In this article, I’m going to show you how to add dark mode to your LCL application on Windows (and Lazarus IDE too!)

PS: This method is for Windows only. Other platforms do not need this method, as setting the system theme to dark is enough for LCL applications to switch to dark mode in those enviornments.

Adding dark mode to Lazarus IDE

Step 1 - Prerequisites

• Make sure you’re on the latest Lazarus IDE version
• Make sure you’re using the correct architecture for your device (i.e x86_64 version of the IDE and FPC if you’re on 64-bit, etc)
• Make sure you have a clean install of Lazarus (Why: To avoid having any configuration issues which might prevent the package from applying correct theming, yes I figured this out the hard way)
• Make sure you have enabled dark mode in Windows settings

  Step 2 - Installing dark mode

• Open Lazarus IDE
• Go to https://github.com/zamtmn/metadarkstyle/ and follow the instructions there on installing the metadarkstyle package
• After you’ve installed it, rebuild the IDE

  Step 3 - Final checks

• To check if metadarkstyle was installed correctly, go to Tools > Options and check if you have an option with the name Dark Style under Environment
• If you do, set the PreferredAppMode option to Allow Dark
• Restart your IDE and it should have a dark theme

  Using dark theme in your own application

• Open your project
• Go to Project > Project Inspector…
• Click Add > New Requirement
• In the Package Name field, search for metadarkstyle and add it to your project
• Also add the metadarkstyledsgn package to your project
• After you’ve added it, go to your application file (it should have a .lpr extension)
• In the uses section, add:

  uses
  // ...
  uDarkStyleParams,
  uMetaDarkStyle,
  uDarkStyleSchemes,
  

• Under the begin section, add:

  PreferredAppMode := pamAllowDark;
  uMetaDarkStyle.ApplyMetaDarkStyle(DefaultDark);
  

• Now run your application and it should have dark mode!