MyWidget.h

#ifndef MYWIDGET_H

#define MYWIDGET_H

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#include <QWidget>

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class MyWidget : public QWidget

{

??? Q_OBJECT

public:

??? explicit MyWidget(QWidget *parent = 0);

??? void paintEvent(QPaintEvent *);

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signals:

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public slots:

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};

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#endif // MYWIDGET_H

MyWidget.cpp

#include "MyWidget.h"

#include <QPainter>

#include <QPixmap>

#include <QApplication>

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MyWidget::MyWidget(QWidget *parent) :

??? QWidget(parent)

{

}

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void MyWidget::paintEvent(QPaintEvent *)

{

??? QPixmap pixmap(size());

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??? QPainter p(&pixmap);

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??? //p.translate(100, 100);

??? //p.scale();

??? //消除鋸齒

??? p.setRenderHint(QPainter::Antialiasing);

??? //轉(zhuǎn)換

??? QTransform transform;

??? transform.translate(50,50);

??? //旋轉(zhuǎn)30度

??? transform.rotate(30);

?? // transform.scale(.5, .5);

??? p.setTransform(transform);

#if 1

??? //下面的transform可以覆蓋上面的一個(gè)transform的效果

??? QTransform transform2;

??? //對(duì)整個(gè)效果進(jìn)行縮放

??? transform2.scale(.5, .5);

??? //最后一個(gè)參數(shù)實(shí)現(xiàn)和上面一個(gè)transform實(shí)現(xiàn)組合

??? p.setTransform(transform2, true);

#endif

??? //通過(guò)兩個(gè)點(diǎn)實(shí)現(xiàn)畫線

??? p.drawLine(QPoint(0, 0), QPoint(100, 100));

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??? //p.translate(-100, -100);

??? //鋼筆

??? p.setPen(QPen(Qt::red, 2, Qt::DashLine));

??? //使用刷子

??? p.setBrush(Qt::yellow);

??? //設(shè)置刷子

??? p.setFont(QFont("aaa", 40, 700, true));

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??? p.drawEllipse(QPoint(95, 333), 50, 50);

??? //里面寫上文字

??? p.drawText(QPoint(300, 50), "Hello world");

??? //p.drawPixmap(QPoint(40, 40), QPixmap("../aaa.png"));

??? //p.drawRect(QRect(40, 60, 100, 50));

??? //下面的方式實(shí)現(xiàn)畫一個(gè)圓角矩形

??? p.drawRoundRect(QRect(40, 60, 100, 50));

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??? p.end();

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??? p.begin(this);

??? //通過(guò)下面的方式實(shí)現(xiàn)畫圖，之所以運(yùn)行的結(jié)果是黑絲的圖，是因?yàn)榧拥氖?span lang="EN-US">pixmap

??? p.drawPixmap(0, 0, pixmap);

}

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int main(int argc, char** argv)

{

??? QApplication app(argc, argv);

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??? MyWidget w;

??? w.show();

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??? return app.exec();

}

運(yùn)行結(jié)果：

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