1/*
2 * Copyright 2015 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/SkCanvas.h"
9#include "../include/core/SkData.h"
10#include "../include/core/SkSurface.h"
11#include "../include/effects/SkGradientShader.h"
12#include "../include/gpu/GrContext.h"
13
14// These headers are just handy for writing this example file.  Nothing Skia specific.
15#include <cstdlib>
16#include <ctime>
17#include <fstream>
18#include <iostream>
19#include <memory>
20
21// These setup_gl_context() are not meant to represent good form.
22// They are just quick hacks to get us going.
23#if defined(__APPLE__)
24    #include <OpenGL/OpenGL.h>
25    static bool setup_gl_context() {
26        CGLPixelFormatAttribute attributes[] = { (CGLPixelFormatAttribute)0 };
27        CGLPixelFormatObj format;
28        GLint npix;
29        CGLChoosePixelFormat(attributes, &format, &npix);
30        CGLContextObj context;
31        CGLCreateContext(format, nullptr, &context);
32        CGLSetCurrentContext(context);
33        CGLReleasePixelFormat(format);
34        return true;
35    }
36#else
37    static bool setup_gl_context() {
38        return false;
39    }
40#endif
41
42// Most pointers returned by Skia are derived from SkRefCnt,
43// meaning we need to call ->unref() on them when done rather than delete them.
44template <typename T> std::shared_ptr<T> adopt(T* ptr) {
45    return std::shared_ptr<T>(ptr, [](T* p) { p->unref(); });
46}
47
48static std::shared_ptr<SkSurface> create_raster_surface(int w, int h) {
49    std::cout << "Using raster surface" << std::endl;
50    return adopt(SkSurface::NewRasterN32Premul(w, h));
51}
52
53static std::shared_ptr<SkSurface> create_opengl_surface(int w, int h) {
54    std::cout << "Using opengl surface" << std::endl;
55    std::shared_ptr<GrContext> grContext = adopt(GrContext::Create(kOpenGL_GrBackend, 0));
56    return adopt(SkSurface::NewRenderTarget(grContext.get(),
57                                            SkBudgeted::kNo,
58                                            SkImageInfo::MakeN32Premul(w,h)));
59}
60
61int main(int, char**) {
62    bool gl_ok = setup_gl_context();
63    srand(time(nullptr));
64    std::shared_ptr<SkSurface> surface = (gl_ok && rand() % 2) ? create_opengl_surface(320, 240)
65                                                               : create_raster_surface(320, 240);
66
67    // Create a left-to-right green-to-purple gradient shader.
68    SkPoint pts[] = { {0,0}, {320,240} };
69    SkColor colors[] = { 0xFF00FF00, 0xFFFF00FF };
70    std::shared_ptr<SkShader> shader = adopt(
71            SkGradientShader::CreateLinear(pts, colors, nullptr, 2, SkShader::kRepeat_TileMode));
72
73    // Our text will draw with this paint: size 24, antialiased, with the shader.
74    SkPaint paint;
75    paint.setTextSize(24);
76    paint.setAntiAlias(true);
77    paint.setShader(shader.get());
78
79    // Draw to the surface via its SkCanvas.
80    SkCanvas* canvas = surface->getCanvas();   // We don't manage this pointer's lifetime.
81    static const char* msg = "Hello world!";
82    canvas->clear(SK_ColorWHITE);
83    canvas->drawText(msg, strlen(msg), 90,120, paint);
84
85    // Grab a snapshot of the surface as an immutable SkImage.
86    std::shared_ptr<SkImage> image = adopt(surface->newImageSnapshot());
87    // Encode that image as a .png into a blob in memory.
88    std::shared_ptr<SkData> png = adopt(image->encode(SkImageEncoder::kPNG_Type, 100));
89
90    // This code is no longer Skia-specific.  We just dump the .png to disk.  Any way works.
91    static const char* path = "example.png";
92    std::ofstream(path, std::ios::out | std::ios::binary)
93        .write((const char*)png->data(), png->size());
94    std::cout << "Wrote " << path << std::endl;
95
96    return 0;
97}
98