Convert images when installing

README.md

@@ -19,7 +19,6 @@ When booting on a UEFI-based computer, Windows may show a vendor-defined logo wh
 * Start `setup.exe` and follow the instructions.
 	* You may need to manually disable Secure Boot and then retry.
 	* The installer will launch Paint for editing the image.
-		* Be sure to always use the 24-bit BMP/DIB format.
 	* If Windows later restores the original boot loader, just reinstall.
 	* If you wish to change the image or other configuration, just reinstall.
 	* For advanced settings, edit `config.txt` before installing. No extra support provided!
@@ -48,9 +47,9 @@ The configuration options are described in `config.txt`, which the installer cop
 
 The image path can be changed in the configuration file. The default path is `[EFI System Partition]\EFI\HackBGRT\splash.bmp`.
 
-The image must be a 24-bit BMP file with a 54-byte header. That's a TrueColor BMP3 in Imagemagick, or 24-bit BMP/DIB in Microsoft Paint.
+If you copy the file to ESP manually, note that the image must be a 24-bit BMP file with a 54-byte header. That's a TrueColor BMP3 in Imagemagick, or 24-bit BMP/DIB in Microsoft Paint.
 
-Advanced users may edit the `config.txt` to define multiple images, in which case one is picked at random. The installer copies files whose `path` starts with `\EFI\HackBGRT\`.
+Advanced users may edit the `config.txt` to define multiple images, in which case one is picked at random. The installer copies and converts files whose `path` starts with `\EFI\HackBGRT\`.
 
 ## Recovery
 

config.txt

@@ -16,8 +16,8 @@ boot=\EFI\HackBGRT\bootmgfw-original.efi
 #  - "remove" to remove the BGRT. Makes x and y meaningless.
 #  - "black" to use only a black image. Makes x and y meaningless.
 #  - "path=..." to read a BMP file.
-#    * NOTE: The installer will only install files with path=\EFI\HackBGRT\*.
+#    * NOTE: For path=\EFI\HackBGRT\*, the installer will copy and convert the file if necessary.
-#    * NOTE: The file must be a 24-bit BMP file with a 54-byte header.
+#    * NOTE: For other paths, make sure that the file is a 24-bit BMP file with a 54-byte header.
 #    * NOTE: The file must be on the EFI System Partition. Do not add a drive letter!
 # Examples:
 #  - image=remove

src/Setup.cs

@@ -1,5 +1,7 @@
 using System;
 using System.IO;
+using System.Drawing;
+using System.Drawing.Imaging;
 using System.Linq;
 
 /**
@@ -134,6 +136,32 @@ public class Setup: SetupHelper {
 		Console.WriteLine($"Installed {name} to {newName}.");
 	}
 
+	/**
+	 * Install a single image file, with conversion to 24-bit BMP.
+	 */
+	protected void InstallImageFile(string name) {
+		var newName = Path.Combine(InstallPath, name);
+		// Load the image to check if it's valid.
+		Bitmap img;
+		try {
+			img = new Bitmap(name);
+		} catch {
+			throw new SetupException($"Failed to load image {name}.");
+		}
+		// Copy the bitmap into an empty 24-bit image (required by EFI).
+		using (Bitmap bmp = new Bitmap(img.Width, img.Height, PixelFormat.Format24bppRgb)) {
+			using (Graphics g = Graphics.FromImage(bmp)) {
+				g.DrawImageUnscaledAndClipped(img, new Rectangle(Point.Empty, img.Size));
+			}
+			try {
+				bmp.Save(newName, ImageFormat.Bmp);
+			} catch {
+				throw new SetupException($"Failed to install image {name} to {newName}.");
+			}
+		}
+		Console.WriteLine($"Installed image {name} to {newName}.");
+	}
+
 	/**
 	 * Install files to ESP.
 	 */
@@ -162,7 +190,7 @@ public class Setup: SetupHelper {
 			var delim = "path=\\EFI\\HackBGRT\\";
 			var i = line.IndexOf(delim);
 			if (i > 0) {
-				InstallFile(line.Substring(i + delim.Length));
+				InstallImageFile(line.Substring(i + delim.Length));
 			}
 		}
 		if (!MsLoader.ReplaceWith(NewLoader)) {