基於gtk的imshow:用gtk讀取並顯示圖像

gtk實現imshow，最naive的做法是用gtk的組件去讀取圖像，然后show出來；后續再考慮用GTK顯示用別的方式例如stb image讀取的圖像。先前基於GDI實現imshow時也是這一思路，先能show出來給自己一點信心。

官方代碼

gtk官方文檔提供了這個例子，並且show出來的圖像和原圖大小一致。

#include <gtk/gtk.h>

static void activate (GtkApplication *app, gpointer user_data)
{
    GtkWidget *window;
    GtkWidget *image;

    /*Create a window with a title and a default size*/
    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), "Welcome to GNOME");
    //gtk_window_set_default_size (GTK_WINDOW (window), 300, 300);

    const char* im_pth = "/home/zz/work/libfc/imgs/Lena.png";
    image = gtk_image_new_from_file (im_pth);

    gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (image));

    gtk_widget_show_all (GTK_WIDGET (window));
}


int main (int argc, char **argv)
{
    GtkApplication *app;
    int status;

    app = gtk_application_new ("org.gtk.example",G_APPLICATION_FLAGS_NONE);
    g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
    status = g_application_run (G_APPLICATION (app), argc, argv);
    g_object_unref (app);
    return status;
}

效果：

簡單封裝

從imshow的用戶來講，ta只需要傳入圖片路徑、圖片標題，就應該得到顯示結果。因此可以把上述代碼進行封裝。使用了全局變量my_window，這是因為回調函數無法傳入額外的參數，並且后續要給窗口綁定更多的參數。

#include <gtk/gtk.h>
#include <stdlib.h>

typedef struct MyWindow {
    const char* im_pth;
    const char* title;
} MyWindow;

MyWindow my_window;

static void activate (GtkApplication *app, gpointer user_data)
{
    GtkWidget *window;
    GtkWidget *image;

    /*Create a window with a title and a default size*/
    window = gtk_application_window_new (app);
    gtk_window_set_title (GTK_WINDOW (window), my_window.title);
    //gtk_window_set_default_size (GTK_WINDOW (window), 300, 300);

    image = gtk_image_new_from_file (my_window.im_pth);

    gtk_container_add (GTK_CONTAINER (window), GTK_WIDGET (image));

    gtk_widget_show_all (GTK_WIDGET (window));
}

void show_image_gtk_temp()
{
    GtkApplication *app;
    int status;

    app = gtk_application_new ("org.gtk.example",G_APPLICATION_FLAGS_NONE);
    g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
    status = g_application_run (G_APPLICATION (app), 0, NULL);
    g_object_unref (app);
}

void gtk_show_image_v1(const char* im_pth, const char* title) {
   
    my_window.im_pth = im_pth;
    my_window.title = title;

    show_image_gtk_temp();
}

int main() {
    const char* im_pth = "/home/zz/work/libfc/imgs/fruits.jpg";
    const char* title = "fruit";
    gtk_show_image_v1(im_pth, title);

    return 0;
}

參考

https://developer.gnome.org/gnome-devel-demos/stable/image.c.html.en

Platform Demos in C