[Panel-devel] Design of Sensor and meters

[Vinay Khaitan]

Pedro has done some refactoring of superkaramba. He has encountered some 
design troubles. They are similiar to what I had earlier talked about i.e. 
meters dont know the format sensor's return value. And type of return value 
doesn't give any information about that.
So I am proposing a solution to it. it is from combining old, new and mine 
ideas.

class arbitSensor::public Sensor
{
/* all the sensors will have some user readable/writable attributes. They 
can be set from themefile in format sensor.updateInterval=1000 */
Q_PROPERTY(int updateInterval READ updateInterval WRITE setUpdateInterval) 
/*We will use Q_PROPERTY macro. so that setProperty() work.*/
/* All the Sensors return values about information contained into them. But 
how the meters would understand the format of return values(see my earlier 
example in a mail, of tasksensor)? Pedro was getting some trouble with it.
I ask to dump the idea of single return value.
I propose that there would be a "value" parameter in theme file which will 
have values with some %arguments.
taking example of richtextlabel and bar connected to cpusensor,
(I dont want to use cryptic %u etc., they would become difficult in long 
run)
RICHTEXTLABEL value="cpu load of cpu0= %cpu0 user=%cpu0.user 
sytem=%cpu.system"
BAR value=%cpu0.system , we will use the dotted form.
Meters have setValue() slot. they would ask sensor for the value of 
%cpu0.system in QString and sensors would return value in QString.
*/ 

QString returnValue(QString data) ; //data=cpu0.user, returns QString::null 
if data is not supported

signals: 
void update(); //no parameter
}

class arbitMeter: public Meter
{
Q_PROPERTY(QString value READ value WRITE setValue); //all the meters have 
some attributes which can be set

void setValue( QString);
void attachToSensor(Sensor* sensor)
{
connect(sensor, SIGNAL(update()),this,SLOT(updateNow()));
//other stuff
}

//I am forgetting some other necessary functions

}

The idea of multimeter appealed me.
We can have things like this in theme file,

MULTIMETER meter=bar number=2 orientation=horizontal, separationX=50 
separationY=50 value.1=cpu0.system bar.x=0 bar.y=etc
value.2=cpu1.systemSENSOR=cpusensor

The separation stuff would set the separation of multiple meters. 
orientation is separation orientation.

So with this format, making of (non interactive )taskbar with the tasksensor 
I described in one mail is just one line,
(x is for variable number)
MULTIMETER meter=RICHTEXTLABEL number=x value.x=task.x separation=(50,50) 
orientation=horizontal mask=alpha, background=beta etc.

I know, this idea would be modified, but IMHO, this works smoothly from the 
point of view of separation of meters and sensors, theme creation ease and 
superkarama coding.

Comments?

Vinay Khaitan
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