Improvement: Add predefined blur kernels

- Add a few predefined blur kernels, requested by jerri in #104.

- Add compton-convgen.py to generate blur kernels.

bin/compton-convgen.py

@@ -0,0 +1,132 @@
+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+# vim:fileencoding=utf-8
+
+import math, argparse
+
+class CGError(Exception):
+	def __init__(self, value):
+		self.value = value
+	def __str__(self):
+		return repr(self.value)
+
+class CGBadArg(CGError): pass
+class CGInternal(CGError): pass
+
+def mbuild(width, height):
+	"""Build a NxN matrix filled with 0."""
+	result = list()
+	for i in range(height):
+		result.append(list())
+		for j in range(width):
+			result[i].append(0.0)
+	return result
+
+def mdump(matrix):
+	"""Dump a matrix in natural format."""
+	for col in matrix:
+		print("[ ", end = '');
+		for ele in col:
+			print(format(ele, "13.6g") + ", ", end = " ")
+		print("],")
+
+def mdumpcompton(matrix):
+	"""Dump a matrix in compton's format."""
+	width = len(matrix[0])
+	height = len(matrix)
+	print("{},{},".format(width, height), end = '')
+	for i in range(height):
+		for j in range(width):
+			if int(height / 2) == i and int(width / 2) == j:
+				continue;
+			print(format(matrix[i][j], ".6f"), end = ",")
+	print()
+
+def mnormalize(matrix):
+	"""Scale a matrix according to the value in the center."""
+	width = len(matrix[0])
+	height = len(matrix)
+	factor = 1.0 / matrix[int(height / 2)][int(width / 2)]
+	if 1.0 == factor: return matrix
+	for i in range(height):
+		for j in range(width):
+			matrix[i][j] *= factor
+	return matrix
+
+def mmirror4(matrix):
+	"""Do a 4-way mirroring on a matrix from top-left corner."""
+	width = len(matrix[0])
+	height = len(matrix)
+	for i in range(height):
+		for j in range(width):
+			x = min(i, height - 1 - i)
+			y = min(j, width - 1 - j)
+			matrix[i][j] = matrix[x][y]
+	return matrix
+
+def gen_gaussian(width, height, factors):
+	"""Build a Gaussian blur kernel."""
+
+	if width != height:
+		raise CGBadArg("Cannot build an uneven Gaussian blur kernel.")
+
+	size = width
+	sigma = float(factors.get('sigma', 0.84089642))
+
+	result = mbuild(size, size)
+	for i in range(int(size / 2) + 1):
+		for j in range(int(size / 2) + 1):
+			diffx = i - int(size / 2);
+			diffy = j - int(size / 2);
+			result[i][j] = 1.0 / (2 * math.pi * sigma) * pow(math.e, - (diffx * diffx + diffy * diffy) / (2 * sigma * sigma))
+	mnormalize(result)
+	mmirror4(result)
+
+	return result
+
+def gen_box(width, height, factors):
+	"""Build a box blur kernel."""
+	result = mbuild(width, height)
+	for i in range(height):
+		for j in range(width):
+			result[i][j] = 1.0
+	return result
+
+def gen_invalid(width, height, factors):
+	raise CGBadArg("Unknown kernel type.")
+
+def args_readfactors(lst):
+	"""Parse the factor arguments."""
+	factors = dict()
+	if lst:
+		for s in lst:
+			res = s.partition('=')
+			if not res[0]:
+				raise CGBadArg("Factor has no key.")
+			if not res[2]:
+				raise CGBadArg("Factor has no value.")
+			factors[res[0]] = float(res[2])
+	return factors
+
+parser = argparse.ArgumentParser(description='Build a convolution kernel.')
+parser.add_argument('type', help='Type of convolution kernel. May be "gaussian" (factor sigma = 0.84089642) or "box".')
+parser.add_argument('width', type=int, help='Width of convolution kernel. Must be an odd number.')
+parser.add_argument('height', nargs='?', type=int, help='Height of convolution kernel. Must be an odd number. Equals to width if omitted.')
+parser.add_argument('-f', '--factor', nargs='+', help='Factors of the convolution kernel, in name=value format.')
+parser.add_argument('--dump-compton', action='store_true', help='Dump in compton format.')
+args = parser.parse_args()
+
+width = args.width
+height = args.height
+if not height:
+	height = width
+if not (width > 0 and height > 0):
+	raise CGBadArg("Invalid width/height.")
+factors = args_readfactors(args.factor)
+
+funcs = dict(gaussian = gen_gaussian, box = gen_box)
+matrix = (funcs.get(args.type, gen_invalid))(width, height, factors)
+if args.dump_compton:
+	mdumpcompton(matrix)
+else:
+	mdump(matrix)

