Get mouse down and mouse up events from slider

I am implementing (in R2016a) a continuous slider using a listener as follows:

sld = uicontrol('Style', 'slider');
sld.addlistener('ContinuousValueChange', @(src, evt) callbk(src, evt));

What I also want to do is to have callbacks when the mouse is first clicked on the slider and then when it is released. I can't find any appropriate events to do this in the uicontrol class.

Does anyone have suggestions?

Answer 1

[Jan]

The standard callback of the slider is called, when the mouse is released:

function main
sld = uicontrol('Style', 'slider', 'Callback', {@callbk, 'released'});
sld.addlistener('ContinuousValueChange', @(h, e) callbk(h, e, 'moved'));
end

function callbk(SliderH, EventData, Event)
disp(Event)
end

The WindowButtonDownFcn does not trigger, when the mouse is over the slider.

Then Java helps:

function main
hSlider    = uicontrol('style','slider');
jScrollBar = findjobj(hSlider);
jScrollBar.AdjustmentValueChangedCallback = @(h,e) callbk(h, e, 'moved');
jScrollBar.MousePressedCallback           = @(h,e) callbk(h, e, 'clicked');
jScrollBar.MouseReleasedCallback          = @(h,e) callbk(h, e, 'released');
end

function callbk(SliderH, EventData, Event)
disp(Event)
end

With FEX: findjobj

[Etaoin Shrdlu]

Thanks, Jan. This "undocumented Matlab" use of Java does the trick. Interestingly, it doesn't signal mouse up or down when the buttons on either end of the slider are pushed.

[Jan]

@Etaoin: See the MouseClickedCallback. Further events: http://undocumentedmatlab.com/blog/uicontrol-callbacks

Answer 2

[Walter Roberson]

I do not know if there are any listeners that can be configured for this. If there are not, then the figure property WindowButtonUpFcn is the only mouse-release callback.

[Etaoin Shrdlu]

Walter: Thanks for the thought, but once the mouse is over the slider, none of the figure events (e.g. WindowButtonUpFcn) will be triggered.

[Walter Roberson]

Good point.

Set the slider enable property off. Use the figure WindowButtonUpFcn and WindowButtonDownFcn and WindowButtonMotionFcn to figure out where you are and to adjust the slider Value appropriately.

[Jan]

You do not need the WindowButtonUpFcn, because the slider's Callback performs this action already.

[Walter Roberson]

However if you have set the slider to disable then the slider's callback would not be active.