使用drm实现屏幕两个区域刷新的C代码

以下是使用 DRM（Direct Rendering Manager）实现屏幕两个区域刷新的C代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <xf86drm.h>
#include <xf86drmMode.h>

#define BUF_SIZE 1024

int main(int argc, char *argv[]) {
    int fd, ret, i;
    uint32_t crtc_id, connector_id;
    drmModeRes *resources;
    drmModeConnector *connector;
    drmModeEncoder *encoder;
    drmModeCrtc *crtc;
    uint32_t *fb_ids;
    uint32_t *bufs[2];
    uint32_t width, height, stride;
    uint64_t size;
    struct drm_mode_create_dumb create_arg;
    struct drm_mode_map_dumb map_arg;

    /* Open the DRM device */
    fd = open("/dev/dri/card0", O_RDWR);
    if (fd < 0) {
        perror("open");
        exit(1);
    }

    /* Get the available resources */
    resources = drmModeGetResources(fd);
    if (!resources) {
        perror("drmModeGetResources");
        exit(1);
    }

    /* Find a connected connector */
    for (i = 0; i < resources->count_connectors; i++) {
        connector = drmModeGetConnector(fd, resources->connectors[i]);
        if (connector->connection == DRM_MODE_CONNECTED) {
            connector_id = connector->connector_id;
            break;
        }
        drmModeFreeConnector(connector);
    }
    if (i == resources->count_connectors) {
        perror("No connected connector found");
        exit(1);
    }

    /* Find an encoder for the connector */
    for (i = 0; i < resources->count_encoders; i++) {
        encoder = drmModeGetEncoder(fd, resources->encoders[i]);
        if (encoder->encoder_id == connector->encoder_id) {
            break;
        }
        drmModeFreeEncoder(encoder);
    }
    if (i == resources->count_encoders) {
        perror("No encoder found for the connector");
        exit(1);
    }

    /* Find a CRTC for the encoder */
    crtc_id = encoder->crtc_id;
    crtc = drmModeGetCrtc(fd, crtc_id);
    if (!crtc) {
        perror("drmModeGetCrtc");
        exit(1);
    }

    /* Get the framebuffer size */
    width = connector->modes[0].hdisplay;
    height = connector->modes[0].vdisplay;
    stride = width * 4; /* Assume 32 bits per pixel */
    size = stride * height;

    /* Create two dumb buffers */
    for (i = 0; i < 2; i++) {
        memset(&create_arg, 0, sizeof(create_arg));
        create_arg.width = width;
        create_arg.height = height;
        create_arg.bpp = 32;
        ret = drmIoctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_arg);
        if (ret < 0) {
            perror("DRM_IOCTL_MODE_CREATE_DUMB");
            exit(1);
        }

        bufs[i] = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, create_arg.handle);
        if (bufs[i] == MAP_FAILED) {
            perror("mmap");
            exit(1);
        }

        memset(bufs[i], 0, size);
    }

    /* Map the first buffer */
    memset(&map_arg, 0, sizeof(map_arg));
    map_arg.handle = create_arg.handle;
    ret = drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &map_arg);
    if (ret < 0) {
        perror("DRM_IOCTL_MODE_MAP_DUMB");
        exit(1);
    }
    fb_ids[0] = create_arg.handle;

    /* Map the second buffer */
    memset(&map_arg, 0, sizeof(map_arg));
    map_arg.handle = create_arg.handle;
    ret = drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &map_arg);
    if (ret < 0) {
        perror("DRM_IOCTL_MODE_MAP_DUMB");
        exit(1);
    }
    fb_ids[1] = create_arg.handle;

    /* Set the mode on the CRTC */
    ret = drmModeSetCrtc(fd, crtc_id, fb_ids[0], 0, 0, &connector_id, 1, &connector->modes[0]);
    if (ret < 0) {
        perror("drmModeSetCrtc");
        exit(1);
    }

    /* Wait for a key press */
    printf("Press any key to switch buffers\n");
    getchar();

    /* Switch to the second buffer */
    ret = drmModeSetCrtc(fd, crtc_id, fb_ids[1], 0, 0, &connector_id, 1, &connector->modes[0]);
    if (ret < 0) {
        perror("drmModeSetCrtc");
        exit(1);
    }

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

    /* Free the resources */
    drmModeFreeCrtc(crtc);
    drmModeFreeEncoder(encoder);
    drmModeFreeConnector(connector);
    drmModeFreeResources(resources);
    drmModeRmFB(fd, fb_ids[0]);
    drmModeRmFB(fd, fb_ids[1]);
    munmap(bufs[0], size);
    munmap(bufs[1], size);
    close(fd);

    return 0;
}

这个例子创建了两个 dumb buffers，然后切换这两个 buffer 来实现屏幕两个区域的刷新。你可以根据你的需求修改这个例子来实现你自己的功能。