[FFmpeg-devel] [PATCH] avcodec/cdgraphics: fix transparency handling

[Paul B Mahol <onemda@gmail.com>]

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavcodec/cdgraphics.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/libavcodec/cdgraphics.c b/libavcodec/cdgraphics.c
index c9e265fa53..06f8392094 100644
--- a/libavcodec/cdgraphics.c
+++ b/libavcodec/cdgraphics.c
@@ -68,7 +68,7 @@ typedef struct CDGraphicsContext {
     AVFrame *frame;
     int hscroll;
     int vscroll;
-    int transparency;
+    uint8_t alpha[CDG_PALETTE_SIZE];
     int cleared;
 } CDGraphicsContext;
 
@@ -79,7 +79,9 @@ static av_cold int cdg_decode_init(AVCodecContext *avctx)
     cc->frame = av_frame_alloc();
     if (!cc->frame)
         return AVERROR(ENOMEM);
-    cc->transparency = -1;
+
+    for (int i = 0; i < CDG_PALETTE_SIZE; i++)
+        cc->alpha[i] = 0xFFU;
 
     avctx->pix_fmt = AV_PIX_FMT_PAL8;
     return ff_set_dimensions(avctx, CDG_FULL_WIDTH, CDG_FULL_HEIGHT);
@@ -120,9 +122,7 @@ static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
         r = ((color >> 8) & 0x000F) * 17;
         g = ((color >> 4) & 0x000F) * 17;
         b = ((color     ) & 0x000F) * 17;
-        palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b;
-        if (cc->transparency >= 0)
-            palette[cc->transparency] &= 0xFFFFFF;
+        palette[i + array_offset] = cc->alpha[i + array_offset] << 24 | r << 16 | g << 8 | b;
     }
     cc->frame->palette_has_changed = 1;
 }
@@ -346,7 +346,8 @@ static int cdg_decode_frame(AVCodecContext *avctx,
                 return ret;
             break;
         case CDG_INST_TRANSPARENT_COL:
-            cc->transparency = cdg_data[0] & 0xF;
+            for (int i = 0; i < CDG_PALETTE_SIZE; i++)
+                cc->alpha[i] = 255 - ((cdg_data[i] & 0x3f) << 2);
             break;
         default:
             break;
-- 
2.33.0

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