c - 在 GTK 中使用多线程？

Question

如何在 GTK 中使用多线程？我有 2 个线程，一个初始化 GUI，然后连续运行 gtk_main() 来绘制我的 gui，另一个线程执行我所有的程序逻辑和计算，但是当我的程序逻辑线程更新 GtkImage 时，它​​会随机且不一致地停止更新并卡住并且不会再在表单上绘制任何内容。

我已经阅读并被告知只能从 gtk 线程调用 GTK 函数，但这是不可能的，因为一旦你调用 gtk_main() ，它就会卡在那里，直到程序退出。

有人知道如何让我的程序和 GUI 协同工作，并向我展示它如何与我现有的程序一起工作的示例吗？

我已经在这个问题上坚持了几个小时了，需要尽快为一家公司完成这个脚本，以便他们可以使用它来帮助自动化其制造工厂的一项任务。

例如。

static GtkWidget* gtk_image;

void my_thread()
{

while (1) {

//wait for input

//do program logic

//update gtk_image to new image

}

}

void gui_thread() {
//initialize gui

//call gtk_main //it never exits this function until program is closed so you can see how its impossible to make any drawing calls from this thread

}

我的实际代码如下所示(其中 cam_main 和 main_gtk 是我提到的线程):

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdarg.h>
#include <gphoto2/gphoto2-camera.h>
#include <gphoto2/gphoto2-context.h>
#include <wiringPi.h>
#include <gtk/gtk.h>
#include <pthread.h>

    //program
    static int running = 1;
    //libgphoto2
    static CameraList* list;
    static Camera** cams;
    static GPContext* context;
    static const char *name, *value;
    static int ret, count;
    static int pic = 0;
    static int front = 1;
    static const char* workingDir;
    //GTK
    static GtkWidget *window, *vbox,*hboxDir, *hboxCamLabels, *hboxFrontPics, *hboxBackPics, *hboxStatus, *lblDir, *btnConfigDir, *lblCams, *lblFront, *lblBack, *lblCurrentStatus;
    static GtkWidget *front_cams[3];
    static GtkWidget *back_cams[3];
    static GdkPixbuf *pxbscaled = NULL;
    static GdkPixbuf *pixbuf = NULL;
    static GError* err = NULL;

static void btnConfigDir_ConfigureDirectory(GtkWidget* widget, gpointer data) {
    GtkWidget *dialog;
GtkFileChooserAction action = GTK_FILE_CHOOSER_ACTION_OPEN;
gint res;

                dialog = gtk_file_chooser_dialog_new ("Open File", window,
                                      action,
                                      "_Cancel",
                                      GTK_RESPONSE_CANCEL,
                                      "_Open",
                                      GTK_RESPONSE_ACCEPT,
                                      NULL);

res = gtk_dialog_run (GTK_DIALOG (dialog));
if (res == GTK_RESPONSE_ACCEPT)
  {
    char *filename;
    GtkFileChooser *chooser = GTK_FILE_CHOOSER (dialog);
    workingDir = gtk_file_chooser_get_filename (chooser);
  }

  //gtk_label_set_text((GTK_LABEL)lblDir, workingDir);

gtk_widget_destroy (dialog);
}

void* main_gtk() {
    //GTK WIDGET QUEUE REDRAW WOULD REDRAW AT APPROPRIATE TIME


    //INIT GTK
    gtk_init(NULL, NULL);

    //SETUP WINDOW
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    //button1=gtk_button_new_with_label("Click me");
    //gtk_button_set_label(GTK_BUTTON(button1), "click me 1");
    g_signal_connect(window,"delete-event", G_CALLBACK(gtk_main_quit), NULL);

    workingDir = "/media/pi/SD CARD";
    lblDir = gtk_label_new("Save to: dir\t");
    btnConfigDir = gtk_button_new_with_label("Configure Directory");
    g_signal_connect(btnConfigDir, "clicked", G_CALLBACK(btnConfigDir_ConfigureDirectory), NULL);
    lblCams = gtk_label_new("\t\t\t\t\t\t\t\tCAM 1\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tCAM2\t\t\t\t\t\t\t\t\t\t\t\t\t\t\tCAM3");
    lblFront = gtk_label_new("Front");
    lblBack = gtk_label_new("Back ");
    lblCurrentStatus = gtk_label_new("Current Status: Idle");

    //SET WINDOW SIZE AND TITLE
    //gtk_widget_set_size_request(window, 600, 400);
    gtk_window_set_title(GTK_WINDOW(window), "CaptureGui");

    //RESIZE IMAGES
    //image
    front_cams[0] = gtk_image_new();
    front_cams[1] = gtk_image_new();
    front_cams[2] = gtk_image_new();
    back_cams[0] = gtk_image_new();
    back_cams[1] = gtk_image_new();
    back_cams[2] = gtk_image_new();

