Form Designer

// Fixes.cpp
//
// Author : David Shepherd
//			Copyright (c) 2002, DaeDoe-Software
//
/////////////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Fixes.h"

void DrawDragRect(CDC &dc, LPCRECT lpRect, SIZE size, LPCRECT lpRectLast, SIZE sizeLast, HBRUSH hBrush, HBRUSH hBrushLast)
{
	// first, determine the update region and select it
	HRGN hRgnNew;
	HRGN hRgnOutside, hRgnInside;
	hRgnOutside = ::CreateRectRgnIndirect(lpRect);
	RECT rect = *lpRect;
	::InflateRect(&rect, -size.cx, -size.cy);
	::IntersectRect(&rect, &rect, lpRect);
	hRgnInside = ::CreateRectRgnIndirect(&rect);
	hRgnNew = ::CreateRectRgn(0, 0, 0, 0);
	::CombineRgn(hRgnNew, hRgnOutside, hRgnInside, RGN_XOR);

	HBRUSH hBrushOld = NULL;
	if(hBrush == NULL)
		hBrush = CDCHandle::GetHalftoneBrush();
	if(hBrushLast == NULL)
		hBrushLast = hBrush;

	HRGN hRgnLast = NULL, hRgnUpdate = NULL;
	if(lpRectLast != NULL)
	{
		// find difference between new region and old region
		hRgnLast = ::CreateRectRgn(0, 0, 0, 0);
		::SetRectRgn(hRgnOutside, lpRectLast->left, lpRectLast->top, lpRectLast->right, lpRectLast->bottom);
		rect = *lpRectLast;
		::InflateRect(&rect, -sizeLast.cx, -sizeLast.cy);
		::IntersectRect(&rect, &rect, lpRectLast);
		::SetRectRgn(hRgnInside, rect.left, rect.top, rect.right, rect.bottom);
		::CombineRgn(hRgnLast, hRgnOutside, hRgnInside, RGN_XOR);

		// only diff them if brushes are the same
		if(hBrush == hBrushLast)
		{
			hRgnUpdate = ::CreateRectRgn(0, 0, 0, 0);
			::CombineRgn(hRgnUpdate, hRgnLast, hRgnNew, RGN_XOR);
		}
	}
	if(hBrush != hBrushLast && lpRectLast != NULL)
	{
		// brushes are different -- erase old region first
		SelectClipRgn(dc,hRgnLast);
		GetClipBox(dc,&rect);
		hBrushOld = (HBRUSH)SelectObject(dc,hBrushLast);
		PatBlt(dc,rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, PATINVERT);
		SelectObject(dc,hBrushOld);
		hBrushOld = NULL;
	}

	// draw into the update/new region
	SelectClipRgn(dc,hRgnUpdate != NULL ? hRgnUpdate : hRgnNew);
	GetClipBox(dc,&rect);
	hBrushOld = (HBRUSH)SelectObject(dc,hBrush);
	PatBlt(dc,rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, PATINVERT);

	// cleanup DC
	if(hBrushOld != NULL)
		SelectObject(dc,hBrushOld);
	SelectClipRgn(dc,NULL);
	
	DeleteObject(hRgnOutside);
	DeleteObject(hRgnInside);
	DeleteObject(hRgnNew);
	if(hRgnLast!=NULL)
	{
		DeleteObject(hRgnLast);
	}
	if(hRgnUpdate!=NULL)
	{
		DeleteObject(hRgnUpdate);
	}
	if(hBrush!=NULL)
	{
		DeleteObject(hBrush);
	}
}