GLG Custom Control

Windows only: A Win32 control that may be used to integrate GLG drawings in a Windows program. More...

Detailed Description

Windows only: A Win32 control that may be used to integrate GLG drawings in a Windows program.

GLG Custom Control is a Windows wrapper designed for embedding GLG drawings in the programs using a Win32 API. It allows embedding GLG drawings into the Windows interface hierarchy as a custom window control (a window with a custom window type).

The control's class name is "GlgControl". The GLG library registers it when the library is initialized with GlgInit.

Creating GLG Custom Control

The control is created by passing "GlgControl" as the class name parameter of CreateWindow. The viewport object containing the control's drawing is assigned to the control via GlgSetDefaultViewport:

GlgObject viewport = GlgLoadWidgetFromFile( "drawing.g" );  /* Load the drawing from a file. */
if( !viewport )
  return FALSE;
 
GlgSetDefaultViewport( viewport );  /* Set the drawing to be displayed in the custom control. */
 
/* Create a GLG control to display graphics. */
HWND GlgControl = CreateWindow( "GlgControl", "GlgControl", WS_VISIBLE | WS_CHILD | WS_BORDER, 10, 10, 600, 400, parent_hWnd, NULL, hInstance, NULL );
 
GlgDropObject( viewport );   /* Drop: viewport was referenced by the control. */
 
GlgInitialDraw( viewport );  /* Display the drawing inside the control. */

Alternatively, GlgSetWindowViewport may be used to assign the control's drawing after the control has been created instead of using GlgSetDefaultViewport before a call to CreateWindow.

The examples_c_cpp\animation\GlgAnimationW.c file in the GLG installation directory on Windows provides an example of using the control in a Windows application.

Include file: GlgApi.h

Functions
GlgLong CALLBACK	GlgControlWindowProc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
	Windows only: Passes messages to the GLG Custom Control. More...
GlgObject	GlgGetWindowViewport (HWND window)
	Windows only: Returns a viewport object used by the GLG Custom Control. More...
void	GlgSetDefaultViewport (GlgObject viewport)
	Windows only: Sets a drawing to be used by the GLG Custom Control. More...
void	GlgSetWindowViewport (HWND window, GlgObject viewport)
	Windows only: Sets or replaces the viewport of the GLG Custom Control after its window has been created. More...

Function Documentation

GlgControlWindowProc()

GlgLong CALLBACK GlgControlWindowProc	(	HWND	hwnd,
		UINT	msg,
		WPARAM	wParam,
		LPARAM	lParam
	)

Windows only: Passes messages to the GLG Custom Control.

This function is used by the window procedure of the control's parent window to pass messages to the control.

The examples_c_cpp\animation\GlgAnimationW.c file in the GLG installation directory on Windows provides an example of using this function.

Parameters

hwnd	The window ID of the GLG Control.
msg	The message to be passed.
wParam	The message parameter.
lParam	The message parameter.

Returns

The result of the message processing, depends on the message sent, see Win32 API WINPROC.

GlgGetWindowViewport()

GlgObject GlgGetWindowViewport

(

HWND

window

)

Windows only: Returns a viewport object used by the GLG Custom Control.

Parameters

window

A window handle of the GLG Custom Control.

Returns

The viewport object used by the GLG Custom Control, or NULL if a window other than the GLG Custom Control is passed as the window parameter.

GlgSetDefaultViewport()

void GlgSetDefaultViewport

(

GlgObject

viewport

)

Windows only: Sets a drawing to be used by the GLG Custom Control.

Parameters

viewport

Specifies a viewport object containing a drawing to be displayed in the GLG Custom Control.

The function is used to pass the viewport to the CreateWindow function that creates the custom control. The viewport will be assigned to the custom control created by the next call to CreateWindow after GlgSetDefaultViewport is invoked.

Alternatively, GlgSetWindowViewport may be used to assign the control's drawing after the control has been created instead of using GlgSetDefaultViewport before a call to CreateWindow.

Since every custom control needs its own copy of the viewport, a viewport instance may be used to create only one GLG Custom Control. To create several custom controls with the same drawing, load a new instance of the drawing for each control or use GlgCopyObject to create copies of the viewport, then select them using GlgSetDefaultViewport before creating each control or widget. This function references the viewport object using GlgReferenceObject.

The examples_c_cpp\animation\GlgAnimationW.c file in the GLG installation directory on Windows provides an example of using this function.

GlgSetWindowViewport()

void GlgSetWindowViewport	(	HWND	window,
		GlgObject	viewport
	)

Windows only: Sets or replaces the viewport of the GLG Custom Control after its window has been created.

Parameters

window	The window handle of the GLG Custom Control.
viewport	The viewport to be used as the control's drawing.

Each custom control has to have its own instance of the viewport. To display the same drawing in several custom controls, load a new instance of the drawing for each control or use GlgCopyObject to create copies of the viewport. This function references the viewport object using GlgReferenceObject.