Notify if dependencies are not met.

Author: bartTC

qrcode/image/pil.py

@@ -10,6 +10,9 @@ class PilImage(qrcode.image.base.BaseImage):
     kind = "PNG"
 
     def new_image(self, **kwargs):
+        if not Image:
+            raise ImportError("PIL library not found.")
+
         back_color = kwargs.get("back_color", "white")
         fill_color = kwargs.get("fill_color", "black")
 

qrcode/image/pure.py

@@ -14,6 +14,9 @@ class PyPNGImage(BaseImage):
     needs_drawrect = False
 
     def new_image(self, **kwargs):
+        if not PngWriter:
+            raise ImportError("PyPNG library not installed.")
+
         return PngWriter(self.pixel_size, self.pixel_size, greyscale=True, bitdepth=1)
 
     def drawrect(self, row, col):