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Hello All,
I am developing a paint like application in which user can insert the .bmp file and can resize and rotate.
So when i rotate the .bmp then then the .bmp inserted disappears and whole screen attains the default color of the dialog.
This problem has not been come in case of 0 degree rotation.

I am using virtual window concept in my application to paint the screen.
My code is as below :

Class variables :
C++
   protected:

           CDC m_memDC;

           int maxX,maxY;

           CBitmap m_bmp;

           CBitmap m_bitmap;

           CBrush m_bkbrush;

void CRotateBitmapView::OnInitialUpdate()

{

     CFormView::OnInitialUpdate();

     GetParentFrame()->RecalcLayout();

     ResizeParentToFit();

 

////////////// Begin - Virtual Window//////////////////////


       maxX = GetSystemMetrics(SM_CXSCREEN);

      maxY = GetSystemMetrics(SM_CYSCREEN);

      CClientDC DC(this);

      COLORREF crBkgnd = RGB(255,255,255);

      m_memDC.CreateCompatibleDC(&DC);

      m_bkbrush.CreateSolidBrush(crBkgnd);

      m_bmp.CreateCompatibleBitmap(&DC,maxX,maxY);

      m_memDC.SelectObject(&m_bmp);

      m_memDC.SelectObject(&m_bkbrush);

      m_memDC.PatBlt(0,0,maxX,maxY,PATCOPY);

 ///////////// End - Virtual Window /////////////////////

}

void CRotateBitmapView::OnDraw(CDC* pDC)

{

//////////////// Begin - Virtual Window ////////////////////////

 pDC->BitBlt(0, 0, maxX, maxY, &m_memDC, 0, 0, SRCCOPY);

//////////////// End - Virtual Window //////////////////////////

}

void CRotateBitmapView::OnBnClickedButton5()
{
   BITMAP bm;

   m_bitmap.DeleteObject();

   m_bitmap.LoadBitmapW(IDB_BITMAP1);

   HBITMAP hBitmap = (HBITMAP)m_bitmap.GetSafeHandle();

   switch(m_Combo.GetCurSel())
   {
case 1:
  GetRotatedBMP(hBitmap,90.0f);
  break;
case 2:
  GetRotatedBMP(hBitmap,180.0f);
  break;
case 3:
  GetRotatedBMP(hBitmap,270.0f);
  break;
default:
  GetRotatedBMP(hBitmap,0.0f);
  break;
   }
}

void CRotateBitmapView::GetRotatedBMP(HBITMAP hBitmap,double angle)
{
CClientDC m_memDC(this);
BITMAP bm;
m_bitmap.GetBitmap(&bm);
CDC memdc;
memdc.CreateCompatibleDC(&m_memDC);
memdc.SelectObject(&m_bitmap);
   CClientDC dc(this);

   COLORREF rgb = RGB(255,255,255);
   CBrush brush ;
   brush.CreateSolidBrush(rgb);
   dc.FillRect(CRect(0,0,bm.bmWidth,bm.bmHeight),&brush);
   dc.FillRect(CRect(0,0,bm.bmHeight,bm.bmWidth),&brush);
   const float PI  = 3.141529f;
   const float radians = (float)angle / (360.0f / (2 * PI));
float cosine = (float)cos(radians);
float sine = (float)sin(radians);
int x1 = (int)(bm.bmHeight * sine);
int y1 = (int)(bm.bmHeight * cosine);
int x2 = (int)(bm.bmWidth * cosine + bm.bmHeight * sine);
int y2 = (int)(bm.bmHeight * cosine - bm.bmWidth * sine);
int x3 = (int)(bm.bmWidth * cosine);
int y3 = (int)(-bm.bmWidth * sine);
int minx = min(0,min(x1, min(x2,x3)));
int miny = min(0,min(y1, min(y2,y3)));
int maxx = max(0,max(x1, max(x2,x3)));
int maxy = max(0,max(y1, max(y2,y3)));

XFORM xf;
xf.eM11 = cosine;
xf.eM12 = -sine;
xf.eM21 = sine;
xf.eM22 = cosine;
xf.eDx = (float)-minx;
xf.eDy = (float)-miny;

   // Note that functions below are not supported on Windows 95/98

   ::SetGraphicsMode(m_memDC.m_hDC, GM_ADVANCED);
   ::SetWorldTransform(m_memDC.m_hDC, &xf);
   m_memDC.StretchBlt(0,0,bm.bmWidth,bm.bmHeight,&memdc,0,0,bm.bmWidth,bm.bmHeight,SRCCOPY);
   InvalidateRect(NULL);
}


Please help....
Regards Gurmeet Singh
Posted
Updated 3-Sep-10 21:57pm
v2
Comments
Sandeep Mewara 4-Sep-10 2:57am    
PRE tags are your friend. Use it to format code part.

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