FLTK 1.3.7
Fl_Surface_Device Class Reference

A drawing surface that's susceptible to receive graphical output. More...

#include <Fl_Device.H>

Inheritance diagram for Fl_Surface_Device:
Fl_Device Fl_Copy_Surface Fl_Display_Device Fl_Image_Surface Fl_Paged_Device Fl_PostScript_File_Device Fl_Printer Fl_System_Printer Fl_PostScript_Printer

Public Member Functions

const char * class_name ()
 Returns the name of the class of this object. More...
Fl_Graphics_Driverdriver ()
 Returns the graphics driver of this drawing surface.
void driver (Fl_Graphics_Driver *graphics_driver)
 Sets the graphics driver of this drawing surface.
virtual void set_current (void)
 Make this surface the current drawing surface. More...
virtual ~Fl_Surface_Device ()
 The destructor.
- Public Member Functions inherited from Fl_Device
virtual ~Fl_Device ()
 Virtual destructor. More...

Static Public Member Functions

static Fl_Surface_Devicesurface ()
 The current drawing surface. More...

Static Public Attributes

static const char * class_id = "Fl_Surface_Device"
- Static Public Attributes inherited from Fl_Device
static const char * class_id = "Fl_Device"
 A string that identifies each subclass of Fl_Device. More...

Protected Member Functions

 Fl_Surface_Device (Fl_Graphics_Driver *graphics_driver)
 Constructor that sets the graphics driver to use for the created surface.

Detailed Description

A drawing surface that's susceptible to receive graphical output.

Any FLTK application has at any time a current drawing surface to which all drawing requests are directed. The current surface is given by Fl_Surface_Device::surface(). When main() begins running, the current drawing surface has been set to the computer's display, an instance of the Fl_Display_Device class.

A drawing surface other than the computer's display, is typically used as follows:

  1. Create surface, an object from a particular Fl_Surface_Device derived class (e.g., Fl_Copy_Surface, Fl_Printer).
  2. Memorize what is the current drawing surface with Fl_Surface_Device *old_current = Fl_Surface_Device::surface();
  3. Call surface->set_current(); to redirect all graphics requests to surface which becomes the new current drawing surface (not necessary with class Fl_Printer because it is done by Fl_Printer::start_job()).
  4. At this point any of the Drawing functions (e.g., fl_rect()) or the Color & Font functions or Drawing Images functions (e.g., fl_draw_image(), Fl_Image::draw()) operates on the new current drawing surface. Certain drawing surfaces allow additional ways to draw to them (e.g., Fl_Printer::print_widget(), Fl_Image_Surface::draw()).
  5. After all drawing requests have been performed, redirect graphics requests back to their previous destination with old_current->set_current();.
  6. Delete surface.

Member Function Documentation

◆ class_name()

const char* Fl_Surface_Device::class_name ( )

Returns the name of the class of this object.

Use of the class_name() function is discouraged because it will be removed from future FLTK versions.

The class of an instance of an Fl_Device subclass can be checked with code such as:

if ( instance->class_name() == Fl_Printer::class_id ) { ... }

Reimplemented from Fl_Device.

Reimplemented in Fl_Printer, Fl_PostScript_Printer, Fl_System_Printer, Fl_PostScript_File_Device, Fl_Paged_Device, Fl_Image_Surface, and Fl_Display_Device.

◆ set_current()

void Fl_Surface_Device::set_current ( void  )

Make this surface the current drawing surface.

This surface will receive all future graphics requests.

Reimplemented in Fl_Printer, Fl_Image_Surface, and Fl_Copy_Surface.

◆ surface()

static Fl_Surface_Device* Fl_Surface_Device::surface ( )

The current drawing surface.

In other words, the Fl_Surface_Device object that currently receives all graphics output

The documentation for this class was generated from the following files: