I have this QML progress bar:

import QtQuick.Controls 2.0 as QQC20

Item 
 QQC20.ProgressBar 
 id: progressbar_id
 visible: false // even if "true", the progress bar does NOT show up on UI
 from: editorScene.progressbarMin
 to: editorScene.progressbarMax
 value: editorScene.progressbarVal

 onValueChanged: 
 console.log("Progressbar value changed: ", progressbar_id.value)
 
 onVisibleChanged: 
 console.log("Progressbar visibility chanaged: ", progressbar_id.visible)
 
 

I can confirm that the progress bar value and visibility are changed by the methods onValueChanged and onVisibleChanged.

However, the problem is that the progress bar does NOT show up on the UI! How can I actually show the progress bar on the UI? Can anybody give me a hint?

Right now, all you're doing is creating a Qml type which you can use as part of your API. To actually see it, you need to create an instance of it under a ApplicationWindow or Window.

There are two ways you can accomplish this. You can

1. Use the item directly.


2. Save your Qml Progress Bar Item in a separate file, and create an object in an ApplicationWindow.

Lé Code

Method 1

Directly insert your codeblock as a child of an ApplicationWindow.

// Main.qml
import QtQuick 2.0 // for `Item`
import QtQuick.Window 2.0 // for `ApplicationWindow`
import QtQuick.Controls 2.0 // as QQC20 // no need to label a namespace unless disambiguation is necessary

ApplicationWindow 

 width: 480 // set the dimensions of the application window
 height: 320

 // here's your item
 Item 
 anchors.centerIn: parent // place in centre of window

 ProgressBar 
 id: progressbar_id

 anchors.horizontalCenter: parent.horizontalCenter // horizontally align the progress bar

 from: 0 // don't know what editorScene is
 to: 100 // so I'm using raw values
 value: 5

 onValueChanged: 
 console.log("Progressbar value changed: ", progressbar_id.value)
 
 onVisibleChanged: 
 // side note: I'm not getting any output from this handler
 console.log("Progressbar visibility chanaged: ", progressbar_id.visible)
 
 
 

 // provide user-interaction for changing progress bar's value
 MouseArea 
 anchors.fill: parent // clicking anywhere on the background
 onClicked: progressbar_id.value += 5; // increments the progress bar
 // and triggers onValueChanged
 

Method 2

Save your item into a new qml file.

// MyProgressBar.qml
import QtQuick 2.0 // for `Item`
import QtQuick.Controls 2.0 // for `ProgressBar`

// here is your item, it has grown up to be a file of its own 🚼
Item 

 property alias value: progressbar_id.value // for user-interaction

 ProgressBar 
 id: progressbar_id

 anchors.horizontalCenter: parent.horizontalCenter // centre horizontally

 from: 0
 to: 100
 value: 5

 onValueChanged: 
 console.log("Progressbar value changed: ", progressbar_id.value)
 
 onVisibleChanged: 
 console.log("Progressbar visibility chanaged: ", progressbar_id.visible)
 
 

Then call it from your ApplicationWindow in Main.qml.

// Main.qml
import QtQuick 2.0
import QtQuick.Window 2.0 // for `ApplicationWindow`

// import "relative/path/to/progressbar" // use this if MyProgressBar.qml is not in the same folder as Main.qml

ApplicationWindow 

 width: 480
 height: 320

 MyProgressBar 
 id: progressbar_id
 

 MouseArea 
 anchors.fill: parent
 onClicked: progressbar_id.value += 5;
 

Make sure that your qml files are in the same directory. If not, place an import "relative/path" at the top of the Main.qml file among the other import statements.

For example, if

• Your Qml project is in /Users/Lorem/Project,


• The full path to your Main.qml is /Users/Lorem/Project/Main.qml, and


• The full path to your MyProgressBar.qml is /Users/Lorem/Project/qml/MyProgressBar.qml...

Then use import "qml" in Main.qml to import the subdirectory/subfolder. Remember, you're importing the directory, not the file itself.

Result

This is what the result resembles when I run it from a macOS.

At startup.

After 3 clicks on the background.

There is also console/debug output after each click:

Progressbar value changed: 10
Progressbar value changed: 15
Progressbar value changed: 20