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LBitmapBase::CreateLeadDC

Summary

Provides a powerful set of graphics features by creating a Microsoft Windows device context, using the LBitmapBase object's bitmap as the display surface.

Syntax

#include "ltwrappr.h"

virtual HDC LBitmapBase::CreateLeadDC()

Returns

Value	Meaning
>0	Function was successful. The return value is the HDC.
NULL	An error occurred.

Comments

This allows you to create an infinite number of drawing capabilities such as paint, erase, color erase and brush, pen, spray gun, flood fill, color tube, text overlay, curve, line, rectangle, polygon, ellipse, freehand shapes, cut and paste, and more.

All Windows GDI functions can be used to draw to the bitmap using the returned HDC. The HDC must be freed with the LBitmapBase::DeleteLeadDC function.

Note: For WIN32 applications, this function ensures that the bitmap's view perspective is BOTTOM_LEFT, flipping the bitmap if necessary. This can affect functions that use bitmap coordinates. For more information, refer to Accounting for View Perspective.

If a region is defined for the bitmap, GDI functions act only on the region, not on the entire bitmap.

Required DLLs and Libraries

LTDIS
LTFIL
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64.

Example

L_INT LBitmapBase__CreateLeadDCExample() 
{ 
   L_INT nRet; 
   LBitmapBase MyBitmap; 
 
   HDC hDC; 
 
   MyBitmap.SetFileName(MAKE_IMAGE_PATH(TEXT("image1.cmp")));  
   nRet =MyBitmap.Load(); 
   if(nRet !=SUCCESS) 
      return nRet; 
   hDC=MyBitmap.CreateLeadDC(); 
 
   /*use the returned DC to draw to the bitmap*/ 
   if(hDC) /*finished using the DC*/ 
      MyBitmap.DeleteLeadDC(hDC); 
 
   return SUCCESS; 
}