代碼有效,但在執行時按下鼠標時會出現以下警告消息:??QPainter :: begin:構件繪畫只能作爲paintEvent的結果開始
QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::setPen: Painter not active
QPainter::drawRects: Painter not active
加入修飾進一步向下
#include <QTextEdit>
class QTextEditEnter : public QTextEdit
{
Q_OBJECT
public:
QTextEditEnter(QWidget *_parent);
protected:
virtual void paintEvent(QPaintEvent *_event);
void mousePressEvent(QMouseEvent *evt);
int m_color;
void mouseDoubleClickEvent(QMouseEvent *e);
signals:
void signalPressEnter();
};
#include "qtexteditenter.h"
#include <qpainter.h>
#include <QMouseEvent>
QTextEditEnter::QTextEditEnter(QWidget *_parent) :
QTextEdit(_parent)
{
this->setFrameStyle(QFrame::Sunken);
m_color = 0;
setAttribute(Qt::WA_PaintOutsidePaintEvent, true);
}
void QTextEditEnter::paintEvent(QPaintEvent *_event)
{
QPainter pnt(viewport());
pnt.setPen(QColor(255, 0, 0, 0xff));
pnt.drawRect(0, 0, width()-1, height()-1);
}
void QTextEditEnter::mousePressEvent(QMouseEvent *e)
{
QPainter p(this->viewport());
p.setPen(QColor(0,0,0,0xff));
p.drawRect(this->viewport()->rect());
p.begin(this);
switch(m_color){
case 0:
p.setPen(Qt::red);
break;
case 1:
p.setPen(Qt::green);
break;
}
p.drawEllipse(e->pos(),2,2);
p.end();
}
void QTextEditEnter::mouseDoubleClickEvent(QMouseEvent *e)
{
m_color++;
if (m_color > 1) m_color = 0;
}
-------------------改性--- -------------
void QTextEditEnter::paintEvent(QPaintEvent *_event)
{
if(1){
QPainter pnt(this->viewport());
pnt.setPen(QColor(0xff, 0, 0, 0xff));
pnt.drawRect(0, 0, width()-1, height()-1);
pnt.setPen(QColor(0, 0xff, 0, 0xff));
pnt.drawRect(10, 10, width()-20, height()-20);
}
if(flagModify == 1){
QPainter p(this->viewport());
switch(m_color){
case 0:
p.setPen(Qt::red);
break;
case 1:
p.setPen(Qt::green);
break;
}
p.begin(this);
p.drawEllipse(x, y, 2, 2);
p.end();
flagModify = 0;
}
}
void QTextEditEnter::mousePressEvent(QMouseEvent *e)
{
x = e->pos().x();
y = e->pos().y();
flagModify = 1;
this->update(this->rect());
}
錯誤清楚地解釋了這個問題 - 你試圖用p.begin繪製mousePressEvent,而不是在paintEvent函數中繪製。雖然它可能似乎有效,但可能會在稍後導致問題;如果沒有其他的話,肯定會有表現如果要在按下鼠標時使對象繪畫,請使用窗口的更新功能讓對象知道它需要重新繪製自己。 – TheDarkKnight
增加了修改但是同樣的錯誤 – jdl