使用drm的over_plane显示YUV420像素格式的示例C语言代码

以下是使用 DRM 和 Over Plane 显示 YUV420 像素格式的示例 C 代码:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <xf86drm.h>
#include <xf86drmMode.h>

#define WIDTH 640
#define HEIGHT 480

int main(int argc, char *argv[])
{
    int fd;
    drmModeCrtcPtr crtc;
    drmModePlaneResPtr plane_resources;
    drmModePlanePtr plane;
    drmModeObjectPropertiesPtr props;
    uint32_t crtc_id, plane_id, blob_id;
    uint32_t format = DRM_FORMAT_YUV420;
    uint32_t handles[3], pitches[3], offsets[3];
    uint32_t fb_id, bo_handles[4], flags = 0;
    uint8_t *buf;
    int ret, i, j;

    /* Open the DRM device */
    fd = open("/dev/dri/card0", O_RDWR);
    if (fd < 0) {
        fprintf(stderr, "Failed to open DRM device: %s\n", strerror(errno));
        return -1;
    }

    /* Get the CRTC information */
    crtc = drmModeGetCrtc(fd, 0);
    if (!crtc) {
        fprintf(stderr, "Failed to get CRTC information: %s\n", strerror(errno));
        close(fd);
        return -1;
    }
    crtc_id = crtc->crtc_id;

    /* Get the plane resources */
    plane_resources = drmModeGetPlaneResources(fd);
    if (!plane_resources) {
        fprintf(stderr, "Failed to get plane resources: %s\n", strerror(errno));
        drmModeFreeCrtc(crtc);
        close(fd);
        return -1;
    }

    /* Find the primary plane */
    for (i = 0; i < plane_resources->count_planes; i++) {
        plane = drmModeGetPlane(fd, plane_resources->planes[i]);
        if (!plane) {
            fprintf(stderr, "Failed to get plane information: %s\n", strerror(errno));
            continue;
        }

        props = drmModeObjectGetProperties(fd, plane->plane_id, DRM_MODE_OBJECT_PLANE);
        for (j = 0; j < props->count_props; j++) {
            drmModePropertyPtr prop = drmModeGetProperty(fd, props->props[j]);
            if (!strcmp(prop->name, "type") && props->prop_values[j] == DRM_PLANE_TYPE_PRIMARY) {
                plane_id = plane->plane_id;
                drmModeFreeProperty(prop);
                break;
            }
            drmModeFreeProperty(prop);
        }
        drmModeFreeObjectProperties(props);
        drmModeFreePlane(plane);
    }

    /* Create the buffer object */
    buf = malloc(WIDTH * HEIGHT * 3 / 2);
    if (!buf) {
        fprintf(stderr, "Failed to allocate buffer: %s\n", strerror(errno));
        drmModeFreePlaneResources(plane_resources);
        drmModeFreeCrtc(crtc);
        close(fd);
        return -1;
    }
    memset(buf, 0x80, WIDTH * HEIGHT * 3 / 2);

    ret = drmPrimeFDToHandle(fd, STDIN_FILENO, &handles[0]);
    if (ret < 0) {
        fprintf(stderr, "Failed to get handle for file descriptor: %s\n", strerror(errno));
        free(buf);
        drmModeFreePlaneResources(plane_resources);
        drmModeFreeCrtc(crtc);
        close(fd);
        return -1;
    }

    /* Configure the buffer object */
    pitches[0] = WIDTH;
    pitches[1] = pitches[2] = WIDTH / 2;
    offsets[0] = 0;
    offsets[1] = WIDTH * HEIGHT;
    offsets[2] = offsets[1] + WIDTH * HEIGHT / 4;

    bo_handles[0] = handles[0];
    bo_handles[1] = bo_handles[2] = bo_handles[3] = 0;

    ret = drmModeAddFB2(fd, WIDTH, HEIGHT, format, bo_handles, pitches, offsets, &fb_id, flags);
    if (ret < 0) {
        fprintf(stderr, "Failed to add frame buffer: %s\n", strerror(errno));
        free(buf);
        drmModeFreePlaneResources(plane_resources);
        drmModeFreeCrtc(crtc);
        close(fd);
        return -1;
    }

    /* Set the plane mode */
    ret = drmModeSetPlane(fd, plane_id, crtc_id, fb_id, 0, 0, 0, WIDTH, HEIGHT, 0, 0, WIDTH << 16, HEIGHT << 16);
    if (ret < 0) {
        fprintf(stderr, "Failed to set plane mode: %s\n", strerror(errno));
        drmModeRmFB(fd, fb_id);
        free(buf);
        drmModeFreePlaneResources(plane_resources);
        drmModeFreeCrtc(crtc);
        close(fd);
        return -1;
    }

    /* Wait for input */
    printf("Press any key to exit...\n");
    getchar();

    /* Clean up */
    drmModeRmFB(fd, fb_id);
    free(buf);
    drmModeFreePlaneResources(plane_resources);
    drmModeFreeCrtc(crtc);
    close(fd);

    return 0;
}

这是一个简单的示例代码，它打开 DRM 设备，获取 CRTC 信息，找到主平面，创建 YUV420 帧缓冲区对象，将帧缓冲区对象传递给主平面，然后等待输入并在退出时清除资源。请注意，此示例仅涵盖了 DRM 和 Over Plane 基础知识，实际应用需要更多的代码来实现更复杂的功能。