GraphicImage Template

copyRectRotate()

Rotate a rectangular area of a source image into a destination image

Syntax

GraphicImage = rb.GraphicImage.copyRectRotate(src_image, angle, source_rect, centre)

Parameters

The 'copyRectRotate' method takes 4 parameters:

Results

The 'copyRectRotate' method returns GraphicImage:

Remarks

copyRectRotate allows applications to rotate areas of one image by an arbitrary number of degrees into a target image. The source and destination image *can* be the same, but the results if the copied region does not overlap the source. It is recommended that a scratch image be created into which to rotate the source.

The only mandatory parameter is the target image into which a rectangle from the source image is to be copied.

Defaults

• angle
  This defaults to zero degrees, although the default itself is not particularly useful! It is recommended that the angle be specified.
• source_rect
  Defaults to the whole of the source image
• centre
  Defaults to the centre of the destination image

Example

To rotate an image by 90 degrees :

  var src = new GraphicImage;
  src.make('/images/sample.gif','image/gif');

  var image_rotated = new GraphicImage;

  // Create a canvas in the destination that has the source width 
  // and height transposed.
  image_rotated.create(src.height, src.width);

  // Because we want the whole of the source image copied, rotated round the
  // centre of the destination image the only parameters we need are the
  // destination and the angle.
  src.copyRectRotate(image_rotated, 90);