Implement free panning

[gis2all]

Is your feature request related to a problem? Please describe.

When I use ImageGlass, I often need to move the image at a small zoom ratio, but unfortunately it seems that Imageglass does not support the floating operation in this case.

Describe the solution you'd like

Compared to another view software 2345picture, you can find the difference between them. I hope developers can add this feature, thank you.

ImageGlass	2345Picture

Describe alternatives you've considered

Additional context

[d2phap]

Thanks for the suggestion

[laxsjo]

I would like to give my thoughts on why I think that this feature is very important, since this in my opinion is something that's very important for how it feels to use the program.

Here are a couple of examples of when this feature would be helpful.

When is this a problem

When zooming out/in I would expect the image to move such that the point which was under the cursor would stay under the cursor.

This is the currently implemented behaviour when zooming in and out, except when being zoomed out. When zooming out enough for the borders of the image to become visible it suddenly starts moving towards the center of the screen.

How it currently works in ImageGlass. (Notice how the cursor doesn't stay on the red cross due to the image moving towards the window center)	Example of how it should work (I used paint.net here)

The one on the left feels very jarring to me. I commonly want to quickly zoom out and in again to see what part of the image I'm currently looking at, which causes the view to be shifted from where it was before zooming out and in.

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This also makes it clumsy to precisely zoom in at a specific point of the image when you're already zoomed out. Since the image begins zooming in around the center, before zooming in around the cursor position, the final point under the cursor is not the same as the one before zooming.

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Additionally it feels very claustrophobic when panning around while zoomed in, since you're stopped from panning it further than the edge of the image. When you want to view some part of the image that is close to the edge you are forced to place that part at the edge of your screen. So when using a moderately large monitor, this quickly becomes uncomfortable, since you have to look off towards the side.

How to fix this issue

All of these issues are caused by you not being allowed to pan the image when fully zoomed out and not being able to pan an image further than it touching the windows border. So you simply need to allow these actions to fix this.

How to implement this

As far as I know (and correct me if I'm wrong), the current functionality would be more complicated to implement than the proposed one, since the current version does extra checks and behaves differently when zoomed out vs zoomed in.

This tells me that you probably have some good reason for making it this way, which is why I think this proposal should implemented as an option (which could be called Allow Free Panning as an example ;))

[6Tom]

First of all, I really appreciate d2phap's hard work and selfless dedication. Thank you very much.

This is really one of the most useful features. For example, as a practitioner in the construction industry, I often need to view various architectural drawings. Just like using AutoCAD, my colleagues and I often need to zoom and pan around to view the drawings carefully.

For this demand, we have to use a rogue software from China: 2345pic. I really hope that our imageglass project can add this function, so that we can completely get rid of the rogue software 2345pic.