Qt :：QGraphicsPixmapItem :重写paint()方法？
Qt :：QGraphicsPixmapItem :重写paint()方法？
提问于 2014-02-18 03:36:10
我想要覆盖可以显示图像并可以在同一项目上使用QPainter绘图的QGraphicsPixmapItem。
我重写了类和鼠标事件并绘制methods.When，每当我单击按钮时，它成功地调用鼠标和绘制事件，但它不在图像像素图上绘制。
我使用setPixmap函数将图像加载到此item对象，即
QGraphicsSelectionPixmapItem selectionitem;
selectionitem->setPixmap(imagePixmap); 这是我的重写类：
头文件:qraphicsselectionPixmapitem.h
#ifndef QGRAPHICSSELECTIONPIXMAPITEM_H
#define QGRAPHICSSELECTIONPIXMAPITEM_H
#include <QGraphicsPixmapItem>
#include <QDebug>
#include <QGraphicsSceneMouseEvent>
#include <QList>
#include <QVector>
#include <QPainter>
#include <QPixmap>
class QGraphicsSelectionPixmapItem : public QGraphicsPixmapItem
{
public:
QGraphicsSelectionPixmapItem(QGraphicsItem *parent = NULL);
void mouseMoveEvent(QGraphicsSceneMouseEvent *e);
void mousePressEvent(QGraphicsSceneMouseEvent *e);
void mouseReleaseEvent(QGraphicsSceneMouseEvent *e);
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
QList<QPointF> points;
QVector<QPointF> polyPoints;
bool mClickflag;
};
#endif // QGRAPHICSSELECTIONPIXMAPITEM_Hcpp文件: qgraphicsselectionpixmapitem.cpp
#include "qgraphicsselectionpixmapitem.h"
QGraphicsSelectionPixmapItem::QGraphicsSelectionPixmapItem(QGraphicsItem *parent): QGraphicsPixmapItem(parent)
{
}
void QGraphicsSelectionPixmapItem::mousePressEvent(QGraphicsSceneMouseEvent *e)
{
mClickflag = true;
qDebug()<<e->pos();
if(e->lastPos()!=e->pos()){
points.append(e->pos());
polyPoints<<e->pos();
update();
}
}
void QGraphicsSelectionPixmapItem::mouseMoveEvent(QGraphicsSceneMouseEvent *e)
{
}
void QGraphicsSelectionPixmapItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *e)
{
mClickflag = false;
}
void QGraphicsSelectionPixmapItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
qDebug()<<"in Paint ";
if(!polyPoints.empty())
{
painter->setPen(QPen(QColor(255,0,0),3));
painter->drawPolyline(polyPoints);
}
QGraphicsPixmapItem::paint(painter,option,widget);
}回答 1
Stack Overflow用户
发布于 2014-02-19 23:27:39
我找到了这个解决方案:使用QPainterPath在QGraphicsItem上存储和绘制任何内容。
在头文件中添加：
QPainterPath m_path;
bool firstClick;在cpp文件中修改mousePressEvent和paint函数：
QGraphicsSelectionPixmapItem::QGraphicsSelectionPixmapItem(QGraphicsItem *parent): QGraphicsPixmapItem(parent)
{
firstClick=true;
}
void QGraphicsSelectionPixmapItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
m_path.setFillRule(Qt::WindingFill);
if(firstClick)
{
m_path.moveTo(event->pos());
firstClick=false;
}
else
m_path.lineTo(event->pos());
update();
}
void QGraphicsSelectionPixmapItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
update();
}
void QGraphicsSelectionPixmapItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
}
void QGraphicsSelectionPixmapItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
QGraphicsPixmapItem::paint(painter,option,widget);
if(m_path.isEmpty())
return;
QPen pen(QColor(255,0,0));
pen.setWidth(1);
painter->setPen(pen);
painter->setRenderHint(QPainter::Antialiasing);
painter->setBrush(QColor(255,0,0,100));
painter->drawPath(m_path);
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/21837818
复制相关文章
相似问题
腾讯云开发者
