gtk_adjustment_get_value段错误

我想用C++编写一些简单的东西，用GTK +和开罗，但我有一些麻烦使用gtk_adjustment_get_value函数。gtk_adjustment_get_value段错误

这是我的代码：

#include <cairo.h> 
#include <gtk/gtk.h> 
#include <math.h> 
#include <stdlib.h> 
#include <gtk/gtkhscale.h> 
#include <math.h> 

typedef struct 
{ 
    GtkAdjustment *adj[2]; //Adjustments para as escalas 
    GtkWidget *scale[2];  //Escalas 
} ProgInfo; 

gboolean 
on_expose_event (GtkWidget *widget, 
      GdkEventExpose *event, 
     gpointer data) 
{ 
    cairo_t *cr; 
    double pos1x, pos1y; 
    static gdouble pos2x = 450., pos2y = 290.; //Coordenadas Espelho 
    static gdouble pos3x = 450., pos3y = 250.; 
    ProgInfo *pinfo; 

    cr = gdk_cairo_create(widget->window); 

    pinfo = (ProgInfo *) data; 

    pos1x = gtk_adjustment_get_value (pinfo->adj[0]); 

    //Objecto 

    cairo_set_source_rgb (cr, 0, 0, 0); 
    cairo_set_line_width (cr, 1.0); 
    cairo_rectangle (cr, (double) pos1x, (double) pos1y, 20, 80); 
    cairo_stroke_preserve (cr); 
    cairo_set_source_rgb (cr, 1, 1, 1); 
    cairo_fill (cr); 

    cairo_set_source_rgb (cr, 0, 0, 0); 
    cairo_set_line_width (cr, 1.0); 
    cairo_rectangle (cr, (gint) pos3x, (gint) pos3y, 5, 80); 
    cairo_stroke_preserve (cr); 
    cairo_set_source_rgb (cr, 1, 1, 1); 
    cairo_fill (cr); 

    cairo_stroke(cr); 
    cairo_destroy(cr); 

    return FALSE; 
} 


int main (int argc, char *argv[]) 
{ 

    GtkWidget *window, *vbox, *vbox1, *frame, *frame1, *frame2, *label, *label1, *label2, *hbox, *hbox1, *hscale; 
    char string[40] = "Posição Objecto", string1[30] = "Posição Espelho"; 
    ProgInfo *pinfo; 
    gdouble pos1x; 
    pinfo = (ProgInfo *) calloc (1, sizeof (ProgInfo)); 

    gtk_init(&argc, &argv); 

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL); 

    g_signal_connect (window, "expose-event", G_CALLBACK(on_expose_event), NULL); 
    g_signal_connect (window, "destroy", G_CALLBACK(gtk_main_quit), NULL); 

    gtk_window_set_position (GTK_WINDOW(window), GTK_WIN_POS_CENTER); 
    gtk_window_set_title (GTK_WINDOW(window), "Projecto Óptica"); 
    gtk_window_set_default_size (GTK_WINDOW(window), 800, 600); 
    gtk_widget_set_app_paintable (window, TRUE); 

    vbox = gtk_vbox_new (FALSE, 0); 
    gtk_container_add (GTK_CONTAINER (window), vbox); 

    hbox1 = gtk_hbox_new (FALSE, 0); 
    gtk_container_add (GTK_CONTAINER (vbox), hbox1); 

    vbox1 = gtk_vbox_new (FALSE, 0); 
    gtk_box_pack_end (GTK_BOX (hbox1), vbox1, FALSE, FALSE, 20); 

    //Posição Objecto 
    label2 = gtk_label_new (string); 
    gtk_box_pack_start (GTK_BOX (vbox1), label2, FALSE, FALSE, 20); 

    pinfo->adj[0] = (GtkAdjustment *) gtk_adjustment_new (0.7, 0.0, 1.0, 0.001, 1.0, 0.0); 
    //Os parâmetros são, por ordem: valor inicial, valor mínimo e valor máximo 
    pinfo->scale[0] = gtk_hscale_new (GTK_ADJUSTMENT (pinfo->adj[0])); 
    gtk_box_pack_start (GTK_BOX (vbox1), pinfo->scale[0], FALSE, TRUE, 5); 

    //Posição Espelho 
    label1 = gtk_label_new (string1); 
    gtk_box_pack_start (GTK_BOX (vbox1), label1, FALSE, FALSE, 20); 

    pinfo->adj[1] = (GtkAdjustment *)gtk_adjustment_new (0.0, 0.0, 101.0, 0.1, 1.0, 1.0); 
    pinfo->scale[1] = gtk_hscale_new (GTK_ADJUSTMENT (pinfo->adj[1])); 
    gtk_box_pack_start (GTK_BOX (vbox1), pinfo->scale[1], FALSE, FALSE, 0); 

    gtk_widget_show_all(window); 
    gtk_main(); 

    return 0; 
}

我创建了几个滑块与HSCALE小部件，它们显示了罚款，在窗口，我可以移动它们，一切是正常的。但是我想让我的变量pos1x在我移动滑块时改变。我尝试使用gtk_adjustment_get_value函数来做到这一点，但我得到了分段错误。我发现，如果我注释掉这一行：

pos1x = gtk_adjustment_get_value (pinfo->adj[0]);

段故障不会再发生了，但应用程序没有做什么，我想无论是。我意识到这可能非常简单，我对GTK +的工作原理缺乏了解，但是我一直在尝试过去的几个小时，我无法弄清楚什么是错的。我会很感激你所提供的任何帮助。

噢，抱歉在这里放了这么大的代码块，但我不确定你需要哪个部分。

来源

2014-01-10 FranciscoS

您与用户数据指针设置为NULL连接到暴露事件在这里：

g_signal_connect (window, "expose-event", G_CALLBACK(on_expose_event), NULL);

但在处理你希望它是指向ProgInfo。您应该用pinfo替换NULL。

来源

2014-01-10 09:38:47 jku

gtk_adjustment_get_value段错误

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