    GdkPixbuf* pxb;
    pxb = gdk_pixbuf_new(0, 0, 8, 500, 300);
    gtk_image_set_from_pixbuf(GTK_IMAGE(front_cams[0]), pxb);
    gtk_image_set_from_pixbuf(GTK_IMAGE(front_cams[1]), pxb);
    gtk_image_set_from_pixbuf(GTK_IMAGE(front_cams[2]), pxb);
    gtk_image_set_from_pixbuf(GTK_IMAGE(back_cams[0]), pxb);
    gtk_image_set_from_pixbuf(GTK_IMAGE(back_cams[1]), pxb);
    gtk_image_set_from_pixbuf(GTK_IMAGE(back_cams[2]), pxb);

    //g_print("1");

    //front_cams[0] = gtk_image_new_from_file("/media/pi/SD CARD/cam-1_0_a_front.jpg");
    //set_image_scaled(front_cams[0], "/media/pi/SD CARD/cam-1_1_a_front.jpg");
    //set_image_scaled(front_cams[1], "/media/pi/SD CARD/cam-1_1_a_front.jpg");
    //set_image_scaled(front_cams[2], "/media/pi/SD CARD/cam-1_1_b_back.jpg");

    //PACK
    hboxDir = gtk_box_new(0, 0);
    hboxCamLabels = gtk_box_new(0, 0);
    hboxFrontPics = gtk_box_new(0, 0);
    hboxBackPics = gtk_box_new(0, 0);
    hboxStatus = gtk_box_new(0, 0);
    vbox = gtk_vbox_new(0, 10);
    gtk_box_pack_end(GTK_BOX(hboxDir), btnConfigDir, 0, 0, 0);
    gtk_box_pack_end(GTK_BOX(hboxDir), lblDir, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(hboxCamLabels), lblCams, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(hboxFrontPics), lblFront, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(hboxFrontPics), front_cams[0], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxFrontPics), front_cams[1], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxFrontPics), front_cams[2], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxBackPics), lblBack, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(hboxBackPics), back_cams[0], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxBackPics), back_cams[1], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxBackPics), back_cams[2], 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(hboxStatus), lblCurrentStatus, 0, 0, 10);
    gtk_box_pack_start(GTK_BOX(vbox), hboxDir, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(vbox), hboxCamLabels, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(vbox), hboxFrontPics, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(vbox), hboxBackPics, 0, 0, 0);
    gtk_box_pack_start(GTK_BOX(vbox), hboxStatus, 0, 0, 0);


    //gtk_box_pack_start(GTK_BOX(hbox), front_cams[0], 0, 0, 0);
    //gtk_box_pack_start(GTK_BOX(hbox), front_cams[1], 0, 0, 0);
    //gtk_box_pack_start(GTK_BOX(hbox), front_cams[2], 0, 0, 0);
    //gtk_box_pack_start(GTK_BOX(hbox), back_cams[0], 0, 0, 0);
    //gtk_box_pack_start(GTK_BOX(hbox), back_cams[1], 0, 0, 0);
    //gtk_box_pack_start(GTK_BOX(hbox), back_cams[2], 0, 0, 0);
    gtk_container_add(GTK_CONTAINER(window), vbox);

    //ADD ELEMENTS TO GUI
    //gtk_container_add(GTK_CONTAINER(window), image1);
    //gtk_container_add(GTK_CONTAINER(window), image2);
    //image2 = gtk_image_new_from_file("/media/pi/SD CARD/cam-1_0_b_back.jpg");
    //gtk_container_add(GTK_CONTAINER(window), image2);

    //SHOW GUI
    gtk_widget_show_all(window);
    gtk_main();
}

void set_image_scaled(GtkWidget* img, const char* path) {
    pixbuf = gdk_pixbuf_new_from_file(path, &err);
    g_assert_no_error(err);
    pxbscaled = gdk_pixbuf_scale_simple(pixbuf, 500, 300, GDK_INTERP_BILINEAR);
    gtk_image_set_from_pixbuf(GTK_IMAGE(img), pxbscaled);
    g_object_unref(pixbuf);
    g_object_unref(pxbscaled);
}

void* cam_main() {
    while (running == 1) {
    if (digitalRead(4) == 0)
        {
            printf("taking pics of %s item %i\n", (front == 1) ? "front" : "back", pic);
            for (int i = 0; i < count; i++)
            {
                int fd, retval;
                CameraFile *file;
                CameraFilePath cfPath;
                strcpy(cfPath.folder, "/");
                strcpy(cfPath.name, "foo1.jpg");
                printf("Capturing cam%i...\n", i + 1);
                int res = gp_camera_capture(cams[i], GP_CAPTURE_IMAGE, &cfPath, context);
                //printf(gp_port_result_as_string(res));
                printf("capture result: %i\n", res);
                //Camera won't take pic if busy and will continue to program end
                char buf[256];
                snprintf(buf, sizeof(buf), "%s/cam-%i_%i_%s.jpg", workingDir, i + 1, pic, (front == 1) ? "a_front" : "b_back"); //a_ to make front come before back otherwise systems will order incorrectly
                fd = open(buf, O_CREAT | O_WRONLY, 0644);
                retval = gp_file_new_from_fd(&file, fd);
                retval = gp_camera_file_get(cams[i], cfPath.folder, cfPath.name, GP_FILE_TYPE_NORMAL, file, context);
                retval = gp_camera_file_delete(cams[i], cfPath.folder, cfPath.name, context);
                gp_file_free(file);
                //debug
                //if (front == 1 && i == 0)
                //  set_image_scaled(front_cams[0], buf);
                if (front == 1)
                    set_image_scaled(front_cams[i], buf);
                else
                    set_image_scaled(back_cams[i], buf);
            }
            if (front == 1)
                front = 0;
            else
            {
                front = 1;
                pic += 1;
            }
            printf("pics taken...\n");
        }
    }
}

