Qt: Difference between revisions

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<code>nix-shell -p qt5Full -p qtcreator --run qtcreator</code>

Tip: if it finds no Qt Kits, <code>rm -rf ~/.config/QtProject*</code> and start again.

Tip: if it finds no Qt Kits, <code>rm -rf ~/.config/QtProject*</code> and start again. Sometimes it finds a kit, but cannot find a suitable qt version for it, in this case you can also type <code>which qmake</code> in your nix-shell and add a new entry in the <code>QT-Versions</code> tab in <code>Tools->Options->Kits</code>.

For using direnv, create a '''shell.nix''' file in the root of your project and paste these lines into it:

# shell.nix

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Happy qt coding :)

=== Explicit Dependencies ===

However if fetching the entirety of <code>pkgs.qt6.full</code> is not appealing and you know which parts of Qt you need, your first instinct might be adding something like <code>pkgs.qt6.qtdeclarative</code> for creating QML-based Qt programs to <code>buildInputs</code>, '''however''' that will not work and you will get compile errors for missing libraries. <code>pkgs.qt6.full</code> is actually [https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/libraries/qt-6/default.nix#L94-L144 creating an environment that contains all Qt libraries] that allows <code>qmake</code> and tools to find those libraries, so you must do the same and <code>pkgs.qt6.env</code> will help make one. For example:

# shell.nix

{ pkgs ? import <nixpkgs> {} }:

let

# pkgs.qt6.env already includes pkgs.qt6.qtbase

# And using `with` to prevent a lot of typing.

qtEnv = with pkgs.qt6; env "qt-custom-${qtbase.version}" [

qtdeclarative

];

in

pkgs.mkShell {

buildInputs = [

qtEnv

# pkgs.qt6.qtdeclarative depends on pkgs.libglvnd

# Also worth noting it could be in qtEnv if preferred for "relatedness" reasons

pkgs.libglvnd

pkgs.qtcreator

];

}

</syntaxhighlight>

== Packaging ==

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</syntaxHighlight>

For actual python applications, you ~~can~~ also use something like (~~TODO: check difference between wrapGAppsHook and wrapQtAppsHook~~) :

For actual python applications, you may also use something like that (to test) :

python3.pkgs.buildPythonApplication {

pname = "~~gnome-music~~";

pname = "blabla";

version = "3.32.2";

nativeBuildInputs = [

~~wrapGAppsHook~~

wrapQtAppsHook

~~gobject-introspection~~

...

];

~~dontWrapGApps~~ = true;

dontWrapQtApps = true; # wrapQtApps won't patch script anyway. TODO: save to use if it contains executables?

# Arguments to be passed to `makeWrapper`, only used by buildPython*

preFixup = ''

~~makeWrapperArgs~~+=("''${gappsWrapperArgs[@]}")

qtWrapperArgs+=("''${gappsWrapperArgs[@]}")

# You can manually patch scripts using: wrapQtApp "$out/bin/myapp". TODO: check when it's required.

'';

}

</syntaxHighlight>

== Migrating apps from Qt5 to Qt6 ==

# Replace <code>libsForQt5.callPackage</code> with <code>qt6Packages.callPackage</code>

# Add the dependency [https://www.qt.io/blog/porting-from-qt-5-to-qt-6-using-qt5compat-library qt5compat]

# Hope for the best ; )

<code>qt5compat</code> is only needed for Qt5 projects, which are not-yet migrated to Qt6.

Maybe add libraries like <code>qtwayland</code>

Conditional blocks in qmake <code>*.pro</code> files

lessThan(QT_MAJOR_VERSION, 6) {

# qt5, qt4, ...

QT += x11extras

}

equals(QT_MAJOR_VERSION, 6) {

# qt6

QT += core-private

}

</syntaxHighlight>

See also:

* [https://doc.qt.io/qt-6/portingguide.html Porting to Qt 6]

* [https://stackoverflow.com/questions/18663331 How to check the selected version of Qt in a .pro file?]

== Hello world involving QML, Qt5, nix and cmake, qmake or meson ==

You can find [https://gist.github.com/tobiasBora/04d0febda0b3f09707b5e1b7b85390a5 here] a minimal example to use QML, cmake, nix and Qt5, and [https://gist.github.com/tobiasBora/6f114cca1affb5528c872ca01d7e28c1 here] is the same example with qmake instead and [https://gist.github.com/tobiasBora/812701e8741814393f3df7b23a11eb4b here] is the same with meson instead. There is nothing special to nix there, but note that if you provide the qml file using something like <code>qrc:///main.qml</code>, then you need to write a qrc file that lists all the resources that must be included in the qt resource manager. This file is then used to compile the resources and include them in the binary (you have to compile the binaries, either automatically with cmake or qmake, or manually using rcc). With cmake you compile it using <code>qt5_add_resources(SOURCES qml.qrc)</code> ([https://doc.qt.io/qt-5/qtcore-cmake-qt5-add-resources.html doc]) as illustrated in the above example (make sure to use a variable as the source and to reuse the same variable in <code>add_executable</code>).

