pango can not draw text on default root window ???

["zhu shenqi" <zhusqi hotmail com>]

Hi, all
 I want to draw on screen use gdk and pango but I fail. I can draw text on 
root window user XDrawImageString() but gdk_draw_layout can not do it and 
my pango code can draw text on a gtk window. I don't know why ???

My code:

#include <stdio.h>
#include <gtk/gtk.h>
#include <string.h>

void convert_color( GdkColor *gcolor, PangoAttrColor *attr )
{
   gcolor->red = attr->color.red;
   gcolor->green = attr->color.green;
   gcolor->blue = attr->color.blue;
}
                                                                           
          
int SetPangoTextColor( PangoLayout *layout, GdkColor *color1, GdkColor 
*color2, PangoAttrType nFlag )
{
   GdkColor oldcolor;                                                      
               
   PangoAttrList *attr_list = pango_layout_get_attributes( layout );
                    
   if (attr_list == NULL)
   {
       /* Create attr list if there wasn't one */
       attr_list = pango_attr_list_new ();
       pango_layout_set_attributes (layout, attr_list);
       pango_attr_list_unref (attr_list);
   }
                    
   PangoAttrIterator *iter = pango_attr_list_get_iterator( attr_list );
                    
   if( iter == NULL )
       return FALSE;
                     
   PangoAttribute *attr = pango_attr_iterator_get( iter, nFlag );
   if( attr && color2 )
   {
       convert_color( &oldcolor, (PangoAttrColor *)attr );
       color2->red = oldcolor.red;
       color2->green = oldcolor.green;
       color2->blue = oldcolor.blue;
   }
   PangoAttribute* tmp_attr = NULL;
                          
   if( nFlag == PANGO_ATTR_FOREGROUND )
       tmp_attr = pango_attr_foreground_new (color1->red, color1->green, 
color1->blue);
   else
       tmp_attr = pango_attr_background_new (color1->red, color1->green, 
color1->blue);
                                        
   if( tmp_attr )
   {
       tmp_attr->start_index = 0;
       tmp_attr->end_index = 2147483647;
       attr = pango_attribute_copy( tmp_attr );
       pango_attribute_destroy( tmp_attr );
       pango_attr_list_change( attr_list, attr );
   }
                    
   pango_attr_iterator_destroy( iter );
                          
   return TRUE;
}

int draw_some_text(GdkDrawable *drawable, GdkGC * gc , PangoContext 
*context, GdkColormap * colorMap)
{
   PangoFontDescription *font_desc;
   PangoLayout *layout = pango_layout_new(context);

   gunichar uc = 0x00D4;
   gchar text[64];
   gint ui = 0;
                                                                           
     
   PangoRectangle ink_rect, log_rect;
                                                                   
   ui = g_unichar_to_utf8(uc, text);
   text[ui] = 0;
                                                                           

   font_desc = pango_font_description_new();
   pango_font_description_set_family(font_desc, "ZYSong18030");
   pango_font_description_set_size(font_desc, 48*PANGO_SCALE);
   pango_layout_set_font_description(layout, font_desc);
   pango_layout_set_text(layout, "Hello", -1);
   pango_layout_get_pixel_extents(layout, &ink_rect, &log_rect);
                                                                           
               
   GdkColor textColor;
   textColor.red = 0;
   textColor.green = 0;
   textColor.blue = 0;

   if (!gdk_colormap_alloc_color(colorMap, &textColor, TRUE, TRUE))
   {
     g_error ("couldn't allocate color");
   }
                                                                           
    
   int ret = SetPangoTextColor( layout, &textColor, NULL, 
PANGO_ATTR_FOREGROUND );
   if( !ret )
       return FALSE;
   //g_print("Ink: {%d, %d, %d, %d}\n", ink_rect.x, ink_rect.y, 
ink_rect.width, ink_rect.height);
   //g_print("Log: {%d, %d, %d, %d}\n", log_rect.x, log_rect.y, 
log_rect.width, log_rect.height);
                                                                           
    
   gdk_draw_layout(drawable, gc, 30, 20, layout);
   pango_font_description_free(font_desc);
   g_object_unref(layout);
   return TRUE;
}
                                                             
int main( int argc, char *argv[] )
{
   /* GtkWidget is the storage type for widgets */
   GtkWidget *window;
   //GtkWidget *button;
                                                                       
   /* This is called in all GTK applications. Arguments are parsed
    * from the command line and are returned to the application. */
   gtk_init (&argc, &argv);
                                                                           
     
   /* create a new window */
   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
                                                                           
     
   GdkRectangle rect;
   rect.x = 50;
   rect.y = 50;
   rect.width = 500;
   rect.height = 500;
                                                                           

   GdkColor bkcr;// = { 0, 65535, 0, 0 };
   GdkColor fecr;// = { 0, 0, 0, 0 };
   GdkWindow * pWindow = gdk_get_default_root_window();
                                                                           
  
   GdkColormap *colormap = gdk_colormap_get_system();
   bkcr.red = 0xffff;
   bkcr.green = 0;
   bkcr.blue = 0;
                                                                           
  
   fecr.red = 0;
   fecr.green = 0xffff;
   fecr.blue = 0;
   if (!gdk_colormap_alloc_color(colormap, &bkcr, TRUE, TRUE))
   {
     g_error ("couldn't allocate color");
   }
   if (!gdk_colormap_alloc_color(colormap, &fecr, TRUE, TRUE))
   {
     g_error ("couldn't allocate color");
   }
                                                                           

   GdkGC * gc = gdk_gc_new(pWindow);
   GdkFill fill = GDK_SOLID;
   gdk_gc_set_fill(gc, fill);
   gdk_gc_set_colormap(gc, colormap);
   gdk_gc_set_exposures(gc, TRUE);
   gdk_gc_set_subwindow(gc, GDK_INCLUDE_INFERIORS);
   gdk_gc_set_background(gc, &bkcr);
   gdk_gc_set_foreground(gc, &fecr);
   gdk_gc_set_clip_rectangle (gc, &rect);
   gdk_draw_rectangle((GdkWindow*)pWindow, gc, 1, 50, 50, 500,500);
                                                                          
   PangoContext *context = gdk_pango_context_get();
   pango_context_set_base_dir(context, PANGO_DIRECTION_LTR);
   pango_context_set_language(context, gtk_get_default_language());
   gdk_pango_context_set_colormap(context, colormap);

   int ret = draw_some_text(pWindow, gc, context, colormap);
   if( !ret )
       printf("draw text fail\n");
                                                                           
           
   gdk_window_show_unraised(pWindow);
   gtk_widget_show (window);
   gtk_main ();

   return 0;
}

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