Merge pull request #2675 from telecos/BmpIccProfileSupport

Implement BMP icc profile support

Author: 197g

src/codecs/bmp/decoder.rs

@@ -64,6 +64,9 @@ const RLE_ESCAPE_DELTA: u8 = 2;
 /// The maximum width/height the decoder will process.
 const MAX_WIDTH_HEIGHT: i32 = 0xFFFF;
 
+/// The value of the V5 header field indicating an embedded ICC profile ("MBED").
+const PROFILE_EMBEDDED: u32 = 0x4D424544;
+
 #[derive(PartialEq, Copy, Clone)]
 enum ImageType {
     Palette,
@@ -490,6 +493,7 @@ pub struct BmpDecoder<R> {
     colors_used: u32,
     palette: Option<Vec<[u8; 3]>>,
     bitfields: Option<Bitfields>,
+    icc_profile: Option<Vec<u8>>,
 }
 
 enum RLEInsn {
@@ -521,6 +525,7 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
             colors_used: 0,
             palette: None,
             bitfields: None,
+            icc_profile: None,
         }
     }
 
@@ -778,6 +783,38 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
         Ok(())
     }
 
+    /// Read ICC profile data from BITMAPV5HEADER if present.
+    fn read_icc_profile(&mut self, bmp_header_offset: u64) -> ImageResult<()> {
+        // Seek to bV5CSType field (56 bytes from header start)
+        self.reader.seek(SeekFrom::Start(bmp_header_offset + 56))?;
+        let cs_type = self.reader.read_u32::<LittleEndian>()?;
+
+        // Only embedded profiles are supported (not linked profiles)
+        if cs_type != PROFILE_EMBEDDED {
+            return Ok(());
+        }
+
+        // Seek to bV5ProfileData at offset 112
+        self.reader.seek(SeekFrom::Start(bmp_header_offset + 112))?;
+
+        let profile_offset = self.reader.read_u32::<LittleEndian>()?;
+        let profile_size = self.reader.read_u32::<LittleEndian>()?;
+
+        if profile_size == 0 || profile_offset == 0 {
+            return Ok(());
+        }
+
+        // Profile offset is from the beginning of the file
+        self.reader
+            .seek(SeekFrom::Start(u64::from(profile_offset)))?;
+        let mut profile_data = vec![0u8; profile_size as usize];
+        self.reader.read_exact(&mut profile_data)?;
+
+        self.icc_profile = Some(profile_data);
+
+        Ok(())
+    }
+
     fn read_metadata(&mut self) -> ImageResult<()> {
         if !self.has_loaded_metadata {
             self.read_file_header()?;
@@ -842,6 +879,11 @@ impl<R: BufRead + Seek> BmpDecoder<R> {
                 }
             };
 
+            // Read ICC profile if present (V5 header or later)
+            if bmp_header_size >= BITMAPV5HEADER_SIZE {
+                self.read_icc_profile(bmp_header_offset)?;
+            }
+
             self.reader
                 .seek(SeekFrom::Start(bmp_header_end + bitmask_bytes_offset))?;
 
@@ -1359,6 +1401,10 @@ impl<R: BufRead + Seek> ImageDecoder for BmpDecoder<R> {
         }
     }
 
+    fn icc_profile(&mut self) -> ImageResult<Option<Vec<u8>>> {
+        Ok(self.icc_profile.clone())
+    }
+
     fn read_image(mut self, buf: &mut [u8]) -> ImageResult<()> {
         assert_eq!(u64::try_from(buf.len()), Ok(self.total_bytes()));
         self.read_image_data(buf)
@@ -1477,4 +1523,29 @@ mod test {
             assert_eq!(ref_img, no_hdr_img);
         }
     }
+
+    #[test]
+    fn test_icc_profile() {
+        // V5 header file without embedded ICC profile
+        let f =
+            BufReader::new(std::fs::File::open("tests/images/bmp/images/V5_24_Bit.bmp").unwrap());
+        let mut decoder = BmpDecoder::new(f).unwrap();
+        let profile = decoder.icc_profile().unwrap();
+        assert!(profile.is_none());
+
+        // Test files with embedded ICC profiles
+        let f =
+            BufReader::new(std::fs::File::open("tests/images/bmp/images/rgb24prof.bmp").unwrap());
+        let mut decoder = BmpDecoder::new(f).unwrap();
+        let profile = decoder.icc_profile().unwrap();
+        assert!(profile.is_some());
+        assert_eq!(profile.unwrap().len(), 3048);
+
+        let f =
+            BufReader::new(std::fs::File::open("tests/images/bmp/images/rgb24prof2.bmp").unwrap());
+        let mut decoder = BmpDecoder::new(f).unwrap();
+        let profile = decoder.icc_profile().unwrap();
+        assert!(profile.is_some());
+        assert_eq!(profile.unwrap().len(), 540);
+    }
 }