Qt笔记——绘图(QBitmap,QPixmap,QImage,QPicture)

Qt笔记——绘图(QBitmap,QPixmap,QImage,QPicture)

https://www.cnblogs.com/dalanjing/p/8724876.html

• QPainter绘图
  • 重写绘图事件，虚函数
  • 如果窗口绘图，必须放在绘图事件里实现
  • 绘图事件内部自动调用，窗口需要重绘的时候，状态改变
• 绘图设备（QPixmap，QImage，QBitmap，QPicture）
  • QPixmap图片背景透明，针对屏幕进行优化了，和平台相关，不能对图片进行修改
  • QImage 和平台无关，可以对图片进行修改，在线程中绘图
  • QPicture 保存绘图 的状态（二进制文件）
  • pixmap.save("../pixmap.png"); 保存图片
  • setWindowFlags(Qt::FramelessWindowHint | windowFlags());去除边框
  • setAttribute(Qt::WA_TranslucentBackground);设置透明

QPainter

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#ifndef WIDGET_H #define WIDGET_H   #include   namespace Ui { class Widget; }   class Widget : public QWidget {     Q_OBJECT   public:     explicit Widget(QWidget *parent = 0);     ~Widget();   protected:     void paintEvent(QPaintEvent *event);   private slots:     void on_pushButton_clicked();   private:     Ui::Widget *ui;     int x=0; };   #endif // WIDGET_H

　　

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#include "widget.h" #include "ui_widget.h" #include #include #include Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this); }   Widget::~Widget() {     delete ui; }   void Widget::paintEvent(QPaintEvent *event) {     //QPainter p(this);     QPainter p;//创建画家对象     p.begin(this);//指定当前窗口为绘图设备     //画背景图     //p.drawPixmap(0,0, width(), height(), QPixmap("../Image/bk.png"));     //p.drawPixmap(rect(),QPixmap("../Image/bk.png"));       //定义画笔     QPen pen;     pen.setWidth(5);//设置线宽     pen.setColor(QColor(124,123,0));//rgb     pen.setStyle(Qt::DashDotDotLine);       QBrush brush;     brush.setColor(Qt::red);     brush.setStyle(Qt::Dense1Pattern);       //p.setPen(pen);     p.setBrush(brush);     //画直线     p.drawLine(50,50,150,50);     p.drawLine(50, 50,50,150 );       //画矩形     p.drawRect(x,150,100,50);       p.drawEllipse(QPoint(150,150),25,50);       p.drawPixmap(x,180,80,80,QPixmap("../Image/face.png"));       p.end(); }   void Widget::on_pushButton_clicked() {     x += 20;     if(x>width())     {         x = 0;     }     update(); }

　QBitmap

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#ifndef WIDGET_H #define WIDGET_H   #include   namespace Ui { class Widget; }   class Widget : public QWidget {     Q_OBJECT   public:     explicit Widget(QWidget *parent = 0);     ~Widget();   protected:     void paintEvent(QPaintEvent *event);   private:     Ui::Widget *ui; };   #endif // WIDGET_H

　　

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#include "widget.h" #include "ui_widget.h" #include #include Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this); }   Widget::~Widget() {     delete ui; }   void Widget::paintEvent(QPaintEvent *event) {     QPainter p(this);     //QPixmap图片背景透明     p.drawPixmap(0,0,QPixmap("../Image/butterfly.png"));     //QBitmap     p.drawPixmap(200,0, QBitmap("../Image/butterfly.png"));     //QPixmap 图片背景白色     QPixmap pixmap;     pixmap.load("../Image/butterfly1.png");   }

　QPixmap

 

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#ifndef WIDGET_H #define WIDGET_H   #include   namespace Ui { class Widget; }   class Widget : public QWidget {     Q_OBJECT   public:     explicit Widget(QWidget *parent = 0);     ~Widget();   private:     Ui::Widget *ui; };   #endif // WIDGET_H

　　

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#include "widget.h" #include "ui_widget.h" #include Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this);     QPixmap pixmap(400, 300);     QPainter p(&pixmap);     p.fillRect(0,0,400,300,QBrush(Qt::white));       pixmap.fill(Qt::white);     p.drawPixmap(0,0,80,80,QPixmap("../Image/face.png"));       //保存图片     pixmap.save("../pixmap.png"); }   Widget::~Widget() {     delete ui; }

　QImage

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#include "widget.h" #include "ui_widget.h" #include   Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this);       QImage image(400,300,QImage::Format_ARGB32);     QPainter p;     p.begin(&image);       p.drawLine(50,50,100,100);       for(int i=0;i<50;i++)     {         for(int j=0;j<50;j++)         {             image.setPixel(QPoint(i,j),qRgb(0,255,0));           }     }     p.end();       image.save("../image.png"); }   Widget::~Widget() {     delete ui; }

QPicture

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#include "widget.h" #include "ui_widget.h" #include #include Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this);     QPicture picture;     QPainter p;     p.begin(&picture);     p.drawLine(50,50,100,100);     p.end();       picture.save("../picture.png"); }   Widget::~Widget() {     delete ui; }   void Widget::paintEvent(QPaintEvent *event) { //    QPicture pic; //    pic.load("../picture.png");     QPainter p(this); //    p.drawPicture(0,0,pic);       QPixmap pixmap;     pixmap.load("../Image/face.png");     QImage tempImage = pixmap.toImage();     p.drawImage(0,0, tempImage);       QImage image;     image.load("../Image/face.png");     QPixmap tempPixmap = QPixmap::fromImage(image); }

窗口透明

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#include "widget.h" #include "ui_widget.h" #include #include #include Widget::Widget(QWidget *parent) :     QWidget(parent),     ui(new Ui::Widget) {     ui->setupUi(this);     setWindowFlags(Qt::FramelessWindowHint | windowFlags());       setAttribute(Qt::WA_TranslucentBackground); }   Widget::~Widget() {     delete ui; }   void Widget::paintEvent(QPaintEvent *event) {     QPainter p(this);     p.drawLine(50,50,100,100); }   void Widget::mousePressEvent(QMouseEvent *event) {     if(event->button() == Qt::RightButton)     {      close();      qDebug()<<"close";     }     else if(event->button() == Qt::LeftButton)     {         p = event->globalPos() - this->frameGeometry().topLeft();         qDebug()<<"left";     } }   void Widget::mouseMoveEvent(QMouseEvent *event) {     if(event->button() & Qt::LeftButton)     {             move(event->globalPos()-p);     } }