I want to draw a QComboBox inside a delegate, which works fine except that I can't figure out how to draw the inital text that's visible inside the combo box.
The documentation says that QStyleOptionComboBox.currentText holds: "the text for the current item of the combo box." but setting the variable does not have any effect.
This is my code:
void MyDelegate::paint(QPainter *painter,
const QStyleOptionViewItem& option,
const QModelIndex& index) const
{
QStyleOptionComboBox comboBoxOption;
comboBoxOption.rect = option.rect;
comboBoxOption.state = option.state;
comboBoxOption.state |= QStyle::State_Enabled;
comboBoxOption.editable = false;
comboBoxOption.currentText = "CCC"; // This doesn't show up.
QApplication::style()->drawComplexControl(QStyle::CC_ComboBox, &comboBoxOption, painter);
}
Looking at qwindowsxpstyle.cpp I don't see where the text of a "real" combo box is drawn since currentText is not used inside the drawComplexControl method. The only place where it seems to be used for Windows XP style is in qcommonstyle.cpp (Line 2107, Qt 4.7.2), but I can't figure out how those two classes play together.
It seems you also need to force Qt to draw the combo box label, in addition to the complex control. Try this:
QApplication::style()->drawControl(QStyle::CE_ComboBoxLabel, &comboBoxOption, painter)
If I read the documentation, and source, correctly that might force QStyle to draw a combo box label. It seems odd that you'd have to specify both...but I don't know a whole lot about how Qt styles draw themselves, to be honest.
Related
Is there any way to customize focus rect size for QTreeView item? I have reviewed source code of paint() event of QStyledItemDelegate, and there is query for textRect inside them, but i not found the way to resize focus rect, it only paint a part of cell, containing text, i need to focus rect fill the entire cell rect. Any help?
cell focus rect example
The default selection highlight depends on the current app style. On Windows it's partial, which is how other Windows apps behave. With Fusion style (default on Linux) the selection highlight already covers the full item rectangle. Not sure on Mac.
Anyway, it's easily controlled with a style option which is set in the item delegate. All we need to do is set a flag, and luckily the style option init function is virtual. This is the same flag which is set by default for some styles. Try this item delegate:
class HighlightDelegate : public QStyledItemDelegate
{
public:
using QStyledItemDelegate::QStyledItemDelegate;
protected:
void initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const override
{
QStyledItemDelegate::initStyleOption(option, index);
option->showDecorationSelected = true;
}
};
I need to draw an icon on the items of a QTableView.
What I'm getting now is the following (each big rectangle is an item):
with the following code in the method
QVariant myClass::data(const QModelIndex& index, int role) const
...
case Qt::DecorationRole:
{
QPixmap pix(m_cellSize, m_cellSize);
QPainter painter( &pix );
painter.setFont( QFont("Arial", m_cellSize / 2) );
painter.setPen(Qt::black);
painter.drawRect(0, 0, m_cellSize - 1, m_cellSize - 1);
painter.drawText( QRect(0, 0, m_cellSize, m_cellSize), Qt::AlignTop, QString::number(m_letters[index.row()][index.column()].number) );
QIcon icon(pix);
return icon;
}
...
I do a drawRect only to see how the pixmap is and where the text is inside it. I can align the text in the pixmap but I cannot align the icon inside the item.
In few words, I need to draw this icon on the top left corner of the table view item but I don't know how to. It's always vertically aligned.
Any help would be appreciated.
You can investigate if changing Qt::TextAlignmentRole makes a difference, but my guess is it won't. The usual way to solve this is to implement a custom delegate, i.e subclass QStyledItemDelegate, and override the paint method. I suspect this might also give better performance, since you could do your custom drawing there, and return you model data in Qt::DisplayRole as a QString instead.
I'm making a few assumptions in this, but if you look at the examples of custom item delegates I think you will see something very close to what you need.
1) How can I wrap text in a QGraphicsTextItem to fit a fixed rectangle, with width and height ?
Right now I am experimenting with creating a text, getting its bounding rectangle, and resizing it to fit the box - but I can't get wrapping.
class TTT: public QGraphicsTextItem {
TTT() {
{
setPlainText("abcd");
qreal x = m_itemSize.width()/boundingRect().width();
qreal y = m_itemSize.height()/boundingRect().height();
scale(x, y);
}
void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget) {
// experiment with clip regions
// text gets covered by hole in clip
QRegion r0(boundingRect().toRect());
QRegion r1(QRect(5, 5, 10, 10), QRegion::Ellipse);
QRegion r2 = r0.subtracted(r1);
painter->setClipRegion(r2);
painter->setBrush(Qt::yellow);
painter->drawRect(boundingRect());
QGraphicsTextItem::paint(painter, option, widget);
}
}
What makes wrapping happen, how can I trigger it ?
Right now, as I keep typing, the box is automatically expanding.
2) Is it possible to wrap the text in a QGraphicsItem / QGraphicTextItem subclass in a shape that is not a rectangle ?
(Something like in the image above)
I tried to use clipRegion, see code above, but I guess it is not the right way to go, clipping cuts the text but did not wrap.
Maybe it would... If I could figure out how to wrap text in the first place ?
Qt 4.8
You did not specify Qt version but try:
void QGraphicsTextItem::setTextWidth(qreal width)
Sets the preferred width for the item's text. If the actual text is wider than >the specified width then it will be broken into multiple lines.
If width is set to -1 then the text will not be broken into multiple lines >unless it is enforced through an explicit line break or a new paragraph.
The default value is -1.
In answer to 1) I'd opt not to use the QGraphicsTextItem, but draw the text directly in your QGraphicsItem's paint function using the drawText overloaded function, which takes a QTextOption parameter.
