From b2720dba0f7427cf23be889f7c87ab25d9c6da85 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Sat, 2 May 2020 23:48:43 +0200
Subject: mp_image: add some helpers

This is really basic for planar image data access; not sure why there
weren't such helpers before.

They also handle trickier formats that use bit-packing, or they would be
mich simpler. (This affects only BGR4/BGR4/MONOW/MONOH, I hope whoever
invented them is proud of triggering so many special cases for so little
gain.)
---
 video/mp_image.c | 20 ++++++++++++++++++++
 video/mp_image.h |  3 +++
 2 files changed, 23 insertions(+)

diff --git a/video/mp_image.c b/video/mp_image.c
index dba787452e..cd0fe17713 100644
--- a/video/mp_image.c
+++ b/video/mp_image.c
@@ -1041,3 +1041,23 @@ void memset16_pic(void *dst, int fill, int unitsPerLine, int height, int stride)
         }
     }
 }
+
+// Pixel at the given luma position on the given plane, possibly rounded down.
+void *mp_image_pixel_ptr(struct mp_image *img, int plane, int x, int y)
+{
+    return img->planes[plane] +
+           img->stride[plane] * (ptrdiff_t)(y >> img->fmt.ys[plane]) +
+           (size_t)(x >> img->fmt.xs[plane]) * img->fmt.bpp[plane] / 8;
+}
+
+// Number of bytes for w pixels, using luma pixels, possibly rounded up.
+// x0 is the start pixel; matters if the start pixel is rounded down.
+// (E.g. 8 bpp, x0=7, w=7 => pixels 0..15 => 2 bytes)
+size_t mp_image_plane_bytes(struct mp_image *img, int plane, int x0, int w)
+{
+    int bpp = img->fmt.bpp[plane];
+    int xs = img->fmt.xs[plane];
+    size_t b_x0 = (x0 >> xs) * bpp / 8;
+    size_t b_x1 = (((x0 + w + (1 << xs) - 1) >> xs) * bpp + 7) / 8;
+    return b_x1 - b_x0;
+}
diff --git a/video/mp_image.h b/video/mp_image.h
index e51022dd5c..f111d35129 100644
--- a/video/mp_image.h
+++ b/video/mp_image.h
@@ -185,4 +185,7 @@ void memcpy_pic(void *dst, const void *src, int bytesPerLine, int height,
 void memset_pic(void *dst, int fill, int bytesPerLine, int height, int stride);
 void memset16_pic(void *dst, int fill, int unitsPerLine, int height, int stride);
 
+void *mp_image_pixel_ptr(struct mp_image *img, int plane, int x, int y);
+size_t mp_image_plane_bytes(struct mp_image *img, int plane, int x0, int w);
+
 #endif /* MPLAYER_MP_IMAGE_H */
-- 
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