src/compton.c

@@ -4237,6 +4237,9 @@ usage(void) {
     "  --blur-background-fixed.\n"
     "  A 7x7 Guassian blur kernel looks like:\n"
     "    --blur-kern '7,7,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000102,0.003494,0.029143,0.059106,0.029143,0.003494,0.000102,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.001723,0.059106,0.493069,0.493069,0.059106,0.001723,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000102,0.003494,0.029143,0.059106,0.029143,0.003494,0.000102,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003'\n"
+    "  May also be one the predefined kernels: 3x3box (default), 5x5box,\n"
+    "  7x7box, 3x3gaussian, 5x5gaussian, 7x7gaussian, 9x9gaussian,\n"
+    "  11x11gaussian.\n"
     "--blur-background-exclude condition\n"
     "  Exclude conditions for background blur.\n"
     "--resize-damage integer\n"
@@ -4589,6 +4592,31 @@ parse_matrix_err:
   return NULL;
 }
 
+/**
+ * Parse a convolution kernel.
+ */
+static inline XFixed *
+parse_conv_kern(session_t *ps, const char *src) {
+  static const struct {
+    const char *name;
+    const char *kern_str;
+  } CONV_KERN_PREDEF[] = {
+    { "3x3box", "3,3,1,1,1,1,1,1,1,1," },
+    { "5x5box", "5,5,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1," },
+    { "7x7box", "7,7,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1," },
+    { "3x3gaussian", "3,3,0.243117,0.493069,0.243117,0.493069,0.493069,0.243117,0.493069,0.243117," },
+    { "5x5gaussian", "5,5,0.003493,0.029143,0.059106,0.029143,0.003493,0.029143,0.243117,0.493069,0.243117,0.029143,0.059106,0.493069,0.493069,0.059106,0.029143,0.243117,0.493069,0.243117,0.029143,0.003493,0.029143,0.059106,0.029143,0.003493," },
+    { "7x7gaussian", "7,7,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.001723,0.059106,0.493069,0.493069,0.059106,0.001723,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003," },
+    { "9x9gaussian", "9,9,0.000000,0.000000,0.000001,0.000006,0.000012,0.000006,0.000001,0.000000,0.000000,0.000000,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000000,0.000001,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000001,0.000006,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000006,0.000012,0.001723,0.059106,0.493069,0.493069,0.059106,0.001723,0.000012,0.000006,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000006,0.000001,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000001,0.000000,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000000,0.000000,0.000000,0.000001,0.000006,0.000012,0.000006,0.000001,0.000000,0.000000," },
+    { "11x11gaussian", "11,11,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000001,0.000006,0.000012,0.000006,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000000,0.000000,0.000000,0.000001,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000001,0.000000,0.000000,0.000006,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000006,0.000000,0.000000,0.000012,0.001723,0.059106,0.493069,0.493069,0.059106,0.001723,0.000012,0.000000,0.000000,0.000006,0.000849,0.029143,0.243117,0.493069,0.243117,0.029143,0.000849,0.000006,0.000000,0.000000,0.000001,0.000102,0.003493,0.029143,0.059106,0.029143,0.003493,0.000102,0.000001,0.000000,0.000000,0.000000,0.000003,0.000102,0.000849,0.001723,0.000849,0.000102,0.000003,0.000000,0.000000,0.000000,0.000000,0.000000,0.000001,0.000006,0.000012,0.000006,0.000001,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000,0.000000," },
+  };
+  for (int i = 0;
+      i < sizeof(CONV_KERN_PREDEF) / sizeof(CONV_KERN_PREDEF[0]); ++i)
+    if (!strcmp(CONV_KERN_PREDEF[i].name, src))
+      return parse_matrix(ps, CONV_KERN_PREDEF[i].kern_str);
+  return parse_matrix(ps, src);
+}
+
 /**
  * Parse a condition list in configuration file.
  */
@@ -5097,7 +5125,7 @@ get_cfg(session_t *ps, int argc, char *const *argv, bool first_pass) {
       case 301:
         // --blur-kern
         free(ps->o.blur_kern);
-        if (!(ps->o.blur_kern = parse_matrix(ps, optarg)))
+        if (!(ps->o.blur_kern = parse_conv_kern(ps, optarg)))
           exit(1);
       case 302:
         // --resize-damage