Please Explain Rotation Options

[haytil]

Hello,

Could someone explain what the following options specifically do - when enabled or not enabled - when using the "Free Rotate" Image Effect?

• All Layers

• Rotate single layer around canvas center

Through experimentation, I've gathered that if "All Layers" is selected, then the entirety of each layer of the image is rotated. If not, then only the current active selection is rotated (or if there is no current active selection, only the current layer is rotated). But I cannot figure out what the second option ("Rotate single layer around canvas center") does - enabling it or not enabling it seems to have no effect on the resultant rotated image.

With both options possibly selected or not selected, that should result in 4 different permutations (and 4 different potential results), yet I can only determine and demonstrate two results. Is my understanding of the first option correct? And what does the second option do? The "Help" menu also seems to omit this option from its entry on the "Free Rotate command" entirely.

An explanation would be helpful - an example of how to demonstrate the difference would also be insightful (as learning through experimentation is helpful to me).

(For reference, I'm using Paint Shop Pro 8 - though I imagine the explanation applies to later versions as well. If you only know the answer for later versions, that might still be helpful and applicable)

[LeviFiction]

By default when you rotate, it rotates around the layer's own center point. But when you check that checkbox it'll rotate around the center of the entire image. So to see this result you'd need a layer that's smaller than the whole image, and off-center.

Here are two screenshots. One rotates 90 degrees around its own center, the other rotates 90 degrees around the image center. The layer center is represented by an orange/red dot. And the image center by the white dot.

Here's the layer before rotation

layeroffset.png

Here's the layer rotated around it's own center

layercenter.png

Here's the layer rotated around the image center

imagecenter.png