Image display control scrolling does not work properly when zoomed in

[DirkLV]

I am using a ROI on an image in the image display control. When zooming into the image to fine-adjust the positioning of the ROI, the image scrolling does not work properly. As far as I understand, the image should scroll automatically when the ROI is leaving the visible area. However, the scrolling behaviour seems to depend on the origin of the Labview panel, not the origin of the image display control, which might require to move the ROI way out of the visible area before the scrolling takes place. In other words: the coordinate system of the image display control is shifted with respect to the true visible image area, depending on where you place it on the front panel. As a consequence, when clicking on a ROI which is in the visible area, but is outside of what Labview thinks is the visible area, it might immediately jump to the left border of the image, making the positioning of the ROI really difficult.

Has anyone noticed this behaviour, and what would be a reliable solution to avoid this? 

Dirk

[ThSa]

Did you mean the property "autosize tools palette" with "automatically scroll"?

If this is so, it's not correct that the image is resized!

This property is responsible for resizing the ROI palette on left side of the image only!

I don't know about any property which supports an auto scroll with an image control!

It could be more helpfully to post screenhots or your program!

regards,

ThSa

Message Edited by ThSa on 10-11-2005 04:25 AM

[DirkLV]

Hello,

no, I am not talking about the tools palette. Just place an image control with some image in it on a new VI front panel. Then, use the rectangle from the tools and select a ROI in the image. If you zoom in (using the magnification glass), and then grab the ROI and move it around, the image scroll with the ROI. So far, so good. If you now place the image control elsewhere on the panel, or add new control above it, resize the panel, etc. , this scrolling when moving the ROI will not work correctly if the origin (0,0) of the panel is far away from the image control.

I have attached a VI for simplicity (although there is hardly any code in it).

If you make a ROI and try to move it down, you will notice that scrolling starts if you move the mouse out to about 10cms below the image (depens on your screen, of course). After that, if you click on the ROI, the scroll bars and ROI might jump up to the upper end of the image. Imagine how annoying this is if you try to finely adjust the ROI position. 

I think it is a bug in the implementation of the image display control.

Thanks,

Dirk

[ThSa]

Ok, i understand you now!

Which IMAQ Vision version do you have?

[DirkLV]

Oh, I forgot that: LV 7.1 with IMAQ Vision 7.01

Dirk

[ThSa]

I've tested it with 7.1 and i couldn't detect this behavior...

There is a CAR for it already (Vision 7.0)!

regards,

ThSa