//! Codec for chunk type 13 = FLI_BLACK.

use ::{Raster,RasterMut};

/// Magic for a FLI_BLACK chunk - No Data.
///
/// This chunk has no data following the header.  All pixels in the
/// frame are set to color index 0.
pub const FLI_BLACK: u16 = 13;

/// Decode a FLI_BLACK chunk.
pub fn decode_fli_black(dst: &mut RasterMut) {
    let start = dst.stride * dst.y;
    let end = dst.stride * (dst.y + dst.h);
    for row in dst.buf[start..end].chunks_mut(dst.stride) {
        let start = dst.x;
        let end = start + dst.w;
        for e in &mut row[start..end] {
            *e = 0;
        }
    }
}

/// True if the frame can be encoded by FLI_BLACK.
pub fn can_encode_fli_black(next: &Raster) -> bool {
    let start = next.stride * next.y;
    let end = next.stride * (next.y + next.h);
    next.buf[start..end].chunks(next.stride)
            .all(|row| row.iter().all(|&e| e == 0))
}

//! Codec for chunk type 13 = FLI_BLACK.

use ::RasterMut;

/// Magic for a FLI_BLACK chunk - No Data.
///
/// This chunk has no data following the header.  All pixels in the
/// frame are set to color index 0.
pub const FLI_BLACK: u16 = 13;

/// Decode a FLI_BLACK chunk.
pub fn decode_fli_black(dst: &mut RasterMut) {
    let start = dst.stride * dst.y;
    let end = dst.stride * (dst.y + dst.h);
    for row in dst.buf[start..end].chunks_mut(dst.stride) {
        let start = dst.x;
        let end = start + dst.w;
        for e in &mut row[start..end] {
            *e = 0;
        }
    }
}

--- 
+++ 
@@ -1,6 +1,6 @@
 //! Codec for chunk type 13 = FLI_BLACK.
 
-use ::RasterMut;
+use ::{Raster,RasterMut};
 
 /// Magic for a FLI_BLACK chunk - No Data.
 ///
@@ -20,3 +20,11 @@
         }
     }
 }
+
+/// True if the frame can be encoded by FLI_BLACK.
+pub fn can_encode_fli_black(next: &Raster) -> bool {
+    let start = next.stride * next.y;
+    let end = next.stride * (next.y + next.h);
+    next.buf[start..end].chunks(next.stride)
+            .all(|row| row.iter().all(|&e| e == 0))
+}
Add test for encoding FLI_BLACK.

While it is generally not helpful to try encoding a frame as a
FLI_BLACK chunk mid-animation, it can be helpful in the very first
frame which lacks the delta compression options and must rewrite the
entire screen.  Doing so also helps with postage stamp creation.
