Package org.gnome.gtk

Interface PrintOperation.DrawPageCallback

All Superinterfaces:

FunctionPointer

Enclosing class:

PrintOperation

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public static interface PrintOperation.DrawPageCallback
extends FunctionPointer

Functional interface declaration of the DrawPageCallback callback.

See Also:

• run(org.gnome.gtk.PrintContext, int)

Method Summary

Modifier and Type	Method	Description
void	run(@Nullable PrintContext context, int pageNr)	Emitted for every page that is printed.
default MemorySegment	toCallback(Arena arena)	Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment, int) method.
default void	upcall(MemorySegment sourcePrintOperation, MemorySegment context, int pageNr)	The upcall method is called from native code.

Method Details

run

void run(@Nullable PrintContext context,
 int pageNr)

Emitted for every page that is printed.

The signal handler must render the pageNr's page onto the cairo context obtained from context using PrintContext.getCairoContext().

static void
 draw_page (GtkPrintOperation *operation,
            GtkPrintContext   *context,
            int                page_nr,
            gpointer           user_data)
 {
   cairo_t *cr;
   PangoLayout *layout;
   double width, text_height;
   int layout_height;
   PangoFontDescription *desc;
   
   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 (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, "some text", -1);
   pango_layout_set_width (layout, width * PANGO_SCALE);
   pango_layout_set_alignment (layout, PANGO_ALIGN_CENTER);
      		      
   pango_layout_get_size (layout, NULL, &layout_height);
   text_height = (double)layout_height / PANGO_SCALE;
   
   cairo_move_to (cr, width / 2,  (HEADER_HEIGHT - text_height) / 2);
   pango_cairo_show_layout (cr, layout);
   
   g_object_unref (layout);
 }
 

Use PrintOperation.setUseFullPage(boolean) and PrintOperation.setUnit(org.gnome.gtk.Unit) before starting the print operation to set up the transformation of the cairo context according to your needs.

upcall

default void upcall(MemorySegment sourcePrintOperation,
 MemorySegment context,
 int pageNr)

The upcall method is called from native code. The parameters are marshaled and run(org.gnome.gtk.PrintContext, int) is executed.

toCallback

default MemorySegment toCallback(Arena arena)

Creates a native function pointer to the upcall(java.lang.foreign.MemorySegment, java.lang.foreign.MemorySegment, int) method.

Specified by:

toCallback in interface FunctionPointer

Parameters:

arena - the arena in which the function pointer is allocated

Returns:

the native function pointer