int main(int argc, char **argv)
{
    //Kill any processes using cams
    system("pkill -f gphoto2");

    //Wiring pi init
    wiringPiSetupGpio();

    //Init
    context = gp_context_new();

    detect_cams();


    pthread_t logic_thread_handle, gui_thread_handle;
    pthread_create(&logic_thread_handle, NULL, cam_main, NULL);
    pthread_create(&gui_thread_handle, NULL, main_gtk, NULL);
    pthread_join(gui_thread_handle, 0);
    pthread_join(logic_thread_handle, 0);

    //Deinit
    for (int i = 0; i < count; i++)
    {
        gp_camera_exit(cams[i], context);
        gp_camera_free(cams[i]);
    }
    return 0;
}

void detect_cams() {
    //Detecting all cameras and loading them into mem
        //Detecting all cameras
    ret = gp_list_new(&list);
    if (ret < GP_OK) return 1;
    gp_list_reset(list);
    count = gp_camera_autodetect(list, context);
    if (count < 1)
    {
        printf("No cameras detected.\n");
        return 1;
    }


    //Open all cameras
    printf("Number of cameras: %d\n", count);
    cams = calloc(sizeof (Camera*), count);
    for (int i = 0; i < count; i++)
    {
        gp_list_get_name(list, i, &name);
        gp_list_get_value(list, i, &value);
        ret = open_cam(&cams[i], name, value, context);
        if (ret < GP_OK)
            fprintf(stderr, "Camera %s on port %s failed to open\n", name, value);
    }
}

int open_cam(Camera ** camera, const char *model, const char *port, GPContext *context) {
    GPPortInfoList      *portinfolist = NULL;
    CameraAbilitiesList *abilities = NULL;
    int     ret, m, p;
    CameraAbilities a;
    GPPortInfo  pi;

    ret = gp_camera_new (camera);
    if (ret < GP_OK) return ret;

    if (!abilities) {
        /* Load all the camera drivers we have... */
        ret = gp_abilities_list_new (&abilities);
        if (ret < GP_OK) return ret;
        ret = gp_abilities_list_load (abilities, context);
        if (ret < GP_OK) return ret;
    }

    /* First lookup the model / driver */
        m = gp_abilities_list_lookup_model (abilities, model);
    if (m < GP_OK) return ret;
        ret = gp_abilities_list_get_abilities (abilities, m, &a);
    if (ret < GP_OK) return ret;
        ret = gp_camera_set_abilities (*camera, a);
    if (ret < GP_OK) return ret;

    if (!portinfolist) {
        /* Load all the port drivers we have... */
        ret = gp_port_info_list_new (&portinfolist);
        if (ret < GP_OK) return ret;
        ret = gp_port_info_list_load (portinfolist);
        if (ret < 0) return ret;
        ret = gp_port_info_list_count (portinfolist);
        if (ret < 0) return ret;
    }

    /* Then associate the camera with the specified port */
        p = gp_port_info_list_lookup_path (portinfolist, port);
        switch (p) {
        case GP_ERROR_UNKNOWN_PORT:
                fprintf (stderr, "The port you specified "
                        "('%s') can not be found. Please "
                        "specify one of the ports found by "
                        "'gphoto2 --list-ports' and make "
                        "sure the spelling is correct "
                        "(i.e. with prefix 'serial:' or 'usb:').",
                                port);
                break;
        default:
                break;
        }
        if (p < GP_OK) return p;

        ret = gp_port_info_list_get_info (portinfolist, p, &pi);
        if (ret < GP_OK) return ret;
        ret = gp_camera_set_port_info (*camera, pi);
        if (ret < GP_OK) return ret;
    return GP_OK;
}

Answer 1

I have read and been told to only call GTK functions from the gtk thread but that is impossible as once you call gtk_main() it will be stuck there until the program exits.

不，这并非不可能。即使 gtk_main() 处于事件状态，控制权也会通过回调返回到您的程序。在您的线程中，您可以使用 gdk_threads_add_idle() 安排在 GTK 线程中调用的回调。请参阅GTK3 and multithreading, replacing deprecated functions了解更多信息。