FreeImage库如何转换图片格式？

FreeImage下载地址：http://freeimage.sourceforge.net/

//freeimagemain.h

#ifndef FREEIMAGEMAIN_H
#define FREEIMAGEMAIN_H

#include <QWidget>
#include <QtCore>
#include <QStatusBar>
#include <QFileDialog>
#include "FreeImage.h"
namespace Ui {
class FreeImageMain;
}

class FreeImageMain : public QWidget
{
    Q_OBJECT

public:
    explicit FreeImageMain(QWidget *parent = 0);
    ~FreeImageMain();
    bool ImageTransformationImage(QString sourcePath,QString destinationPath) const;
    //根据文件路径获取格式
    int GetImagePathSuffix(QString path) const;
private:
    Ui::FreeImageMain *ui;
    QTextCodec *textCodec;
    QString m_sourcePath;
    QString m_destinationPath;
    QStatusBar *statusBar;
};

#endif // FREEIMAGEMAIN_H

//freeimagemain.cpp

#include "freeimagemain.h"
#include "ui_freeimagemain.h"
#include <stdio.h>
#include <stdlib.h>
FreeImageMain::FreeImageMain(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::FreeImageMain)
{
    ui->setupUi(this);
    textCodec = QTextCodec::codecForName("GBK");
    statusBar = new QStatusBar;
    ui->verticalLayout->addWidget(statusBar);
    QObject::connect(ui->pushButton_load,&QPushButton::pressed,[=](){
        this->m_sourcePath = QFileDialog::getOpenFileName(this,tr(textCodec->toUnicode("加载位图").toStdString().data()), "./", tr("Image Files (*ico *.png *.jpg *.bmp)"));
        if(this->m_sourcePath.isEmpty())
        {
            statusBar->showMessage(textCodec->toUnicode("位图加载路径不能为空！"),3000);
        }
        else
        {
            statusBar->showMessage(textCodec->toUnicode("位图加载路径获取成功！"),3000);
        }
    });
    QObject::connect(ui->pushButton_save,&QPushButton::pressed,[=](){
        //源路径为空直接返回
        if(this->m_sourcePath.isEmpty())
        {
            statusBar->showMessage(textCodec->toUnicode("请先加载位图路径！"),3000);
            return;
        }
        this->m_destinationPath = QFileDialog::getSaveFileName(this,tr(textCodec->toUnicode("加载位图").toStdString().data()), "./", tr("Image Files (*ico *.png *.jpg *.bmp)"));
        if(this->m_destinationPath.isEmpty())
        {
            statusBar->showMessage(textCodec->toUnicode("存储位图路径不能为空！"),3000);
            return;
        }
        else
        {
            statusBar->showMessage(textCodec->toUnicode("位图存储路径获取成功！"),3000);
            this->ImageTransformationImage(m_sourcePath,m_destinationPath);
        }
    });
}

