LBitmapBase::Rotate

#include "ltwrappr.h"

virtual L_INT LBitmapBase::Rotate(nAngle, uFlags=ROTATE_RESIZE, crFill=0)

Rotates the class object's bitmap by the number of degrees specified.

Returns

Comments

This function has the following features:

• It uses the center of the image as the center of rotation.

• It can rotate the image clockwise or counterclockwise up to 360 degrees in 1-degree increments.

• It can resize the image to accommodate the rotated height and width, or it can retain the original height and width, cropping the bitmap as necessary.

• It uses black as the background color to fill any new area created by the rotation.

To update a status bar or detect a user interrupt during execution of this function, refer to LBase::EnableStatusCallBack.

ROTATE_RESAMPLE and ROTATE_BICUBIC can be combined with ROTATE_RESIZE, but they can not be combined with each other. Therefore, you can pass ROTATE_RESAMPLE|ROTATE_RESIZE, but not ROTATE_RESAMPLE|ROTATE_BICUBIC.

If ROTATE_RESIZE is set, then the image is resized. Otherwise, the image is cropped.

Interpolation can be done while rotating certain images. This produces superior output, eliminating the jaggedness occurring when rotating images at angles that are not multiple of 90. (ie when nAngle is not a multiple of 9000).

The only images that are interpolated are:

• 8-bit grayscale images (for best results, all gray values should be in the bitmaps palette). If the rotation doesnt give the expected results, you can call LBitmapBase::GrayScale(8) to change the bitmap into a proper grayscale bitmap.

• 12-bit and 16-bit grayscale bitmaps that dont have a palette. Grayscale bitmaps can have a palette if they have been loaded from certain DICOM images or if the LBitmap::WindowLevel function has been called. Call LBitmapBase::GrayScale(12) or LBitmapBase::GrayScale(16) if LBitmapBase::Rotate doesnt seem to do any interpolation during the rotation.

• 16-bit color images

• 24-bit, 32-bit, 48-bit and 64-bit color images

For the other images, LBitmapBase::Rotate ignores the resampling flags and the rotate is performed without interpolation.

Required DLLs and Libraries

See Also

Example

L_INT LBitmapBase__RotateExample()
{
   L_INT nRet;
   LBitmapBase MyBitmap;
   MyBitmap.SetFileName(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\image1.cmp")); 
   nRet =MyBitmap.Load();
   if(nRet !=SUCCESS)
      return nRet;
   if(MyBitmap.IsAllocated())
      nRet = MyBitmap.Rotate(4500,ROTATE_RESIZE, RGB(255, 0, 0));
   return nRet;
}