[Panel-devel] Connection of Sensor and Meter

[Vinay Khaitan]

Hi, 

Having a parent/child relationship between meters sounds like just another 
> way
> to do what we are already doing according to your example. Currently 
> people
> create those items in a certain order to have them display the way they 
> like,
> i.e. bar image first, and graph image second.


I have thought about this idea too. But parent-child relation in qwidget is 
slightly different that qobjects. If a widget is visually child of any other 
qwidget, then only we can make that type of realtionship.
I dont know, if in future we would want to implement that thing or not(may 
be a reality, in case something like textlabel in Tablemeter), but that is 
not the substitute of what I wanted here.
And yes, we can introduce something like Z ordering in meters.


> My general thought on how this will work is in this fashion:
> 1) Meter connects to a Sensor, which has some default interval for 
> reporting 
> data
> 2) Sensor reports new data to Meter using qt signals/slots
> 3) Meter redraws/refreshes its display when it received data from Sensor
> 4) Meter waits while there is no data to change(saving cpu usage by not 
> redrawing, unlike how SK currently is implemented)
> 
> No need for a separate interval for Meters.

What about the cases, in which data changes every millisecond (cpu load)? 
sensor can have only one interval, and two meters want to refresh in 
different intervals? We need to have meter update interval.

> On a side note, since Meters will be qwidgets, they will have to be able 
> to
> handle events such as mouse clicks to replace the current clickArea
> functionality, and keyboard presses to replace the keyPressed 
> functionality.

I am replacing that as I am converting meter to qwidgets. 

One more idea came into my mind. If we replace the current design of one 
karambaWidget which encompasses all meters to independent meters?
Right now, faked transparency is achieved by krootpixmap. mouse interaction 
is still to karamba theme. If we separate out meters, then we can have a 
real desktop instead of karambaWidget. And I also dont think that this is 
difficult to do. This will also allow users to move meters independently to 
where they wish ( but they can be grouped together still)!

Old design of karamba is not the answer to current requirements. That 
karamba was limited, we dont want that now.
Design should be future perfect. At that requires that needs should be 
directly mapped to design. That means.....
If two instance of sensor does the same thing, there is no meaning in 
instantiating that again and again whatever the future may require! 
I have given enough possibilities which can create trouble with old karamba 
design.
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