2008/7/4 Michael van der Gulik <mikevdg at gmail.com>:
>
>
> On Fri, Jul 4, 2008 at 2:16 PM, Igor Stasenko <siguctua at gmail.com> wrote:
>>
>> 2008/7/4 Michael van der Gulik <mikevdg at gmail.com>:
>>
>> > What I was considering doing was making the Canvas the source of events.
>> > Every Canvas has a model which must implement event handling methods and
>> > a
>> > #drawOn:bounds: method. A Canvas can ask the model to redraw itself when
>> > the
>> > Canvas becomes dirty (e.g. when sub-canvases move and the canvas has no
>> > cached state).
>> >
>>
>> A dirty/clean is a not a basic canvas capability.
>> Needless to say, that for some devices (including GL) sometimes its
>> easier and faster to redraw everything from scratch rather than care
>> about dirty areas.  Some devices (like printers) have nothing to do
>> with dirty/clean approach.
>> Don't let a premature optimizations influence the basic model! :)
>
> On reflection, yes, it is a premature optimisation. Hmm...
>
>
>> Right, also, don't forget about relative mouse pointer motion. A good
>> illustration of capturing a relative mouse movement is 3D first person
>> shooter game :) It is not interesting where mouse cursor is, its only
>> interested in amount of mouse movement along its two axises.
>> And in fact, mouse, as device generates relative events, is knows
>> nothing about screen size , or where mouse cursor are allowed to be.
>> So, binding mouse to a screen space is wrong by its nature. Event
>> should generate a relative movement, and then World (or top-level
>> handler) can translate such events to absolute coordinates in its own
>> space (if it cares).
>
>
> IIRC, mouse pointer events normally contain absolute coordinates in most
> windowing systems, including Squeak.
>
> Mouse velocity could be passed as extra information in the event. Mouse
> pointer capture could be done using some key combination, although this is a
> "nice-to-have" feature that I won't implement in the first release.
>

I don't like to centralize event system around single device such as
mouse. It needs an abstraction.
Think about different devices, such as stylus pen, or multi-touch sensor screen.
Any device can generate a 'click' event, or some gestures which then
transformed to events.
Event system should be flexible enough to able to work with wide range
of input devices , not only mouse.

> Gulik.
>
> --
> http://people.squeakfoundation.org/person/mikevdg
> http://gulik.pbwiki.com/
>
>
>



-- 
Best regards,
Igor Stasenko AKA sig.