An id problem, please help me.

open-src

Someone can tell me that why the id, gridViewDelegate, can not be referenced in GridView object in the snippet of my main.qml below:
@Item{

.........
GridViewDelegate{
id:gridViewDelegate
width: parent.width/5; height: parent.height/3
}

GridView{
    id:gridView
    anchors.fill: parent

    model: pictureModel
    delegate: gridViewDelegate
}

.........
}@

thisisbhaskar

deligate takes a component, not a concrete item. GridView is going to create instances of your component when ever needed based on the data in Model.

One thing you can do is to place your GridViewDeligate inside a component item and assing component item's id to deligate

@ Component {
id: gridViewComponent
GridViewDelegate{
id:gridViewDelegate
width: parent.width/5; height: parent.height/3
}
}
delegate: gridViewComponent @

This should work :) and I hope you understand why we need to do this.

open-src

@Vijay Bhaska Reddy

Thanks for your reply!
In fact,my problem is:
I have three qml documents, PictureGridView.qml、PictureGridViewDelegate.qml、 and main.qml. The model has exposed to qml from C++, its name is pictureModel. I create the GridViewDelegate object, Why I can't reference it using its id?

Here is PictureGridView.qml:
@import Qt 4.7

Item {
anchors.fill: parent
property int cellWith: gridView.cellWidth
property int cellWith: gridView.cellHeight

GridView {
    id:gridView
    flow: GridView.TopToBottom
    highlight: Rectangle { color: "lightsteelblue"; radius: 5 }
    focus: true
}

}@

Here is PictureGridViewDelegate.qml:
@import Qt 4.7

Item{
property alias mode: image.fillMode

Image{
    id:picture

    visible: true
    smooth: true
    opacity: 1
    fillMode: Image.PreserveAspectCrop
    source: pathName

    MouseArea {
        focus: true
        hoverEnabled : true
        anchors.fill: parent          
    }
}

}
@

Here is the main.qml:

@Item{

.........
GridViewDelegate{
id:gridViewDelegate
width: parent.width/5; height: parent.height/3
}

GridView{
    id:gridView
    anchors.fill: parent

    model: pictureModel
    delegate: gridViewDelegate
}

.........
}@

According to qml documents API, the GridViewDelegate is a qml compomnent type, why it have to be placed into a _ Component_ element?

Btw: I am puzzle about multifile programming in qml, can you give me any guidance again?

Hornsj2

First off, you are never declaring a PictureGridView element or a PictureGridViewDelegate element in your main.qml file.

There is no type named GridViewDelegate in QML, custom type names are based off the file name (so the type name would be PictureGridViewDelegate).

The types you have available based on those files are

PictureGridView
PictureGridViewDelegate

Try using those types in place of GridViewDelegate and GridView.

open-src

I am too careless!
I modify the main.qml:
@
Item{

.........
PictureGridViewDelegate{
id:pictureGridViewDelegate
source: pathName
mode: Image.PreserveAspectCrop
}

PictureGridView{
    id:pictureGridView
    anchors.fill: parent


    model: pictureModel
    delegate: pictureGridViewDelegate

}

.........
}@
But the QtCreator say that "Unable to assign QObject* to QDeclarativeComponent*" in the PictureGridViewDelegate object above.

Hornsj2

I'm not sure becasue I haven't bothered to look at the docs. However, can a root object in QML be of type Item?

Try rectangle.

thisisbhaskar

mm... you never have model and deligate available in your PictureGridView. If you look at your PictureGridView qml file, you have an item and then you have an GridView inside that item.

@PictureGridView{
id:pictureGridView
anchors.fill: parent

    model: pictureModel
    delegate: pictureGridViewDelegate

}@

I would suggest you to go through few introductory videos / tutorial of qml.

open-src

@Vijay Bhaska Reddy

Thanks a lot.
I confused the concept of the component, I have believed the top-level item element MUST be Item\Component\Rectangle\FocusScope\QtObject in a single qml once, then I think it a mistake now...