Update src/docked_app.in

* Support pixbufs without an alpha channel

Signed-off-by: Daniel Llewellyn <[email protected]>

src/docked_app.in

@@ -110,17 +110,23 @@ def get_backlight_color(pixbuf):
  rowstride = pixbuf.props.rowstride
  height = pixbuf.props.height
 
+ num_channels = pixbuf.get_n_channels()
+ has_alpha = pixbuf.get_has_alpha()
+
  img = pixbuf.get_pixels()
  r_total = g_total = b_total = 0
  total = 0.0
 
  for w_count in range(width):
  for h_count in range(height):
- pix_index = (h_count * rowstride + w_count * 4)
+ pix_index = (h_count * rowstride + w_count * num_channels)
  pix_r = img[pix_index]
  pix_g = img[pix_index + 1]
  pix_b = img[pix_index + 2]
- pix_a = img[pix_index + 3]
+ if has_alpha:
+ pix_a = img[pix_index + 3]
+ else:
+ pix_a = 255
 
  saturation = float(max(pix_r, max(pix_g, pix_b)) - min(pix_r, min(pix_g, pix_b))) / 255.0
  relevance = .1 + .9 * (float(pix_a) / 255) * saturation