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I have to make scrollbar with handle of fixed size since its background image becomes ugly when being scaled. I use the following style sheet:
QScrollBar::handle:vertical {
border-image:url(:/images/handle.png);
min-height: 47px;
max-height: 47px;
height: 47px;
width:10px;
}
but it seems like max-height isn't valid property. How to prevent handle scaling?
793
Simply add the Scrollbar. size call on the OnValueChange for the scrollRect with the value you want. That's pretty much the same performance cost as setting a fixed size by code, without having to write any.
To get the width of the scrollbar, you use the offsetWidth and clientWidth of the Element : The offsetWidth returns the width of the Element in pixels including the scrollbar. The clientWidth returns the with of the Element in pixels without the scrollbar.
The scrollbar-width property is used to set the width or thickness of an element's scrollbar when shown. This property can be used on pages where the user interface requires the element to be displayed more prominently and shrinking the scrollbar width gives more space to the element.
scrollbar-width accepts the following values: auto is the default value and will render the standard scrollbars for the user agent. thin will tell the user agent to use thinner scrollbars, when applicable. none will hide the scrollbar completely, without affecting the element's scrollability.
Little trick, from Qt source code: myScrollbar.h
class myScrollBar : public QScrollBar
{
Q_OBJECT
public:
myScrollBar(Qt::Orientation orientation, QWidget *parent = 0);
void setSliderLength(int length);
protected:
void paintEvent(QPaintEvent *);
private:
QRect subControlRect(QStyle::ComplexControl cc, const QStyleOptionComplex *opt, QStyle::SubControl sc, /*const*/ QWidget *widget);
QRect visualRect(Qt::LayoutDirection direction, const QRect &boundingRect, const QRect &logicalRect);
int sliderPositionFromValue(int min, int max, int logicalValue, int span, bool upsideDown);
private:
int _sliderLength;
};
myScrollbar.cpp
myScrollBar::myScrollBar(Qt::Orientation orientation, QWidget *parent)
: QScrollBar(orientation, parent),
_sliderLength(100)
{
}
void myScrollBar::paintEvent(QPaintEvent *e)
{
qDebug() << "scrollbar paintevent";
//Q_D(QScrollBar);
QScrollBar::paintEvent(e);
QPainter painter(this);
QStyleOptionSlider opt;
initStyleOption(&opt);
opt.subControls = QStyle::SC_All;
QWidget *widget = this;
// if (d->pressedControl) {
// opt.activeSubControls = (QStyle::SubControl)d->pressedControl;
// if (!d->pointerOutsidePressedControl)
// opt.state |= QStyle::State_Sunken;
// } else {
// opt.activeSubControls = (QStyle::SubControl)d->hoverControl;
// }
QPainter *p = &painter;
//style()->drawComplexControl(QStyle::CC_ScrollBar, &opt, &p, this);
if (const QStyleOptionSlider *scrollbar = &opt) {
// Make a copy here and reset it for each primitive.
QStyleOptionSlider newScrollbar = *scrollbar;
QStyle::State saveFlags = scrollbar->state;
if (scrollbar->subControls & QStyle::SC_ScrollBarSubLine) {
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarSubLine, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarSubLine))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarSubLine, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarAddLine) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarAddLine, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarAddLine))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarAddLine, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarSubPage) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarSubPage, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarSubPage))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarSubPage, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarAddPage) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarAddPage, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarAddPage))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarAddPage, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarFirst) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarFirst, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarFirst))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarFirst, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarLast) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
newScrollbar.rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarLast, widget);
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarLast))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarLast, &newScrollbar, p, widget);
}
}
if (scrollbar->subControls & QStyle::SC_ScrollBarSlider) {
newScrollbar.rect = scrollbar->rect;
newScrollbar.state = saveFlags;
QRect rect = subControlRect(QStyle::CC_ScrollBar, &newScrollbar, QStyle::SC_ScrollBarSlider, widget);
newScrollbar.rect = QRect(rect.topLeft(), QSize(rect.width(), 100));
if (newScrollbar.rect.isValid()) {
if (!(scrollbar->activeSubControls & QStyle::SC_ScrollBarSlider))
newScrollbar.state &= ~(QStyle::State_Sunken | QStyle::State_MouseOver);
style()->drawControl(QStyle::CE_ScrollBarSlider, &newScrollbar, p, widget);
if (scrollbar->state & QStyle::State_HasFocus) {
QStyleOptionFocusRect fropt;
fropt.QStyleOption::operator=(newScrollbar);
fropt.rect.setRect(newScrollbar.rect.x() + 2, newScrollbar.rect.y() + 2,
newScrollbar.rect.width() - 5,
newScrollbar.rect.height() - 5);
style()->drawPrimitive(QStyle::PE_FrameFocusRect, &fropt, p, widget);
}
}
}
}
}
void myScrollBar::setSliderLength(int length)
{
_sliderLength = length;
}
QRect myScrollBar::subControlRect(QStyle::ComplexControl cc, const QStyleOptionComplex *opt, QStyle::SubControl sc, /*const*/ QWidget *widget)
{
QRect ret;
switch (cc) {
case QStyle::CC_ScrollBar:
if (const QStyleOptionSlider *scrollbar = qstyleoption_cast<const QStyleOptionSlider *>(opt)) {
const QRect scrollBarRect = scrollbar->rect;
int sbextent = 0;
if (!style()->styleHint(QStyle::SH_ScrollBar_Transient, scrollbar, widget))
sbextent = style()->pixelMetric(QStyle::PM_ScrollBarExtent, scrollbar, widget);
int maxlen = ((scrollbar->orientation == Qt::Horizontal) ?
