用Qt实现在窗口上画线，类似于画笔功能。
头文件
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 |
#ifndef MyPaint_h__ #define MyPaint_h__
#include <QtWidgets/QWidget>
class MyPaint :public QWidget { Q_OBJECT public: MyPaint(QWidget *parent = nullptr);
void mousePressEvent(QMouseEvent *event); void mouseMoveEvent(QMouseEvent *event); void mouseReleaseEvent(QMouseEvent *event); void paintEvent(QPaintEvent *event);
private: std::vector<std::vector<QPoint>> _lines;
};
#endif // MyPaint_h__ |
实现
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 |
#include "MyPaint.h" #include <QPainter> #include <QMouseEvent>
MyPaint::MyPaint(QWidget *parent):QWidget(parent) {
}
void MyPaint::mousePressEvent(QMouseEvent *event) //鼠标按下的时候新增加一条线，并记录起点 { std::vector<QPoint> line; line.push_back(event->pos()); _lines.push_back(line); }
void MyPaint::mouseMoveEvent(QMouseEvent *event)//鼠标移动的时候新增加点 { auto &line = _lines[_lines.size() - 1]; line.push_back(event->pos());
update(); //更新，重新绘制窗口，自动调用paintEvent }
void MyPaint::mouseReleaseEvent(QMouseEvent *event) { auto &line = _lines[_lines.size() - 1]; line.push_back(event->pos()); }
void MyPaint::paintEvent(QPaintEvent *event) //绘制所有的线 { //QPainter painter(this); //painter.setPen(QPen(Qt::red, 3, Qt::DashLine)); //painter.setBrush(Qt::blue); //painter.drawRect(QRect(10, 10, 100, 30)); //painter.drawEllipse(130, 10, 50, 50); //painter.drawLine(QLine(200, 10, 300, 20)); //painter.drawText(QPoint(10, 70), "hello" ); QPainter painter(this); painter.setPen(QPen(Qt::green, 3)); for (const auto &line : _lines) { for (int i=0;i<line.size()-1;i++) { painter.drawLine(line.at(i), line.at(i + 1)); } } } |
效果
