/*
    Copyright 2006-2017 The QElectroTech Team
    This file is part of QElectroTech.
    
    QElectroTech is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.
    
    QElectroTech is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>
*/
#include "qetapp.h"

#if defined(Q_OS_WIN32)
    #include "ShellScalingApi.h"
#endif

/**
 * @brief main
 * Main function of QElectroTech
 * @param argc : number of paramètres
 * @param argv : paramètres
 * @return
 */
int main(int argc, char **argv)
{
        //Some setup, notably to use with QSetting.
    QCoreApplication::setOrganizationName("QElectroTech");
    QCoreApplication::setOrganizationDomain("qelectrotech.org");
    QCoreApplication::setApplicationName("QElectroTech");
        //Creation and execution of the application
        //HighDPI

    #if defined(Q_OS_WIN32)
        typedef BOOL (*SetProcessDpiAwarenessT)(PROCESS_DPI_AWARENESS value);
        QLibrary user32("user32.dll", NULL);
        SetProcessDpiAwarenessT SetProcessDpiAwarenessD=(SetProcessDpiAwarenessT)user32.resolve("SetProcessDpiAwarenessInternal");
        if(SetProcessDpiAwarenessD)
            SetProcessDpiAwarenessD(PROCESS_DPI_UNAWARE); //Process_DPI_Unaware
    #elif defined(Q_OS_MAC)
       QApplication::setAttribute (Qt::AA_EnableHighDpiScaling);
    #else
        qputenv("QT_DEVICE_PIXEL_RATIO", QByteArray("1"));
    #endif

    return(QETApp(argc, argv).exec());
}

sources/main.cpp:42:43: error: call of overloaded 'QLibrary(const char [11], NULL)' is ambiguous
         QLibrary user32("user32.dll", NULL);
                                           ^
In file included from ../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtCore/QtCore:88:0,
                 from ../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtXml/QtXmlDepends:3,
                 from ../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtXml/QtXml:3,
                 from sources/nameslist.h:20,
                 from sources/ElementsCollection/elementslocation.h:21,
                 from sources/qetapp.h:26,
                 from sources/main.cpp:18:
../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtCore/qlibrary.h:71:14: note: candidate: QLibrary::QLibrary(const QString&, const QString&, QObject*)
     explicit QLibrary(const QString& fileName, const QString &version, QObject *parent = Q_NULLPTR);
              ^~~~~~~~
../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtCore/qlibrary.h:70:14: note: candidate: QLibrary::QLibrary(const QString&, int, QObject*)
     explicit QLibrary(const QString& fileName, int verNum, QObject *parent = Q_NULLPTR);
              ^~~~~~~~
../../mxe/usr/x86_64-w64-mingw32.static/qt5/include/QtCore/qlibrary.h:69:14: note: candidate: QLibrary::QLibrary(const QString&, QObject*)
     explicit QLibrary(const QString& fileName, QObject *parent = Q_NULLPTR);

#ifdef Q_OS_WIN
#include <Windows.h>

typedef enum PROCESS_DPI_AWARENESS {
    PROCESS_DPI_UNAWARE = 0,
    PROCESS_SYSTEM_DPI_AWARE = 1,
    PROCESS_PER_MONITOR_DPI_AWARE = 2
} PROCESS_DPI_AWARENESS;
#endif

/*
    Copyright 2006-2017 The QElectroTech Team
    This file is part of QElectroTech.
    
    QElectroTech is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.
    
    QElectroTech is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>
*/
#include "qetapp.h"

#ifdef Q_OS_WIN
#include <windows.h>
#include <winuser.h>
#endif


/**
 * @brief main
 * Main function of QElectroTech
 * @param argc : number of paramètres
 * @param argv : paramètres
 * @return
 */
int main(int argc, char **argv)
{
        //Some setup, notably to use with QSetting.
    QCoreApplication::setOrganizationName("QElectroTech");
    QCoreApplication::setOrganizationDomain("qelectrotech.org");
    QCoreApplication::setApplicationName("QElectroTech");
        //Creation and execution of the application
      //HighDPI



#ifdef Q_OS_WIN
#ifndef DPI_ENUMS_DECLARED
    typedef enum PROCESS_DPI_AWARENESS
    {
        PROCESS_DPI_UNAWARE = 0,
        PROCESS_SYSTEM_DPI_AWARE = 1,
        PROCESS_PER_MONITOR_DPI_AWARE = 2
    } PROCESS_DPI_AWARENESS;
#endif
    typedef BOOL (WINAPI * SETPROCESSDPIAWARE_T)(void);
    typedef HRESULT (WINAPI * SETPROCESSDPIAWARENESS_T)(PROCESS_DPI_AWARENESS);

