Allow NULL for dst_y in planar formats. BUG=libyuv:631 TEST=unittests build/pass

source/convert_from.cc

 /*
  *  Copyright 2012 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 28 matching lines @@
                       int src_y_width, int src_y_height,
                       int dst_uv_width, int dst_uv_height) {
   const int dst_y_width = Abs(src_y_width);
   const int dst_y_height = Abs(src_y_height);
   const int src_uv_width = SUBSAMPLE(src_y_width, 1, 1);
   const int src_uv_height = SUBSAMPLE(src_y_height, 1, 1);
   if (src_y_width == 0 || src_y_height == 0 ||
       dst_uv_width <= 0 || dst_uv_height <= 0) {
     return -1;
   }
-  ScalePlane(src_y, src_stride_y, src_y_width, src_y_height,
-             dst_y, dst_stride_y, dst_y_width, dst_y_height,
-             kFilterBilinear);
+  if (dst_y) {
+    ScalePlane(src_y, src_stride_y, src_y_width, src_y_height,
+               dst_y, dst_stride_y, dst_y_width, dst_y_height,
+               kFilterBilinear);
+  }
   ScalePlane(src_u, src_stride_u, src_uv_width, src_uv_height,
              dst_u, dst_stride_u, dst_uv_width, dst_uv_height,
              kFilterBilinear);
   ScalePlane(src_v, src_stride_v, src_uv_width, src_uv_height,
              dst_v, dst_stride_v, dst_uv_width, dst_uv_height,
              kFilterBilinear);
   return 0;
 }
 
 // 420 chroma is 1/2 width, 1/2 height
@@ skipping 303 matching lines @@
                const uint8* src_v, int src_stride_v,
                uint8* dst_y, int dst_stride_y,
                uint8* dst_uv, int dst_stride_uv,
                int width, int height) {
   int y;
   void (*MergeUVRow_)(const uint8* src_u, const uint8* src_v, uint8* dst_uv,
       int width) = MergeUVRow_C;
   // Coalesce rows.
   int halfwidth = (width + 1) >> 1;
   int halfheight = (height + 1) >> 1;
-  if (!src_y || !src_u || !src_v || !dst_y || !dst_uv ||
+  if (!src_u || !src_v || !dst_uv ||
       width <= 0 || height == 0) {
     return -1;
   }
   // Negative height means invert the image.
   if (height < 0) {
     height = -height;
     halfheight = (height + 1) >> 1;
-    dst_y = dst_y + (height - 1) * dst_stride_y;
+    if (dst_y) {
+      dst_y = dst_y + (height - 1) * dst_stride_y;
+    }
     dst_uv = dst_uv + (halfheight - 1) * dst_stride_uv;
     dst_stride_y = -dst_stride_y;
     dst_stride_uv = -dst_stride_uv;
   }
   if (src_stride_y == width &&
       dst_stride_y == width) {
     width *= height;
     height = 1;
     src_stride_y = dst_stride_y = 0;
   }
@@ skipping 23 matching lines @@
 #endif
 #if defined(HAS_MERGEUVROW_NEON)
   if (TestCpuFlag(kCpuHasNEON)) {
     MergeUVRow_ = MergeUVRow_Any_NEON;
     if (IS_ALIGNED(halfwidth, 16)) {
       MergeUVRow_ = MergeUVRow_NEON;
     }
   }
 #endif
 
-  CopyPlane(src_y, src_stride_y, dst_y, dst_stride_y, width, height);
+  if (dst_y) {
+    CopyPlane(src_y, src_stride_y, dst_y, dst_stride_y, width, height);
+  }
   for (y = 0; y < halfheight; ++y) {
     // Merge a row of U and V into a row of UV.
     MergeUVRow_(src_u, src_v, dst_uv, halfwidth);
     src_u += src_stride_u;
     src_v += src_stride_v;
     dst_uv += dst_stride_uv;
   }
   return 0;
 }
 
@@ skipping 719 matching lines @@
     default:
       return -1;  // unknown fourcc - return failure code.
   }
   return r;
 }
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif