How to generate particles from the center of my window? (qml)

Question

I am working with the particle system in qml, but I want my particles originating from the center of my rectangle.

The foregoing I can tell you that it is already done, but what I do not like is that the particles emerge in disorder and without direction.
I would like the particles to spread evenly from the center to the ends, but I do not know how to do it.
If someone I could suggest some idea.
I annex my code.

Corrections, ideas or suggestions that solve my problem are accepted.

import QtQuick 2.0
import QtQuick.Particles 2.0

Rectangle {
    id: bg
    width: 360
    height: 360
    color: "black"

    ParticleSystem {
        id: particleSys
    }

    Emitter{
        id: emitter
        anchors.centerIn: parent
        height: 14; width: 16
        system: particleSys
        emitRate: 80
        lifeSpan: 4000
        lifeSpanVariation: 500
        maximumEmitted: 1000
        size: 5
        endSize: 40           

        velocity: TargetDirection{     
            targetX: 0; targetY: 0
            targetVariation: 360
            magnitude: 250
        }
    }

    ImageParticle{
        source: "images/blueBlip.png"      //My image
        system: particleSys
    }
} 

Thanks.

Answer 1

I am the person who asked the question.
I found a solution to my question.

To emit ordered particles you can make use of the burst() method.

This event allows us to emit a certain number of particles from our emitter. You can manipulate it according to what you need.

I implemented it through a Timmer:

Timer{
    interval: 500; running: true; repeat: true
    onTriggered: particles.burst(particles.emitRate)
}

The code would look like this:

import QtQuick 2.0
import QtQuick.Particles 2.0

Rectangle {
    id: bg
    width: 360
    height: 360
    color: "black"

    ParticleSystem {
        id: particleSys
    }

    Emitter{
        id: particles
        anchors.centerIn: parent
        height: 14; width: 16
        system: particleSys
        emitRate: 80
        lifeSpan: 4000
        lifeSpanVariation: 500
        maximumEmitted: 1000
        size: 5
        endSize: 40           

        velocity: TargetDirection{     
            targetX: 0; targetY: 0
            targetVariation: 360
            magnitude: 250
        }

        Timer{
              interval: 500; running: true; repeat: true
              onTriggered: particles.burst(particles.emitRate)
        }
    }

    ImageParticle{
        source: "images/blueBlip.png"      //My image
        system: particleSys
    }
} 

If someone knows a more efficient way or someone can improve it ... contribute your answer.
Thanks.