    HMODULE shcore = LoadLibraryA("Shcore.dll");
    SETPROCESSDPIAWARENESS_T SetProcessDpiAwareness = NULL;
    if (shcore) {
        SetProcessDpiAwareness = (SETPROCESSDPIAWARENESS_T) GetProcAddress(shcore, "SetProcessDpiAwareness");
    }
    HMODULE user32 = LoadLibraryA("User32.dll");
    SETPROCESSDPIAWARE_T SetProcessDPIAware = NULL;
    if (user32) {
        SetProcessDPIAware = (SETPROCESSDPIAWARE_T) GetProcAddress(user32, "SetProcessDPIAware");
    }
    qDebug()<<"SetProcessDpiAwareness---"<<*SetProcessDpiAwareness;
    
    if (user32) {
        FreeLibrary(user32);
    }
    if (shcore) {
        FreeLibrary(shcore);
    }
#endif 

#if QT_VERSION >= QT_VERSION_CHECK(5,6,0)
    QApplication::setAttribute(Qt::AA_DisableHighDpiScaling);
#else
    float sca =  winDpiScale();
    sca = qRound(sca);
    // qDebug()<<"sca:"<<sca;
    QByteArray b = QByteArray::number(sca,'f',0);
    qputenv("QT_DEVICE_PIXEL_RATIO",b);
#endif

#ifdef Q_OS_WIN
    SetProcessDPIAware();
#endif
 
    return(QETApp(argc, argv).exec());
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
<dependency>
  <dependentAssembly>
    <assemblyIdentity
     type="win32"
     name="Microsoft.Windows.Common-Controls"
     version="6.0.0.0" processorArchitecture="*"
     publicKeyToken="6595b64144ccf1df"
     language="*">
    </assemblyIdentity>
  </dependentAssembly>
</dependency>
    <asmv3:application>
        <asmv3:windowsSettings>
            <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/pm</dpiAware> <!-- fallback for Windows 7 and 8 -->
            <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">permonitorv2,permonitor</dpiAwareness> <!-- falls back to per-monitor if per-monitor v2 is not supported -->
            <gdiScaling xmlns="http://schemas.microsoft.com/SMI/2017/WindowsSettings">true</gdiScaling> <!-- enables GDI DPI scaling -->
        </asmv3:windowsSettings>
    </asmv3:application>
</assembly>

svn diff
Index: qelectrotech.exe.manifest
===================================================================
--- qelectrotech.exe.manifest   (nonexistent)
+++ qelectrotech.exe.manifest   (copie de travail)
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
+
+<dependency>
+  <dependentAssembly>
+    <assemblyIdentity
+     type="win32"
+     name="Microsoft.Windows.Common-Controls"
+     version="6.0.0.0" processorArchitecture="*"
+     publicKeyToken="6595b64144ccf1df"
+     language="*">
+    </assemblyIdentity>
+  </dependentAssembly>
+</dependency>
+    <asmv3:application>
+        <asmv3:windowsSettings>
+            <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/pm</dpiAware> 
+<!-- fallback for Windows 7 and 8 -->
+            <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">permonitorv2,permonitor</dpiAwareness> 
+<!-- falls back to per-monitor if per-monitor v2 is not supported -->
+            <gdiScaling xmlns="http://schemas.microsoft.com/SMI/2017/WindowsSettings">true</gdiScaling> 
+<!-- enables GDI DPI scaling -->
+        </asmv3:windowsSettings>
+    </asmv3:application>
+</assembly>
Index: qelectrotech.pro
===================================================================
--- qelectrotech.pro    (révision 5226)
+++ qelectrotech.pro    (copie de travail)
@@ -30,6 +30,8 @@
        QET_COMMON_TBT_PATH        = 'titleblocks/'
        QET_LANG_PATH              = 'lang/'
        QET_LICENSE_PATH           = './'
+               # Liste des ressources Windows
+    RC_FILE = qelectrotech.rc
 }
 macx {
        # Chemins MacOS X
Index: qelectrotech.rc
===================================================================
--- qelectrotech.rc     (nonexistent)
+++ qelectrotech.rc     (copie de travail)
@@ -0,0 +1,4 @@
+#include <windows.h>
+
+ID_ICON1 ICON DISCARDABLE "qelectrotech.ico"
+1 RT_MANIFEST "qelectrotech.exe.manifest"

by the way you should not use QT_DEVICE_PIXEL_RATIO anymore, it will be removed in future qt

#if QT_VERSION >= QT_VERSION_CHECK(5, 6, 0)
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
#else
    qputenv("QT_DEVICE_PIXEL_RATIO", QByteArray("auto"));
#endif 

--- sources/diagramprintdialog.cpp
+++ sources/diagramprintdialog.cpp
@@ -354,7 +354,7 @@
 */
 void DiagramPrintDialog::print(const QList<Diagram *> &diagrams, bool fit_page, const ExportProperties options) {
     //qDebug() << "Demande d'impression de " << diagrams.count() << "schemas.";
-#if QT_VERSION >= QT_VERSION_CHECK(5, 0, 0)
+#if QT_VERSION >= QT_VERSION_CHECK(5, 6, 0)
     #ifdef Q_OS_WIN
         #ifdef QT_DEBUG
             qDebug() << "--";