From c17489b831959f6543a506a21b4f333e629b47f5 Mon Sep 17 00:00:00 2001
From: Kostya Shishkov <kostya.shishkov@gmail.com>
Date: Wed, 21 Oct 2020 18:22:18 +0200
Subject: [PATCH] core/scale: fill absent planes during scale process

---
 nihav-core/src/scale/scale.rs | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/nihav-core/src/scale/scale.rs b/nihav-core/src/scale/scale.rs
index b0415c9..eb8ff6c 100644
--- a/nihav-core/src/scale/scale.rs
+++ b/nihav-core/src/scale/scale.rs
@@ -41,6 +41,14 @@ fn scale_line<T:Copy>(src: &[T], dst: &mut [T], src_w: usize, dst_w: usize) {
     }
 }
 
+fn fill_plane<T: Copy>(dst: &mut [T], w: usize, h: usize, stride: usize, val: T) {
+    for row in dst.chunks_mut(stride).take(h) {
+        for el in row.iter_mut().take(w) {
+            *el = val;
+        }
+    }
+}
+
 macro_rules! scale_loop {
     ($sbuf:expr, $dbuf:expr) => {
             let fmt = $sbuf.get_info().get_format();
@@ -61,6 +69,32 @@ macro_rules! scale_loop {
                     doff += dstride;
                 }
             }
+            let dfmt = $dbuf.get_info().get_format();
+            let ndcomp = dfmt.get_num_comp();
+            if ndcomp > ncomp {
+                if !fmt.alpha && dfmt.alpha {
+                    let acomp = ndcomp - 1;
+                    let dstride = $dbuf.get_stride(acomp);
+                    let (dw, dh) = $dbuf.get_dimensions(acomp);
+                    let doff = $dbuf.get_offset(acomp);
+                    let dst = $dbuf.get_data_mut().unwrap();
+                    fill_plane(&mut dst[doff..], dw, dh, dstride, 0);
+                }
+                if fmt.model.is_yuv() && ((!fmt.alpha && ncomp == 1) || (fmt.alpha && ncomp == 2)) && ndcomp >= 3 {
+                    let uval = 1 << (dfmt.comp_info[1].unwrap().depth - 1);
+                    let vval = 1 << (dfmt.comp_info[2].unwrap().depth - 1);
+
+                    let ustride = $dbuf.get_stride(1);
+                    let vstride = $dbuf.get_stride(2);
+                    let (uw, uh) = $dbuf.get_dimensions(1);
+                    let (vw, vh) = $dbuf.get_dimensions(2);
+                    let uoff = $dbuf.get_offset(1);
+                    let voff = $dbuf.get_offset(2);
+                    let dst = $dbuf.get_data_mut().unwrap();
+                    fill_plane(&mut dst[uoff..], uw, uh, ustride, uval);
+                    fill_plane(&mut dst[voff..], vw, vh, vstride, vval);
+                }
+            }
     };
 }
 
-- 
2.30.2