Using Skia With GLFW (Or any other framework that provides an OpenGL context [GLUT,SDL,etc...])

gistfile1.txt

#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#include "glfw/glfw.h"

#include "skia/include/gpu/GrContext.h"
#include "skia/include/gpu/GrRenderTarget.h"
#include "skia/include/gpu/GrGLInterface.h"
#include "skia/include/gpu/SkGpuDevice.h"
#include "skia/include/gpu/SkGpuCanvas.h"
#include "skia/include/gpu/SkNativeGLContext.h"
#include "skia/include/core/SkCanvas.h"
#include "skia/include/core/SkGraphics.h"

int main( int ac,char** av )
{
    SkAutoGraphics ag;
    int window_width = 800,
         window_height = 600;
    //*
    if( glfwInit() == GL_FALSE )
    {
        printf( "Could not initialize GLFW. Aborting.\n" );
        exit( 0 );
    }

    // This function calls wglMakeCurrent somewhere in its execution, so make sure that (or its platform specific equivalent) it is called when porting to other frameworks.
    if (glfwOpenWindow(window_width, window_height, 8,8,8,8,24,8, GLFW_WINDOW) == GL_FALSE)
    {
        printf( "Could not open GLFW window. Aborting.\n" );
        exit( 0 );
    }
    // */

    const GrGLInterface* fGL = GrGLCreateNativeInterface();
    GrContext* fGrContext = GrContext::Create( kOpenGL_Shaders_GrEngine,(GrPlatform3DContext)fGL );
    if( fGrContext == 0x0 )
    {
        printf("\nfGrContext was null");
        exit( 0 );
    }


    GrRenderTarget* fGrRenderTarget;)


    GrPlatformRenderTargetDesc desc;)
    desc.fWidth = window_width;)
    desc.fHeight = window_height;)
    desc.fConfig = kSkia8888_PM_GrPixelConfig;)
    GR_GL_GetIntegerv(fGL, GR_GL_SAMPLES, &desc.fSampleCnt);)
    GR_GL_GetIntegerv(fGL, GR_GL_STENCIL_BITS, &desc.fStencilBits);)
    GrGLint buffer;)
    GR_GL_GetIntegerv(fGL, GR_GL_FRAMEBUFFER_BINDING, &buffer);)
    desc.fRenderTargetHandle = buffer;

    // I had some serious trouble with segmentation faults and failures arising from this function. Perhaps some more robust error checking is in order?
    fGrRenderTarget = fGrContext->createPlatformRenderTarget(desc);

    // Canvi (Canvasses?) only really care about the device they contain, so you can ignore the SkGpuCanvas.
    SkCanvas* gpuCanvas = new SkCanvas();
    gpuCanvas->setDevice(new SkGpuDevice(fGrContext,fGrRenderTarget))->unref();

    glfwSetWindowTitle( "Skia GLFW Test" );

    while( true )
    {
        // Draw a red background with a gray, semi-transparent circle in the top left corner.
        gpuCanvas->drawColor( SK_ColorRED );
        SkRect r(SkRect::MakeWH(200,200));
        SkPaint p;
        p.setARGB( 200,100,100,100 );
        gpuCanvas->drawOval( r,p );

        glfwSwapBuffers();
        fGrContext->flush(false);
        Sleep( 1 );
    }
    return 1;
}

This gist no longer works because skia's API has changed, so users may be interested in a more recent bootstrap (Feb 2018): https://gist.github.com/ad8e/dd150b775ae6aa4d5cf1a092e4713add