PanZoom enhanced

[phisi]

Adds ZoomLimit flag to PanZoom If the flag is set to PanZoom.MIN_TICKS PanZoom.calculateZoom( ...) will be limited not to zoom in beyond one visible grid line (if applicable).

Default behavior is not changed. Should not break any existing code using this class.

[phisi]

I must admit I did not look into XYPlot.innerLimits. To understand the way the grid is drawn I looked at XYGraphWidget.drawGrid(). I don't see how innerLimits would change the outcome of that function.

[halfhp]

Hmm perhaps I've misunderstood the purpose of this change. The basic intent appears to be to provide a new way of specifying a zoom limit to work with the StepModel changes.

This PR contains this new logic:

// make sure we do not zoom in too far (there should be at least one grid line visible)
if (plot.getDomainStepValue() > (scale*span)) {...}

Which determines whether or not to operate on a zoom event using a new algorithm. The intent of innerLimits and outerLimits however is that these are the only two values that PanZoom needs to worry about to determine whether or not to prevent pan/zoom as a result of hitting a limit

Rather than making these calculations on every zoom event, I wonder if we can instead calculate and set the appropriate innerLimit one time up front, either when we attach the PanZoom instance or perhaps when we add the StepModelFit instance. The former is probably cleaner, however the later would have the benefit that it would recalculate any time the StepModel changes.

[phisi]

I played around a little with the innerLimits and could get some of the functionality I want. The problem is that the innerLimits also interfere with the framing model (that is the only code where they are realy used). To get everything I propably would have to mess around there too...

To clarify the desired functionality: Lets say we start with the PanZoomDemo Range 0-1000 Domain 0-3000 now you can zoom in and pan around. The limits are the outer limits (can not pan outside those) with the commit there is an additional limit on the zoom (not pan) the range/domain on display can not be smaller than a certain value (currently the getStepValue() but could be anything). So you could for example view the range 103-104 (min. step 1) at domain 2452-2462 (min. step 10).

• When you pan, it works and moves around at the minimum zoom level
• When you try to zoom in further, it won't (as the step would be larger than the new span)
• When you zoom out, everything behaves as it has previously

[phisi]

I added a stub javadoc. Please fell free to expand. Thanks

[halfhp]

Thanks - merged!