Add framebuffer displaying in v4l2 capture program.

module/v4l2_camera/main_fb.c

@@ -0,0 +1,166 @@
+/**
+ * File: main_fb.c
+ * Author: Joe Shang
+ * Brief: Display camera data using framebuffer.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+#include <assert.h>
+#include <linux/fb.h>
+#include <sys/mman.h>
+#include <sys/ioctl.h>
+
+#include "capture.h"
+#include "decoder.h"
+#include "decoder_mjpeg.h"
+#include "decoder_yuv422.h"
+
+#define CAM_WIDTH       320
+#define CAM_HEIGHT      240
+
+int fb_width;
+int fb_height;
+
+Decoder *decoder = NULL;
+unsigned char rgb_buf[CAM_WIDTH * CAM_HEIGHT * 3];
+unsigned char rgb565_buf[CAM_WIDTH * CAM_HEIGHT * 2];
+
+static void rgb888_to_rgb565(unsigned char *out_buf, unsigned char *in_buf, int width, int height)
+{
+    int i;
+    int j;
+    unsigned char *in_dot;
+    unsigned short *out_dot;
+    unsigned char *in_line;
+    unsigned char *out_line;
+
+    assert((out_buf != NULL) && (in_buf != NULL));
+
+    in_line = in_buf;
+    out_line = out_buf;
+    for (i = 0; i < height; i++)
+    {
+        in_dot = in_line;
+        out_dot = (unsigned short *)out_line;
+
+        for (j = 0; j < width; j++)
+        {
+            *out_dot = (((in_dot[0] >> 3) & 0x1f) << 0)     /* R */
+                       | (((in_dot[1] >> 2) & 0x3f) << 5)   /* G */
+                       | (((in_dot[2] >> 3) & 0x1f) << 11); /* B */
+
+            in_dot += 3;
+            out_dot++;
+        }
+
+        in_line += width * 3;
+        out_line += width * 2;
+    }
+}
+
+static void draw_image(void *ctx, void *buf_start, int buf_size)
+{
+    int i;
+
+    /* find start point of middle-display */
+    unsigned char *fb_line_start = ctx + fb_width * (fb_height - CAM_HEIGHT) + (fb_width - CAM_WIDTH);
+    unsigned char *src_line_start = rgb565_buf;
+
+    decoder_decode(decoder, rgb_buf, buf_start, buf_size);
+    rgb888_to_rgb565(rgb565_buf, rgb_buf, CAM_WIDTH, CAM_HEIGHT);
+
+    for (i = 0; i < CAM_HEIGHT; i++)
+    {
+        memcpy(fb_line_start, src_line_start, CAM_WIDTH * 2);
+
+        fb_line_start += fb_width * 2;
+        src_line_start += CAM_WIDTH * 2;
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    int fbfd;
+    int format;
+    char *fbp = NULL;
+    struct fb_var_screeninfo vinfo;
+    unsigned long screen_size = 0;
+
+    CameraDevice camera;
+
+    if (argc != 4)
+    {
+        fprintf(stderr, "Usage: %s camera camera_fomat framebuffer\n", argv[0]);
+        exit(EXIT_FAILURE);
+    }
+
+    if (strcmp(argv[2], "yuyv") == 0)
+    {
+        format = PIX_FMT_YUYV;
+        decoder = decoder_yuv422_create();
+    }
+    else if (strcmp(argv[2], "mjpeg") == 0)
+    {
+        format = PIX_FMT_MJPEG;
+        decoder = decoder_mjpeg_create();
+    }
+    else
+    {
+        fprintf(stderr, "unsupported format, support yuyv and mjpeg\n");
+        exit(EXIT_FAILURE);
+    }
+
+    /* camera setting */
+    camera_init(&camera, argv[1], CAM_WIDTH, CAM_HEIGHT, 5, format);
+    camera_open_set(&camera);
+
+    /* framebuffer setting */
+    /* open framebuffer */
+    fbfd = open(argv[3], O_RDWR);
+    if (fbfd == -1)
+    {
+        fprintf(stderr, "cannot open framebuffer device\n");
+        exit(EXIT_FAILURE);
+    }
+
+    /* get variable screen infomation */
+    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo))
+    {
+    }
+
+    if (vinfo.bits_per_pixel != 16)
+    {
+        fprintf(stderr, "not supported bits_per_pixel, it only supports 16 bit color\n");
+        exit(EXIT_FAILURE);
+    }
+
+    /* figure out the size of screen in bytes */
+    fb_width = vinfo.xres;
+    fb_height = vinfo.yres;
+    screen_size = vinfo.xres * vinfo.yres * 2;
+    printf("frame buffer: width = %d, height = %d\n", vinfo.xres, vinfo.yres);
+
+    /* mmap framebuffer device to memory */
+    fbp = (char *)mmap(NULL, screen_size, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0); 
+    if ((int)fbp == -1)
+    {
+        fprintf(stderr, "failed to map framebuffer device to memory\n");
+        exit(EXIT_FAILURE);
+    }
+
+    for (;;)
+    {
+        camera_read_frame(&camera, draw_image, fbp);
+    }
+
+    munmap(fbp, screen_size);
+    close(fbfd);
+    camera_close(&camera);
+    decoder_destroy(decoder);
+
+    return 0;
+}