Cascades Development

[nareshkodumuri]

Hi,

I am not able to understand the concept and usage of attachedObjects Property in qml.please anybody explaine the concept and usage of attachedObjects property  with an example.

Thanks,

Naresh Kodumuri.

[lingBB10Dev]

Not sure if you had a chance to read the description about the attachedobjects

https://developer.blackberry.com/cascades/reference/bb__cascades__uiobject.html#attachedobjects

Usually, the attachedObjects property is  used to contain "non-UI" objects,  e.g.: objects wrapping some "business logic". They are used to reduce the code of exchanging information between qml and c++ code.

There are some example apps you may want to consult for the usages of attachedObjects.

https://github.com/blackberry/Cascades-Samples

For example:

 MultithreadingCallBacks101,  it uses attachedObjects property to contain counter objects.

 FunWithSensors, it uses attachedObjects property to contain sensor object.

[ekke]

attached Objects are not only used for Business Logic.

You have to use attached Objects to attach UI COntrols or Pages etc not visible from startup.

one example: Sheets

attachedObjects: [
        Sheet {
            id: loginSheet
            content: LoginSheet {
                id: loginContent
            }
        },
        Sheet {
            id: helpSheet
            content: HelpSheet {
                id: helpContent
            }
        }
]

 then it's easy to say helpSheet.visible = true to push the sheet on top

or a NavigationPane can hold all the Pages as attached Objects

and you can push them easy:

ActionItem {
                title: qsTr ("About")
                ActionBar.placement: ActionBarPlacement.OnBar
                onTriggered: {
                    navigationPane.push(aboutSite)
                }
            }

I'm also using attachedObjects to store Images there if I per ex. switch many times between them (per ex. for Landscape / Portrait)

attachedObjects: [
            // we need this image as background for the HomeScreen
            // because we toggle often we use an ImageTracker
            // TODO: different background images for different sizes of smartphone or tablet
            ImageTracker {
                id: backgroundLandscape
                imageSource: "asset:///images/bg-1280x768.png"
            }, 
            // the BackgroundImage
            ImageTracker {
                id: backgroundPortrait
                imageSource: "asset:///images/bg-768x1280.png"
            },
            // the Website
            ImageTracker {
                id: websiteImage
                imageSource: "asset:///images/website.png"
            },
            // the Fan-of-The-Month
            ImageTracker {
                id: fomImage
                imageSource: "asset:///images/fom-61.png"
            },
            // application supports changing the Orientation
            OrientationHandler {
                onUiOrientationChanged: {
                    if (uiOrientation == UiOrientation.Landscape) {
                        backgroundImage.image = backgroundLandscape.image
                    } else {
                        backgroundImage.image = backgroundPortrait.image
                    }
                }
            }
        ]

only some examples

you'll find all of them now (or after my next pushes ;-) here in this Cascades Open Source Project by me:

opendataspace

ekke

[nareshkodumuri]

Hi,

Thanks for ur reply.Now i got an idea about attached objects and it's usage.Thanks for helping me.

Regards,

Naresh Kodumuri.