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

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

1#ifndef WIDGET_H
2#define WIDGET_H
3
4#include <QWidget>
5
6namespace Ui {
7class Widget;
8}
9
10class Widget : public QWidget
11{
12    Q_OBJECT
13
14public:
15    explicit Widget(QWidget *parent = 0);
16    ~Widget();
17
18protected:
19    void paintEvent(QPaintEvent *event);
20
21private slots:
22    void on_pushButton_clicked();
23
24private:
25    Ui::Widget *ui;
26    int x=0;
27};
28
29#endif // WIDGET_H
30
31#include "widget.h"
32#include "ui_widget.h"
33#include <QPainter>
34#include <QPen>
35#include <QBrush>
36Widget::Widget(QWidget *parent) :
37    QWidget(parent),
38    ui(new Ui::Widget)
39{
40    ui->setupUi(this);
41}
42
43Widget::~Widget()
44{
45    delete ui;
46}
47
48void Widget::paintEvent(QPaintEvent *event)
49{
50    //QPainter p(this);
51    QPainter p;//创建画家对象
52    p.begin(this);//指定当前窗口为绘图设备
53    //画背景图
54    //p.drawPixmap(0,0, width(), height(), QPixmap("../Image/bk.png"));
55    //p.drawPixmap(rect(),QPixmap("../Image/bk.png"));
56
57    //定义画笔
58    QPen pen;
59    pen.setWidth(5);//设置线宽
60    pen.setColor(QColor(124,123,0));//rgb
61    pen.setStyle(Qt::DashDotDotLine);
62
63    QBrush brush;
64    brush.setColor(Qt::red);
65    brush.setStyle(Qt::Dense1Pattern);
66
67    //p.setPen(pen);
68    p.setBrush(brush);
69    //画直线
70    p.drawLine(50,50,150,50);
71    p.drawLine(50, 50,50,150 );
72
73    //画矩形
74    p.drawRect(x,150,100,50);
75
76    p.drawEllipse(QPoint(150,150),25,50);
77
78    p.drawPixmap(x,180,80,80,QPixmap("../Image/face.png"));
79
80    p.end();
81}
82
83void Widget::on_pushButton_clicked()
84{
85    x += 20;
86    if(x>width())
87    {
88        x = 0;
89    }
90    update();
91}

　QBitmap

1#ifndef WIDGET_H
2#define WIDGET_H
3
4#include <QWidget>
5
6namespace Ui {
7class Widget;
8}
9
10class Widget : public QWidget
11{
12    Q_OBJECT
13
14public:
15    explicit Widget(QWidget *parent = 0);
16    ~Widget();
17
18protected:
19    void paintEvent(QPaintEvent *event);
20
21private:
22    Ui::Widget *ui;
23};
24
25#endif // WIDGET_H
26
27#include "widget.h"
28#include "ui_widget.h"
29#include <QPainter>
30#include <QBitmap>
31Widget::Widget(QWidget *parent) :
32    QWidget(parent),
33    ui(new Ui::Widget)
34{
35    ui->setupUi(this);
36}
37
38Widget::~Widget()
39{
40    delete ui;
41}
42
43void Widget::paintEvent(QPaintEvent *event)
44{
45    QPainter p(this);
46    //QPixmap图片背景透明
47    p.drawPixmap(0,0,QPixmap("../Image/butterfly.png"));
48    //QBitmap
49    p.drawPixmap(200,0, QBitmap("../Image/butterfly.png"));
50    //QPixmap 图片背景白色
51    QPixmap pixmap;
52    pixmap.load("../Image/butterfly1.png");
53
54}

