✨(icu_lib): fix RLE decoding and handle empty image data

Corrected the index increment in the RLE decoding process to ensure proper data handling. Added a check for zero-sized image data, returning an empty `RgbaImage` when the data size is 0.

Signed-off-by: Benign X <[email protected]>

icu_lib/src/endecoder/lvgl/lvgl.rs

@@ -102,6 +102,10 @@ impl EnDecoder for LVGL {
         log::trace!("Decoding image with data size: {}", data.len());
         let img_desc = ImageDescriptor::decode(data);
 
+        if img_desc.data_size == 0 {
+            return MiData::RGBA(RgbaImage::new(0, 0));
+        }
+
         let header = &img_desc.header;
 
         log::trace!("Decoding image with color format: {:?}", header.cf());

icu_lib/src/endecoder/lvgl/mod.rs

@@ -384,6 +384,11 @@ impl ImageDescriptor {
                 } else {
                     log::error!("Data size mismatch ideal_data_size: {idea_data_size}, data_size: {data_size}, {:#?}", header);
                 }
+                return Self {
+                    header: ImageHeader::V9(header),
+                    data_size: 0,
+                    data: vec![],
+                };
             }
             ImageHeader::V8(_) => {}
             ImageHeader::Unknown => {

icu_lib/src/endecoder/utils/rle.rs

@@ -130,15 +130,15 @@ impl RleCoder {
             if ctrl & 0x80 == 0 {
                 // Run-length mode
                 result.extend((0..ctrl).flat_map(|_| block.iter().copied()));
+                i += self.block_size;
             } else {
                 // Direct copy mode
                 let count = (ctrl & 0x7f) as usize;
                 let bytes = count * self.block_size;
                 let slice = data.get(i..i + bytes).ok_or(RleError::InvalidInput)?;
                 result.extend_from_slice(slice);
-                i += bytes - self.block_size;
+                i += bytes;
             }
-            i += self.block_size;
         }
 
         Ok(result)