Merge pull request #283 from youknowone/caption-error

`wand.image.Image.caption` raises TypeError with better description
emcconville · Mar 30, 2016 · ddb549f · ddb549f
2 parents 4726601 + d004a70
commit ddb549f
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diff --git a/tests/image_test.py b/tests/image_test.py
@@ -1246,6 +1246,17 @@ def test_caption(fx_asset):
         )
 
 
+def test_caption_without_font(fx_asset):
+    with Image(width=144, height=192, background=Color('#1e50a2')) as img:
+        with raises(TypeError):
+            img.caption(
+                'Test message',
+                left=5, top=144,
+                width=134, height=20,
+                gravity='center'
+            )
+
+
 def test_setfont(fx_asset):
     with Image(width=144, height=192, background=Color('#1e50a2')) as img:
         font = Font(

diff --git a/wand/image.py b/wand/image.py
@@ -916,9 +916,14 @@ def caption(self, text, left=0, top=0, width=None, height=None, font=None,
             width = self.width - left
         if height is None:
             height = self.height - top
+        if not font:
+            try:
+                font = self.font
+            except TypeError:
+                raise TypeError('font must be specified or existing in image')
         with Image() as textboard:
             library.MagickSetSize(textboard.wand, width, height)
-            textboard.font = font or self.font
+            textboard.font = font
             textboard.gravity = gravity or self.gravity
             with Color('transparent') as background_color:
                 library.MagickSetBackgroundColor(textboard.wand,