Emit 'warning' event for non-critical problems #2032

lib/constructor.js

@@ -45,8 +45,13 @@ const debuglog = util.debuglog('sharp');
  * JPEG, PNG, WebP or TIFF format image data can be streamed out from this object.
  * When using Stream based output, derived attributes are available from the `info` event.
  *
+ * Non-critical problems encountered during processing are emitted as `warning` events.
+ *
  * Implements the [stream.Duplex](http://nodejs.org/api/stream.html#stream_class_stream_duplex) class.
  *
+ * @emits Sharp#info
+ * @emits Sharp#warning
+ *
  * @example
  * sharp('input.jpg')
  *   .resize(300, 200)
@@ -230,7 +235,10 @@ const Sharp = function (input, options) {
     linearA: 1,
     linearB: 0,
     // Function to notify of libvips warnings
-    debuglog: debuglog,
+    debuglog: warning => {
+      this.emit('warning', warning);
+      debuglog(warning);
+    },
     // Function to notify of queue length changes
     queueListener: function (queueLength) {
       Sharp.queue.emit('change', queueLength);