1/*
2 * Copyright 2017 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 "gm.h"
9#include "SkCanvas.h"
10#include "SkPath.h"
11#include "SkResourceCache.h"
12#include "SkShadowUtils.h"
13
14void draw_shadow(SkCanvas* canvas, const SkPath& path, int height, SkColor color, SkPoint3 lightPos,
15                 SkScalar lightR, bool isAmbient, uint32_t flags, SkResourceCache* cache) {
16    SkScalar ambientAlpha = isAmbient ? .5f : 0.f;
17    SkScalar spotAlpha = isAmbient ? 0.f : .5f;
18    SkShadowUtils::DrawShadow(canvas, path, height, lightPos, lightR, ambientAlpha, spotAlpha,
19                              color, flags, cache);
20}
21
22static constexpr int kW = 800;
23static constexpr int kH = 800;
24
25DEF_SIMPLE_GM(shadow_utils, canvas, kW, kH) {
26    // SkShadowUtils uses a cache of SkVertices meshes. The vertices are created in a local
27    // coordinate system and then translated when reused. The coordinate system depends on
28    // parameters to the generating draw. If other threads are hitting the cache while this GM is
29    // running then we may have different cache behavior leading to slight rendering differences.
30    // To avoid that we use our own isolated cache rather than the global cache.
31    SkResourceCache cache(1 << 20);
32
33    SkTArray<SkPath> paths;
34    paths.push_back().addRoundRect(SkRect::MakeWH(50, 50), 10, 10);
35    SkRRect oddRRect;
36    oddRRect.setNinePatch(SkRect::MakeWH(50, 50), 9, 13, 6, 16);
37    paths.push_back().addRRect(oddRRect);
38    paths.push_back().addRect(SkRect::MakeWH(50, 50));
39    paths.push_back().addCircle(25, 25, 25);
40    paths.push_back().cubicTo(100, 50, 20, 100, 0, 0);
41    paths.push_back().addOval(SkRect::MakeWH(20, 60));
42
43    static constexpr SkScalar kPad = 15.f;
44    static constexpr SkPoint3 kLightPos = {250, 400, 500};
45    static constexpr SkScalar kLightR = 100.f;
46    static constexpr SkScalar kHeight = 50.f;
47    canvas->translate(3 * kPad, 3 * kPad);
48    canvas->save();
49    SkScalar x = 0;
50    SkScalar dy = 0;
51    SkTDArray<SkMatrix> matrices;
52    matrices.push()->reset();
53    SkMatrix* m = matrices.push();
54    m->setRotate(33.f, 25.f, 25.f);
55    m->postScale(1.2f, 0.8f, 25.f, 25.f);
56    for (auto& m : matrices) {
57        for (auto flags : {kNone_ShadowFlag, kTransparentOccluder_ShadowFlag}) {
58            for (const auto& path : paths) {
59                SkRect postMBounds = path.getBounds();
60                m.mapRect(&postMBounds);
61                SkScalar w = postMBounds.width() + kHeight;
62                SkScalar dx = w + kPad;
63                if (x + dx > kW - 3 * kPad) {
64                    canvas->restore();
65                    canvas->translate(0, dy);
66                    canvas->save();
67                    x = 0;
68                    dy = 0;
69                }
70
71                canvas->save();
72                canvas->concat(m);
73                draw_shadow(canvas, path, kHeight, SK_ColorRED, kLightPos, kLightR, true, flags,
74                            &cache);
75                draw_shadow(canvas, path, kHeight, SK_ColorBLUE, kLightPos, kLightR, false, flags,
76                            &cache);
77
78                // Draw the path outline in green on top of the ambient and spot shadows.
79                SkPaint paint;
80                paint.setColor(SK_ColorGREEN);
81                paint.setAntiAlias(true);
82                paint.setStyle(SkPaint::kStroke_Style);
83                paint.setStrokeWidth(0);
84                canvas->drawPath(path, paint);
85                canvas->restore();
86
87                canvas->translate(dx, 0);
88                x += dx;
89                dy = SkTMax(dy, postMBounds.height() + kPad + kHeight);
90            }
91        }
92    }
93    // Show where the light is in x,y as a circle (specified in device space).
94    SkMatrix invCanvasM = canvas->getTotalMatrix();
95    if (invCanvasM.invert(&invCanvasM)) {
96        canvas->save();
97        canvas->concat(invCanvasM);
98        SkPaint paint;
99        paint.setColor(SK_ColorBLACK);
100        paint.setAntiAlias(true);
101        canvas->drawCircle(kLightPos.fX, kLightPos.fY, kLightR / 10.f, paint);
102        canvas->restore();
103    }
104}
105