xref: /third_party/skia/example/HelloWorld.cpp (revision cb93a386) 
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 "example/HelloWorld.h"
9
10#include "include/core/SkCanvas.h"
11#include "include/core/SkFont.h"
12#include "include/core/SkGraphics.h"
13#include "include/core/SkSurface.h"
14#include "include/effects/SkGradientShader.h"
15
16using namespace sk_app;
17
18Application* Application::Create(int argc, char** argv, void* platformData) {
19    return new HelloWorld(argc, argv, platformData);
20}
21
22HelloWorld::HelloWorld(int argc, char** argv, void* platformData)
23        : fBackendType(Window::kNativeGL_BackendType)
24        , fRotationAngle(0) {
25    SkGraphics::Init();
26
27    fWindow = Window::CreateNativeWindow(platformData);
28    fWindow->setRequestedDisplayParams(DisplayParams());
29
30    // register callbacks
31    fWindow->pushLayer(this);
32
33    fWindow->attach(fBackendType);
34}
35
36HelloWorld::~HelloWorld() {
37    fWindow->detach();
38    delete fWindow;
39}
40
41void HelloWorld::updateTitle() {
42    if (!fWindow || fWindow->sampleCount() <= 1) {
43        return;
44    }
45
46    SkString title("Hello World ");
47    title.append(Window::kRaster_BackendType == fBackendType ? "Raster" : "OpenGL");
48    fWindow->setTitle(title.c_str());
49}
50
51void HelloWorld::onBackendCreated() {
52    this->updateTitle();
53    fWindow->show();
54    fWindow->inval();
55}
56
57void HelloWorld::onPaint(SkSurface* surface) {
58    auto canvas = surface->getCanvas();
59
60    // Clear background
61    canvas->clear(SK_ColorWHITE);
62
63    SkPaint paint;
64    paint.setColor(SK_ColorRED);
65
66    // Draw a rectangle with red paint
67    SkRect rect = SkRect::MakeXYWH(10, 10, 128, 128);
68    canvas->drawRect(rect, paint);
69
70    // Set up a linear gradient and draw a circle
71    {
72        SkPoint linearPoints[] = { { 0, 0 }, { 300, 300 } };
73        SkColor linearColors[] = { SK_ColorGREEN, SK_ColorBLACK };
74        paint.setShader(SkGradientShader::MakeLinear(linearPoints, linearColors, nullptr, 2,
75                                                     SkTileMode::kMirror));
76        paint.setAntiAlias(true);
77
78        canvas->drawCircle(200, 200, 64, paint);
79
80        // Detach shader
81        paint.setShader(nullptr);
82    }
83
84    // Draw a message with a nice black paint
85    SkFont font;
86    font.setSubpixel(true);
87    font.setSize(20);
88    paint.setColor(SK_ColorBLACK);
89
90    canvas->save();
91    static const char message[] = "Hello World";
92
93    // Translate and rotate
94    canvas->translate(300, 300);
95    fRotationAngle += 0.2f;
96    if (fRotationAngle > 360) {
97        fRotationAngle -= 360;
98    }
99    canvas->rotate(fRotationAngle);
100
101    // Draw the text
102    canvas->drawSimpleText(message, strlen(message), SkTextEncoding::kUTF8, 0, 0, font, paint);
103
104    canvas->restore();
105}
106
107void HelloWorld::onIdle() {
108    // Just re-paint continously
109    fWindow->inval();
110}
111
112bool HelloWorld::onChar(SkUnichar c, skui::ModifierKey modifiers) {
113    if (' ' == c) {
114        fBackendType = Window::kRaster_BackendType == fBackendType ? Window::kNativeGL_BackendType
115                                                                   : Window::kRaster_BackendType;
116        fWindow->detach();
117        fWindow->attach(fBackendType);
118    }
119    return true;
120}
121