fix: installer not interrupted when system version not fit (>=Windows…

… 8.1)

output/install.nsi

@@ -73,6 +73,7 @@ LangString LNKFORUPDATER ${LANG_TRADCHINESE} "【小狼毫】檢查新版本"
 LangString LNKFORSETUP ${LANG_TRADCHINESE} "【小狼毫】安裝選項"
 LangString LNKFORUNINSTALL ${LANG_TRADCHINESE} "卸載小狼毫"
 LangString CONFIRMATION ${LANG_TRADCHINESE} "安裝前，請先卸載舊版本的小狼毫。$\n$\n按下「確定」移除舊版本，按下「取消」放棄本次安裝。"
+LangString SYSTEMVERSIONNOTOK ${LANG_TRADCHINESE} "您的系统不被支持，最低系統要求:Windows 8.1!"
 
 !insertmacro MUI_LANGUAGE "SimpChinese"
 LangString DISPLAYNAME ${LANG_SIMPCHINESE} "小狼毫输入法"
@@ -88,6 +89,7 @@ LangString LNKFORUPDATER ${LANG_SIMPCHINESE} "【小狼毫】检查新版本"
 LangString LNKFORSETUP ${LANG_SIMPCHINESE} "【小狼毫】安装选项"
 LangString LNKFORUNINSTALL ${LANG_SIMPCHINESE} "卸载小狼毫"
 LangString CONFIRMATION ${LANG_SIMPCHINESE} '安装前，请先卸载旧版本的小狼毫。$\n$\n点击 "确定" 移除旧版本，或点击 "取消" 放弃本次安装。'
+LangString SYSTEMVERSIONNOTOK ${LANG_SIMPCHINESE} "您的系統不被支持，最低系统要求:Windows 8.1!"
 
 !insertmacro MUI_LANGUAGE "English"
 LangString DISPLAYNAME ${LANG_ENGLISH} "Weasel"
@@ -103,10 +105,49 @@ LangString LNKFORUPDATER ${LANG_ENGLISH} "Weasel Check for Updates"
 LangString LNKFORSETUP ${LANG_ENGLISH} "Weasel Installation Preference"
 LangString LNKFORUNINSTALL ${LANG_ENGLISH} "Uninstall Weasel"
 LangString CONFIRMATION ${LANG_ENGLISH} "Before installation, please uninstall the old version of Weasel.$\n$\nPress 'OK' to remove the old version, or 'Cancel' to abort installation."
+LangString SYSTEMVERSIONNOTOK ${LANG_ENGLISH} "Your system not supported, minimium system required: Windows 8.1!"
 
 ;--------------------------------
 
+Var /GLOBAL WindowsVersion
+Var /GLOBAL MajorVersion
+Var /GLOBAL MinorVersion
+Var /GLOBAL DotPosition
+
+Function FindDotPosition
+  StrCpy $DotPosition 0 ; Initialize position
+  loop:
+  IntOp $DotPosition $DotPosition + 1 ; Increment position
+  StrCpy $0 $WindowsVersion 1 $DotPosition ; Get character at current position
+  StrCmp $0 "." 0 loop ; If character is not ".", continue loop
+FunctionEnd
+
 Function .onInit
+  ; read CurrentVersion to check if system is equal or greater than Windows 8.1
+  ; if not >= 8.1, quit and MessageBox(if not silent)
+  ReadRegStr $WindowsVersion HKLM "SOFTWARE\Microsoft\Windows NT\CurrentVersion" CurrentVersion
+
+  Call FindDotPosition
+  StrCpy $MajorVersion $WindowsVersion $DotPosition
+  IntOp $DotPosition $DotPosition + 1
+  StrCpy $WindowsVersion $WindowsVersion "" $DotPosition
+  Call FindDotPosition
+  StrCpy $MinorVersion $WindowsVersion $DotPosition
+
+  ${If} $MajorVersion < 6
+    IfSilent quit
+    MessageBox MB_OK '$(SYSTEMVERSIONNOTOK)'
+    quit:
+    Quit
+  ${ElseIf} $MajorVersion == 6
+    ${If} $MinorVersion < 3
+      IfSilent quit2
+      MessageBox MB_OK '$(SYSTEMVERSIONNOTOK)'
+      quit2:
+      Quit
+    ${EndIf}
+  ${EndIf}
+  ; 
   ReadRegStr $R0 HKLM "Software\Rime\Weasel" "InstallDir"
   StrCmp $R0 "" 0 skip
   ; The default installation directory