Removed composite tile render warning.

overviewer_core/tileset.py

@@ -984,9 +984,6 @@ class TileSet(object):
                 # Ignore errors if it's "file doesn't exist"
                 if e.errno != errno.ENOENT:
                     raise
-            logging.warning(
-                "Tile %s was requested for render, but no children were found! "
-                "This is probably a bug.", imgpath)
             return
 
         # Create the actual image now
@@ -1049,7 +1046,8 @@ class TileSet(object):
         The argument is a RenderTile object
 
         The image is rendered and saved to disk in the place this tileset is
-        configured to save images.
+        configured to save images, unless the rendered image is blank, in
+        which case no image is saved to disk.
 
         """
 
@@ -1073,18 +1071,6 @@ class TileSet(object):
                 logging.debug("%s deleted", tile)
             return
 
-        # Create the directory if not exists
-        dirdest = os.path.dirname(imgpath)
-        if not os.path.exists(dirdest):
-            try:
-                os.makedirs(dirdest)
-            except OSError as e:
-                # Ignore errno EEXIST: file exists. Due to a race condition,
-                # two processes could conceivably try and create the same
-                # directory at the same time
-                if e.errno != errno.EEXIST:
-                    raise
-
         # Compile this image
         tileimg = Image.new("RGBA", (384, 384), self.options['bgcolor'])
 
@@ -1120,6 +1106,24 @@ class TileSet(object):
                 logging.error("Full error was:", exc_info=1)
                 sys.exit(1)
 
+        # Don't save if the output is blank (384*384 pixels all colored bgcolor at 0% opacity)
+        # The viewer will fill in this missing tile with the default blank tile created in the
+        # AssetManager, so there's no need to spend compute time on compressing and disk space
+        # & network traffic on serving a blank image.
+        if tileimg.getcolors() == [(147456, self.options['bgcolor'])]:
+            return
+
+        # Create the directory if not exists
+        dirdest = os.path.dirname(imgpath)
+        if not os.path.exists(dirdest):
+            try:
+                os.makedirs(dirdest)
+            except OSError as e:
+                # Ignore errno EEXIST: file exists. Due to a race condition,
+                # two processes could conceivably try and create the same
+                # directory at the same time
+                if e.errno != errno.EEXIST:
+                    raise
         # Save them
         with FileReplacer(imgpath, capabilities=self.fs_caps) as tmppath:
             if self.imgextension == 'jpg':