, float* kernel, int wh) {
416    SkASSERT(wh & 0x1);
417
418    int halfFilterSize = (wh-1)/2;
419
420    float r = 0.0f, g = 0.0f, b = 0.0f;
421    for (int yOff = 0; yOff < wh; ++yOff) {
422        int ySamp = y + yOff - halfFilterSize;
423
424        if (ySamp < 0) {
425            ySamp = 0;
426        } else if (ySamp > bm.height()-1) {
427            ySamp = bm.height()-1;
428        }
429
430        for (int xOff = 0; xOff < wh; ++xOff) {
431            int xSamp = x + xOff - halfFilterSize;
432
433            if (xSamp < 0) {
434                xSamp = 0;
435            } else if (xSamp > bm.width()-1) {
436                xSamp = bm.width()-1;
437            }
438
439            float filter = kernel[yOff*wh + xOff];
440
441            SkPMColor c = *bm.getAddr32(xSamp, ySamp);
442
443            r += SkGetPackedR32(c) * filter;
444            g += SkGetPackedG32(c) * filter;
445            b += SkGetPackedB32(c) * filter;
446        }
447    }
448
449    U8CPU r8, g8, b8;
450
451    r8 = (U8CPU) (r+0.5f);
452    g8 = (U8CPU) (g+0.5f);
453    b8 = (U8CPU) (b+0.5f);
454
455    return SkPackARGB32(255, r8, g8, b8);
456}
457
458SkBitmap slow_blur(const SkBitmap& src, float sigma) {
459    SkBitmap dst;
460
461    dst.allocN32Pixels(src.width(), src.height(), true);
462
463    int wh;
464    std::unique_ptr<float[]> kernel(create_2d_kernel(sigma, &wh));
465
466    for (int y = 0; y < src.height(); ++y) {
467        for (int x = 0; x < src.width(); ++x) {
468            *dst.getAddr32(x, y) = blur_pixel(src, x, y, kernel.get(), wh);
469        }
470    }
471
472    return dst;
473}
474
475// compute the intersection point between the diagonal and the ellipse in the
476// lower right corner
477static SkPoint intersection(SkScalar w, SkScalar h) {
478    SkASSERT(w > 0.0f || h > 0.0f);
479
480    return SkPoint::Make(w / SK_ScalarSqrt2, h / SK_ScalarSqrt2);
481}
482
483// Use the intersection of the corners' diagonals with their ellipses to shrink
484// the bounding rect
485SkRect compute_central_occluder(const SkRRect& rr) {
486    const SkRect r = rr.getBounds();
487
488    SkScalar newL = r.fLeft, newT = r.fTop, newR = r.fRight, newB = r.fBottom;
489
490    SkVector radii = rr.radii(SkRRect::kUpperLeft_Corner);
491    if (!radii.isZero()) {
492        SkPoint p = intersection(radii.fX, radii.fY);
493
494        newL = SkTMax(newL, r.fLeft + radii.fX - p.fX);
495        newT = SkTMax(newT, r.fTop + radii.fY - p.fY);
496    }
497
498    radii = rr.radii(SkRRect::kUpperRight_Corner);
499    if (!radii.isZero()) {
500        SkPoint p = intersection(radii.fX, radii.fY);
501
502        newR = SkTMin(newR, r.fRight + p.fX - radii.fX);
503        newT = SkTMax(newT, r.fTop + radii.fY - p.fY);
504    }
505
506    radii = rr.radii(SkRRect::kLowerRight_Corner);
507    if (!radii.isZero()) {
508        SkPoint p = intersection(radii.fX, radii.fY);
509
510        newR = SkTMin(newR, r.fRight + p.fX - radii.fX);
511        newB = SkTMin(newB, r.fBottom - radii.fY + p.fY);
512    }
513
514    radii = rr.radii(SkRRect::kLowerLeft_Corner);
515    if (!radii.isZero()) {
516        SkPoint p = intersection(radii.fX, radii.fY);
517
518        newL = SkTMax(newL, r.fLeft + radii.fX - p.fX);
