Qt 绘图(QBitmap,QPixmap,QImage,QPicture)

QPainter绘图绘图设备（QPixmap，QImage，QBitmap，QPicture）
- 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

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

 #ifndef WIDGET_H

 #define WIDGET_H

 #include <QWidget>

 namespace Ui {

 class Widget;

 }

 class Widget : public QWidget

 {

     Q_OBJECT

 public:

     explicit Widget(QWidget *parent = );

     ~Widget();

 protected:

     void paintEvent(QPaintEvent *event);

 private slots:

     void on_pushButton_clicked();

 private:

     Ui::Widget *ui;

     int x=;

 };

 #endif // WIDGET_H

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 #include <QPen>

 #include <QBrush>

 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();//设置线宽

     pen.setColor(QColor(,,));//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(,,,);

     p.drawLine(, ,, );

     //画矩形

     p.drawRect(x,,,);

     p.drawEllipse(QPoint(,),,);

     p.drawPixmap(x,,,,QPixmap("../Image/face.png"));

     p.end();

 }

 void Widget::on_pushButton_clicked()

 {

     x += ;

     if(x>width())

     {

         x = ;

     }

     update();

 }

QBitmap

 #ifndef WIDGET_H

 #define WIDGET_H

 #include <QWidget>

 namespace Ui {

 class Widget;

 }

 class Widget : public QWidget

 {

     Q_OBJECT

 public:

     explicit Widget(QWidget *parent = );

     ~Widget();

 protected:

     void paintEvent(QPaintEvent *event);

 private:

     Ui::Widget *ui;

 };

 #endif // WIDGET_H

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 #include <QBitmap>

 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(,,QPixmap("../Image/butterfly.png"));

     //QBitmap

     p.drawPixmap(,, QBitmap("../Image/butterfly.png"));

     //QPixmap 图片背景白色

     QPixmap pixmap;

     pixmap.load("../Image/butterfly1.png");

 }

QPixmap

 #ifndef WIDGET_H

 #define WIDGET_H

 #include <QWidget>

 namespace Ui {

 class Widget;

 }

 class Widget : public QWidget

 {

     Q_OBJECT

 public:

     explicit Widget(QWidget *parent = );

     ~Widget();

 private:

     Ui::Widget *ui;

 };

 #endif // WIDGET_H

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 Widget::Widget(QWidget *parent) :

     QWidget(parent),

     ui(new Ui::Widget)

 {

     ui->setupUi(this);

     QPixmap pixmap(, );

     QPainter p(&pixmap);

     p.fillRect(,,,,QBrush(Qt::white));

     pixmap.fill(Qt::white);

     p.drawPixmap(,,,,QPixmap("../Image/face.png"));

     //保存图片

     pixmap.save("../pixmap.png");

 }

 Widget::~Widget()

 {

     delete ui;

 }

QImage

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 Widget::Widget(QWidget *parent) :

     QWidget(parent),

     ui(new Ui::Widget)

 {

     ui->setupUi(this);

     QImage image(,,QImage::Format_ARGB32);

     QPainter p;

     p.begin(&image);

     p.drawLine(,,,);

     for(int i=;i<;i++)

     {

         for(int j=;j<;j++)

         {

             image.setPixel(QPoint(i,j),qRgb(,,));

         }

     }

     p.end();

     image.save("../image.png");

 }

 Widget::~Widget()

 {

     delete ui;

 }

QPicture

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 #include <QPicture>

 Widget::Widget(QWidget *parent) :

     QWidget(parent),

     ui(new Ui::Widget)

 {

     ui->setupUi(this);

     QPicture picture;

     QPainter p;

     p.begin(&picture);

     p.drawLine(,,,);

     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(,, tempImage);

     QImage image;

     image.load("../Image/face.png");

     QPixmap tempPixmap = QPixmap::fromImage(image);

 }

窗口透明

 #include "widget.h"

 #include "ui_widget.h"

 #include <QPainter>

 #include <QMouseEvent>

 #include <QDebug>

 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(,,,);

 }

 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);

     }

 }

巴特西

Qt 绘图(QBitmap,QPixmap,QImage,QPicture)

QPainter

QBitmap

QPixmap

QImage

QPicture

窗口透明

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