scrollBarRect.width() : scrollBarRect.height()) - (sbextent * 2);
int sliderlen;
// calculate slider length
if (scrollbar->maximum != scrollbar->minimum) {
uint range = scrollbar->maximum - scrollbar->minimum;
sliderlen = (qint64(scrollbar->pageStep) * maxlen) / (range + scrollbar->pageStep);
int slidermin = style()->pixelMetric(QStyle::PM_ScrollBarSliderMin, scrollbar, widget);
if (_sliderLength < slidermin || range > INT_MAX / 2)
_sliderLength = slidermin;
if (_sliderLength > maxlen)
_sliderLength = maxlen;
//length of the slider
sliderlen = _sliderLength;
} else {
sliderlen = maxlen;
}
int sliderstart = sbextent + this->sliderPositionFromValue(scrollbar->minimum,
scrollbar->maximum,
scrollbar->sliderPosition,
maxlen - sliderlen,
scrollbar->upsideDown);
switch (sc) {
case QStyle::SC_ScrollBarSubLine: // top/left button
if (scrollbar->orientation == Qt::Horizontal) {
int buttonWidth = qMin(scrollBarRect.width() / 2, sbextent);
ret.setRect(0, 0, buttonWidth, scrollBarRect.height());
} else {
int buttonHeight = qMin(scrollBarRect.height() / 2, sbextent);
ret.setRect(0, 0, scrollBarRect.width(), buttonHeight);
}
break;
case QStyle::SC_ScrollBarAddLine: // bottom/right button
if (scrollbar->orientation == Qt::Horizontal) {
int buttonWidth = qMin(scrollBarRect.width()/2, sbextent);
ret.setRect(scrollBarRect.width() - buttonWidth, 0, buttonWidth, scrollBarRect.height());
} else {
int buttonHeight = qMin(scrollBarRect.height()/2, sbextent);
ret.setRect(0, scrollBarRect.height() - buttonHeight, scrollBarRect.width(), buttonHeight);
}
break;
case QStyle::SC_ScrollBarSubPage: // between top/left button and slider
if (scrollbar->orientation == Qt::Horizontal)
ret.setRect(sbextent, 0, sliderstart - sbextent, scrollBarRect.height());
else
ret.setRect(0, sbextent, scrollBarRect.width(), sliderstart - sbextent);
break;
case QStyle::SC_ScrollBarAddPage: // between bottom/right button and slider
if (scrollbar->orientation == Qt::Horizontal)
ret.setRect(sliderstart + sliderlen, 0,
maxlen - sliderstart - sliderlen + sbextent, scrollBarRect.height());
else
ret.setRect(0, sliderstart + sliderlen, scrollBarRect.width(),
maxlen - sliderstart - sliderlen + sbextent);
break;
case QStyle::SC_ScrollBarGroove:
if (scrollbar->orientation == Qt::Horizontal)
ret.setRect(sbextent, 0, scrollBarRect.width() - sbextent * 2,
scrollBarRect.height());
else
ret.setRect(0, sbextent, scrollBarRect.width(),
scrollBarRect.height() - sbextent * 2);
break;
case QStyle::SC_ScrollBarSlider:
if (scrollbar->orientation == Qt::Horizontal)
ret.setRect(sliderstart, 0, sliderlen, scrollBarRect.height());
else
ret.setRect(0, sliderstart, scrollBarRect.width(), sliderlen);
break;
default:
break;
}
ret = visualRect(scrollbar->direction, scrollBarRect, ret);
}
return ret;
}
}
QRect myScrollBar::visualRect(Qt::LayoutDirection direction, const QRect &boundingRect, const QRect &logicalRect)
{
if (direction == Qt::LeftToRight)
return logicalRect;
QRect rect = logicalRect;
rect.translate(2 * (boundingRect.right() - logicalRect.right()) +
logicalRect.width() - boundingRect.width(), 0);
return rect;
}
int myScrollBar::sliderPositionFromValue(int min, int max, int logicalValue, int span, bool upsideDown)
{
if (span <= 0 || logicalValue < min || max <= min)
return 0;
if (logicalValue > max)
return upsideDown ? span : min;
uint range = max - min;
uint p = upsideDown ? max - logicalValue : logicalValue - min;
if (range > (uint)INT_MAX/4096) {
double dpos = (double(p))/(double(range)/span);
return int(dpos);
} else if (range > (uint)span) {
return (2 * p * span + range) / (2*range);
} else {
uint div = span / range;
uint mod = span % range;
return p * div + (2 * p * mod + range) / (2 * range);
}
// equiv. to (p * span) / range + 0.5
// no overflow because of this implicit assumption:
// span <= 4096
}
eg:
myScrollBar *bar = new myScrollBar(Qt::Vertical, ui->treeWidget);
ui->treeWidget->setVerticalScrollBar(bar);
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