　QPixmap

1#ifndef WIDGET_H
2#define WIDGET_H
3
4#include <QWidget>
5
6namespace Ui {
7class Widget;
8}
9
10class Widget : public QWidget
11{
12    Q_OBJECT
13
14public:
15    explicit Widget(QWidget *parent = 0);
16    ~Widget();
17
18private:
19    Ui::Widget *ui;
20};
21
22#endif // WIDGET_H
23
24#include "widget.h"
25#include "ui_widget.h"
26#include <QPainter>
27Widget::Widget(QWidget *parent) :
28    QWidget(parent),
29    ui(new Ui::Widget)
30{
31    ui->setupUi(this);
32    QPixmap pixmap(400, 300);
33    QPainter p(&pixmap);
34    p.fillRect(0,0,400,300,QBrush(Qt::white));
35
36    pixmap.fill(Qt::white);
37    p.drawPixmap(0,0,80,80,QPixmap("../Image/face.png"));
38
39    //保存图片
40    pixmap.save("../pixmap.png");
41}
42
43Widget::~Widget()
44{
45    delete ui;
46}

　QImage

1#include "widget.h"
2#include "ui_widget.h"
3#include <QPainter>
4
5Widget::Widget(QWidget *parent) :
6    QWidget(parent),
7    ui(new Ui::Widget)
8{
9    ui->setupUi(this);
10
11    QImage image(400,300,QImage::Format_ARGB32);
12    QPainter p;
13    p.begin(&image);
14
15    p.drawLine(50,50,100,100);
16
17    for(int i=0;i<50;i++)
18    {
19        for(int j=0;j<50;j++)
20        {
21            image.setPixel(QPoint(i,j),qRgb(0,255,0));
22
23        }
24    }
25    p.end();
26
27    image.save("../image.png");
28}
29
30Widget::~Widget()
31{
32    delete ui;
33}

QPicture

1#include "widget.h"
2#include "ui_widget.h"
3#include <QPainter>
4#include <QPicture>
5Widget::Widget(QWidget *parent) :
6    QWidget(parent),
7    ui(new Ui::Widget)
8{
9    ui->setupUi(this);
10    QPicture picture;
11    QPainter p;
12    p.begin(&picture);
13    p.drawLine(50,50,100,100);
14    p.end();
15
16    picture.save("../picture.png");
17}
18
19Widget::~Widget()
20{
21    delete ui;
22}
23
24void Widget::paintEvent(QPaintEvent *event)
25{
26//    QPicture pic;
27//    pic.load("../picture.png");
28    QPainter p(this);
29//    p.drawPicture(0,0,pic);
30
31    QPixmap pixmap;
32    pixmap.load("../Image/face.png");
33    QImage tempImage = pixmap.toImage();
34    p.drawImage(0,0, tempImage);
35
36    QImage image;
37    image.load("../Image/face.png");
38    QPixmap tempPixmap = QPixmap::fromImage(image);
39}

窗口透明

1#include "widget.h"
2#include "ui_widget.h"
3#include <QPainter>
4#include <QMouseEvent>
5#include <QDebug>
6Widget::Widget(QWidget *parent) :
7    QWidget(parent),
8    ui(new Ui::Widget)
9{
10    ui->setupUi(this);
11    setWindowFlags(Qt::FramelessWindowHint | windowFlags());
12
13    setAttribute(Qt::WA_TranslucentBackground);
14}
15
16Widget::~Widget()
17{
18    delete ui;
19}
20
21void Widget::paintEvent(QPaintEvent *event)
22{
23    QPainter p(this);
24    p.drawLine(50,50,100,100);
25}
26
27void Widget::mousePressEvent(QMouseEvent *event)
28{
29    if(event->button() == Qt::RightButton)
30    {
31     close();
32     qDebug()<<"close";
33    }
34    else if(event->button() == Qt::LeftButton)
35    {
36        p = event->globalPos() - this->frameGeometry().topLeft();
37        qDebug()<<"left";
38    }
39}
40
41void Widget::mouseMoveEvent(QMouseEvent *event)
42{
43    if(event->button() & Qt::LeftButton)
44    {
45            move(event->globalPos()-p);
46    }
47}

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

QPainter

QBitmap

QPixmap

QImage

QPicture

窗口透明

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