Skip to content

Handle missing min/max gracefully for sliders/scrollbars #32

Closed
Closed
Handle missing min/max gracefully for sliders/scrollbars#32

Description

@imagejan
imagejan
opened on Oct 3, 2017

Currently, the UI hangs when trying to use a numeric parameter with style=slider, but min or max undefined:

#@ int (style=slider) a

This should be handled gracefully, by checking for softMin != null and softMax != null here:

scijava-ui-swing/src/main/java/org/scijava/ui/swing/widget/SwingNumberWidget.java

Lines 102 to 124 in 221d3c6

// add optional widgets, if specified
if (model.isStyle(NumberWidget.SCROLL_BAR_STYLE)) {
int smx = softMax.intValue();
if (smx < Integer.MAX_VALUE) smx++;
scrollBar =
new JScrollBar(Adjustable.HORIZONTAL, softMin.intValue(), 1, softMin
.intValue(), smx);
scrollBar.setUnitIncrement(stepSize.intValue());
setToolTip(scrollBar);
getComponent().add(scrollBar);
scrollBar.addAdjustmentListener(this);
}
else if (model.isStyle(NumberWidget.SLIDER_STYLE)) {
slider =
new JSlider(softMin.intValue(), softMax.intValue(), softMin.intValue());
slider.setMajorTickSpacing((softMax.intValue() - softMin.intValue()) / 4);
slider.setMinorTickSpacing(stepSize.intValue());
slider.setPaintLabels(true);
slider.setPaintTicks(true);
setToolTip(slider);
getComponent().add(slider);
slider.addChangeListener(this);
}

If no slider or scroll bar can be rendered, we should fallback to the standard textfield/spinner combination and log a warning message.

Activity

  1. ctrueden commented on Nov 3, 2017

    @ctrueden
    ctrueden
    on Nov 3, 2017
    Member

    I did some digging. The reason it freezes is not because min and max are null—that would throw an NPE after all. It's because min defaults to Integer.MIN_VALUE and max to Integer.MAX_VALUE. The UI builder then proceeds to try to make a slider or scroll bar with a massively huge range, and the CPU goes to 100% indefinitely. The problem is this and that lines of code in the DefaultWidgetModel.

    A possible fix would be to change the code that creates the JScrollBar or JSlider to be more conservative about what it feeds to those constructors. This would also guard against the case of explicit min="-1000000000", max="1000000000" sorts of inputs.

  2. imagejan commented on Nov 3, 2017

    @imagejan
    imagejan
    on Nov 3, 2017
    MemberAuthor

    Thanks for digging, @ctrueden!
    I think we can tackle this at the same time as allowing non-integer step sizes in sliders (see #31), by adjusting the step size in case the number of possible steps gets unreasonably high (the acceptable limit might have to be found by testing with different settings).

  3. ctrueden
    closed this as completedin 32ddc3con Nov 3, 2017

  4. ctrueden commented on Nov 3, 2017

    @ctrueden
    ctrueden
    on Nov 3, 2017
    Member

    I believe I have fixed the integer cases. Handling non-integers will be more involved, though.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type

    Projects

    No projects

      Milestone

      No milestone

      Relationships

      None yet

      Development

      No branches or pull requests

      Issue actions