Change Desktop Wallpaper

amahta

You need to use Windows API interfaces (IDesktopWallpaper to be precise) to do this in newer versions of Windows such as 8 and 10.
Checkout this post for more info.

QT-static-prgm

I tried the code, but i get some errors. I hope you understand them. I fixed some of them by using NULL instead of nullptr.

#include "shobjidl.h"
#include <QDebug>

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

	HRESULT hr = CoInitialize(NULL);
	IDesktopWallpaper *pDesktopWallpaper = NULL;
	hr = CoCreateInstance(__uuidof(DesktopWallpaper), NULL, CLSCTX_ALL, IID_PPV_ARGS(&pDesktopWallpaper));
	if (FAILED(hr))
	{
		qDebug() << "error";
	}
	else
	{
		pDesktopWallpaper->SetWallpaper(NULL, QString("C:\\Users\\Amin\\Desktop\\test.jpg").toStdWString().c_str());
	}

	return 0;
}

QT += core
QT -= gui

TARGET = WallpaperChanger
#CONFIG += console
CONFIG -= app_bundle
LIBS += -lOle32

TEMPLATE = app

SOURCES += main.cpp

D:\workspaces\Qt_default\WallpaperChanger\main.cpp:17: Fehler: invalid use of incomplete type 'IDesktopWallpaper {aka struct IDesktopWallpaper}'
pDesktopWallpaper->SetWallpaper(NULL, QString("C:\Users\Amin\Desktop\test.jpg").toStdWString().c_str());
^
C:\Qt\Qt5.5.1\Tools\mingw492_32\i686-w64-mingw32\include\shobjidl.h:987: Fehler: forward declaration of 'IDesktopWallpaper {aka struct IDesktopWallpaper}'
typedef interface IDesktopWallpaper IDesktopWallpaper;
^
C:\Qt\Qt5.5.1\Tools\mingw492_32\i686-w64-mingw32\include\combaseapi.h:79: Fehler: invalid static_cast from type 'IDesktopWallpaper*' to type 'IUnknown*'
static_cast<IUnknown *> (*pp);
^

amahta

First of all, please try the same thing with a Widgets application. And create it by selecting new project, the Widgets Application. Do NOT use console project to try it! (Your project does not seem to be even Console anyway!)
Next, you seem to be using MingW compiler, not sure but you may be facing the problem because of that. The interface mentioned here belongs to recent SDKs of Windows and therefore it might not work correctly (link correctly) with a MingW compiler.
I would suggest using a recent MSVC compiler.

QT-static-prgm

OK, i changed it to widgets application. And yes i'm using MinGW.
I tried to config MSVC for my Qt Creator, but i wasn't successfull:

:-1: Warnung: LNK4044: Nicht erkannte Option /lshell32; wird ignoriert.
:-1: Warnung: LNK4044: Nicht erkannte Option /LC:\Qt\Qt5.5.1\5.5\mingw492_32\lib; wird ignoriert.
:-1: Warnung: LNK4044: Nicht erkannte Option /lQt5Cored; wird ignoriert.
:-1: Fehler: LNK1104: Datei "C:\Qt\Qt5.5.1\5.5\mingw492_32\lib\qtmaind.lib" kann nicht geöffnet werden.

I'm sure i need the libs for msvc, but i couldn't find them. Are there the libs pre compiled? Or do i need to take the qt-everywhere-opensource-src-5.5.1.zip and build the source with my compiler on my own??
(I have Visual Studio Enterprise 2015 installed)

amahta

Unfortunately pre-compiled Libs for Qt are not provided with the official release (not yet!) but you can try building from source yourself.
I would suggest installing a lower version of MSVC compiler such as MSVC2013 (Community Edition is free btw) and using pre-compiled libraries if you are not comfortable with building sources yourself, or if you would prefer official builds.

QT-static-prgm

Ok i'll try to build the source. I did it a while ago with MinGW for static linking. So i hope it will be similar to this.
What's the difference between qt-everywhere-opensource-src-5.5.1 http://download.qt.io/archive/qt/5.5/5.5.1/single/ and qt5-opensource-src-5.5.1 http://download.qt.io/archive/qt/5.5/5.5.1/submodules/

Why should i use a lower version of MSVC?? I recently updated from VS 2013 Ultimate to VS 2015. So i'd prefer the newer one. But if this is a problem I can install VS2013 again.

amahta

@QT-static-prgm
Single is like an All-In-One package of modules but submodules version offers all modules separately.
Most probably you need Single version.
I'll suggest taking a look at this page and also this post

You need to use the lower version if you want the official build. If not, you can build yourself.
Good luck

QT-static-prgm

Thank you very much. Your tutorial is great. But i have some problems again:

+ cd qtbase
+ C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtbase\configure.bat -top-level -static -debug-and-release -prefix "C:\Qt\5.5.1\msvc2015_static" -platform win32-msvc2015 -qt-zlib -qt-pcre -qt-libpng -qt-libjpeg -qt-freetype -opengl desktop -qt-sql-sqlite -qt-sql-odbc -no-openssl -opensource -confirm-license -make libs -nomake tools -nomake examples -nomake tests

This is the Qt for Windows Open Source Edition.

You have already accepted the terms of the license.