== Troubleshooting ==

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</pre>

The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-hook.sh in nixpkgs]

The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-apps-hook.sh in nixpkgs]

==== Debugging methods ====

@@ Line 7: / Line 7: @@
 <code>nix-shell -p qt5Full -p qtcreator --run qtcreator</code>
-Tip: if it finds no Qt Kits, <code>rm -rf ~/.config/QtProject*</code> and start again.
+Tip: if it finds no Qt Kits, <code>rm -rf ~/.config/QtProject*</code> and start again. Sometimes it finds a kit, but cannot find a suitable qt version for it, in this case you can also type <code>which qmake</code> in your nix-shell and add a new entry in the <code>QT-Versions</code> tab in <code>Tools->Options->Kits</code>.
 For using direnv, create a '''shell.nix''' file in the root of your project and paste these lines into it:
 <syntaxHighlight lang=nix>
 # shell.nix
@@ Line 27: / Line 28: @@
 Happy qt coding :)
+=== Explicit Dependencies ===
+However if fetching the entirety of <code>pkgs.qt6.full</code> is not appealing and you know which parts of Qt you need, your first instinct might be adding something like <code>pkgs.qt6.qtdeclarative</code> for creating QML-based Qt programs to <code>buildInputs</code>, '''however''' that will not work and you will get compile errors for missing libraries. <code>pkgs.qt6.full</code> is actually [https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/libraries/qt-6/default.nix#L94-L144 creating an environment that contains all Qt libraries] that allows <code>qmake</code> and tools to find those libraries, so you must do the same and <code>pkgs.qt6.env</code> will help make one. For example:
+<syntaxhighlight lang="nix">
+# shell.nix
+{ pkgs ? import <nixpkgs> {} }:
+let
+  # pkgs.qt6.env already includes pkgs.qt6.qtbase
+  # And using `with` to prevent a lot of typing.
+  qtEnv = with pkgs.qt6; env "qt-custom-${qtbase.version}" [
+    qtdeclarative
+  ];
+in
+  pkgs.mkShell {
+    buildInputs = [
+      qtEnv
+      # pkgs.qt6.qtdeclarative depends on pkgs.libglvnd
+      # Also worth noting it could be in qtEnv if preferred for "relatedness" reasons
+      pkgs.libglvnd
+      pkgs.qtcreator
+    ];
+}
+</syntaxhighlight>
 == Packaging ==
@@ Line 114: / Line 139: @@
 </syntaxHighlight>
-For actual python applications, you can also use something like (TODO: check difference between wrapGAppsHook and wrapQtAppsHook) :
+For actual python applications, you may also use something like that (to test) :
 <syntaxHighlight>
 python3.pkgs.buildPythonApplication {
-   pname = "gnome-music";
+   pname = "blabla";
    version = "3.32.2";
    nativeBuildInputs = [
-     wrapGAppsHook
+     wrapQtAppsHook
-    gobject-introspection
      ...
    ];
-   dontWrapGApps = true;
+   dontWrapQtApps = true; # wrapQtApps won't patch script anyway. TODO: save to use if it contains executables?
    # Arguments to be passed to `makeWrapper`, only used by buildPython*
    preFixup = ''
-    makeWrapperArgs+=("''${gappsWrapperArgs[@]}")
+        qtWrapperArgs+=("''${gappsWrapperArgs[@]}")
+        # You can manually patch scripts using: wrapQtApp "$out/bin/myapp". TODO: check when it's required.
    '';
 }
 </syntaxHighlight>
+== Migrating apps from Qt5 to Qt6 ==
+# Replace <code>libsForQt5.callPackage</code> with <code>qt6Packages.callPackage</code>
+# Add the dependency [https://www.qt.io/blog/porting-from-qt-5-to-qt-6-using-qt5compat-library qt5compat]
+# Hope for the best ; )
+<code>qt5compat</code> is only needed for Qt5 projects, which are not-yet migrated to Qt6.
+Maybe add libraries like <code>qtwayland</code>
+Conditional blocks in qmake <code>*.pro</code> files
+<syntaxHighlight lang=pro>
+lessThan(QT_MAJOR_VERSION, 6) {
+  # qt5, qt4, ...
+  QT += x11extras
+}
+equals(QT_MAJOR_VERSION, 6) {
+  # qt6
+  QT += core-private
+}
+</syntaxHighlight>
+See also:
+* [https://doc.qt.io/qt-6/portingguide.html Porting to Qt 6]
+* [https://stackoverflow.com/questions/18663331 How to check the selected version of Qt in a .pro file?]
+== Hello world involving QML, Qt5, nix and cmake, qmake or meson ==
+You can find [https://gist.github.com/tobiasBora/04d0febda0b3f09707b5e1b7b85390a5 here] a minimal example to use QML, cmake, nix and Qt5, and [https://gist.github.com/tobiasBora/6f114cca1affb5528c872ca01d7e28c1 here] is the same example with qmake instead and [https://gist.github.com/tobiasBora/812701e8741814393f3df7b23a11eb4b here] is the same with meson instead. There is nothing special to nix there, but note that if you provide the qml file using something like <code>qrc:///main.qml</code>, then you need to write a qrc file that lists all the resources that must be included in the qt resource manager. This file is then used to compile the resources and include them in the binary (you have to compile the binaries, either automatically with cmake or qmake, or manually using rcc). With cmake you compile it using <code>qt5_add_resources(SOURCES qml.qrc)</code> ([https://doc.qt.io/qt-5/qtcore-cmake-qt5-add-resources.html doc]) as illustrated in the above example (make sure to use a variable as the source and to reuse the same variable in <code>add_executable</code>).
 == Troubleshooting ==
@@ Line 172: / Line 230: @@
 </pre>
-The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-hook.sh in nixpkgs]
+The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-apps-hook.sh in nixpkgs]
 ==== Debugging methods ====