fix missing icon in control panel for Windows

CMakeLists.txt

@@ -1345,7 +1345,8 @@ set (CPACK_PACKAGE_INSTALL_DIRECTORY ${CPACK_PACKAGE_NAME})
 set (CPACK_PACKAGE_ICON "${CMAKE_SOURCE_DIR}/resources/images\\\\OrcaSlicer.ico")
 set (CPACK_NSIS_MUI_ICON "${CPACK_PACKAGE_ICON}")
 set (CPACK_NSIS_MUI_UNIICON "${CPACK_PACKAGE_ICON}")
-set (CPACK_NSIS_INSTALLED_ICON_NAME  "$INSTDIR\\\\orca-slicer.exe")
+# Relative to the install dir: CPack's NSIS template prefixes $INSTDIR itself.
+set (CPACK_NSIS_INSTALLED_ICON_NAME "orca-slicer.exe")
 set (CPACK_PACKAGE_CHECKSUM SHA256)
 set (CPACK_PACKAGE_INSTALL_REGISTRY_KEY "OrcaSlicer")
 set (CPACK_NSIS_ENABLE_UNINSTALL_BEFORE_INSTALL ON)

build_win.bat

@@ -42,6 +42,7 @@ call :add_arg build_deps bool d deps "Download and build the dependencies, neede
 call :add_arg build_slicer bool s slicer "Build OrcaSlicer"
 call :add_arg build_tests bool "" tests "Build the unit tests"
 call :add_arg run_tests bool "" run-tests "Build the unit tests and run them"
+call :add_arg make_installer bool "" installer "Build OrcaSlicer and package it into an NSIS installer"
 call :add_arg pack_deps bool p pack "Bundle the built dependencies into a zip file"
 call :add_arg install_deps bool u install-deps "Install or update CMake, Perl and Git with WinGet"
 call :add_arg install_vs string "" install-vs "Also install Visual Studio: buildtools or ide"
@@ -185,6 +186,9 @@ if "%build_deps%%build_slicer%%pack_deps%%install_deps%%install_vs%" == "" (
     if "%run_tests%" == "ON" set "build_slicer=ON"
 )
 
+REM The installer packages the slicer build, so it always needs one.
+if "%make_installer%" == "ON" set "build_slicer=ON"
+
 REM Options like --config or -j only shape a build. Without one of the actions
 REM there is nothing for them to shape, so say so rather than resolving a whole
 REM build and reporting it took no time. The block above may have added one.
@@ -222,6 +226,30 @@ if "%build_slicer%" == "ON" if "%install_slicer%" == "ON" if not "%slicer_target
     echo --install needs the executable, but --slicer-target names "%slicer_target%".
     exit /b 1
 )
+REM cpack runs the same install, so it has the same need.
+if "%make_installer%" == "ON" if not "%slicer_target%" == "" if /I not "%slicer_target%" == "OrcaSlicer" (
+    echo --installer needs the executable, but --slicer-target names "%slicer_target%".
+    exit /b 1
+)
+
+REM cpack finds makensis on PATH or through the registry key the NSIS installer
+REM writes, so look in the same places, and before the build rather than after
+REM it. The value is read past its REG_SZ marker because the name column is
+REM localised and may hold spaces.
+if not "%make_installer%" == "ON" goto :nsis_ready
+if "%dry_run%" == "ON" goto :nsis_ready
+where makensis >nul 2>nul && goto :nsis_ready
+for %%v in (32 64) do (
+    for /f "delims=" %%l in ('reg query "HKLM\SOFTWARE\NSIS" /ve /reg:%%v 2^>nul ^| findstr REG_SZ') do (
+        set "nsis_line=%%l"
+        set "nsis_line=!nsis_line:*REG_SZ=!"
+        for /f "tokens=*" %%d in ("!nsis_line!") do if exist "%%d\makensis.exe" goto :nsis_ready
+    )
+)
+echo NSIS was not found, and --installer needs it to build the installer.
+echo Install it with "winget install NSIS.NSIS", then run this again.
+exit /b 1
+:nsis_ready
 if not "%vs_version%" == "" if "!vs_gen_%vs_version%!" == "" (
     echo Unknown Visual Studio release "%vs_version%". Known releases: 2019, 2022, 2026.
     exit /b 1
@@ -734,6 +762,14 @@ if "%build_slicer%" == "ON" (
         call :print_and_run cmake --build "%build_dir%" --target install --config %build_type%
         %error_check%
     )
+
+    REM cpack installs into its own staging tree, so this does not need -i.
+    REM Unlike CI it skips the preset cache, whose packaging step prunes the
+    REM checkout's preset JSONs.
+    if "%make_installer%" == "ON" (
+        call :print_and_run cpack -G NSIS -C %build_type% --config "%build_dir%\CPackConfig.cmake" -B "%build_dir%"
+        %error_check%
+    )
 )
 
 REM Elapsed wall clock. The 1%%a-100 trick strips a leading zero, which set /A
@@ -820,6 +856,16 @@ REM worked out the same way in either run.
     if "%build_slicer%" == "ON" if not "%linked%" == "ON" echo   Target        %slicer_target%
     if "%build_slicer%" == "ON" if not "%using_ninja%" == "ON" echo   Solution      %build_full%\!solution!
     if "%pack_deps%" == "ON" if defined bundle echo   Bundle        !bundle!
+    if "%make_installer%" == "ON" (
+        REM The file name carries the version, which only CMake knows, so name
+        REM the newest match, or the pattern when there is none yet.
+        set "installer="
+        for /f "delims=" %%f in ('dir /b /o-d "!build_full!\OrcaSlicer_Windows_Installer_*.exe" 2^>nul') do (
+            if not defined installer set "installer=!build_full!\%%f"
+        )
+        if not defined installer set "installer=!build_full!\OrcaSlicer_Windows_Installer_*.exe"
+        echo   Installer     !installer!
+    )
 
     echo.
     echo Next