自定义 QStyledItemDelegate 绘制多种颜色的文本
Custom QStyledItemDelegate to draw text with multiple colors
我想在 QTableWidget
中显示两列,显示两个刺之间的差异(之前由一些 Levenshtein 距离算法计算)。零件存储在每个QTableWidgetItem
的数据里面,作为一个QStringList
。第一部分必须显示黑色,下一个显示红色,然后再次交替显示黑色、红色等。
为此,我实现了一个 QStyledItemDelegate
和一个最终调用 drawText()
方法的自定义 paint()
函数:
void DifferencesDelegate::drawText(QPainter *painter,
const QStyleOptionViewItem &option,
const QModelIndex &index) const
{
painter->save();
const QPen defaultPen = painter->pen();
QStyleOptionViewItem opt = option;
initStyleOption(&opt, index);
opt.text.clear();
QStyle *style = opt.widget ? opt.widget->style() : QApplication::style();
style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, opt.widget);
opt.rect.moveRight(opt.rect.right() + 3);
int color = 1;
for (const QString &part : index.data(Qt::UserRole).toStringList()) {
color++;
color = color % 2;
if (color) {
painter->setPen(Qt::red);
} else {
painter->setPen(defaultPen);
}
style->drawItemText(painter, opt.rect, opt.displayAlignment, opt.palette, true, part);
opt.rect.moveRight(opt.rect.right() + painter->fontMetrics().width(part));
}
painter->restore();
}
只要列的宽度足够,这就会导致正确的绘制:
但是一旦列变小,我就会出现混乱的溢出:
这肯定是由于 opt.rect
应用于显示的每个部分,而不是整个文本。
唯一的问题是我不知道如何解决这个问题;-)任何帮助将不胜感激!提前致谢!
出乎意料的是,我设法解决了它;-)
void DifferencesDelegate::drawText(QPainter *painter, const QStyleOptionViewItem &option,
const QModelIndex &index) const
{
if (! index.data(Qt::UserRole).isValid()) {
TableDelegate::drawText(painter, option, index);
return;
}
painter->save();
const QPen defaultPen = painter->pen();
QStyleOptionViewItem opt = option;
initStyleOption(&opt, index);
opt.text.clear();
QStyle *style = opt.widget ? opt.widget->style() : QApplication::style();
style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, opt.widget);
constexpr int offset = 3;
const QString ellipsis = QStringLiteral("…");
const int ellipsisWidth = painter->fontMetrics().width(ellipsis);
const int rightBorder = opt.rect.left() + opt.rect.width() - offset;
QRect drawRect;
int color = 1;
int partWidth;
bool overflow = false;
opt.rect.moveRight(opt.rect.right() + offset);
const QStringList parts = index.data(Qt::UserRole).toStringList();
const int partsCount = parts.count();
for (int i = 0; i < partsCount; i++) {
color++;
color = color % 2;
if (color) {
painter->setPen(Qt::red);
} else {
painter->setPen(defaultPen);
}
partWidth = painter->fontMetrics().width(parts.at(i));
drawRect = opt.rect;
if (drawRect.left() + partWidth + (i == partsCount - 1 ? 0 : ellipsisWidth) > rightBorder) {
drawRect.setWidth(rightBorder - drawRect.left() - ellipsisWidth);
overflow = true;
}
style->drawItemText(painter, drawRect, opt.displayAlignment, opt.palette, true,
parts.at(i));
if (overflow) {
drawRect.setLeft(rightBorder - ellipsisWidth);
drawRect.setWidth(ellipsisWidth);
style->drawItemText(painter, drawRect, opt.displayAlignment, opt.palette, true,
ellipsis);
break;
}
opt.rect.moveRight(opt.rect.right() + partWidth);
}
painter->restore();
}
我想在 QTableWidget
中显示两列,显示两个刺之间的差异(之前由一些 Levenshtein 距离算法计算)。零件存储在每个QTableWidgetItem
的数据里面,作为一个QStringList
。第一部分必须显示黑色,下一个显示红色,然后再次交替显示黑色、红色等。
为此,我实现了一个 QStyledItemDelegate
和一个最终调用 drawText()
方法的自定义 paint()
函数:
void DifferencesDelegate::drawText(QPainter *painter,
const QStyleOptionViewItem &option,
const QModelIndex &index) const
{
painter->save();
const QPen defaultPen = painter->pen();
QStyleOptionViewItem opt = option;
initStyleOption(&opt, index);
opt.text.clear();
QStyle *style = opt.widget ? opt.widget->style() : QApplication::style();
style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, opt.widget);
opt.rect.moveRight(opt.rect.right() + 3);
int color = 1;
for (const QString &part : index.data(Qt::UserRole).toStringList()) {
color++;
color = color % 2;
if (color) {
painter->setPen(Qt::red);
} else {
painter->setPen(defaultPen);
}
style->drawItemText(painter, opt.rect, opt.displayAlignment, opt.palette, true, part);
opt.rect.moveRight(opt.rect.right() + painter->fontMetrics().width(part));
}
painter->restore();
}
只要列的宽度足够,这就会导致正确的绘制:
但是一旦列变小,我就会出现混乱的溢出:
这肯定是由于 opt.rect
应用于显示的每个部分,而不是整个文本。
唯一的问题是我不知道如何解决这个问题;-)任何帮助将不胜感激!提前致谢!
出乎意料的是,我设法解决了它;-)
void DifferencesDelegate::drawText(QPainter *painter, const QStyleOptionViewItem &option,
const QModelIndex &index) const
{
if (! index.data(Qt::UserRole).isValid()) {
TableDelegate::drawText(painter, option, index);
return;
}
painter->save();
const QPen defaultPen = painter->pen();
QStyleOptionViewItem opt = option;
initStyleOption(&opt, index);
opt.text.clear();
QStyle *style = opt.widget ? opt.widget->style() : QApplication::style();
style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, opt.widget);
constexpr int offset = 3;
const QString ellipsis = QStringLiteral("…");
const int ellipsisWidth = painter->fontMetrics().width(ellipsis);
const int rightBorder = opt.rect.left() + opt.rect.width() - offset;
QRect drawRect;
int color = 1;
int partWidth;
bool overflow = false;
opt.rect.moveRight(opt.rect.right() + offset);
const QStringList parts = index.data(Qt::UserRole).toStringList();
const int partsCount = parts.count();
for (int i = 0; i < partsCount; i++) {
color++;
color = color % 2;
if (color) {
painter->setPen(Qt::red);
} else {
painter->setPen(defaultPen);
}
partWidth = painter->fontMetrics().width(parts.at(i));
drawRect = opt.rect;
if (drawRect.left() + partWidth + (i == partsCount - 1 ? 0 : ellipsisWidth) > rightBorder) {
drawRect.setWidth(rightBorder - drawRect.left() - ellipsisWidth);
overflow = true;
}
style->drawItemText(painter, drawRect, opt.displayAlignment, opt.palette, true,
parts.at(i));
if (overflow) {
drawRect.setLeft(rightBorder - ellipsisWidth);
drawRect.setWidth(ellipsisWidth);
style->drawItemText(painter, drawRect, opt.displayAlignment, opt.palette, true,
ellipsis);
break;
}
opt.rect.moveRight(opt.rect.right() + partWidth);
}
painter->restore();
}