imgutils: create misc functions for dealing with buffers

Move the lavc/imgconvert functions and rename them as follows:
  avpicture_get_size -> av_image_get_buffer_size()
  avpicture_fill     -> av_image_fill_arrays()
  avpicture_layout   -> av_image_copy_to_buffer()

The new functions have an align parameter, which allows to define the
linesize alignment assumed in the buffer (which is set or read).

The names of the functions are consistent with the lavu/samples API
(av_samples_get_buffer_size(), av_samples_fill_arrays()).

A redundant check has been dropped from av_image_fill_arrays().

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavutil/imgutils.c

@@ -24,6 +24,7 @@
 #include "common.h"
 #include "imgutils.h"
 #include "internal.h"
+#include "intreadwrite.h"
 #include "log.h"
 #include "mathematics.h"
 #include "pixdesc.h"
@@ -298,3 +299,83 @@ void av_image_copy(uint8_t *dst_data[4], int dst_linesizes[4],
         }
     }
 }
+
+int av_image_fill_arrays(uint8_t *dst_data[4], int dst_linesize[4],
+                         const uint8_t *src, enum AVPixelFormat pix_fmt,
+                         int width, int height, int align)
+{
+    int ret, i;
+
+    ret = av_image_check_size(width, height, 0, NULL);
+    if (ret < 0)
+        return ret;
+
+    ret = av_image_fill_linesizes(dst_linesize, pix_fmt, width);
+    if (ret < 0)
+        return ret;
+
+    for (i = 0; i < 4; i++)
+        dst_linesize[i] = FFALIGN(dst_linesize[i], align);
+
+    return av_image_fill_pointers(dst_data, pix_fmt, height, src, dst_linesize);
+}
+
+int av_image_get_buffer_size(enum AVPixelFormat pix_fmt,
+                             int width, int height, int align)
+{
+    uint8_t *data[4];
+    int linesize[4];
+    int ret;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
+    if (!desc)
+        return AVERROR_BUG;
+
+    ret = av_image_check_size(width, height, 0, NULL);
+    if (ret < 0)
+        return ret;
+
+    // do not include palette for these pseudo-paletted formats
+    if (desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
+        return width * height;
+
+    return av_image_fill_arrays(data, linesize, NULL, pix_fmt,
+                                width, height, align);
+}
+
+int av_image_copy_to_buffer(uint8_t *dst, int dst_size,
+                            const uint8_t * const src_data[4],
+                            const int src_linesize[4],
+                            enum AVPixelFormat pix_fmt,
+                            int width, int height, int align)
+{
+    int i, j, nb_planes = 0, linesize[4];
+    int size = av_image_get_buffer_size(pix_fmt, width, height, align);
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
+
+    if (size > dst_size || size < 0 || !desc)
+        return AVERROR(EINVAL);
+
+    for (i = 0; i < desc->nb_components; i++)
+        nb_planes = FFMAX(desc->comp[i].plane, nb_planes);
+
+    nb_planes++;
+
+    av_image_fill_linesizes(linesize, pix_fmt, width);
+    for (i = 0; i < nb_planes; i++) {
+        int h, shift = (i == 1 || i == 2) ? desc->log2_chroma_h : 0;
+        const uint8_t *src = src_data[i];
+        h = (height + (1 << shift) - 1) >> shift;
+
+        for (j = 0; j < h; j++) {
+            memcpy(dst, src, linesize[i]);
+            dst += FFALIGN(linesize[i], align);
+            src += src_linesize[i];
+        }
+    }
+
+    if (desc->flags & AV_PIX_FMT_FLAG_PAL)
+        memcpy((unsigned char *)(((size_t)dst + 3) & ~3),
+               src_data[1], 256 * 4);
+
+    return size;
+}