How to use "SetWorldTransform"

how about setting the XFORM eDx and eDy to the point about which rotation occurs?

Maybe some code could help ...

   hDC = BeginPaint( hWnd, (LPPAINTSTRUCT)&ps );

      /* Rita kursskivan som bakgrund till kompassen */
      SetMapMode( hDC, MM_ANISOTROPIC );


      SetViewportOrgEx( hDC, ClientRect.left, ClientRect.top, NULL );

      SetViewportExtEx( hDC, XSize, YSize, NULL );
      PlayMetaFile( hDC, hMFBackGround );

      /* Rita skillnadsfalt */
      if( Compass[ CpIx ]->Active ){
         SelectObject( hDC, YellowBrush );
      }
      else SelectObject( hDC, BlackBrush );

      SelectObject( hDC, GetStockObject( NULL_PEN ) );
      SetMapMode( hDC, MM_TEXT );

      /* Rita pie:n */
      Pie( hDC, Origo.x - DiffRadius, Origo.y - DiffRadius,
                Origo.x + DiffRadius, Origo.y + DiffRadius,
                Start.x, Start.y, Stop.x, Stop.y );

      /* Rita kompass nal */
      NeedleWidth = NeedleRect.right - NeedleRect.left;
      NeedleHight = NeedleRect.bottom - NeedleRect.top;

      SetMapMode( hDC, MM_ANISOTROPIC );

      SetViewportOrgEx( hDC, (int)(Origo.x - NeedleWidth/2.0),
         (int)(Origo.y - NeedleHight/2.0), NULL );


      SetViewportExtEx( hDC, NeedleWidth, NeedleHight, NULL );

      Rotation = (float)(Compass[ CpIx ]->ComCourse * DEGTORAD);

      NeedleXForm.eM11 = (float)cos( Rotation );
      NeedleXForm.eM12 = (float)sin( Rotation );
      NeedleXForm.eM21 = (float)-sin( Rotation );
      NeedleXForm.eM22 = (float)cos( Rotation );

      OldGraphMode = SetGraphicsMode( hDC, GM_ADVANCED );
     
      SetWorldTransform( hDC, &NeedleXForm );

      PlayMetaFile( hDC, hMFNeedle );

      SetGraphicsMode( hDC, OldGraphMode );
   EndPaint( hWnd, (LPPAINTSTRUCT)&ps );

Thanks danny_pav

. but i've tried that and it doesnt work

any other suggestions ?

AndersCarlsson,
do you keep in mind that SetWorldTransform does not supported on Win 95 ?

Use the eDx and eDy members of NeedleXForm to perform the horizontal and vertical translation (how much you want to move by).

danny_pav had this ...what's the effect of this

NickRepin: I work on a NT machine.

Answers2000: I don't want to move the picture just rotate it.

If i set some values in eDx and eDy the picture moves to that position it seems (upper left corner). I want it to stay in center and rotate around the center of the metafile.

Try to call SetViewportExt and SetViewportOrg again after calling SetGraphicsMode.
Also, I think it would be better to call SetWindowExt and SetWindowOrg along with viewport functions after changing map/graphics mode. At least, that's how I did it, and all worked fine.

NickRepin
I´ve tried to call SetViewportExt and Org again after SetGraphicsMode and to set XFORM eDx and eDy to the center of my metafile. But that doesn´t help at all, it still rotates around the upper left corner. Probably i´ve made some misstake somewhere, but i can´t find it. I´ve increased the points to 150 cause this is important for me.

World transformation doesn't depend on Window and Viewport settings. You should rotate like this:


   XFORM x1,x2,x3,result1,result2;
   
   // At first, move the center of the metafile in the center
   // of the world space
   x1.eDx=-center.x;  // Center of your metafile
   x1.eDy=-center.y;
   x1.eM11=1;x1.eM12=0;x1.eM21=0;x1.eM22=1;

   // Next, rotate around center of the world space
   x2.eDx=0;
   x2.eDy=0;
   x2.eM11=cos(Angle);
   x2.eM12=sin(Angle);
   x2.eM21=-sin(Angle);
   x2.eM22=cos(Angle);

   // The last, return metafile back in its place
   x3.eDx=center.x;
   x3.eDy=center.y;
   x3.eM11=1;x3.eM12=0;x3.eM21=0;x3.eM22=1;

   // Now do eral job
   CombineTransform(result1,&x1,&x2);
   CombineTransform(result2,&result1,&x3);
   SetWorldTransform(dc,&result2);

Good luck!

Type errors...

// Now do REAL job....
..

Minus is so little on screen:
  x1.eDX= - center.x
  x2.eDY= - center.y

It didn´t work NickRepin.
My MetaFile still rotates around the upper left corner
My code is as follows:

      OldGraphMode = SetGraphicsMode( hDC, GM_ADVANCED );

      SetViewportOrgEx( hDC, (int)(Origo.x - NeedleWidth/2.0),
         (int)(Origo.y - NeedleHight/2.0), NULL );
      SetViewportExtEx( hDC, NeedleWidth, NeedleHight, NULL );

        Pivot.x = (int)(NeedleWidth/2.0);
        Pivot.y = (int)(NeedleHight/2.0);

     
        // At first move the center of the metafile
        // in the center of the world space
        x1.eDx = -Pivot.x;
        x1.eDy = -Pivot.y;
        x1.eM11 = 1;
        x1.eM12 = 0;
        x1.eM21 = 0;
        x1.eM22 = 1;

        // Next rotate around center of world space
        x2.eDx = 0;
        x2.eDy = -Pivot.y;
        x2.eM11 = (float)cos( Rotation );
        x2.eM12 = (float)sin( Rotation );
        x2.eM21 = (float)-sin( Rotation );
        x2.eM22 = (float)cos( Rotation );

        // The last, return metafile back in its place
        x3.eDx = Pivot.x;
        x3.eDy = Pivot.y;
        x3.eM11 = 1;
        x3.eM12 = 0;
        x3.eM21 = 0;
        x3.eM22 = 1;

        // Now do real job
      CombineTransform(&result1, &x1, &x2 );
      CombineTransform(&result2, &result1, &x3 );

      SetWorldTransform( hDC, &result2 );

      PlayMetaFile( hDC, hMFNeedle );

      SetGraphicsMode( hDC, OldGraphMode );

   /* Avsluta uppdatering av klientarean */
   EndPaint( hWnd, (LPPAINTSTRUCT)&ps );


Whats wrong i think you can help me if you can ther´s another 100 points there for you.

1) x2.eDY must be 0
-------------------
2) Check result of SetGraphicsMode(GM_ADVANCED)

OK!
1) I just followed your "Type error" comment.
2) SetGraphicsMode result is nonzero.

I tried to move the centerpoint step by step, and finally i succeeded with center.x = 252 and center.y = 640.
I don´t understand why, cause my windowsize is 125*125.
Must i set windowextension or what ?

Another words, if I understood, instead of NeedleSize/2 use
Pivot=Origo