[Qt-interest] QTreeView, additional images

[Thomas Ehrnhoefer]

Currently investigating custom drawing, but i am failing to make the icon
appear.

I used to create the QStandardItem with a label and an icon, and it showed
up fine. Now I added my own QStyledItemDelegate implementation.
First of all, if I set .text on the QStyleOptionViewItem, it does not
override what is set on the QStandardItem (but if I invoke the empty
constructor there, the value I set in my delegate's paint method gets used).
This is a bit confusing as I would have thought that overriding the paint
method takes precedence over the QStandardItem's value.

Additionally (and more importantly) I am failing to draw an image. Again, I
was hoping just to set the new icon on the option, but that draws nothing.
Here is the code:

void MyItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &
option, const QModelIndex &index) const

{

    QStyleOptionViewItemV4 optionv4(option);

    optionv4.text = "test";

    optionv4.font.setBold(true);

    optionv4.icon = imageProvider->icon(ImageProvider::MyImage);

    QStyledItemDelegate::paint(painter, optionv4, index);

}


I am trying to understand the mechanisms before going into custom drawing,
but I seem to fail with this simple example.

Thanks for any input

Thomas

On Tue, Apr 26, 2011 at 7:32 AM, Thomas Ehrnhoefer <
thomas.ehrnhoefer at tasktop.com> wrote:

> Thanks Andre, Eckhard,
>
> I will see what I can find out about the things you mentioned.
> Sadly caching each of the images in composite form is less than ideal, as
> the combinations are plenty, and at least one of the images is retrieved
> from the network.
>
>
> On Tue, Apr 26, 2011 at 2:15 AM, Eckhard Jokisch <e.jokisch at orange-moon.de
> > wrote:
>
>> On Tuesday 26 April 2011 01:27:54 Thomas Ehrnhoefer wrote:
>> > Hi
>> >
>> > I have a TreeViewer, and I would like to have additional images
>> available.
>> > I don't want multiple columns, just additional decorations (images) to
>> > (some) of the items (e.g. a "changed" indicator). An example would be
>> > http://oboedit.org/docs/images/tree_view_single.png
>> >
>> > Since I am new to Qt, I am wondering what the best way (if there is any)
>> to
>> > do this would be. Most likely some custom drawing I assume, but I am
>> unsure
>> > on how/where to start.
>> >
>> > Any hints are very welcome
>> >
>> > Thanks
>> > Thomas
>>
>> I think what you are looking for is something like the below implemented
>> into
>> your ::data() function of the model where "item" is an item out of the
>> model
>> and the item->status() returns either CHANGED or UNCHANGED or somethins
>> else
>> useful.
>> The switch over the actual index.column() allows you to have different
>> icons in
>> different collumns - which you don't need right now but you never know
>> what's
>> coming next ;)
>>
>> Cheers
>> Eckhard
>> .....
>> QVariant YourModel::::data(const QModelIndex &index, int role) const
>>  {
>>     if (!index.isValid())
>>         return QVariant();
>>
>>        if (role == Qt::DecorationRole )
>>       {
>>         QPixmap p;
>>
>>         switch(index.column())
>>         {
>>         case 0:
>>             switch(item->status() )
>>             {
>>             case CHANGED:
>>                 p.load(":/icons/changed-icon.png");
>>                 break;
>>             case UNCHANGED:
>>                 p.load(":/icons/unchanged-icon.png");
>>                 break;
>>             default:
>>                 p.load(":/icons/some-icon.png");
>>                 break;
>>             }
>>             break;
>>         case 1:
>>             if(p.isNull())
>>             {
>>                 p.load(":/icons/warn.png");
>>             }
>>             else
>>             {
>>                 p.load(":/icons/ok.png");
>>             }
>>             break;
>>         default:
>>             break;
>>         }
>>         return p;
>>       }
>> .....
>> }
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>>
>
>
>
> --
> Thomas Ehrnhoefer
> Software Developer, http://tasktop.com
>



-- 
Thomas Ehrnhoefer
Software Developer, http://tasktop.com
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