C++ GGLContext::blendFunc方法代码示例

int gr_init(void)
{
    gglInit(&gr_context);
    GGLContext *gl = gr_context;

    gr_init_font();
    gr_vt_fd = open("/dev/tty0", O_RDWR | O_SYNC);
    if (gr_vt_fd < 0) {
        // This is non-fatal; post-Cupcake kernels don't have tty0.
    } else if (ioctl(gr_vt_fd, KDSETMODE, (void*) KD_GRAPHICS)) {
        // However, if we do open tty0, we expect the ioctl to work.
        perror("failed KDSETMODE to KD_GRAPHICS on tty0");
        gr_exit();
        return -1;
    }

    gr_fb_fd = get_framebuffer(gr_framebuffer);
    if (gr_fb_fd < 0) {
        perror("Unable to get framebuffer.\n");
        gr_exit();
        return -1;
    }

    get_memory_surface(&gr_mem_surface);

    fprintf(stderr, "framebuffer: fd %d (%d x %d)\n",
            gr_fb_fd, gr_framebuffer[0].width, gr_framebuffer[0].height);

    /* start with 0 as front (displayed) and 1 as back (drawing) */
    gr_active_fb = 0;
    if (!has_overlay)
        set_active_framebuffer(0);
    gl->colorBuffer(gl, &gr_mem_surface);

    gl->activeTexture(gl, 0);
    gl->enable(gl, GGL_BLEND);
    gl->blendFunc(gl, GGL_SRC_ALPHA, GGL_ONE_MINUS_SRC_ALPHA);

#ifdef TW_SCREEN_BLANK_ON_BOOT
    printf("TW_SCREEN_BLANK_ON_BOOT := true\n");
    gr_fb_blank(true);
    gr_fb_blank(false);
#endif

    if (!alloc_ion_mem(fi.line_length * vi.yres))
        allocate_overlay(gr_fb_fd, gr_framebuffer);

    return 0;
}

int gr_init(void)
{
    GGLContext *gl;
    int fd;

    gglInit(&gr_context);
    gl = gr_context;

    gr_init_font();

    fd = open("/dev/tty0", O_RDWR | O_SYNC);
    if(fd < 0) return -1;

    if(ioctl(fd, KDSETMODE, (void*) KD_GRAPHICS)) {
        close(fd);
        return -1;
    }

    gr_fb_fd = get_framebuffer(gr_framebuffer);
    
    if(gr_fb_fd < 0) {
        ioctl(fd, KDSETMODE, (void*) KD_TEXT);
        close(fd);
        return -1;
    }

    gr_vt_fd = fd;

        /* start with 0 as front (displayed) and 1 as back (drawing) */
    gr_active_fb = 0;
    set_active_framebuffer(0);
    gl->colorBuffer(gl, gr_framebuffer + 1);

    gl->activeTexture(gl, 0);
    gl->enable(gl, GGL_BLEND);
    gl->blendFunc(gl, GGL_SRC_ALPHA, GGL_ONE_MINUS_SRC_ALPHA);

    return 0;
}

// Scale image function
int res_scale_surface(gr_surface source, gr_surface* destination, float scale_w, float scale_h) {
    GGLContext *gl = NULL;
    GGLSurface* sc_mem_surface = NULL;
    *destination = NULL;
    GGLSurface *surface = (GGLSurface*)source;
    int w = gr_get_width(source), h = gr_get_height(source);
    int sx = 0, sy = 0, dx = 0, dy = 0;
    float dw = (float)w * scale_w;
    float dh = (float)h * scale_h;

    // Create a new surface that is the appropriate size
    sc_mem_surface = init_display_surface((int)dw, (int)dh);
    if (!sc_mem_surface) {
        printf("gr_scale_surface failed to init_display_surface\n");
        return -1;
    }
    sc_mem_surface->format = surface->format;

    // Initialize the context
    gglInit(&gl);
    gl->colorBuffer(gl, sc_mem_surface);
    gl->activeTexture(gl, 0);

    // Enable or disable blending based on source surface format
    if (surface->format == GGL_PIXEL_FORMAT_RGBX_8888) {
        gl->disable(gl, GGL_BLEND);
    } else {
        gl->enable(gl, GGL_BLEND);
        gl->blendFunc(gl, GGL_ONE, GGL_ZERO);
    }

    // Bind our source surface to the context
    gl->bindTexture(gl, surface);

    // Deal with the scaling
    gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_MIN_FILTER, GGL_LINEAR);
    gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_MAG_FILTER, GGL_LINEAR);
    gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_WRAP_S, GGL_CLAMP);
    gl->texParameteri(gl, GGL_TEXTURE_2D, GGL_TEXTURE_WRAP_T, GGL_CLAMP);
    gl->texEnvi(gl, GGL_TEXTURE_ENV, GGL_TEXTURE_ENV_MODE, GGL_REPLACE);
    gl->texGeni(gl, GGL_S, GGL_TEXTURE_GEN_MODE, GGL_AUTOMATIC);
    gl->texGeni(gl, GGL_T, GGL_TEXTURE_GEN_MODE, GGL_AUTOMATIC);
    gl->enable(gl, GGL_TEXTURE_2D);

    int32_t grad[8];
    memset(grad, 0, sizeof(grad));
    // s, dsdx, dsdy, scale, t, dtdx, dtdy, tscale   <- this is wrong!
    // This api uses block floating-point for S and T texture coordinates.
    // All values are given in 16.16, scaled by 'scale'. In other words,
    // set scale to 0, for 16.16 values.

    // s, dsdx, dsdy, t, dtdx, dtdy, sscale, tscale
    float dsdx = (float)w / dw;
    float dtdy = (float)h / dh;
    grad[0] = ((float)sx - (dsdx * dx)) * 65536;
    grad[1] = dsdx * 65536;
    grad[3] = ((float)sy - (dtdy * dy)) * 65536;
    grad[5] = dtdy * 65536;
//    printf("blit: w=%d h=%d dx=%d dy=%d dw=%f dh=%f dsdx=%f dtdy=%f s0=%x dsdx=%x t0=%x dtdy=%x\n",
//                    w,   h,    dx,   dy,   dw,   dh,   dsdx,   dtdy, grad[0], grad[1], grad[3], grad[5]);
    gl->texCoordGradScale8xv(gl, 0 /*tmu*/, grad);

    // draw / scale the source surface to our target context
    gl->recti(gl, dx, dy, dx + dw, dy + dh);
    gglUninit(gl);
    gl = NULL;
    // put the scaled surface in our destination
    *destination = (gr_surface*) sc_mem_surface;
    // free memory used in the source
    res_free_surface(source);
    source = NULL;
    return 0;
}