Re: Drawing Area in Scrolled Window

[Russell Shaw <rjshaw iprimus com au>]

dhendrix socrates Berkeley EDU wrote:
> Thanks in advance for taking the time to read this.  Here is a very short
> code to produce a scrolled window with a child that IS NOT a table.  You
> see almost every example on the web uses tables, and they seem to work.
> But if you want to have a drawable area in a scrolled window (imagine if
> you wanted to zoom in on an picture), it doesn't seem to work.
>
> The scrollbars are always as big as the mainwindow, and can hence never
> move!  How can I make this scrolled window a scrolling window?  I have
> tried messing with the adjustments to no avail.  I have tried changing
> various size parameters, all with the same useless scrollbars.
>
> HERE IS THE CODE:
>
> static GdkPixmap *PixMap = NULL; /* Backing pixmap */
> int InnerWindow_x=100, InnerWindow_y=100;
>
> static gint exposeInnerWindow( GtkWidget *widget, GdkEventExpose *event )
> {
>   gdk_draw_pixmap(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);
>
>   return FALSE;
> }
>
> static gint configureInnerWindow( GtkWidget *widget, GdkEventConfigure
> *event ) {
>   if (PixMap) {
>     gdk_pixmap_unref(PixMap);
>   }
>   PixMap = gdk_pixmap_new(widget->window,
>                           widget->allocation.width,
>                           widget->allocation.height,
>                           -1);
>   gdk_draw_rectangle (PixMap,
>                       widget->style->black_gc,
>                       TRUE,
>                       0, 0,
>                       widget->allocation.width,
>                       widget->allocation.height);
>   gtk_widget_draw(widget,NULL);
>   return TRUE;
> }
>
> void quit ()
> {
>   gtk_exit (0);
> }
>
> int main( int   argc,
>           char *argv[] )
> {
>   GtkWidget *MainWindow, *vbox;
>   GtkWidget *scrolledWindow, *InnerWindow;
>   GtkObject *viewerHAdjustment, *viewerVAdjustment;
>   GtkWidget *wordListWindow, *wordList;
>   GtkObject *wordListHAdjustment, *wordListVAdjustment;
>   GtkWidget *button;
>
>   gtk_init (&argc, &argv);
>
>   MainWindow = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>   gtk_widget_set_name (MainWindow, "CASPER");
>
>   vbox = gtk_vbox_new (FALSE, 0);
>   gtk_container_add (GTK_CONTAINER (MainWindow), vbox);
>   gtk_widget_show (vbox);
>
>   /* setup scrolled window */
>   viewerHAdjustment=gtk_adjustment_new(0,0,100,1.0,1.0,1.0);
>   viewerVAdjustment=gtk_adjustment_new(0,0,100,1.0,1.0,1.0);
>
> scrolledWindow=gtk_scrolled_window_new(GTK_ADJUSTMENT(viewerHAdjustment),GTK_ADJUSTMENT(viewerVAdjustment));
>
> gtk_widget_set_usize(GTK_WIDGET(scrolledWindow),InnerWindow_x,InnerWindow_y);

scrolledWindow now 100x100

>   gtk_box_pack_start(GTK_BOX(vbox),scrolledWindow,TRUE,TRUE,0);
>   gtk_widget_show(scrolledWindow);
>
>   /* Create the child of the scrolled window */
>   InnerWindow = gtk_drawing_area_new ();
>
> gtk_widget_set_usize(GTK_WIDGET(scrolledWindow),2*InnerWindow_x,2*InnerWindow_y);

scrolledWindow now 200x200

> gtk_scrolled_window_add_with_viewport(GTK_SCROLLED_WINDOW(scrolledWindow),
> InnerWindow);

InnerWindow has no fixed size (gtk_drawing_area), so it fits within the scrolled
window without need for scrollbars. Try setting the gtk_drawing_area to a size
larger than scrolledWindow.

>   gtk_widget_show (InnerWindow);