[Interest] QCombobox - resize list view to horizontal contents
daniel.price at fxhome.com
Mon Sep 3 18:20:59 CEST 2012
I have a Qt-Windows applicastion.
I have a non-editable QComboBox subclass with a custom QAbstractListModel driving it. I have a simple QListView subclass acting as the view for the combobox.
I need the list view (NOT the combo) to resize horizontally to fit the widest string in the list instead of being fixed to the width of the combo button.
Previously, I used a QListWidget subclass as a the view and overrode the sizeHint():
struct ComboListWidget : public QListWidget
ComboListWidget(QWidget *parent = 0)
virtual QSize sizeHint() const
int maxWidth = 0;
for (int i=0; i < count(); ++i)
QListWidgetItem *it = item(i);
const QSize sz = fm.size(Qt::TextSingleLine, it->text());
maxWidth = qMin(qMax(maxWidth, sz.width()), MaxListWidth);
QMargins mar = contentsMargins();
int hpad = (mar.left() + mar.right()) * 2;
return QSize(maxWidth + hpad, 0);
But this code was really expensive, particularly if the list contains dozens of entries.
As I'm now using a custom model, I tried to implement a custom SizeHintRole:
if (role == Qt::SizeHintRole)
const QString &text = data(index, Qt::DisplayRole).value<QString>();
QFontMetrics fontMetrics(data(index, Qt::FontRole).value<QFont>());
//QSize size(fontMetrics.width(text), fontMetrics.height());
return QSize(1000,20); // ignores the 1000
But the list view only uses the vertical size and I nothing I do seems to work. If I set the list view to a fixed width in it's constructor, it breaks the selection-highlight such that it only extends as far as the combobox's width.
This only seems to be a problem on Windows. On OSX, the list view expands correctly with no additional code.
There must be a way to do this - please help!
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