printing.c

Linux下gtk图形界面开发的各种gtk控件调用方法示例

/* Printing
 *
 * GtkPrintOperation offers a simple API to support printing
 * in a cross-platform way.
 *
 */

#include <math.h>
#include <gtk/gtk.h>
#include "demo-common.h"

/* In points */
#define HEADER_HEIGHT (10*72/25.4)
#define HEADER_GAP (3*72/25.4)

typedef struct 
{
  gchar *filename;
  gdouble font_size;

  gint lines_per_page;  
  gchar **lines;
  gint num_lines;
  gint num_pages;
} PrintData;

static void
begin_print (GtkPrintOperation *operation, 
	     GtkPrintContext   *context,
	     gpointer           user_data)
{
  PrintData *data = (PrintData *)user_data;
  char *contents;
  int i;
  double height;

  height = gtk_print_context_get_height (context) - HEADER_HEIGHT - HEADER_GAP;
  
  data->lines_per_page = floor (height / data->font_size);
  
  g_file_get_contents (data->filename, &contents, NULL, NULL);

  data->lines = g_strsplit (contents, "\n", 0);
  g_free (contents);

  i = 0;
  while (data->lines[i] != NULL)
    i++;
  
  data->num_lines = i;
  data->num_pages = (data->num_lines - 1) / data->lines_per_page + 1;

  gtk_print_operation_set_n_pages (operation, data->num_pages);
}

static void
draw_page (GtkPrintOperation *operation,
	   GtkPrintContext   *context,
	   gint               page_nr,
	   gpointer           user_data)
{
  PrintData *data = (PrintData *)user_data;
  cairo_t *cr;
  PangoLayout *layout;
  gint text_width, text_height;
  gdouble width;
  gint line, i;
  PangoFontDescription *desc;
  gchar *page_str;

  cr = gtk_print_context_get_cairo_context (context);
  width = gtk_print_context_get_width (context);

  cairo_rectangle (cr, 0, 0, width, HEADER_HEIGHT);
  
  cairo_set_source_rgb (cr, 0.8, 0.8, 0.8);
  cairo_fill_preserve (cr);
  
  cairo_set_source_rgb (cr, 0, 0, 0);
  cairo_set_line_width (cr, 1);
  cairo_stroke (cr);

  layout = gtk_print_context_create_pango_layout (context);

  desc = pango_font_description_from_string ("sans 14");
  pango_layout_set_font_description (layout, desc);
  pango_font_description_free (desc);

  pango_layout_set_text (layout, data->filename, -1);
  pango_layout_get_pixel_size (layout, &text_width, &text_height);

  if (text_width > width)
    {
      pango_layout_set_width (layout, width);
      pango_layout_set_ellipsize (layout, PANGO_ELLIPSIZE_START);
      pango_layout_get_pixel_size (layout, &text_width, &text_height);
    }

  cairo_move_to (cr, (width - text_width) / 2,  (HEADER_HEIGHT - text_height) / 2);
  pango_cairo_show_layout (cr, layout);

  page_str = g_strdup_printf ("%d/%d", page_nr + 1, data->num_pages);
  pango_layout_set_text (layout, page_str, -1);
  g_free (page_str);

  pango_layout_set_width (layout, -1);
  pango_layout_get_pixel_size (layout, &text_width, &text_height);
  cairo_move_to (cr, width - text_width - 4, (HEADER_HEIGHT - text_height) / 2);
  pango_cairo_show_layout (cr, layout);
  
  g_object_unref (layout);
  
  layout = gtk_print_context_create_pango_layout (context);
  
  desc = pango_font_description_from_string ("mono");
  pango_font_description_set_size (desc, data->font_size * PANGO_SCALE);
  pango_layout_set_font_description (layout, desc);
  pango_font_description_free (desc);
  
  cairo_move_to (cr, 0, HEADER_HEIGHT + HEADER_GAP);
  line = page_nr * data->lines_per_page;
  for (i = 0; i < data->lines_per_page && line < data->num_lines; i++) 
    {
      pango_layout_set_text (layout, data->lines[line], -1);
      pango_cairo_show_layout (cr, layout);
      cairo_rel_move_to (cr, 0, text_height);
      line++;
    }

  g_object_unref (layout);
}

static void
end_print (GtkPrintOperation *operation, 
	   GtkPrintContext   *context,
	   gpointer           user_data)
{
  PrintData *data = (PrintData *)user_data;

  g_free (data->filename);
  g_strfreev (data->lines);
  g_free (data);
}


GtkWidget *
do_printing (GtkWidget *do_widget)
{
  GtkPrintOperation *operation;
  PrintData *data;
  GError *error = NULL;

  operation = gtk_print_operation_new ();
  data = g_new0 (PrintData, 1);
  data->filename = demo_find_file ("printing.c", NULL);
  data->font_size = 12.0;

  g_signal_connect (G_OBJECT (operation), "begin-print", 
		    G_CALLBACK (begin_print), data);
  g_signal_connect (G_OBJECT (operation), "draw-page", 
		    G_CALLBACK (draw_page), data);
  g_signal_connect (G_OBJECT (operation), "end-print", 
		    G_CALLBACK (end_print), data);

  gtk_print_operation_run (operation, GTK_PRINT_OPERATION_ACTION_PRINT_DIALOG, GTK_WINDOW (do_widget), &error);

  g_object_unref (operation);

  if (error)
    {
      GtkWidget *dialog;
      
      dialog = gtk_message_dialog_new (GTK_WINDOW (do_widget),
				       GTK_DIALOG_DESTROY_WITH_PARENT,
				       GTK_MESSAGE_ERROR,
				       GTK_BUTTONS_CLOSE,
				       "%s", error->message);
      g_error_free (error);
      
      g_signal_connect (dialog, "response",
			G_CALLBACK (gtk_widget_destroy), NULL);
      
      gtk_widget_show (dialog);      
    }
  

  return NULL;
}