A Kitten Dies Every Time You Use Scroll Bars

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Juan Conejero

PixInsight Staff
Staff member
If you want to consider yourself an intermediate/advanced PixInsight user, please don't use scroll bars (on a regular basis) to navigate image windows.

There are two ways to perform a temporary switch to Pan mode:

- Press the spacebar key and hold it down, then click the primary mouse button on the image and drag.

- Click the middle mouse button on the image and drag.

Both methods are much faster and more accurate than using scroll bars, plus you can navigate in both plane directions at the same time.

In similar ways, you can:

- Use the mouse wheel to zoom in/out the image.

- Use Ctrl + mouse wheel to zoom in/out centered at the current cursor position on the image.

- Use Ctrl+spacebar to switch to Zoom In mode temporarily. In this mode you can define a rectangular area to approximate the area of the image that will be zoomed in the view.

- Use Ctrl+Alt+spacebar to switch to Zoom Out mode temporarily.

On macOS, replace Ctrl with Cmd in the above list.

So let's save those kitties, please, especially when you record a video!
 
Yes, spacebar + drag works fine on an Apple trackpad. Note that in this case you don't have to click, just press space bar and move your finger on the trackpad. Of course, you can also pinch with two fingers on a trackpad to zoom in/out.
 
- Use Ctrl + mouse wheel to zoom in/out centered at the current cursor position on the image.

hm, does not work as indicated for me - I was expecting the cursor position will act then as the zoom center, but it does not.
Scrolling the mouse wheel causes zooming in, but just away from the respective frame edge
that is in the direction of the cursor position (if it is a little off the center), not from the cursor position itself.
So it is not possible to choose a point by placing the cursor and zoom in on that point by Ctrl + mouse wheel.

Tommy
 
So it is not possible to choose a point by placing the cursor and zoom in on that point by Ctrl + mouse wheel.

I don't see the problem you are describing. When I use Ctrl+Wheel it works as described above. Anyway, the preferred method to zoom in accurately is Ctrl+Spacebar, then click and define a zoom area by dragging.
 
- Press the spacebar key and hold it down, then click the primary mouse button on the image and drag.
This reminds me... I think this is a bug in macOS which has existed for multiple versions.

When I press the space bar, hold it, then click and drag, things work as described. When I let everything go, and press the space bar gain with the intention of repeating this motion to continue my movement, the view snaps back to the point that was framed when I first clicked the space button. If diagnostically useful, this "click" is coming from the trackpad on a MacBook Pro.
 
We cannot reproduce that. It works perfectly on all of our Mac machines, including mice and track pads.
After some more playing around, I've identified the cause of this "inconsistency" I was experiencing.

Because I don't use the actual mechanical click on my trackpad (just touch sensitive) sometimes I will press space, drag on the trackpad to a new point, then release space and move my finger back to the other location, then press space again to repeat the action. Except sometimes I don't actually lift my touch fully from the trackpad. It may also be that another part of my palm, etc., touching the large Apple trackpad isn't being rejected for this operation. When this happens, the next time I press the space key, it hops back to the location the view was at when the space key was initially pressed. If I very deliberately remove my hands and continue with the operation, it works as described.

To that end, is it possible to re-sample the location on the screen when the space key is pressed again as opposed to inheriting the location that seems to still be referenced (up until I remove my finger from the track pad)? It seems like an adjustment to how events are handled is all that may be needed to correct the "issue" without causing other problems.

Thus, I would be able to press and hold space, brush my finger across the trackpad, release space and brush my finger back, press and hold space (now referencing the current location displayed), and brush my finger across the trackpad again?

I spent a little time trying to practice the motion that repeatably avoids hopping back, and with the trackpad configuration for touch operation, and I wasn't able to produce comfortable, fluid, consistent motions.
 
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