From 24a96932230f0740b2eb50c4c3b32cd5dba268fb Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Thu, 13 Aug 2015 20:51:52 -0700
Subject: [PATCH] dec: allow 0 as a scaling dimension

this allows scaling to a particular width/height while preserving the
source aspect ratio using WebPRescalerGetScaledDimensions().

Change-Id: I77b11528753290c1e9bb942ac761c215ccfb8701
---
 src/dec/buffer.c | 9 ++++++---
 src/dec/webp.c   | 8 +++++---
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/dec/buffer.c b/src/dec/buffer.c
index c6e4eb84..63f9d74b 100644
--- a/src/dec/buffer.c
+++ b/src/dec/buffer.c
@@ -181,11 +181,14 @@ VP8StatusCode WebPAllocateDecBuffer(int w, int h,
       h = ch;
     }
     if (options->use_scaling) {
-      if (options->scaled_width <= 0 || options->scaled_height <= 0) {
+      int scaled_width = options->scaled_width;
+      int scaled_height = options->scaled_height;
+      if (!WebPRescalerGetScaledDimensions(
+              w, h, &scaled_width, &scaled_height)) {
         return VP8_STATUS_INVALID_PARAM;
       }
-      w = options->scaled_width;
-      h = options->scaled_height;
+      w = scaled_width;
+      h = scaled_height;
     }
   }
   out->width = w;
diff --git a/src/dec/webp.c b/src/dec/webp.c
index c76a704b..649c73e5 100644
--- a/src/dec/webp.c
+++ b/src/dec/webp.c
@@ -806,11 +806,13 @@ int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
   // Scaling
   io->use_scaling = (options != NULL) && (options->use_scaling > 0);
   if (io->use_scaling) {
-    if (options->scaled_width <= 0 || options->scaled_height <= 0) {
+    int scaled_width = options->scaled_width;
+    int scaled_height = options->scaled_height;
+    if (!WebPRescalerGetScaledDimensions(w, h, &scaled_width, &scaled_height)) {
       return 0;
     }
-    io->scaled_width = options->scaled_width;
-    io->scaled_height = options->scaled_height;
+    io->scaled_width = scaled_width;
+    io->scaled_height = scaled_height;
   }
 
   // Filter