Using this, you can set the WrapMode, for example, with a call to
QTextOption::setWrapMode(QTextOption:: WordWrap)
As for 2) with a non-rectangular shape, I don't think Qt will do this for you.
Doing it yourself you can use QFontMetrics, to work out just how much text would fit in each line, depending upon where it lies within its bounding item.
Alternatively, you could adapt the concept of a text-to-path method.
Is it possible to use clipping in an widgets painEvent, if the widget is using stylesheets?
The background and reason for my question is that I want to make the widget animating when it appears and disappears. (Something like a resizing circle or square, that gets bigger starting as a small area from the center).
My first (and only) thought on how to solve this, was to use the clipping of a QPainter, so that only the required area is drawn.
If I make the Background of the widget transparent and use the primitive drawing functions from QPainter it works fine. But how can I solve this, if the widget has a stylesheet applied? Is it even possible?
The used Qt version is Qt 4.8.6
My questions are:
Is it possible to achieve what I want with the mentioned strategy?
Is it possible in any way to clip all the children, too?
Is my strategy appropriate or is it a bad Idea to solve it that way?
Are there any other ideas, best practices, Qt Classes, ... that can give me what I want?
Additional Information
I haven't much code to show, because I stuck with this clipping things. But here is something to get an idea of what I have tried:
This works.
/* Shows a small red circle inside the widget as expected */
void MyAnimatingWidget::paintEvent(QPaintEvent *ev) {
QPainter painter(this);
QRect rect = this->geometry()
QStyleOption opt;
painter.setClipRegion(QRegion(rect.width()/2,
rect.height()/2,
150, 150,
QRegion::Ellipse));
painter.setPen(QColor(255, 0, 0));
painter.setBrush(QColor(255, 0, 0));
painter.setOpacity(1);
painter.drawRect(rect);
}
But the following doesn't change anything:
/* This shows the widget as usual */
void MyAnimatingWidget::paintEvent(QPaintEvent *ev) {
QPainter painter(this);
QRect rect = this->geometry();
QStyleOption opt;
painter.setClipRegion(QRegion(rect.width()/2,
rect.height()/2,
150, 150,
QRegion::Ellipse));
painter.setRenderHint(QPainter::Antialiasing);
painter.setOpacity(1);
opt.init(this);
style()->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this);
}
Moreover I have noticed, that the stylesheet is also drawn, even if I remove the style()->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this); line at all.
The stylesheet you apply to your widget overrides the OS-specific style(s) widgets are equipped with by default. This can even cause problems, if you want to have a, say, Windows look, but still want to use a stylesheet. Anyway, you can check what each style does in the Qt source directory: src/gui/styles. For style()->drawPrimitive(QStyle::PE_Widget, &opt, &painter, this);, the code reads:
case PE_Widget:
if (w && !rule.hasDrawable()) {
QWidget *container = containerWidget(w);
if (styleSheetCaches->autoFillDisabledWidgets.contains(container)
&& (container == w || !renderRule(container, opt).hasBackground())) {
//we do not have a background, but we disabled the autofillbackground anyway. so fill the background now.
// (this may happen if we have rules like :focus)
p->fillRect(opt->rect, opt->palette.brush(w->backgroundRole()));
}
break;
}
As you can see clipping is not meddled with in any way, so your idea of setting a clip region should work. Now for the painting mystery. The painting of the background happens in void QWidgetPrivate::paintBackground(QPainter *painter, const QRegion &rgn, int flags) const, which is called from void QWidgetPrivate::drawWidget(QPaintDevice *pdev, const QRegion &rgn, const QPoint &offset, int flags, QPainter *sharedPainter, QWidgetBackingStore *backingStore). You can find the code in: /src/gui/kernel/qwidget.cpp. The relevant code reads:
if (q->testAttribute(Qt::WA_StyledBackground)) {
painter->setClipRegion(rgn);
QStyleOption opt;
opt.initFrom(q);
q->style()->drawPrimitive(QStyle::PE_Widget, &opt, painter, q);
}
Maybe turning the attribute off would help? The basic lesson you should draw from my answer is to get accustomed to source diving. The idea behind Qt is nice (instantiating controls, without bothering about implementation details), but it rarely works in practice, i.e. you often need to source dive.
To clip widget's children to arbitrary clip regions, you can capture them into a pixmap, example:
QPixmap pixmap(widget->size());
widget->render(&pixmap);
And then draw the pixmap manually. You might also be able to prevent them repainting automatically (via setUpdatesEnabled() or by hiding them) and then calling their render in you paintEvent handler manually.
I have a QGraphicsTextItem subclass that accepts mouse events (i.e. implements wheelEvent() method.
How can I check on which position within the text the wheel event happened? I would like to get the letter that the mouse pointer pointed at when the wheel event happened.
BTW: one possible solution is to create a series of QGraphicsTextItem objects -- one for every letter. This way each letter can accept it's own events, but I loose all the kerning and other typesetting sophistication.
To get the mouse position, you can use QWheelEvent::pos.
I don't see any API to get the letter at a given QPointF in the item. you could try to get a maybe good enough approximation using QFontMetricsF though, doing something like
const int wx = wheelEvent->pos().x(); //might have to map to item coordinates
const qreal leftX = item->boundingRect().left();
const QFontMetricsF fm( item->font() );
int pos = 0;
while ( fm.width( text.left( pos ) - leftX < wx )
pos++; //could be optimized by something binary-search-like
If that doesn't work out, you could try with a custom text item where you do the painting (QPainter::drawText) yourself, so you have more control over the positioning of the text in the item's coordinate system.