Merge branch 'png2c-fixes'

Improve png2c script, notably make it work with Python 3.9+.

See #23500.

misc/scripts/png2c.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 # This script is a slightly modified version of the original found at
 #
@@ -25,6 +25,9 @@ if len(sys.argv) < 2:
 
 r = re.compile("^([a-zA-Z._][a-zA-Z._0-9]*)[.][pP][nN][gG]$")
 
+# Automatically replace some symbols in the filenames.
+sanitize = str.maketrans('-@', '__')
+
 with_size = 0
 size_suffix = ''
 for path in sys.argv[1:]:
@@ -32,12 +35,12 @@ for path in sys.argv[1:]:
             with_size = 1
             continue
 
-        filename = os.path.basename(path).replace('-','_')
+        filename = os.path.basename(path).translate(sanitize)
         m = r.match(filename)
 
         # Allow only filenames that make sense as C variable names
         if not(m):
-                print("Skipped file (unsuitable filename): " + filename)
+                print("Skipped file (unsuitable filename): " + filename, file=sys.stderr)
                 continue
 
         # Read PNG file as character array
@@ -50,7 +53,7 @@ for path in sys.argv[1:]:
         # Each PNG file starts with a 8 byte signature that should be followed
         # by IHDR chunk which is always 13 bytes in length so the first 16
         # bytes are fixed (or at least we expect them to be).
-        if bytes[0:16].tostring() != b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR':
+        if bytes[0:16].tobytes() != b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR':
                 print('"%s" doesn\'t seem to be a valid PNG file.' % filename)
                 continue