测试framebuffer
static GGLContext *gr_context = 0; static GGLSurface gr_framebuffer[2]; static unsigned gr_active_fb = 0; static int gr_fb_fd = -1; static int gr_vt_fd = -1; static struct fb_var_screeninfo vi; struct fb_fix_screeninfo fi;
// 得到framebuffer的相关信息(可变或固定的) // 及映射数据区域 static int get_framebuffer(GGLSurface *fb) { int fd; void *bits; //将尝试打开两个位置的设备文件 fd = open("/dev/graphics/fb0", O_RDWR); if (fd < 0) { printf("cannot open /dev/graphics/fb0, retrying with /dev/fb0\n"); if ((fd = open("/dev/fb0", O_RDWR)) < 0) { perror("cannot open /dev/fb0"); return -1; } } //得到framebuffer的相关信息 if(ioctl(fd, FBIOGET_FSCREENINFO, &fi) < 0) { perror("failed to get fb0 info"); return -1; } if(ioctl(fd, FBIOGET_VSCREENINFO, &vi) < 0) { perror("failed to get fb0 info"); return -1; } dumpinfo(&fi, &vi); // kernel缓冲区映射到用户空间 bits = mmap(0, fi.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if(bits == MAP_FAILED) { perror("failed to mmap framebuffer"); return -1; } fb->version = sizeof(*fb); fb->width = vi.xres; fb->height = vi.yres; fb->stride = fi.line_length / (vi.bits_per_pixel >> 3); fb->data = bits; fb->format = GGL_PIXEL_FORMAT_RGB_565; // 双缓冲 fb++; fb->version = sizeof(*fb); fb->width = vi.xres; fb->height = vi.yres; fb->stride = fi.line_length / (vi.bits_per_pixel >> 3); fb->data = (void*) (((unsigned) bits) + vi.yres * vi.xres * 2); fb->format = GGL_PIXEL_FORMAT_RGB_565; return fd; }
// 这里假设framebuffer是双缓冲,理论上应当判断下 // 不能直接断定是否双缓冲 static void set_active_framebuffer(unsigned n) { if(n > 1) return; // framebuffer的缓冲区大小,至少要可以两张图片的容量 vi.yres_virtual = vi.yres * 2; vi.yoffset = n * vi.yres; if(ioctl(gr_fb_fd, FBIOPUT_VSCREENINFO, &vi) < 0) { fprintf(stderr,"active fb swap failed!\n"); } else printf("active buffer: %d\n", n); }
// 导出framebuffer的相关信息(x, y , bits_per_pixel等) static void dumpinfo(struct fb_fix_screeninfo *fi, struct fb_var_screeninfo *vi) { fprintf(stderr,"vi.xres = %d\n", vi->xres); fprintf(stderr,"vi.yres = %d\n", vi->yres); fprintf(stderr,"vi.xresv = %d\n", vi->xres_virtual); fprintf(stderr,"vi.yresv = %d\n", vi->yres_virtual); fprintf(stderr,"vi.xoff = %d\n", vi->xoffset); fprintf(stderr,"vi.yoff = %d\n", vi->yoffset); fprintf(stderr, "vi.bits_per_pixel = %d\n", vi->bits_per_pixel); fprintf(stderr, "fi.line_length = %d\n", fi->line_length); }
int gr_init(void) { int fd = -1; // 不太明白,为什么要打开tty0,测试的时候不执行也没有影响 if (!access("/dev/tty0", F_OK)) { fd = open("/dev/tty0", O_RDWR | O_SYNC); if(fd < 0) return -1; if(ioctl(fd, KDSETMODE, (void*) KD_GRAPHICS)) { close(fd); return -1; } } //初始化,framebuffer 数据结构 gr_fb_fd = get_framebuffer(gr_framebuffer); if(gr_fb_fd < 0) { if (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); return 0; }
// 退出,关闭文件等 void gr_exit(void) { close(gr_fb_fd); gr_fb_fd = -1; if (gr_vt_fd >= 0) { ioctl(gr_vt_fd, KDSETMODE, (void*) KD_TEXT); close(gr_vt_fd); gr_vt_fd = -1; } }
int gr_fb_width(void) { return gr_framebuffer[0].width; } int gr_fb_height(void) { return gr_framebuffer[0].height; }
uint16_t red = 0xf800; uint16_t green = 0x07e0; uint16_t blue = 0x001f; // 在缓冲区上绘制图片,一共四个区域 |--|--| | | | |--|--| | | | ----- void draw_grid(int w, int h, uint16_t* loc) { int i, j; int v; int stride = fi.line_length / (vi.bits_per_pixel >> 3); for (j = 0; j < h/2; j++) { for (i = 0; i < w/2; i++) loc[i + j*(stride)] = red; for (; i < w; i++) loc[i + j*(stride)] = green; } for (; j < h; j++) { for (i = 0; i < w/2; i++) loc[i + j*(stride)] = blue; for (; i < w; i++) loc[i + j*(stride)] = 0xffff; } }
// 清空缓冲区数据都为00,视觉上表现为纯黑色 void clear_screen(int w, int h, uint16_t* loc) { int i,j; int stride = fi.line_length / (vi.bits_per_pixel >> 3); for (j = 0; j < h; j++) for (i = 0; i < w; i++) loc[i + j*(stride)] = 0x0000; }
int main(int argc, char **argv) { int w; int h; int id = 0; gr_init(); w = vi.xres; h = vi.yres; // 清空缓冲区数据都为00 clear_screen(w, h, (uint16_t *)gr_framebuffer[0].data); clear_screen(w, h, (uint16_t *)gr_framebuffer[1].data); if (argc > 2) { w = atoi(argv[1]); h = atoi(argv[2]); } if (argc > 3) id = !!atoi(argv[3]); // 绘制图片 draw_grid(w, h, (uint16_t *)gr_framebuffer[id].data); //显示双缓冲的内容,中间和最后加个sleep(),效果会更明显 set_active_framebuffer(!id); set_active_framebuffer(id); return 0; }
posted on 2013-12-05 09:49 love so much 阅读(677) 评论(0) 编辑 收藏 举报