GtkDrawingArea

• realize：元件被初始時
• configure_event：元件尺寸改變時
• expose_event：元件需要重繪時

• gtkdrawingarea_demo.c

#include <gtk/gtk.h>

gboolean expose_event_callback(GtkWidget *widget, 
                               GdkEventExpose *event, 
                               gpointer data) {
                               
    GdkGC *gc = widget->style->fg_gc[GTK_WIDGET_STATE(widget)];
    GdkDrawable *drawable = widget->window;
    GdkColor color;

    // 畫一條線
    gdk_draw_line(drawable, gc, 10, 10, 100, 10);
    // 畫一個空心矩形
    gdk_draw_rectangle(drawable, gc, FALSE, 10, 20, 100, 50);
    
    color.green = 65535;
    color.blue = 0;
    gdk_gc_set_rgb_fg_color(gc, &color);
    
    // 畫一個實心矩形
    gdk_draw_rectangle(drawable, gc, TRUE, 10, 80, 100, 50);
    
    color.green = 0;
    color.blue = 65535;
    gdk_gc_set_rgb_fg_color(gc, &color);
    
    // 畫一個扇形
    gdk_draw_arc(drawable, gc, TRUE,
                10, 150, 100, 50, 45 * 64, 300 * 64);

    // 畫一張圖
    gdk_draw_pixbuf(drawable, gc, gdk_pixbuf_new_from_file("caterpillar.jpg", NULL)
            , 0, 0, 150, 10, -1, -1, 
            GDK_RGB_DITHER_NORMAL, 0, 0);
 
    return TRUE;
}

int main(int argc, char *argv[]) {
    GtkWidget *window;
    GtkWidget *drawing_area;

    gtk_init(&argc, &argv);
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title(GTK_WINDOW(window), "GtkDrawingArea");

    drawing_area = gtk_drawing_area_new();
    gtk_widget_set_size_request(drawing_area, 350, 200);
                  
    g_signal_connect(GTK_OBJECT(drawing_area), "expose_event",  
                     G_CALLBACK(expose_event_callback), NULL);

    gtk_container_add(GTK_CONTAINER(window), drawing_area);

    g_signal_connect(GTK_OBJECT(window), "destroy",
                     G_CALLBACK(gtk_main_quit), NULL);
                     
    gtk_widget_show_all(window);

    gtk_main();

    return 0;
}