add bitmap conversion to utils

thermion_dart/test/helpers.dart

@@ -173,51 +173,6 @@ class TestHelper {
   }
 }
 
-Future<Uint8List> pixelBufferToBmp(
-    Uint8List pixelBuffer, int width, int height) async {
-  final rowSize = (width * 3 + 3) & ~3;
-  final padding = rowSize - (width * 3);
-  final fileSize = 54 + rowSize * height;
-
-  final data = Uint8List(fileSize);
-  final buffer = data.buffer;
-  final bd = ByteData.view(buffer);
-
-  // BMP file header (14 bytes)
-  bd.setUint16(0, 0x4D42, Endian.little); // 'BM'
-  bd.setUint32(2, fileSize, Endian.little);
-  bd.setUint32(10, 54, Endian.little); // Offset to pixel data
-
-  // BMP info header (40 bytes)
-  bd.setUint32(14, 40, Endian.little); // Info header size
-  bd.setInt32(18, width, Endian.little);
-  bd.setInt32(22, -height, Endian.little); // Negative for top-down
-  bd.setUint16(26, 1, Endian.little); // Number of color planes
-  bd.setUint16(28, 24, Endian.little); // Bits per pixel (RGB)
-  bd.setUint32(30, 0, Endian.little); // No compression
-  bd.setUint32(34, rowSize * height, Endian.little); // Image size
-  bd.setInt32(38, 2835, Endian.little); // X pixels per meter
-  bd.setInt32(42, 2835, Endian.little); // Y pixels per meter
-
-  // Pixel data (BMP stores in BGR format)
-  for (var y = 0; y < height; y++) {
-    for (var x = 0; x < width; x++) {
-      final srcIndex = (y * width + x) * 4; // RGBA format
-      final dstIndex = 54 + y * rowSize + x * 3; // BGR format
-      data[dstIndex] = pixelBuffer[srcIndex + 2]; // Blue
-      data[dstIndex + 1] = pixelBuffer[srcIndex + 1]; // Green
-      data[dstIndex + 2] = pixelBuffer[srcIndex]; // Red
-      // Alpha channel is discarded
-    }
-    // Add padding to the end of each row
-    for (var p = 0; p < padding; p++) {
-      data[54 + y * rowSize + width * 3 + p] = 0;
-    }
-  }
-
-  return data;
-}
-
 Future<Uint8List> pixelsToPng(Uint8List pixelBuffer, int width, int height,
     {bool linearToSrgb = false, bool invertAces = false}) async {
   final image = img.Image(width: width, height: height);