fix incorrect bounding-box calculation in ImageResizer

- Under some circumstances, the image resizer was fitting
  the wrong dimension to the user-provided bounding box
  when an init image provided.
- Closes #1470.

ldm/generate.py

@@ -1072,14 +1072,8 @@ class Generate:
         print(
             f'>> image will be resized to fit inside a box {w}x{h} in size.'
         )
-        if image.width > image.height:
-            h = None   # by setting h to none, we tell InitImageResizer to fit into the width and calculate height
-        elif image.height > image.width:
-            w = None   # ditto for w
-        else:
-            pass
         # note that InitImageResizer does the multiple of 64 truncation internally
-        image = InitImageResizer(image).resize(w, h)
+        image = InitImageResizer(image).resize(width=w, height=h)
         print(
             f'>> after adjusting image dimensions to be multiples of 64, init image is {image.width}x{image.height}'
         )

ldm/invoke/image_util.py

@@ -31,10 +31,10 @@ class InitImageResizer():
         elif not width:            # width missing
             width  = int(height*ar)
 
-        # rw and rh are the resizing width and height for the image
-        # they maintain the aspect ratio, but may not completelyl fill up
-        # the requested destination size
-        (rw,rh) = (width,int(width/ar)) if im.width>=im.height else (int(height*ar),height)
+        w_scale = width/im.width
+        h_scale = height/im.height
+        scale = min(w_scale,h_scale)
+        (rw,rh) = (int(scale*im.width),int(scale*im.height))
 
         #round everything to multiples of 64
         width,height,rw,rh = map(