qt 提高图片加载速度

时间：2022-06-05 14:30:41

一，将图片在pc上解析，然后将解析文件放到qrc文件中，读取qrc文件。

1，将图片解析后的二进制文件保存，源码如下，

下载地址：https://files.cnblogs.com/files/senior-engineer/imageTest.rar

main.cpp

#include "widget.h"

#include <QApplication>

int main(int argc, char *argv[])

{

    QApplication a(argc, argv);

    Widget w;

    w.show();

    return a.exec();

}

widget.h

#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 slots:

    void saveImageToFile();

    void refreshImage();

private:

    Ui::Widget *ui;

private:

    QString m_fileName;

    int m_imgWidth;

    int m_imgHeight;

};

#endif // WIDGET_H

widget.cpp

#include "widget.h"

#include "ui_widget.h"

#include <QImage>

#include <QFile>

#include <QDebug>

#include <QResource>

#define IMAG_BIT 3

Widget::Widget(QWidget *parent) :

    QWidget(parent),

    ui(new Ui::Widget)

{

    ui->setupUi(this);

    //m_fileName = "radio_but_eq_p.png";

    m_fileName = "bg.png";

    ui->imageName->setText(m_fileName);

//    QResource resource;

//    resource.setFileName(":/main_bg.png");

//    const uchar* imageData = resource.data();

//    QImage desImage = QImage(imageData, 800,480,QImage::Format_RGB32); //RGB32

//    QPixmap pixmag;

//    pixmag = QPixmap::fromImage(desImage);

//    ui->oldImage->setPixmap(pixmag);

    QPixmap pixmap(":/main_bg.png");

    ui->oldImage->setPixmap(pixmap);

//    QPixmap pixmag;

//    pixmag.load(m_fileName);

//    ui->oldImage->setPixmap(pixmag);

    connect(ui->start, SIGNAL(clicked(bool)), this, SLOT(saveImageToFile()));

    connect(ui->refresh, SIGNAL(clicked(bool)), this, SLOT(refreshImage()));

}

Widget::~Widget()

{

    delete ui;

}

void Widget::saveImageToFile()

{

    QImage image(m_fileName);

  //  QImage image = QImage(800,480,QImage::Format_RGB888); //RGB32

 //   image.load(m_fileName);

    int size = image.byteCount();

    int sizePerLine = image.bytesPerLine();

    int line = size / sizePerLine;

    m_imgWidth = image.width();

    m_imgHeight = image.height();

    qDebug() << "size:" <<size;

    qDebug() << "sizePerLine:" << sizePerLine;

    qDebug() << "line:" << line;

    qDebug() << "width:" << m_imgWidth;

    uchar* imgDataNew = image.bits();

    FILE *pf = fopen("newfile.png", "wb");

    if(pf == NULL)

        return;

    QFile file;

    file.open(pf, QIODevice::WriteOnly); //

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

    {

        uchar* lineData = image.scanLine(i);

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

        {

            file.write((char*)(lineData + j),);

        }

    }

    file.close();

//    QImage desImage = QImage(m_imgWidth,m_imgHeight,QImage::Format_RGB32); //RGB32

//    //RGB分量值

//    int b = 0;

//    int g = 0;

//    int r = 0;

//    int a = 0;

//    //设置像素

//    for (int i=0;i < m_imgHeight;i++)

//    {

//        for (int j=0; j < m_imgWidth * 4;)

//        {

//            b = (int)*(imgDataNew + i * m_imgWidth * 4 + j);

//            g = (int)*(imgDataNew + i * m_imgWidth * 4 + j + 1);

//            r = (int)*(imgDataNew + i * m_imgWidth * 4 + j + 2);

//            a = (int)*(imgDataNew + i * m_imgWidth * 4 + j + 3);

//            desImage.setPixel(j / 4,i,qRgba(r,g,b,a));

//            j = j + 4;

//            //desImage.setPixel(j,i,qRgb(r,g,b));

//        }

//    }

//    QPixmap pixmag;

//    pixmag = QPixmap::fromImage(desImage);

//    ui->newImage->setPixmap(pixmag);

}

void Widget::refreshImage()

{

    QFile file(":/newfile.png");

    //if (!file.open(QIODevice::ReadOnly | QIODevice::Text))

    if (!file.open(QIODevice::ReadOnly))

        return;

    QByteArray array = file.readAll();

    //file.close();

    char* imgDataNew = array.data();

    QImage desImage = QImage(m_imgWidth,m_imgHeight,QImage::Format_RGB32); //RGB32

    //RGB分量值

    int b = ;

    int g = ;

    int r = ;

    int a = ;

    //设置像素

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

    {

        for (int j=; j < m_imgWidth * ;)

        {

            b = (int)*(imgDataNew + i * m_imgWidth *  + j);

            g = (int)*(imgDataNew + i * m_imgWidth *  + j + );

            r = (int)*(imgDataNew + i * m_imgWidth *  + j + );

            a = (int)*(imgDataNew + i * m_imgWidth *  + j + );

            desImage.setPixel(j / ,i,qRgba(r,g,b,a));

            j = j + ;

            //desImage.setPixel(j,i,qRgb(r,g,b));

        }

    }

    QPixmap pixmag;

    pixmag = QPixmap::fromImage(desImage);

    ui->newImage->setPixmap(pixmag);

//    QImage desImage ;

//    if(IMAG_BIT == 3)

//        desImage = QImage(m_imgWidth,m_imgHeight,QImage::Format_RGB888); //RGB24

//    else if(IMAG_BIT == 4)

//        desImage = QImage(m_imgWidth,m_imgHeight,QImage::Format_RGB32); //RGB32

//    //RGB分量值

//    char b = 0;

//    char g = 0;

//    char r = 0;

//    char a = 0;

//    //设置像素

//    for (int i=0;i < m_imgHeight;i++)

//    {

//        for (int j=0; j < m_imgWidth * IMAG_BIT;)

//        {

//            b = (int)*(imgDataNew + i * m_imgWidth * IMAG_BIT + j);

//            g = (int)*(imgDataNew + i * m_imgWidth * IMAG_BIT + j + 1);

//            r = (int)*(imgDataNew + i * m_imgWidth * IMAG_BIT + j + 2);

//            if(IMAG_BIT == 4)

//            {

//                a = (int)*(imgDataNew + i * m_imgWidth * IMAG_BIT + j + 3);

//                desImage.setPixel(j / IMAG_BIT,i,qRgba(r,g,b,a));

//            }

//            else if(IMAG_BIT == 3)

//            {

//                desImage.setPixel(j / IMAG_BIT, i, qRgb(r,g,b));

//            }

//            j = j + IMAG_BIT;

//        }

//    }

//    QPixmap pixmag;

//    pixmag = QPixmap::fromImage(desImage);

//    ui->newImage->setPixmap(pixmag);

}

二，此方法已经试过了，但是open文件时候很耗时，大概200~300ms

(!file.open(QIODevice::ReadOnly))

二，直接加图片放到qrc文件中，读取qrc文件

一，qrc文件中添加图片资源

二，再.pro文件中添加qrc文件

例如：  RESOURCES     = res.qrc

三，在程序中使用图片文件时候，通过“：文件名”

例如：image=new QImage(":1.png");

四，此方法原理对应qt官方文档地址：http://doc.qt.io/qt-5/resources.html

三，将图片转换为数组，然后将图片画到界面上（适用绘制字体）

一，用下面工具将图片转换为数组

https://files.cnblogs.com/files/senior-engineer/fileToC.rar

二，更具对应数每个bit对应的是1或者是0绘制黑白

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