最近在进行linux下的glade和gtk编程。遇到一个棘手的问题，特向高手请教！

需求如下：
滚动显示矢量大地图，要求能够缩放。
问题如下：
我构造了一个滚动窗口，在上面加了一个drawingarea，显示一个大矢量图，我的做法是先把矢量图画在pixmap上，然后显示。因为矢量图很大，而滚动窗口的滚动条是根据drawingarea大小判断的（在程序里我用gtk_widget_set_size_request指定大小这样滚动条就能正确显示）。现在我的矢量图要求能够放大，也就是说矢量图可能达到20000*10000那么大，这个时候我用gtk_widget_set_size_request(drawingarea1,20000,10000)系统会报错。我察看了一下内存，在gtk_widget_set_size_request(drawingarea1,2000,1000)时用了7M内存。如果达到5000*4000就用了36M内存。这样内存消耗实在太大。
请教如下：
是不是我的做法有问题，我该怎么正确显示滚动条。

附加代码如下：
callbacks.c:

gboolean
DrawConfigE                            (GtkWidget       *widget,
                                        GdkEventConfigure *event,
                                        gpointer         user_data)//config事件
{
ReadRegionListData();
ReadCurveListData();
ReadRoadRiverListData();

if (pixmap)
     g_object_unref (pixmap);
   pixmap = gdk_pixmap_new (widget->window,widget->allocation.width,widget->allocation.height, -1);
gdk_draw_rectangle (pixmap,widget->style->white_gc,1,0,0,widget->allocation.width,widget->allocation.height);
int i=0,j=0;
GtkPoint * pointsregion;


GdkGC *gc;
GdkColor color;
gc=gdk_gc_new(widget->window);
/*color.red=0xffff;
color.green=0;
color.blue=0;
gdk_color_alloc(gdk_colormap_get_system(),&color);
gdk_gc_set_foreground(gc,&color);
*/
Point3D tempp;
for(;iblack_gc,1,pointsregion,regionList.pRegion[i].pointcount);
color.red=65535;
        color.green=0;
        color.blue=0;
        gdk_color_alloc(gdk_colormap_get_system(),&color);
        gdk_gc_set_foreground(gc,&color);

gdk_draw_polygon(pixmap,gc,1,pointsregion,regionList.pRegion[i].pointcount);
}
i=0;
GtkPoint * pointscurve;
for(;iblack_gc,pointscurve  ,pcurveList.pPoints[i].pointcount);
}
//-----------------------roadriver------------------------------------
i=0;
GtkPoint * pointleftroad=NULL,*pointrightroad=NULL;
for(;iblack_gc,pointleftroad  ,proadList.pRoadRiver[i].leftpointcount);

pointrightroad=malloc(sizeof(GtkPoint)*proadList.pRoadRiver[i].rightpointcount);
j=0;
      for(;jstyle->black_gc,pointrightroad  ,proadList.pRoadRiver[i].rightpointcount);

}
   return FALSE;
}


gboolean
DrawExposeE                            (GtkWidget       *widget,
                                        GdkEventExpose  *event,
                                        gpointer         user_data)//expose事件
{
gdk_draw_drawable (widget->window,
     widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
     pixmap,
     event->area.x, event->area.y,
     event->area.x, event->area.y,
     event->area.width, event->area.height);
//printf("%d,%d,%d,%d,%d,%dn",event->area.x, event->area.y,
//      event->area.x, event->area.y,
//      event->area.width, event->area.height);

   return FALSE;
}

interface.c:
create_window1 (void)
{
  GtkWidget *window1;
  GtkWidget *scrolledwindow1;
  GtkWidget *viewport1;
  GtkWidget *drawingarea1;
  
  //GtkAdjustment  *adj1, *adj2;

  window1 = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title (GTK_WINDOW (window1), "window1");

  
  g_signal_connect (G_OBJECT (window1), "delete_event",
                    G_CALLBACK (quit),
                    NULL);
  scrolledwindow1 = gtk_scrolled_window_new (NULL, NULL);
  gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(scrolledwindow1),GTK_POLICY_AUTOMATIC,GTK_POLICY_AUTOMATIC);
 
  gtk_widget_show (scrolledwindow1);
  gtk_container_add (GTK_CONTAINER (window1), scrolledwindow1);  
  
  viewport1 = gtk_viewport_new (NULL, NULL);
  gtk_widget_show (viewport1);  
  
  gtk_container_add (GTK_CONTAINER (scrolledwindow1), viewport1);

  drawingarea1 = gtk_drawing_area_new ();


  
  gtk_widget_show (drawingarea1);
  gtk_container_add (GTK_CONTAINER (viewport1), drawingarea1);
  
  
   gtk_drawing_area_size(GTK_DRAWING_AREA(drawingarea1), 600, 400);

  //gtk_widget_set_size_request(drawingarea1,400,300);
  g_signal_connect ((gpointer) drawingarea1, "configure_event",
                    G_CALLBACK (DrawConfigE),
                    NULL);
  g_signal_connect ((gpointer) drawingarea1, "expose_event",
                    G_CALLBACK (DrawExposeE),
                    NULL); 
       
  /* Store pointers to all widgets, for use by lookup_widget(). */
  GLADE_HOOKUP_OBJECT_NO_REF (window1, window1, "window1");
  GLADE_HOOKUP_OBJECT (window1, scrolledwindow1, "scrolledwindow1");
  GLADE_HOOKUP_OBJECT (window1, viewport1, "viewport1");
  GLADE_HOOKUP_OBJECT (window1, drawingarea1, "drawingarea1");

  return window1;
}

你现在用得是scrollwindow吧，用滚动条控件试一下