Imposible to press Display Side by Side button in Clone

[davidh]

version 8.0.8
The Display Input and Preview Side by Side button in Clone Tool seems to be disabled or locked.
I did some cloning several days ago without any problem, but I do not remember whether it was in the previous version.

[jsachs]

The way to clone from one image to another is the select the alternate input image into the Source Image control. To return to cloning from the output image, click its thumbnail in the image browser. To switch to cloning from one of the input images, click its half-size thumbnail in the image browser. For this transformation, this is currently the only way to set the side-by-side button.

[davidh]

I am sorry not to have been more precise.
If NO Source Image is loaded, only Display Input and Display Preview buttons can be used. The third button, Display Input and Preview Side by Side, cannot be pressed, and since there is no thumbnail to click on, the split preview cannot be displayed.

[jsachs]

To clone from the input image to the output image, you need to explicitly select the input image as the Source Image. This is subtly different from cloning from the output image to itself since you always get image data from the original image even when part of it has been cloned over.

[davidh]

Let me sumarize and clarify even more.

Let's say I need to remove a dark stain on a light wall. I choose Lighten Only mode and clone over the stain from the wall around the stain. I suppose this is cloning from the output image to itself.
To see the difference between Before and After in this case, I only can toggle the first two preview buttons because for cloning from the output image to itself the split preview is not available - Side by Side preview button is locked. OK.

Or I can load the same image as the Source image as well. In this case I get the split preview as the default preview.
But there still seems to be a problem. If you, at any moment during cloning, use either Display Input or Display Preview buttons, you will not be able to return back to the split preview because it is no longer possible to depress Display Side by Side button - it has got locked.
To get the split preview back you have to click Undo last operation button, but you also loose the last cloning strokes.

[jsachs]

For the next release, I removed the code that was preventing split screen display with no source image selected, but I am haunted by the suspicion that I put it in there for a reason. Let's see if something shows up and maybe I can address it instead of putting the code back.

[davidh]

The problem was not with the split screen unavailability when no source image is loaded. I mentined it just to make sure, that it was intentional. If it was, for some currently unknown reason, then speaking for myself I can easily do without it. Anyway, thank you.

The issue was in the scenario with a loaded source image. Once you switched from the split screen preview, you could not switch back.
It is now OK.
The question is, if need comes to put the code back, can this again prevent switching back to the split screen in the second scenario, as described above.

[jsachs]

I assume the latest changes now fix the problem you were reporting originally. Let's leave the code the way it is and if something comes up I will try to fix it without breaking anything else.