Big Wacky Sliders


I’m making some waqcky big sliders for touchscreen use. Problem is, they seem to get very small when I increase the sliderthumb size (in a look and feel class).

Am I the only one making big sliders and to run into this?

The problem seems to be that the slider does this:

const int indent = getLookAndFeel().getSliderThumbRadius (*this) + 2;

Which seems redundant, since another set of code then makes sure the slider and thumb draw within the slider rect. So this may have been there a while? I’m guessing that this:

int LookAndFeel::getSliderThumbRadius (Slider& slider) { return jmin (7, slider.getHeight() / 2, slider.getWidth() / 2); }
has forced it to ‘7’ for a while.

Jules, can we ‘fix’ this? Would it break anything else? Seems like the ‘7’ is just working as a hard-coded minimum amount of breathing room around the slider. If in Slider::resized we set an indent (used to inset the slider itself) then the demo seems OK but my app overlaps:

What would the real fix be?



It’s not quite that simple - the resize() callback needs to define the sliderRect region correctly so that the mouse dragging matches what gets drawn. Isn’t it enough to write a l+f that removes the 7 from the getSliderThumbRadius?


Well, I wanted a big thumb, so I used the current L+F draw and overrode the draw background and draw thumb. With that and a large thumb radius, it works the way I want except for the smaller rect.

The mouse and thumb do match though. It seems as if the slider thumb radius is doing 2 jobs? I’m not seeing the design. I used radius so that my thumb is always inside the background, and that works.

Otherwise I’d have to do that math myself. Do you see what I’m getting at?



erm… sorry, I think I’m probably being a bit dumb, can’t see what you mean…


No, it’s a bit odd all round, and I don’t quite get it.

OK, so I tried to mod the standard L+F to demonstrate what I mean, and just changing the thumb size does what I’d expect. Shoot.

So maybe I’m just messing up. Can I just get advice then - if I want my thumb to always be within the background ‘channel’ do I want to change the thumb radius or just draw a bigger thumb?


PS OK, probably/certainly I’m messing up


I’d say that if you want it inside the channel thing, then draw a bigger channel rather than a smaller thumb.