Fun with SetWorldTransform

Environment: VC6, MFC

This code will show you how useful SetWorldTransform can be. The code will enable you to do things such as:

  • Scale to 1/2 of the original size
  • Translate right by 3/4 inch
  • Rotate 30 degrees counterclockwise
  • Shear along the x-axis with a proportionality constant of 1.0
  • Reflect about a horizontal axis

The code was originally part of the MS SDK, but I have enhanced and converted it to MFC to make it easier to understand.

// The Key part to the source code is using 'SetWorldTransform'
// and setting up the XFORM structure

XFORM xForm;

SetGraphicsMode ( pDC->GetSafeHdc (), GM_ADVANCED );
pDC->SetMapMode ( MM_LOENGLISH );

xForm.eM11 = (FLOAT) 0.5;
xForm.eM12 = (FLOAT) 0.0;
xForm.eM21 = (FLOAT) 0.0;
xForm.eM22 = (FLOAT) 0.5;
xForm.eDx  = (FLOAT) 0.0;
xForm.eDy  = (FLOAT) 0.0;
SetWorldTransform ( pDC->GetSafeHdc (), &xForm );

Downloads

Download demo project - 8 Kb
Download source - 22 Kb


Comments

  • Doubt regarding combination of these operations.

    Posted by Legacy on 08/20/2003 12:00am

    Originally posted by: Chandra Prakash Joshi

    In ur example you have shown all the transform operation with respect to the original image. Suppose i want a rectangular(not square) image to rotate 90 degree than zoom 200% than reflect along x axis and than again rotate it -90 degree. and unfortunately i can't use array for storing the list of transformations done on my image. Any suggestion or idea will be of gr8 Help.. ThankU.

    Reply
  • WinNT only...

    Posted by Legacy on 08/14/2003 12:00am

    Originally posted by: Oliver

    Good demonstration of world transformation. Thank you!

    Maybe you should point out that this example code works on WinNT only since SetWorldTransform is unsupported on non-NT systems.
    The usefulness of a function set that does not work on all Win platforms is a point that should be discussed.

    Oliver.

    Reply
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