FreeImageMain::~FreeImageMain()
{
    statusBar->deleteLater();
    delete ui;
}

int FreeImageMain::GetImagePathSuffix(QString path) const
{
    //    QString::compare(path.split(".").constLast(), "BMP", Qt::CaseInsensitive);
    QString Suffix = path.split(".").constLast().toUpper();
    if(Suffix == "BMP")
    {
        return FIF_BMP;
    }
    else if (Suffix == "ICO")
    {
        return FIF_ICO;
    }
    else if (Suffix == "JPEG")
    {
        return FIF_JPEG;
    }
    else if (Suffix == "JNG")
    {
        return FIF_JNG;
    }
    else if (Suffix == "KOALA")
    {
        return FIF_KOALA;
    }
    else if (Suffix == "LBM")
    {
        return FIF_LBM;
    }
    else if (Suffix == "IFF")
    {
        return FIF_IFF;
    }
    else if (Suffix == "MNG")
    {
        return FIF_MNG;
    }
    else if (Suffix == "PBM")
    {
        return FIF_PBM;
    }
    else if (Suffix == "PBMRAW")
    {
        return FIF_PBMRAW;
    }
    else if (Suffix == "PCD")
    {
        return FIF_PCD;
    }
    else if (Suffix == "PCX")
    {
        return FIF_PCX;
    }
    else if (Suffix == "PGM")
    {
        return FIF_PGM;
    }
    else if (Suffix == "PGMRAW")
    {
        return FIF_PGMRAW;
    }
    else if (Suffix == "PNG")
    {
        return FIF_PNG;
    }
    else if (Suffix == "PPM")
    {
        return FIF_LBM;
    }
    else if (Suffix == "PPMRAW")
    {
        return FIF_PPMRAW;
    }
    else if (Suffix == "RAS")
    {
        return FIF_RAS;
    }
    else if (Suffix == "TARGA")
    {
        return FIF_TARGA;
    }
    else if (Suffix == "TIFF")
    {
        return FIF_TIFF;
    }
    else if (Suffix == "WBMP")
    {
        return FIF_WBMP;
    }
    else if (Suffix == "PSD")
    {
        return FIF_PSD;
    }
    else if (Suffix == "CUT")
    {
        return FIF_CUT;
    }
    else if (Suffix == "XBM")
    {
        return FIF_XBM;
    }
    else if (Suffix == "XPM")
    {
        return FIF_XPM;
    }
    else if (Suffix == "DDS")
    {
        return FIF_DDS;
    }
    else if (Suffix == "GIF")
    {
        return FIF_GIF;
    }
    else if (Suffix == "HDR")
    {
        return FIF_HDR;
    }
    else if (Suffix == "FAXG3")
    {
        return FIF_FAXG3;
    }
    else if (Suffix == "SGI")
    {
        return FIF_SGI;
    }
    else if (Suffix == "EXR")
    {
        return FIF_EXR;
    }
    else if (Suffix == "J2K")
    {
        return FIF_J2K;
    }
    else if (Suffix == "JP2")
    {
        return FIF_JP2;
    }
    else if (Suffix == "PFM")
    {
        return FIF_PFM;
    }
    else if (Suffix == "PICT")
    {
        return FIF_PICT;
    }
    else if (Suffix == "RAW")
    {
        return FIF_RAW;
    }
    else if (Suffix == "WEBP")
    {
        return FIF_WEBP;
    }
    else if (Suffix == "JXR")
    {
        return FIF_JXR;
    }
    return FIF_UNKNOWN;

}

bool FreeImageMain::ImageTransformationImage(QString sourcePath, QString destinationPath) const
{
    int imageFormat = FreeImage_GetFIFFromFilename(sourcePath.toStdString().data());//获取文件格式
    //static_cast<FREE_IMAGE_FORMAT>(imageFormat) 把 int 转换成 FREE_IMAGE_FORMAT 枚举类型
    FIBITMAP *dib = FreeImage_Load(static_cast<FREE_IMAGE_FORMAT>(imageFormat),sourcePath.toStdString().data());
    if(dib == NULL)
    {
//        qDebug()<<textCodec->toUnicode("图像加载失败！");
        statusBar->showMessage(textCodec->toUnicode("图像加载失败！"),3000);
        return false;
    }
    //    qDebug()<<textCodec->toUnicode("ImageType：")<<FreeImage_GetImageType(dib);//获取位图类型
    //    qDebug()<<textCodec->toUnicode("BPP：")<<FreeImage_GetBPP(dib);//获取位深
    unsigned int width = FreeImage_GetWidth(dib);//获取图像的宽
    unsigned int height = FreeImage_GetHeight(dib);//获取图像的高
    if(imageFormat == FIF_ICO && width!=height)
    {
//        qDebug()<<textCodec->toUnicode("ICO-请确保位图的宽和高相等！");
        statusBar->showMessage(textCodec->toUnicode("ICO-请确保位图的宽和高相等！"),3000);
    }
    if(FreeImage_Save(static_cast<FREE_IMAGE_FORMAT>(GetImagePathSuffix(destinationPath)),dib,destinationPath.toStdString().data()))
    {
        qDebug()<<textCodec->toUnicode("位图格式转换成功");
        statusBar->showMessage(textCodec->toUnicode("位图格式转换成功"),3000);
        return true;
    }
    else
    {
        qDebug()<<textCodec->toUnicode("位图格式转换失败");
        statusBar->showMessage(textCodec->toUnicode("位图格式转换失败"),3000);
        return false;
    }
}

//RC_ICONS = ./LOGO.ico