519        newB = SkTMin(newB, r.fBottom - radii.fY + p.fY);
520    }
521
522    return SkRect::MakeLTRB(newL, newT, newR, newB);
523}
524
525// The widest inset rect
526SkRect compute_widest_occluder(const SkRRect& rr) {
527    const SkRect& r = rr.getBounds();
528
529    const SkVector& ul = rr.radii(SkRRect::kUpperLeft_Corner);
530    const SkVector& ur = rr.radii(SkRRect::kUpperRight_Corner);
531    const SkVector& lr = rr.radii(SkRRect::kLowerRight_Corner);
532    const SkVector& ll = rr.radii(SkRRect::kLowerLeft_Corner);
533
534    SkScalar maxT = SkTMax(ul.fY, ur.fY);
535    SkScalar maxB = SkTMax(ll.fY, lr.fY);
536
537    return SkRect::MakeLTRB(r.fLeft, r.fTop + maxT, r.fRight, r.fBottom - maxB);
538
539}
540
541// The tallest inset rect
542SkRect compute_tallest_occluder(const SkRRect& rr) {
543    const SkRect& r = rr.getBounds();
544
545    const SkVector& ul = rr.radii(SkRRect::kUpperLeft_Corner);
546    const SkVector& ur = rr.radii(SkRRect::kUpperRight_Corner);
547    const SkVector& lr = rr.radii(SkRRect::kLowerRight_Corner);
548    const SkVector& ll = rr.radii(SkRRect::kLowerLeft_Corner);
549
550    SkScalar maxL = SkTMax(ul.fX, ll.fX);
551    SkScalar maxR = SkTMax(ur.fX, lr.fX);
552
553    return SkRect::MakeLTRB(r.fLeft + maxL, r.fTop, r.fRight - maxR, r.fBottom);
554}
555
556bool copy_to(SkBitmap* dst, SkColorType dstColorType, const SkBitmap& src) {
557    SkPixmap srcPM;
558    if (!src.peekPixels(&srcPM)) {
559        return false;
560    }
561
562    SkBitmap tmpDst;
563    SkImageInfo dstInfo = srcPM.info().makeColorType(dstColorType);
564    if (!tmpDst.setInfo(dstInfo)) {
565        return false;
566    }
567
568    if (!tmpDst.tryAllocPixels()) {
569        return false;
570    }
571
572    SkPixmap dstPM;
573    if (!tmpDst.peekPixels(&dstPM)) {
574        return false;
575    }
576
577    if (!srcPM.readPixels(dstPM)) {
578        return false;
579    }
580
581    dst->swap(tmpDst);
582    return true;
583}
584
585void copy_to_g8(SkBitmap* dst, const SkBitmap& src) {
586    SkASSERT(kBGRA_8888_SkColorType == src.colorType() ||
587             kRGBA_8888_SkColorType == src.colorType());
588
589    SkImageInfo grayInfo = src.info().makeColorType(kGray_8_SkColorType);
590    dst->allocPixels(grayInfo);
591    uint8_t* dst8 = (uint8_t*)dst->getPixels();
592    const uint32_t* src32 = (const uint32_t*)src.getPixels();
593
594    const int w = src.width();
595    const int h = src.height();
596    const bool isBGRA = (kBGRA_8888_SkColorType == src.colorType());
597    for (int y = 0; y < h; ++y) {
598        if (isBGRA) {
599            // BGRA
600            for (int x = 0; x < w; ++x) {
601                uint32_t s = src32[x];
602                dst8[x] = SkComputeLuminance((s >> 16) & 0xFF, (s >> 8) & 0xFF, s & 0xFF);
603            }
604        } else {
605            // RGBA
606            for (int x = 0; x < w; ++x) {
607                uint32_t s = src32[x];
608                dst8[x] = SkComputeLuminance(s & 0xFF, (s >> 8) & 0xFF, (s >> 16) & 0xFF);
609            }
610        }
611        src32 = (const uint32_t*)((const char*)src32 + src.rowBytes());
612        dst8 += dst->rowBytes();
613    }
614}
615
616}  // namespace sk_tool_utils
617