How does RecallPanelState work?

[Peo]

Hi, I usually use SavePanelState/RecallPanelState in my applications to save some parameters that have to be recorded from a test session to another. I noticed this thing: altough the reference manuals of CVI tell that these functions save only the control values and then recall those values to fill the controls already loaded on my uir file, when I recall an old panel state the property of some controls are recalled too. For example, if I have the need to change the limit values (max and min) of a numeric control, I modify my uir file and then send it to final user to modify the application. When he run the new application the control, which property I have modified, has the same property it had the last time I saved the panel state. Therefore, anytime, I need to delete the saved states of a panel to load the correct version of a modified panel, but I lose all parameter saved in it. Isn't there any way to fix this bug, other than change properties programmatically (as I do actually)? When the changes with respect of the original uir file are a lots, the work become great.....

Thanks a lot

Andrea

[LuisG]

Andrea,

In general terms, it is the case that RecallPanelState / SavePanelState is intended to save control values and not control properties. However, when it comes to the specifics of each control there are some examples to this. The exceptions generally fall into two broad categories:

1. Some properties are too tied to the actual value of the control to be separated. The example you gave fits into this category. The value of the numeric is tied to the data type (which is a property) and to the max-min range (also properties) so they are saved along with the value. But something more trivial, like the font or the color, is completely separate of the value, so it is not saved. Another example is with graphs, where the plots (which are basically the 'values' of a graph) are saved, but the range of the axes are also saved, since they are closely related to the plots (especially in autoscale mode).

2. The distinction between values and properties, which made sense for simple controls like strings and numerics, begins to lose some of its meaning as later controls became more complex (trees, tabs, canvases, etc..). So in those cases, it also became difficult to establish a strong separation, when it came to deciding what would be save with SavePanelState. Our general philosophy came to be that when there was some doubt, we made the choice to save something rather than not saving it, since we assumed that that would provide users with the most flexibility.

I realize that this has become cumbersome for you, and I apologize for the inconvenience. Basically, it does mean that you have to programmatically override the properties that you did not want to change, by doing something like this:

        GetCtrlAttribute (panel, control, ATTR_MIN_VALUE, &min);
        RecallPanelState (panel, file, index);
        SetCtrlAttribute (panel, control, ATTR_MIN_VALUE, min);

Luis
NI