QT学习---listWidget自绘

一、自绘的主要步骤是：

1、派生QStyledItemDelegate的子类；

2、重写虚函数：sizeHint()、paint()；

3、设置listWidget的委托对象。

ui.listWidget->setItemDelegate(new MyItemPainter(ui.listWidget));

二、实现：

1、项listWidget部件中添加些测试数据：

ListWidget::ListWidget(QWidget *parent, Qt::WFlags flags)
	: QMainWindow(parent, flags)
{
	ui.setupUi(this);

	
	QListWidgetItem* item1 = new QListWidgetItem;
	QListWidgetItem* item2 = new QListWidgetItem;

	item1->setData(Qt::DecorationRole,QIcon(":/ListWidget/Resources/Save.png"));
	item1->setData(Qt::DisplayRole,"Save");
	item1->setData(Qt::UserRole + 1,"This is Icon of Sage");
	item1->setData(Qt::UserRole + 2,":/ListWidget/Resources/Save.png");

	item2->setData(Qt::DecorationRole,QIcon(":/ListWidget/Resources/grab.png"));
	item2->setData(Qt::DisplayRole,"Grab");
	item2->setData(Qt::UserRole + 1,"This is Icon of Grab");
	item2->setData(Qt::UserRole + 2,":/ListWidget/Resources/grab.png");

	ui.listWidget->addItem(item1);
	ui.listWidget->addItem(item2);

	ui.listWidget->setItemDelegate(new MyItemPainter(ui.listWidget));
	
}

2、在派生的子类中进行重绘操作：

#ifndef MYITEMPAINTER_H
#define MYITEMPAINTER_H

#include <QStyledItemDelegate>

class MyItemPainter : public QStyledItemDelegate
{
	Q_OBJECT

public:
	MyItemPainter(QWidget *parent);
	~MyItemPainter();

private:
	QSize sizeHint ( const QStyleOptionViewItem & option, const QModelIndex & index ) const;
	void paint ( QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index ) const;
};

#endif // MYITEMPAINTER_H

#include "MyItemPainter.h"
#include <QPainter>

MyItemPainter::MyItemPainter(QWidget *parent)
	: QStyledItemDelegate(parent)
{

}

MyItemPainter::~MyItemPainter()
{

}

QSize MyItemPainter::sizeHint ( const QStyleOptionViewItem & option, const QModelIndex & index ) const
{
	//获取每一行的原始大小
	QSize size = QStyledItemDelegate::sizeHint(option,index);
	size.setHeight(60);
	return size;

	//重写之前的默认返回值
	//return QStyledItemDelegate::sizeHint(option,index);
}

void MyItemPainter::paint ( QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index ) const
{
	QRect Rect = option.rect;
	Rect.adjust(2,2,-2,-2);

	//取得对应项的数据
	QString strDisplay = index.data(Qt::DisplayRole).toString();//名称
	QString strTip = index.data(Qt::UserRole + 1).toString();//提示
	QString strPath = index.data(Qt::UserRole + 2).toString();//图标路径

	//显示操作:当选中某一项时
	if (option.state & QStyle::State_Selected)
	{
		painter->setBrush(QColor(50,183,183));
		painter->drawRoundedRect(Rect,2,2);
		painter->setBrush(Qt::NoBrush);
	}

	//画名称
	{
		QRect dst = Rect;
		dst.setLeft(dst.left()+ 10);
		dst.setRight(dst.left()+40);
		dst.setTop(dst.top()+8);
		dst.setBottom(dst.bottom()-40);
		painter->drawText(dst, Qt::AlignLeft | Qt::AlignVCenter, strDisplay);
	}

	//画图标
	{
		QPixmap pmap(strPath);
		QRect dst = Rect;
		dst.setTop(dst.top()+20);
		dst.setRight(dst.left()+40);
		QRect area(0,0,24,24);
		area.moveCenter(dst.center());
		painter->drawPixmap(area,pmap);
	}

	//画提示
	{
		QRect dst = Rect;
		dst.setLeft(dst.left()+45);
		dst.setTop(dst.top()+20);
		painter->drawText(dst, Qt::AlignLeft | Qt::AlignVCenter, strTip);
	}

	//重写之前的默认返回值
	//return QStyledItemDelegate::paint(painter,option,index);
}