Extract Icons using PowerShell

winIconsPowerShell.dart

class Globals {
  static String iconCachePath = "${Directory.current.path}\\cache";
}
class WinUtils {
  
  static Future<List<String>> runPowerShell(List<String> commands) async {
    final io.ProcessResult result = await io.Process.run(
      'powershell',
      <String>['-NoProfile', ...commands],
    );
    if (result.stderr != '') {
      return <String>[];
    }
    List<String> output = result.stdout.toString().trim().split('\n').map((String e) => e.trim()).toList();
    return output;
  }
  static Future<Uint8List> getCachedIcon(String path, {int iconID = 0}) async {
    final WinIcons winIcon = WinIcons();
    if (iconID == 0) {
      winIcon.add(path);
    } else {
      winIcon.add('$path,$iconID');
    }
    await winIcon.fetch(Globals.iconCachePath);
    if (iconID == 0) {
      return File("${Globals.iconCachePath}\\${Win32.getExe(path)}.cached").readAsBytesSync();
    } else {
      return File("${Globals.iconCachePath}\\dll_${iconID}_${Win32.getExe(path)}.cached").readAsBytesSync();
    }
  }

  static String getIconPath(String exe) {
    return "${Globals.iconCachePath}\\$exe.cached";
  }
}
class WinIcons {
  //[0] - Path, [1] - iconINDEX, which is +/- int
  List<List<dynamic>> list = <List<dynamic>>[];
  WinIcons();
  void add(String item) {
    int dll = 0;
    if (item.contains(',')) {
      final String lastItem = item.substring(item.lastIndexOf('.'));
      final List<String> xploded = lastItem.split(',');
      if (xploded.length == 2) {
        dll = int.parse(xploded[1]);
        item = item.replaceAll(',$dll', '');
      }
    }
    list.add(<dynamic>[item, dll]);
  }

  void addAll(List<String> item) {
    for (String element in item) {
      add(element);
    }
  }

  Future<void> fetch(String directory) async {
    List<String> commands = <String>[
      "Add-Type -AssemblyName System.Drawing;",
      "\$Format = [System.Drawing.Imaging.ImageFormat]::Png;",
    ];
    if (list.where((List<dynamic> e) => e[1] != 0).isNotEmpty) {
      commands.add(
          '''add-type -typeDefinition ' using System; using System.Runtime.InteropServices; public class Shell32_Extract {  [DllImport(  "Shell32.dll",  EntryPoint = "ExtractIconExW",  CharSet = CharSet.Unicode,  ExactSpelling = true,  CallingConvention = CallingConvention.StdCall)  ]  public static extern int ExtractIconEx(  string lpszFile ,   int iconIndex ,   out IntPtr phiconLarge,  out IntPtr phiconSmall,  int nIcons  ); }';''');
    }
    int totalAdded = 0;
    for (List<dynamic> element in list) {
      final String path = element[0];
      final int iconID = element[1];
      final String exePath = Win32.getExe(path);
      String exeCache = directory;

      if (iconID != 0) {
        exeCache += "\\dll_${iconID}_$exePath.cached";
        if (File(exeCache).existsSync()) continue;
        totalAdded++;
        commands.addAll(<String>[
          "[System.IntPtr] \$phiconLarge = 0;",
          "[System.IntPtr] \$phiconSmall = 0;",
          "[Shell32_Extract]::ExtractIconEx('$path', $iconID, [ref] \$phiconLarge, [ref] \$phiconSmall, 1);",
          "\$Icon = [System.Drawing.Icon]::FromHandle(\$phiconSmall).ToBitMap().Save('$exeCache',\$Format);",
        ]);
      } else {
        exeCache += "\\$exePath.cached";
        if (File(exeCache).existsSync()) continue;
        totalAdded++;
        commands.add("\$Icon = [System.Drawing.Icon]::ExtractAssociatedIcon('$path').ToBitMap().Save('$exeCache',\$Format);");
      }
    }
    if (totalAdded > 0) {
      print("total new: $totalAdded");
      await WinUtils.runPowerShell(commands);
    }
  }

  Future<List<Uint8List>> getHandleIcons(List<int> handles) async {
    List<String> commands = <String>[
      "Add-Type -AssemblyName System.Drawing;",
      "\$Format = [System.Drawing.Imaging.ImageFormat]::Png;",
    ];
    for (int handle in handles) {
      commands.addAll(<String>[
        "\$MemoryStream = New-Object System.IO.MemoryStream;",
        "[System.Drawing.Icon]::FromHandle($handle).ToBitMap().Save(\$MemoryStream,\$Format);",
        "\$Bytes = \$MemoryStream.ToArray();",
        "\$MemoryStream.Flush();",
        "\$MemoryStream.Dispose();",
        "[convert]::ToBase64String(\$Bytes);",
      ]);
    }
    final List<String> output = await WinUtils.runPowerShell(commands);
    List<Uint8List> list = output.map(base64Decode).toList();

    return list;
  }

  Future<Uint8List> getHandleIcon(int handle) async {
    final List<int> handles = <int>[handle];
    final List<Uint8List> output = await getHandleIcons(handles);
    if (output.isNotEmpty) {
      return output[0];
    } else {
      return Uint8List.fromList(<int>[0]);
    }
  }
}