Qt学习笔记（绘图设备）

绘图设备

QPixmap QBitMap（黑色），QPicture，QWidget
QPixmap 
  创建对象  QPixmap pix(w,h)
  fill填充
  保存 save
  QImage img ( w,h ,format)设置像素色  setPixel
  QPicture 重现和记录 绘图指令 后缀名随便写 无要求

#-------------------------------------------------
#
# Project created by QtCreator 2019-08-17T14:29:11
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = 04_QPainterDevice
TEMPLATE = app

# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

CONFIG += c++11

SOURCES += \
        main.cpp \
        widget.cpp

HEADERS += \
        widget.h

FORMS += \
        widget.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
    res.qrc

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT

public:
    explicit Widget(QWidget *parent = nullptr);
    ~Widget();

private:
    Ui::Widget *ui;

public:
    //绘图

    void paintEvent(QPaintEvent *);


};

#endif // WIDGET_H

#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();

    return a.exec();
}

#include "widget.h"
#include "ui_widget.h"
#include <QPixmap>
#include <QPainter>
#include <QImage>
#include <QPicture>

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    //QPixmap 做绘图设备，对不同平台做了优化
    QPixmap pix(300,300);//指定大小
    //设置默认填充色
    pix.fill(Qt::white);
    QPainter painter(&pix);
    painter.setPen(QPen(Qt::green));
    painter.drawEllipse(QPoint(150,150),100,100);
  //保存的操作
    pix.save("D:/pix.png");//保存到本地


    //QImage 做绘图设备  对像素级访问做了优化
    //参数3，format通常用RGB32  或 ARGB32色味
    QImage img(300,300,QImage::Format_RGB32);//并没有直接宽高 重载
    img.fill(Qt::white);//填充白色
    QPainter painter1(&img);
    painter1.setPen(QPen(Qt::blue));
    painter1.drawEllipse(QPoint(150,150),100,100);
    img.save("D:/img.png");//保存到本地



   QPicture pic;//用于重现记录绘图指令的。
   QPainter painter2;

   painter2.begin(&pic);

   painter2.setPen(QPen(Qt::red));
   painter2.drawEllipse(QPoint(100,100),100,100);

   painter2.end();

 //  保存
   pic.save("D:/pic.zz");//记录指令 不是用来打开的，可以重现
   //后缀名随便写




    //QImage 对像素级做了优化


}

void Widget::paintEvent(QPaintEvent *){
//重现绘图指令 QPictue;
    QPicture pic;
    pic.load("D:\\pic.zz");
    QPainter painter(this);
    painter.drawPicture(0,0,pic);
    //QPicture,记录指令 重现指令，并不是用来画图的











    //QImage 可以修改像素




//    QImage img;
//    img.load(":/Image/Luffy.png");

//    for(int i=50;i<150;i++){
//        for(int j=50;j<150;j++){
//            QRgb value=qRgb(0,255,0);
//            img.setPixel(i,j,value);//设置像素点颜色
//        }
//    }

//    QPainter painter(this);
//    painter.drawImage(QPoint(0,0),img);
}





Widget::~Widget()
{
    delete ui;
}

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Widget</class>
 <widget class="QWidget" name="Widget">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>400</width>
    <height>300</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>Widget</string>
  </property>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>