git-cola: added .desktop file (#403012)

pkgs/by-name/gi/git-cola/package.nix

@@ -7,6 +7,8 @@
   git,
   qt5,
   versionCheckHook,
+  copyDesktopItems,
+  imagemagick,
   nix-update-script,
 }:
 
@@ -38,7 +40,8 @@ python3Packages.buildPythonApplication rec {
     gettext
     qt5.wrapQtAppsHook
     python3Packages.setuptools-scm
-  ];
+    imagemagick
+  ] ++ lib.optionals stdenv.hostPlatform.isLinux [ copyDesktopItems ];
 
   nativeCheckInputs = [
     git
@@ -57,6 +60,19 @@ python3Packages.buildPythonApplication rec {
     makeWrapperArgs+=("''${qtWrapperArgs[@]}")
   '';
 
+  desktopItems = [
+    "share/applications/git-cola-folder-handler.desktop"
+    "share/applications/git-cola.desktop"
+    "share/applications/git-dag.desktop"
+  ];
+
+  postInstall = ''
+    for i in 16 24 48 64 96 128 256 512; do
+      mkdir -p $out/share/icons/hicolor/''${i}x''${i}/apps
+      magick cola/icons/git-cola.svg -background none -resize ''${i}x''${i} $out/share/icons/hicolor/''${i}x''${i}/apps/${pname}.png
+    done
+  '';
+
   passthru.updateScript = nix-update-script { };
 
   meta = {