Fix and document font_test.py.

FONT_TO_PY.md

@@ -270,3 +270,54 @@ keeps the code small and efficient for the common (default) case.
 
 Larger character sets are assumed to be sparse and the emitted code uses an
 index optimised for sparse values and a binary search algorithm.
+
+# Appendix 3: font_test.py
+
+This enables a Python font file to be described and rendered at the command
+prompt. It provides a useful way of checking unknown font files.
+
+It runs under Python 3.2 or above. If you created a font `myfont.py` the
+following will render the supplied string (assuming that `font_test.py` has
+executable privilege):
+
+```bash
+./font_test myfont Hello
+```
+Omitting arguments (or supplying `--help`) will provide usage information.
+
+If no string is provided a default will be printed. This is designed to test
+fonts created with `-k extended`. Other fonts will show `?` characters for
+missing glyphs.
+
+Sample output:
+```bash
+$ ./font_test.py freesans1 Hello
+Vertical map
+Normal bit order
+Proportional spacing
+Dimensions height*max_width 23 * 23
+Start char " " (ord 32) end char "~" (ord 126)
+...................................................
+##.........##................##...##...............
+##.........##................##...##...............
+##.........##................##...##...............
+##.........##................##...##...............
+##.........##................##...##...............
+##.........##.......#####....##...##......#####....
+##.........##......#######...##...##.....#######...
+#############.....###....##..##...##....###...###..
+#############....###......##.##...##...###.....###.
+##.........##....##.......##.##...##...##.......##.
+##.........##....###########.##...##...##.......##.
+##.........##....###########.##...##...##.......##.
+##.........##....##..........##...##...##.......##.
+##.........##....##.......##.##...##...###.....###.
+##.........##.....##.....##..##...##....###...###..
+##.........##......########..##...##.....#######...
+##.........##.......#####....##...##......#####....
+...................................................
+...................................................
+...................................................
+...................................................
+...................................................
+```

font_test.py

@@ -73,66 +73,6 @@ def render_row_vmap(data, row, height, width, reverse):
         print(char, end='')
 
 
-def display(data, hmap, height, width, reverse):
-    bpr = (width - 1)//8 + 1
-    bpc = (height - 1)//8 + 1
-    print('Height: {} Width: {}'.format(height, width))
-    print('Bytes/row: {} Bytes/col: {}'.format(bpr, bpc))
-    print('Data length: {}'.format(len(data)))
-    # Check bytearray is the correct length
-    if hmap:
-        validate_hmap(data, height, width)
-    else:
-        validate_vmap(data, height, width)
-
-    for row in range(height):
-        if hmap:
-            render_row_hmap(data, row, height, width, reverse)
-        else:
-            render_row_vmap(data, row, height, width, reverse)
-        print()
-
-
-# TESTS: in order of code coverage
-# Basic test of Font class functionality
-# Usage font_test.font_test()
-def font_test():
-    fnt = Font('FreeSans.ttf', 20)
-    for char in 'WM_eg!.,':
-        fnt[char][0].display()
-    print(fnt.width)
-
-# Font character streaming
-# Usage font_test.test_stream('abc', 20, False, False, False)
-def test_stream(string, height, monospaced, hmap, reverse):
-    fnt = Font("FreeSans.ttf", height, monospaced)
-    height = fnt.height
-    for char in string:
-        width = fnt[char][1]
-        data = bytearray(fnt.stream_char(char, hmap, reverse))
-        display(data, hmap, height, width, reverse)
-
-
-def chr_addr(index, ordch):
-    offset = 2 * (ordch - 32)
-    return int.from_bytes(index[offset:offset + 2], 'little')
-
-
-# Font.build_arrays
-# Usage font_test.test_arrays('abc', 20, False, False, False)
-def test_arrays(string, height, monospaced, hmap, reverse):
-    fnt = Font("FreeSans.ttf", height, monospaced)
-    height = fnt.height
-    data, index = fnt.build_arrays(hmap, reverse)
-    for char in string:
-        ordch = ord(char)
-        offset = chr_addr(index, ordch)
-        width = int.from_bytes(data[offset:offset + 2], 'little')
-        offset += 2
-        next_offs = chr_addr(index, ordch + 1)
-        display(data[offset:next_offs], hmap, height, width, reverse)
-
-
 # Render a string to REPL using a specified Python font file
 # usage font_test.test_font('freeserif', 'abc')
 # Default tests outliers with fonts created with -k extended
@@ -157,27 +97,20 @@ def test_font(fontfile, string='abg'+chr(126)+chr(127)+chr(176)+chr(177)+chr(937
                 render_row_vmap(data, row, height, width, myfont.reverse())
         print()
 
+usage = '''Usage:
+./font_test fontfile string
+fontfile is a Python font file name with the .py extension omitted.
+string is an optional string to render.
+If string is omitted a challenging test string will be rendered. This
+is for fonts created with -k extended. Other fonts will show "?" for
+nonexistent glyphs.
+Requires Python 3.2 or newer.
+'''
 
-# Create font file, render a string to REPL using it
+if __name__ == "__main__":
-# usage font_test.test_file('FreeSans.ttf', 20, 'xyz')
+    if len(sys.argv) < 2 or sys.argv[1] == '--help':
-def test_file(fontfile, height, string, *, minchar=32, maxchar=126, defchar=ord('?'),
+        print(usage)
-              fixed=False, hmap=False, reverse=False):
+    elif len(sys.argv) == 2:
-    if not write_font('myfont.py', fontfile, height, fixed,
+        test_font(sys.argv[1])
-                      hmap, reverse, minchar, maxchar, defchar):
+    else:
-        print('Failed to create font file.')
+        test_font(sys.argv[1], sys.argv[2])
-        return
-
-    if 'myfont' in sys.modules:
-        del sys.modules['myfont']  # force reload
-    import myfont
-
-    height = myfont.height()
-    for row in range(height):
-        for char in string:
-            data, _, width = myfont.get_ch(char)
-            if myfont.hmap():
-                render_row_hmap(data, row, height, width, myfont.reverse())
-            else:
-                render_row_vmap(data, row, height, width, myfont.reverse())
-        print()
-    os.unlink('myfont.py')