Binding Loop Error While Trying to Increment Progress

Question

I am trying to show incremental changes on a progress bar by clicking a mouse area. The code below compiles and changes the value of the progress bar from 0 to 0.25 after clicking the mouse area. But the change is not permanent. I am trying to increase the current each click by 0.25. I know my code is only setting the value to positive .25 each click. I am just at a loss for how I might increment change in progress bar without global vars. I included the transition to ensure the state change was irreversible, the code still compiles and runs the same. There are two issues.

My change is not permanent in the visible progress bar
My increments do not increase the total value, they are singular value assignments

ProgressBar{
    id: progressBar
    height: 20
    anchors.top: parent.top
    anchors.topMargin: 100
    anchors.horizontalCenter: parent.horizontalCenter
    opacity: 1
    value: 0
    states: State{
        name: "PressedAlso"
        when: mouseArea.pressed == true
        PropertyChanges{
            target: progressBar
            value: + 0.25
        }

    }

    transitions: Transition {
                from: ""; to: "PressedAlso"; reversible: false
    }
}

I've now added this line in the property changes "value: progressBar.visualPosition + 0.25" and removed the "value: 0" line in the progress bar. Application output error - Binding loop detected for property "value". Googling what binding loop is. — CrippledTable, Apr 22 '19 at 17:05
So binding is simply assigning values. A loop is what I am trying to create. Everything seems to be in order, the state just keeps reversing. — CrippledTable, Apr 22 '19 at 19:01
A breakpoint at the value binding line in the property changes object breaks multiple times upon pressing the mouse area. A breakpoint anywhere in the transitions object never breaks. — CrippledTable, Apr 22 '19 at 19:07

score 1 · Accepted Answer · answered Apr 22 '19 at 19:22

Your state PressedAlso means: when the mouse button is pressed, the value is 0.25. Otherwise, the value is implicitly 0.

If you want to increment by 0.25 by pressing the mouse button, you can use onPressed property in your MouseArea:

MouseArea {
  anchors.fill: parent
  id: mouseArea
  onPressed: progressBar.value += 1
}

Binding Loop Error While Trying to Increment Progress

1 Answers1