Skia minimal path example

#include "GLFW/glfw3.h"
#include "include/gpu/GrBackendSurface.h"
#include "include/gpu/GrDirectContext.h"
#include "include/gpu/gl/GrGLInterface.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColorSpace.h"
#include "include/core/SkSurface.h"
#include "include/utils/SkParsePath.h"
#include <stdio.h>
#include <stdlib.h>

GrDirectContext *sContext = nullptr;
SkSurface *sSurface = nullptr;

void error_callback(int error, const char *description) {
    fputs(description, stderr);
}

void key_callback(GLFWwindow *window, int key, int scancode, int action,
                  int mods) {
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}

void init_skia(int w, int h) {
    auto interface = GrGLMakeNativeInterface();
    sContext = GrDirectContext::MakeGL(interface).release();

    GrGLFramebufferInfo framebufferInfo;
    framebufferInfo.fFBOID = 0;
    framebufferInfo.fFormat = GL_RGBA8;

    SkColorType colorType = kRGBA_8888_SkColorType;
    GrBackendRenderTarget backendRenderTarget(w, h, 0, 0, framebufferInfo);
    sSurface = SkSurface::MakeFromBackendRenderTarget(
                   sContext, backendRenderTarget, kBottomLeft_GrSurfaceOrigin,
                   colorType, nullptr, nullptr)
                   .release();
    if (sSurface == nullptr)
        abort();
}

const int kWidth = 960;
const int kHeight = 640;

int main(void) {
    GLFWwindow *window;
    glfwSetErrorCallback(error_callback);
    if (!glfwInit()) {
        exit(EXIT_FAILURE);
    }

    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    window = glfwCreateWindow(kWidth, kHeight, "SkPath render example", NULL, NULL);
    if (!window) {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }
    glfwMakeContextCurrent(window);

    init_skia(kWidth, kHeight);

    glfwSwapInterval(0);
    glfwSetKeyCallback(window, key_callback);

    SkCanvas *canvas = sSurface->getCanvas();

    while (!glfwWindowShouldClose(window)) {
        glfwWaitEvents();

        canvas->clear(SK_ColorBLACK);
        canvas->save();

        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setColor(SK_ColorWHITE);

        SkPath path;
        SkParsePath::FromSVGString(
            "m 70.088251,119.8771 15.654512,29.9861 H 74.806653 L "
            "60.960128,121.4205 h -6.923263 v 28.4427 H 44.555964 V 84.114257 "
            "h 18.52083 q 9.921874,0 14.596178,4.409722 4.718402,4.365624 "
            "4.718402,13.493751 0,6.65868 -3.130902,11.33298 -3.130902,4.63021 "
            "-9.172221,6.52639 z m -16.051386,-4.89479 h 7.408332 q 5.600347,0 "
            "8.378471,-3.2191 2.822222,-3.26319 2.822222,-9.74548 0,-5.732641 "
            "-2.601736,-8.59896 -2.601736,-2.910416 -7.805207,-2.910416 h "
            "-8.202082 z",
            &path);

        canvas->drawPath(path, paint);

        canvas->restore();
        sContext->flush();

        glfwSwapBuffers(window);
    }

    delete sSurface;
    delete sContext;

    glfwDestroyWindow(window);
    glfwTerminate();
    exit(EXIT_SUCCESS);
}