Skia Fiddle

static sk_sp<SkImage> create_gpu_image(GrContext* grContext) {
    const SkImageInfo info = SkImageInfo::MakeN32(20, 20, kOpaque_SkAlphaType);
    auto surface(SkSurface::MakeRenderTarget(grContext, SkBudgeted::kNo, info));
    SkCanvas* canvas = surface->getCanvas();
    canvas->clear(SK_ColorWHITE);
    SkPaint paint;
    paint.setColor(SK_ColorBLACK);
    canvas->drawRect(SkRect::MakeXYWH(5, 5, 10, 10), paint);
    return surface->makeImageSnapshot();
}

void draw(SkCanvas* canvas) {
    GrContext* grContext = canvas->getGrContext();
    if (!grContext) {
        return;
    }
    sk_sp<SkImage> backEndImage = create_gpu_image(grContext);
    canvas->drawImage(backEndImage, 0, 0);
    GrBackendTexture texture;
    SkImage::BackendTextureReleaseProc proc;
    if (!SkImage::MakeBackendTextureFromSkImage(grContext, std::move(backEndImage),
            &texture, &proc)) {
        return;
    }
    sk_sp<SkImage> i2 = SkImage::MakeFromTexture(grContext, texture, kTopLeft_GrSurfaceOrigin,
            kN32_SkColorType, kOpaque_SkAlphaType, nullptr);
    canvas->drawImage(i2, 30, 30);
}

Skia API Documentation