How to threading data in app?

[tanthinh1510]

Hi all!
I created simple app as picture below
threading.png
code in file main.qml

import QtQuick 2.3
import QtQuick.Controls 1.2
 
ApplicationWindow {
    visible: true
    width: 640
    height: 480
Rectangle{
    color: "red"
    width: 100
    height: 100
    anchors.centerIn: parent
    Timer{
       interval: 30
       running: true
       repeat: true
       onTriggered: {
            _processdata.calculator()
       }
    }
}
}

import QtQuick 2.3
import QtQuick.Controls 1.2

ApplicationWindow {
    visible: true
    width: 640
    height: 480
Rectangle{
    color: "red"
    width: 100
    height: 100
    anchors.centerIn: parent
    Timer{
       interval: 30
       running: true
       repeat: true
       onTriggered: {
            _processdata.calculator()
       }
    }
}
}

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I have one component is a rectangle. In rectangle have timer and 30ms it Triggered to call function _processdata.calculator() from class C++
It's works fine if I put less rectangle(1- 100 rectangle). But I put about 500 - 1000 rectangle in my app, It became slow and when I move app, it is shaking shock
Cause is all rectangle call function _processdata.calculator() time.
How to it works fine when I put 500 - 1000 rectangle in my app? Please help me!

[anda_skoa]

Why do you need to call the same function on the same object with multiple timers?
If you want to update whatever it is that the function is doing, just to it with a single timer.

Cheers,
_

[tanthinh1510]

Because a rectangle will call the function and send possition of it to get pixel color. The same function but return different results
Every 30ms. I need the return value of each rectangle.

[anda_skoa]

Because a rectangle will call the function and send possition of it to get pixel color. The same function but return different results

Then this was a very bad choice of example code.

Every 30ms. I need the return value of each rectangle.

And each rectangle needs its own update interval? Or are they updated at the same time?

Cheers,
_

[tanthinh1510]

And each rectangle needs its own update interval? Or are they updated at the same time?

Cheers,
_

They updated at the same time. But I try both cases and results is the sames. It became slow.

[anda_skoa]

They updated at the same time

So you only need one timer.

Ok, then lets ignore your now irrelevant example and concentrate on the actual use case:

- you have a number of rectangles.
- they can change position
- their color depends on that position
- you want to update color for all rectangles every 30 seconds, not on every posiiton change

Correct?

Cheers,
_

[tanthinh1510]

- you have a number of rectangles.
Cheers,
_

Number of rectangles is random. I can enter any number

- they can change position
Cheers,
_

yes, they can change position

- their color depends on that position
Cheers,
_

Yes, their color depends on that position

- you want to update color for all rectangles every 30 seconds, not on every posiiton change
Cheers,
_

Yes. because color screen always change, so I want to update color for all rectangles every 30 miliseconds(not 30 senconds)
I think cause is all rectangle call function at the same time. But I have not found a way to solve.

[anda_skoa]

One approach is to register all rectangles with a controller object.
It runs the timer and on timeout gets the positions from the registered objects and updates the color.

Another approach is to have a model that gets the number of rectangles as its input and generates as many reference objects.
Each such object has a read/write for the position and a read property for the color.

The retangles are then generated using a Repeater, bind their position and color to the given reference object.
The model then updates each reference object with a timer.

Cheers,
_

[tanthinh1510]

One approach is to register all rectangles with a controller object.
It runs the timer and on timeout gets the positions from the registered objects and updates the color.

Another approach is to have a model that gets the number of rectangles as its input and generates as many reference objects.
Each such object has a read/write for the position and a read property for the color.

The retangles are then generated using a Repeater, bind their position and color to the given reference object.
The model then updates each reference object with a timer.

Cheers,
_

Thanks you anda_skoa!
I will try approach of you and update result as soon.
Thanks again.

[tanthinh1510]

I try created list include information of rectangle (possition) to contain all rectangle.
Every 30 milisecond. I get possition from list to get pixelcolor. Result is it slow the same as the last.
Maybe 30 milisecond not enough to calculate all the rectangles in list.

[anda_skoa]

Well, you don't have to guess, you can measure the time spent in update function, see QElapsedTimer.

Cheers,
_