dist: Use Pillow to generate application icons.

dist/Makefile

@@ -3,18 +3,13 @@ man-%: freedoom.adoc
 	a2x -f manpage $*.adoc
 
 icon-freedm:
-	convert -resize 64x64 ../graphics/titlepic/freedm_title2.png \
-	    freedm.png
+	./pillow-resize ../graphics/titlepic/freedm_title2.png freedm.png 64 64
 
 icon-freedoom1:
-	convert -trim +repage -extent 48x48 -gravity center \
-	    -transparent \#00ffff -background \#00ffff \
-	    ../sprites/playa2a8.png freedoom1.png
+	./pillow-compose ../sprites/playa2a8.png freedoom1.png 64 64
 
 icon-freedoom2:
-	convert -trim +repage -extent 64x64 -gravity center \
-	    -transparent \#00ffff -background \#00ffff \
-	    ../sprites/heada1.png freedoom2.png
+	./pillow-compose ../sprites/heada1.png freedoom2.png 64 64
 
 clean:
 	rm -f *.6 *.png freedm.adoc freedoom1.adoc freedoom2.adoc

dist/pillow-compose

@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+
+# Simple and dumb Pillow-based compositor
+# Usage: pillow-compose src-img.png dst-img.png WIDTH HEIGHT
+
+import sys
+from PIL import Image
+
+src = Image.open(sys.argv[1])
+img = Image.new('RGBA', (int(sys.argv[3]), int(sys.argv[4])), (0, 0, 0, 0))
+
+# Pillow's compositing won't accept negative values.  This can happen
+# if the destination image is smaller on at least on axis than the
+# source image.
+if img.size[0] - src.size[0] < 0:
+    off_x = 0
+else:
+    off_x = (img.size[0] - src.size[0]) // 2
+
+if img.size[1] - src.size[1] < 0:
+    off_y = 0
+else:
+    off_y = (img.size[1] - src.size[1]) // 2
+
+img.alpha_composite(src.convert('RGBA'), (off_x, off_y))
+img.save(sys.argv[2])

dist/pillow-resize

@@ -0,0 +1,11 @@
+#!/usr/bin/env python
+
+# Simple and dumb Pillow-based resizer
+# Usage: pillow-resize src-img.png dst-img.png WIDTH HEIGHT
+
+import sys
+from PIL import Image
+
+img = Image.open(sys.argv[1])
+img.thumbnail((int(sys.argv[3]), int(sys.argv[4])))
+img.save(sys.argv[2])