[Interest] Implementing tag cloud with QML

Nuno Santos nunosantos at imaginando.pt
Mon Sep 28 12:36:46 CEST 2015


Item is of class Item
itemList model is of class QList<Item*>

Item has the property tags which is of type QStringList
Each item has ItemManager, the holder of itemList model, as parent

On toggleTag I’m doing this:

void DRCPatch::toggleTag(QString tag)
    if (_tags.contains(tag))

    emit _manager->tagsChanged();

And in fact, the model is returned. I have confirmed that the model property has been called. However, ListView doesn’t update or re-layout if the items are exactly the same. 

If here I do _tags.append(“something”) it will update and behave as expected. 

QStringList ItemManager::tags()
    return _tags;

Any ideas on how to work around this?



> On 28 Sep 2015, at 10:54, Ben Lau <xbenlau at gmail.com> wrote:
> How do you use the toggleTag? And what is the data type of element in itemList.model?
> On 28 September 2015 at 17:19, Nuno Santos <nunosantos at imaginando.pt <mailto:nunosantos at imaginando.pt>> wrote:
> Hi,
> I was trying to implement a tag cloud with a ListView but I'm facing some unexpected problems. My idea was the following:
> A ListView would have a model of tags, based on a QStringList. Other list view would have items (custom model), each item would have associated tags. I want to concentrate the tags in a single list in the UI. So, when you select an item, it will display all the tags, and the ones which are present in that item would get highlighted.
> Every time I click a tag, it will toggle that tag for the respective item. The problem is that for some reason, ListView seems to cache the data model and thus it doesn’t get redrawn. Because the tags are the exactly the same. What changed was item tags list. 
> Is there anyway to bypass the model cache or force the ListView to redraw? I can’t find any suitable method on ListView documentation.
> I’m not finding an obvious solution for this problem and I believe that is a simple solution for it. Any ideas?
> ListView {
> 	id: tagsList
> 	model: tags
> 	delegate: Rectangle {
> 	    color: "transparent"
> 	    border.color: "white"
> 	    border.width: 1
> 	    Text {
> 	        id: tagLabel
> 	        color: "gray"
> 	        text: "#"+modelData
> 	        Component.onCompleted: {
> 	            var tags = itemList.model[itemList.currentIndex].tags;
> 	            for (var i=0;i<tags.length;i++)
> 	            {
> 	                if (tags[i]==modelData)
> 	                    color = "white"
> 	            }
> 	        }
> 	    }
> 	    MouseArea {
> 	        anchors.fill: parent
> 	        onClicked: itemList.model[itemList.currentIndex].toggleTag(modelData)
> 	    }
> 	}
> }
> Thanks in advance,
> Regards,
> Nuno
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