Unexpected Windows cursor/Waveform Graph cursor behavior

[_Y_]

Hi,

I got a very strange Windows cursor behavior with waveform graph. Simplified VI is attached.

LabVIEW 2014 SP1

The problem is:

The VI contains only one waveform graph.

1. I start the VI. Cursor Movement Tool is selected in the Graph Palette by default. Corresponding “Cross with dot” Windows cursor appears when mouse is moved over the plot area (see image). So far so good.

2. I select Zoom in the Graph Palette and use it two-five times (second image).

3. I select Cursor Movement Tool in the Graph Palette again but Windows cursor does not change as it should. It is an open cross now (third image); i.e. the same as shall appear when cross of Graph Cursor Lines is reached.

4. I click mouse three-seven times anywhere in the plot area and the cursor becomes normal (as in the first image).

The problem is not only in shape of the Windows cursor. The whole Graph cursor functionality does not work properly if the Windows cursor has the wrong shape.

Please advise what could cause this problem.

[James.M]

The second pointer that you're seeing is shown when you mouse over a cursor. It's basically a selection tool to move the cursor. Maybe you're just too zoomed in to see the cursor?

Your functionality changes when you have this cursor because it's trying to move around the cursor instead of the normal pointer functionality.

I can recreate your problem by zooming so far in that I don't have the main gridlines on my plot anymore. Is there a reason you're zooming in so far?

[_Y_]

Thank you for reply James,

Yes, such “open cross” Windows cursor is used to pick-up Graph cursors.

However, in the real application (not the simplified one that is attached here) I can see crosspoints of Graph cursors. However, I cannot “pick them up” unless clicking mouse several times to get first cursor and move mouse to Graph cursor crosspoint (where the Windows cursor is changed again).

[James.M]

You main application should function (in terms of user interaction with tools like this) the same way the simplified version works. Do you have code that is moving the cursors around, or assigning values, that could be overriding your user experience?

[_Y_]

I tested the same VI (attached to first message).

1. Right click in any cursor in cursor palette and select "Bring to center".

2. Zoom several times keeping the Graph cursor visible.

3. Select Cursor Movement Tool in the Graph Palette.

The problem is here: the "open cross" Windows cursor cannot pick-up the Graph cursor  unless clicking mouse several times to get first cursor and then moving mouse to Graph cursor crosspoint (where the Windows cursor is changed again).

[James.M]

Honestly dude, I think you're just zooming in so much that the curser has no where to go. Once you've zoomed in past the resolution of the graph, what's the point?

Like I asked above, what are you trying to do? Do you have data points that are so close together that you're zooming in to 6 decimal places? If you have data that you're graphing and then trying to move the cursor and it's not working between data points, attach the data as well.

[_Y_]

It seems, i cannot explain the question in good way

It is not about my data or zooming. It is about strange bahaviour of the Graph. The following sequence of steps illustrates the problem and shows that the zooming is not the issue (or, at least, not the main issue):

I do the following:

1. Start the VI.

2. Select first Graph cursor in Corsor palette and use pop-up menu "Bring to Center".

3. Zoom couple of times (not too much) keeping the Grapg cursor visible.

4. Select Cursor Movement Tool in the Graph Palette.

5. "Open cross" Windows cursor appears from the beginning. I cannot pick up the Graph cursor.

6. Click left button of the mouse several times in any poin of the graph area.

7. Windows cursor is changed to the normal "cross with central point".

8 Now I can pick up the Graph cursor.

I would suspect problems with zoom until p.5. However p.6-8 are done without any change of the zoom.

By the way, I found more:

If I try to move the Graph cursor after p.5, the whole graph moves and fires event "Scale Range Change". It must not happen with Cursor Movement Tool selected.

I can guess only about some strange setting of the graph. May be I am not aware about them

[James.M]

So I think it's still a zooming issue, but not in the way you might think. Here's how I can get around this behavior. If I bring all cursors to the center and then zoom while keeping the cursors in view, the weird behavior doesn't occur.

If I let one of the cursors go off-graph during zooming, after a few zooms the behavior kicks in and that cursor's coordinates move around when the screen is shifting.

I can't explain the cause or a solution really, but I would say just keep the cursors on screen.

[_Y_]

Thank you, you spent lot of time for me.

Unfortunately, the SW must be delivered to customers and saying "watch for cursors" is not the best way. I have to think more about the problem.

[James.M]

If the cursors staying on screen is the problem, and I'm not 100% sure it is but it seemed to help, could you programmatically move the cursors when the user is zooming or scrolling? It still does seem like the problem only occurs when the plot is zoomed in pretty far. Also, maybe the problem goes away if you have actual data on the graph?