1 /*
2 * Copyright 2023 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 "include/core/SkTypes.h"
9
10 #ifdef SK_USE_DRAWING_MIPMAP_DOWNSAMPLER
11
12 #include "include/core/SkBitmap.h"
13 #include "include/core/SkBlendMode.h"
14 #include "include/core/SkMatrix.h"
15 #include "include/core/SkPaint.h"
16 #include "include/core/SkPixmap.h"
17 #include "include/core/SkSamplingOptions.h"
18 #include "include/core/SkScalar.h"
19 #include "src/core/SkDraw.h"
20 #include "src/core/SkMipmap.h"
21 #include "src/core/SkRasterClip.h"
22 #include <memory>
23
24 namespace {
25
26 struct DrawDownSampler : SkMipmapDownSampler {
27 SkPaint fPaint;
28
DrawDownSampler__anon0035eb3a0111::DrawDownSampler29 DrawDownSampler() {
30 // For efficiency, we want to be in src mode when building levels
31 // to avoid any extra trying to "blend".
32 fPaint.setBlendMode(SkBlendMode::kSrc);
33 }
34
35 void buildLevel(const SkPixmap& dst, const SkPixmap& src) override;
36 };
37
choose_options(const SkPixmap & dst,const SkPixmap & src)38 static SkSamplingOptions choose_options(const SkPixmap& dst, const SkPixmap& src) {
39 // if we're a perfect 2x2 downscale, just use bilerp
40 if (dst.width() * 2 == src.width() && dst.height() * 2 == src.height()) {
41 return SkSamplingOptions(SkFilterMode::kLinear, SkMipmapMode::kNone);
42 }
43 // general case -- might experiment with different cubic parameter values
44 const auto cubic = SkCubicResampler::CatmullRom();
45 return SkSamplingOptions(cubic);
46 }
47
buildLevel(const SkPixmap & dst,const SkPixmap & src)48 void DrawDownSampler::buildLevel(const SkPixmap& dst, const SkPixmap& src) {
49 const SkRasterClip rclip(dst.bounds());
50 const SkMatrix mx = SkMatrix::Scale(SkIntToScalar(dst.width()) / src.width(),
51 SkIntToScalar(dst.height()) / src.height());
52 const auto sampling = choose_options(dst, src);
53
54 SkDraw draw;
55 draw.fDst = dst;
56 draw.fCTM = &mx;
57 draw.fRC = &rclip;
58
59 SkBitmap bitmap;
60 bitmap.installPixels(src.info(), const_cast<void*>(src.addr()), src.rowBytes());
61
62 draw.drawBitmap(bitmap, SkMatrix::I(), nullptr, sampling, fPaint);
63 }
64
65 } // namespace
66
MakeDownSampler(const SkPixmap & root)67 std::unique_ptr<SkMipmapDownSampler> SkMipmap::MakeDownSampler(const SkPixmap& root) {
68 return std::make_unique<DrawDownSampler>();
69 }
70
71 #endif
72