本文主要是介绍Android P图形架构之FrameBuffer测试Demo，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
Android FrameBuffer测试记录。
SurfaceFlinger是一个服务，主要是负责合成各窗口的Surface，然后通过OpenGLES显示到FrameBuffer上。
参考资料：
https://android.googlesource.com/platform/system/extras/+/donut-release/tests/framebuffer/fb_test.c
源码：
framebuffer_test.c
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
#include <stdlib.h>
#include "yellow_face.zif"
int main()
{ int fbfd = 0; struct fb_var_screeninfo vinfo; struct fb_fix_screeninfo finfo; //struct fb_cmap cmapinfo; long int screensize = 0; char *fbp = 0; int x = 0, y = 0; //long int location = 0; //int b,g,r; // Open the file for reading and writing fbfd = open("/dev/graphics/fb0", O_RDWR,0); // 打开Frame Buffer设备 if (fbfd < 0) { printf("Error: cannot open framebuffer device.%x\n",fbfd); exit(1); } printf("The framebuffer device was opened successfully.\n"); // Get fixed screen information if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo)) { // 获取设备固有信息 printf("Error reading fixed information.\n"); exit(2); } printf("\ntype:0x%x\n", finfo.type ); // FrameBuffer 类型,如0为象素 printf("visual:%d\n", finfo.visual ); // 视觉类型：如真彩2，伪彩3 printf("line_length:%d\n", finfo.line_length ); // 每行长度 printf("\nsmem_start:0x%lx,smem_len:%u\n", finfo.smem_start, finfo.smem_len ); // 映象RAM的参数 printf("mmio_start:0x%lx ,mmio_len:%u\n", finfo.mmio_start, finfo.mmio_len ); // Get variable screen information if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo)) { // 获取设备可变信息 printf("Error reading variable information.\n"); exit(3); } printf("%dx%d, %dbpp,xres_virtual=%d,yres_virtual=%dvinfo.xoffset=%d,vinfo.yoffset=%d\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel,vinfo.xres_virtual,vinfo.yres_virtual,vinfo.xoffset,vinfo.yoffset); screensize = finfo.line_length * vinfo.yres_virtual;// Map the device to memory 通过mmap系统调用将framebuffer内存映射到用户空间,并返回映射后的起始地址 fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,fbfd, 0); if ((int)fbp == -1) { printf("Error: failed to map framebuffer device to memory.\n"); exit(4); } printf("The framebuffer device was mapped to memory successfully.\n"); /*****************exampel********************/ unsigned char *pTemp = (unsigned char *)fbp;int i, j;//起始坐标(x,y),终点坐标(right,bottom)x = 0;y = 0;int right = 480;//vinfo.xres;int bottom = 1708;//vinfo.yres;//计算偏移量.例如在（x，y）位置写入颜色 pixel值.//offset = (x + y * screen_width) * 4; // (4个字节) for(i=y; i< bottom; i++){for(j=x; j<right; j++){unsigned short data = yellow_face_data[(((i-y) % 128) * 128) + ((j-x) %128)];// *((uint32_t *)(fbp + offset)) = pixel;pTemp[i*finfo.line_length + (j*4) + 2] = (unsigned char)((data & 0xF800) >> 11 << 3);pTemp[i*finfo.line_length + (j*4) + 1] = (unsigned char)((data & 0x7E0) >> 5 << 2);pTemp[i*finfo.line_length + (j*4) + 0] = (unsigned char)((data & 0x1F) << 3);}} /*****************FBIOPAN_DISPLAY********************/ //note：vinfo.xoffset =0 vinfo.yoffset =0 否则FBIOPAN_DISPLAY不成功if (ioctl(fbfd, FBIOPAN_DISPLAY, &vinfo)) { printf("Error FBIOPAN_DISPLAY information.\n"); exit(5); } sleep(10);//finfo.smem_len == screensize == finfo.line_length * vinfo.yres_virtual munmap(fbp,finfo.smem_len);close(fbfd); return 0;
}
mk编译文件源码：
Android.mk
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := eng
LOCAL_SRC_FILES:=framebuffer_test.c
LOCAL_MODULE:=framebuffer_test
LOCAL_CPPFLAGS += -DANDROID
LOCAL_SHARED_LIBRARIES:=libc
LOCAL_C_INCLUDES += $(LOCAL_PATH) $(LOCAL_PATH)/$(KERNEL_DIR)/include
include $(BUILD_EXECUTABLE)
1、mm编译system\bin目录下生成framebuffer_test文件
2、拷贝到机器system/bin目录下
3、执行：stop surfaceflinger，关闭surfaceflinger
4、执行：./framebuffer_test，运行framebuffer_test程序
5、显示图像，执行成功。
这篇关于Android P图形架构之FrameBuffer测试Demo的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
