延续上一篇文章。本文给出了一个QStyledItemDelegate类自定义绘制加自定义编辑框的例子。
为方便读者理清思路，我已经尽量简化本文附加的代码了。此程序模拟用户给出星级评价的效果，
在编辑状态下用户可以设置0~5个星星的评价，在普通状态下界面显示对应数量的金黄色星星。
本文代码在VS2017和Qt5.9环境下测试通过。程序运行界面如下：
头文件。Qt也建议在自绘时同时重写sizeHint()函数给出一个合适的显示空间大小，这里为了简化就不重写了，影响不大：
1 class MStarDelegate : public QStyledItemDelegate 2 { 3 Q_OBJECT 4 5 public: 6 explicit MStarDelegate(QObject *parent = 0); 7 void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const; 8 QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override; 9 void setEditorData(QWidget *editor, const QModelIndex &index) const override; 10 void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override; 11 void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override; 12 };
CPP文件。在paint(...)函数中首先生成五角星的五个顶点坐标，然后在for循环中从左到右以一定间隔绘制指定数量的星星：
1 MStarDelegate::MStarDelegate(QObject *parent) : 2 QStyledItemDelegate(parent) 3 { 4 } 5 6 void MStarDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const 7 { 8 QPointF vertex[5]; /* 五角星 Size=20,20 */ 9 for (int i = 0; i < 5; i++) 10 { 11 vertex[i].setX(+10 * sinf(i * 144.0f * (3.1415926535f / 180.0f))); 12 vertex[i].setY(-10 * cosf(i * 144.0f * (3.1415926535f / 180.0f))); 13 } 14 15 int many = index.data(Qt::DisplayRole).toInt(); 16 painter->setPen(Qt::NoPen); 17 painter->setBrush(QColor(255, 170, 0)); 18 QSize iconSize = option.decorationSize; 19 QRect thisRect = option.rect; 20 int y = thisRect.y() + thisRect.height() / 2; 21 for (int i = 0; i < many; i++) 22 { 23 painter->save(); 24 painter->setRenderHint(QPainter::Antialiasing); 25 qreal left = 2 + iconSize.width() * 0.5 + (2 + iconSize.width()) * i; 26 painter->translate(left, y); 27 painter->scale(iconSize.width() / 20.0, iconSize.height() / 20.0); 28 painter->drawPolygon(vertex, 5, Qt::WindingFill); 29 painter->restore(); 30 } 31 } 32 33 QWidget *MStarDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const 34 { 35 QSpinBox* cbBox = new QSpinBox(parent); 36 cbBox->setRange(0, 5); 37 cbBox->setSuffix(u8"星"); 38 return cbBox; 39 } 40 41 void MStarDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const 42 { 43 QSpinBox* cbWidget = dynamic_cast<QSpinBox*>(editor); 44 cbWidget->setValue(index.data(Qt::DisplayRole).toInt()); 45 } 46 47 void MStarDelegate::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const 48 { 49 int level = dynamic_cast<QSpinBox*>(editor)->value(); 50 model->setData(index, level, Qt::DisplayRole); 51 } 52 53 void MStarDelegate::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const 54 { 55 editor->setGeometry(option.rect); 56 }
主窗口的构造函数代码如下。其中QtTest是主窗口类，ui.tvHost是QTableView控件。
1 QtTest::QtTest(QWidget *parent) 2 : QMainWindow(parent) 3 { 4 ui.setupUi(this); 5 6 ui.tvHost->setItemDelegateForColumn(0, new MStarDelegate(ui.tvHost)); 7 QStandardItemModel* model = new QStandardItemModel(ui.tvHost); 8 model->setHorizontalHeaderLabels({ u8"状态", u8"说明" }); 9 model->setVerticalHeaderLabels({ u8"设备1", u8"设备2", u8"设备3", u8"设备4" }); 10 model->setColumnCount(2); 11 model->setRowCount(4); 12 for (int i = 0; i < 4; i++) 13 { 14 model->setItem(i, 0, new QStandardItem(u8"3")); 15 model->setItem(i, 1, new QStandardItem(u8"示例文字")); 16 } 17 ui.tvHost->setModel(model); 18 }
附：上述代码在测试时候会发现，当鼠标选中星星所在单元格后，星星的背景仍是白色，而不是系统默认的蓝色背景，仿佛没有被选择一样。这个问题需要在paint(...)函数中自己绘制单元格选中时的样式。可在paint(...)函数中添加下述代码绘制蓝色背景：
1 void MStarDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const 2 { 3 ... 4 if (option.state & QStyle::State_Selected) 5 { 6 painter->fillRect(option.rect, option.palette.highlight()); 7 } 8 ... 9 }
代码中option.state代表本单元格的状态。常见的有State_Enabled表示没有被禁用；State_Selected表示被选中；State_HasFocus表示拥有键盘输入焦点，系统默认是在单元格边缘绘制虚线矩形。还有很多其它的我也不太明白是什么意思。
转载自：https://www.cnblogs.com/mengxiangdu/p/17831787.html
class MStarDelegate : public QStyledItemDelegate{ Q_OBJECTpublic: explicit MStarDelegate(QObject *parent = 0); void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const; QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const override; void setEditorData(QWidget *editor, const QModelIndex &index) const override; void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const override; void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const override;};