Question

My slider had a child button widget. I have recently changed my gui to send the mouse coordinates as relative to the widget, so if the widget is at 50,50 and the mouse is at 50,50, it will now report as 0,0.

This has created some problems for my slider. When I would drag around the button it would position to value.

The only solution I have thought of is to take the given mouse coordinate, add back the absolute position of the button, then subtract the absolute position of the slider.

I was however hoping for a solution that did not envole absolute positioning.

I used to receive the absolute mouse position, when I did, I positioned it like this:

int mousePos = getOrientation() == AGUI_HORIZONTAL ? 
    mouseArgs.getPosition().getX() - getAbsolutePosition().getX() :
mouseArgs.getPosition().getY() - getAbsolutePosition().getY();

setValue(positionToValue(mousePos));

mouseArgs gives the mouse position relative to the button. Not relative to the slider, which is what would be needed.

I can obtain the relative locations of the widgets, but I don’t think that would do it.

Thanks

Answer 1

Since this is a custom GUI, I’m going to make some assumptions and restate your question to make sure I’m answering your question.

You have a slider widget that contains a thumb widget. The user can click and drag the thumb to reposition it. Your GUI sends mouse notifications to your widgets in local relative space rather than absolute screen space. Your question is how can the thumb widget respond to the mouse events to move itself around without having to use absolute coordinates?

You can do this by changing who’s responsibility it is to move the thumb widget. It should be the job of the slider widget to position its thumb widget. By doing it that way, all your coordinates can be in the slider widget’s local relative space. Basically it’d be something like (assuming you have some kind of event notification):

1. When created, the slider widget registers for the various mouse events on its child thumb widget.
2. When the thumb receives mouse events, it raises the event passing along its local coordinate.
3. Slider widget receives these events and translates the coordinate from thumb local space to slider local space (i.e., click_x = thumb_x + thumb_mouse_x).
4. Slider can then use this coordinate, which is in the slider’s local relative space, to move the thumb.

In general, parents should be responsible for their children’s layout.