Creating qmake...
execute: File or path is not found (nmake)
execute: File or path is not found (nmake)
Cleaning qmake failed, return code -1

btw what are all these options good for??

did i take the wrong cmd?? I used "MSBuild Befehlszeile für VS2015". There some more in my Start->All Programms->Visual Studio list:
Developer-Eingabeaufforderung für VS2015,
VS2015 x64 ARM Cross Tools-Eingabeaufforderung,
VS2015 x64 Native Tools-Eingabeaufforderung,
VS2015 x64 x86 Cross Tools-Eingabeaufforderung,
VS2015 x86 ARM Cross Tools-Eingabeaufforderung,
VS2015 x86 Native Tools-Eingabeaufforderung,
VS2015 x86 x64 Cross Tools-Eingabeaufforderung

Which one is the right one??

amahta

You should have "Developer Command Prompt for VS2015"
You are using German version so "Developer-Eingabeaufforderung für VS2015" is correct!

QT-static-prgm

It works :D Thank you very much.
ähm ok i just wanted to press send and checked my cmd output and it "finished". But it says:

jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtdeclarative\src\qml\Makefile.Debug [.generated\debug\RegExpJitTables.h] Error 1
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtdeclarative\src\qml\Makefile [debug-all] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtdeclarative\src\Makefile [sub-qml-make_first-ordered] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtdeclarative\Makefile [sub-src-make_first] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\Makefile [module-qtdeclarative-make_first] Error 2

amahta

@QT-static-prgm check your build folder. Most probably you already have most of the libraries built. Continue with "jom install" command.
But you can also check for dependencies and/or remove the module causing the problem, in this case it is qtdeclarative, and then rebuild.

QT-static-prgm

-nomake qtdeclarative doesn't work :/

cd qtbase
C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtbase\configure.bat -top-level -static -debug-and-release -prefix "C:\Qt\5.5.1\msvc2015_static" -platform win32-msvc2015 -c++11 -qt-zlib -qt-pcre -qt-libpng -qt-libjpeg -qt-freetype -opengl desktop -qt-sql-sqlite -qt-sql-odbc -no-openssl -opensource -confirm-license -make libs -nomake tools -nomake examples -nomake tests -nomake qtdeclarative
Unknown part qtdeclarative passed to -nomake.

amahta

@QT-static-prgm It won't. You have to carefully read configure options. I suggest taking a look at this old post of mine about configure options. If I am not mistaken, you need to use "skip" instead of "nomake"

QT-static-prgm

And again, thank you so much. What is qtdeclarative good for??

amahta

@QT-static-prgm it is related to QML. I usually can live without it :)

QT-static-prgm

Next error:

Error: dependent 'C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtdeclarative\lib\Qt5Qmld.lib' does not exist.
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtwebchannel\src\webchannel\Makefile [debug-all] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtwebchannel\src\Makefile [sub-webchannel-make_first] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\qtwebchannel\Makefile [sub-src-make_first] Error 2
jom: C:\Qt\5.5.1\qt-everywhere-opensource-src-5.5.1\Makefile [module-qtwebchannel-make_first] Error 2

I think it's a kind of Windows 10 problem: https://forum.qt.io/topic/58056/compilation-failure-with-vs2015/3

mrjj

@QT-static-prgm
HI just a side note:
I used this on Win 7 to change wallpaper.
(with mingw compiler)
Never tested on window 10, so might not work.

#include "mainwindow.h"
#include <QApplication>
#include <qDebug>

#include <Windows.h>
int setwallpaper (QString filePath ) {
  bool ret = SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, (PVOID)filePath.utf16(), SPIF_SENDWININICHANGE | SPIF_UPDATEINIFILE);
  return ret;
}

int main(int argc, char* argv[]) {
  QApplication a(argc, argv);
  MainWindow w;
  w.show();
  setwallpaper("c:/test.jpg"); // adjust
  return a.exec();
}

QT-static-prgm

Your code looks easy. I'll try it. But for now my program shown above is working with the VS compiler.

Thank you all :D

Ok next i'll try to manipulate the image to show the date and clock in the lower right corner. (my university killed the windows clock. That's why i need this ;))

mrjj

@QT-static-prgm
hehe so you switch compiler and
compiled all of Qt so you can change
the wallpaper each minute and that way
get a clock ???
:))
That is the spirit if I ever saw one :))

but are you sure they allow to change the wallpaper?

QT-static-prgm

@mrjj
That's the aim :D

btw your code works fine as well. It is only faster then the other one. This:

#include "mainwindow.h"
#include <QApplication>
#include <QDebug>
#include "shobjidl.h"
#include <Windows.h>


int setwallpaper (QString filePath ) {
  bool ret = SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, (PVOID)filePath.utf16(), SPIF_SENDWININICHANGE | SPIF_UPDATEINIFILE);
  return ret;
}


int main(int argc, char *argv[])
{
	HRESULT hr = CoInitialize(NULL);
	IDesktopWallpaper *pDesktopWallpaper = NULL;
	hr = CoCreateInstance(__uuidof(DesktopWallpaper), NULL, CLSCTX_ALL, IID_PPV_ARGS(&pDesktopWallpaper));
	if (FAILED(hr))
	{
		qDebug() << "error";
	}
	else
	{
		pDesktopWallpaper->SetWallpaper(NULL, QString("D:\\Bilder\\BMW\\3er nachher.jpg").toStdWString().c_str());
	}

	qDebug() << setwallpaper("D:\\Bilder\\BMW\\f22-wallpaper-1920x1600-16.jpg");

	return 0;
}

causes in first shown the f22-wallpaper-1920x1600-16.jpg image and then 3er nachher. So maybe your code is better and that way there was no need to compile qt for vs.

But ok now i understand building qt a bit better XD