[MPlayer-dev-eng] [PATCH] GUI: Implement a true rotary potmeter

[Hans-Dieter Kosch]

Ingo Brückl wrote:

> Well, and as soon as you try to change a simple feature you're meeting a peck
> of troubles...
> 
> When you click on a potmeter button to grab it, it would already move due to
> its new value now. :-(

No, yes, of course, that's exactly the pretty behaviour (IMO) :-)

Look:

1) Currently: On press nothing happens, on release the value jumps to the new 
position.

2) Currently: On press nothing happens, on drag the value immediately jumps to 
the new position. So, if the user presses and then there's a minimal jitter by 
only 1 px (caused by the user's hand or uneven ground under the mouse), the 
value jumps to the new position. Such a jitter is surely not noticeable to the 
user, and has then the same effect like jumping already on press.

3) New (your revoked change): The value would jump already on press, and from 
there on smoothly follow the drag. This appears to me intuitive and much better 
than if it would jump surprisingly upon a drag ( 2) ).

4) A mouse click is handled widely different in applications. An action may be 
taken already on press or not before release (and this intermixed in a single 
application). So we're free in handling.
Our pure button item reacts on release; that's OK and common practice, as we 
have the chance to drag out of it and nothing happens after release. But with 
the potmeters, there's always an action on drag or release (which is OK, too); 
so we can definitely move the release action to a press action.

So, I suggest: Stay with your change to move the action from release to press. 
It's really not trouble, it's an advance. Your last rpotmeter patch worked 
perfectly regarding that. And the code changes are minimal, I see no risk.

What do you think?

Hans-Dieter

PS: Should you plan to do something during weekend, I'll be closely online and 
assist in testing.