Making a component less sensitive to Dragging in Swing

Question

A JComponent of mine is firing a mouseDragged event too vigorously. When the user is trying to click, it interprets is as a drag even if the mouse has only moved 1 pixel.

How would I add a rule for a particular component that amounted to:

Do not consider it a drag event unless the mouse has moved 10 pixels from the point at which is was pressed down.

Note: I know it's not a system setting in my OS, since only events on that component suffer from this over sensitivity.

Thank you.

Answer 1

If I read your question correctly, you're tracking both click and mousedrag events. Can you track the coordinates upon mousedown, followed by a short computation in mousedrag to see if the mouse has moved your desired minimum numbers of pixels? Of course, you then also want to cancel/reset on mouseup or when the mouse is dragged outside the bounds of your JComponent.

Caveat: I haven't done this myself, but I think it's where I'd start if it were me.

Answer 2

I've had to do exactly this before. Here's my mouse event processing code, cut down to just the bits relating to making drag require a few pixels before being treated as a drag.

public void mousePressed(int mod, Point loc) {
    pressLocation=copyLocation(loc,pressLocation);
    dragLocation=null;
    }

public void mouseReleased(int mod, Point loc) {
    if(pressLocation!=null && dragLocation!=null) {
        // Mouse drag reverted to mouse click - not dragged far enough
        // action for click
        pressLocation=null;
        }
    else if(dragLocation!=null) {
        // action for drag completed
        }
    else {
        // do nothing
        }

    pressLocation=null;
    dragLocation=null;
    }

public void mouseDragged(int mod, Point loc) {
    if(pressLocation!=null) {                                                   // initial drag actions following mouse press
        dragLocation=pressLocation;                                             // consider dragging to be from start point
        if(Math.abs(loc.x-pressLocation.x)<dragMinimum && Math.abs(loc.y-pressLocation.y)<dragMinimum) {
            return;                                                             // not dragged far enough to count as drag (yet)
            }
        // action drag from press location
        pressLocation=null;
        }
    else {
        // action drag from last drag location
        dragLocation=copyLocation(loc,dragLocation);
        }
    }

And note, I also had problems with Java some JVM's generating click events after dragging, which I had to detect and suppress.