Coverage for /usr/lib/python3/dist-packages/PIL/GimpGradientFile.py: 24%

1# 

2# Python Imaging Library 

3# $Id$ 

4# 

5# stuff to read (and render) GIMP gradient files 

6# 

7# History: 

8# 97-08-23 fl Created 

9# 

10# Copyright (c) Secret Labs AB 1997. 

11# Copyright (c) Fredrik Lundh 1997. 

12# 

13# See the README file for information on usage and redistribution. 

14# 

15 

16""" 

17Stuff to translate curve segments to palette values (derived from 

18the corresponding code in GIMP, written by Federico Mena Quintero. 

19See the GIMP distribution for more information.) 

20""" 

21from __future__ import annotations 

22 

23from math import log, pi, sin, sqrt 

24 

25from ._binary import o8 

26 

27EPSILON = 1e-10 

28"""""" # Enable auto-doc for data member 

29 

30 

31def linear(middle, pos): 

32 if pos <= middle: 

33 if middle < EPSILON: 

34 return 0.0 

35 else: 

36 return 0.5 * pos / middle 

37 else: 

38 pos = pos - middle 

39 middle = 1.0 - middle 

40 if middle < EPSILON: 

41 return 1.0 

42 else: 

43 return 0.5 + 0.5 * pos / middle 

44 

45 

46def curved(middle, pos): 

47 return pos ** (log(0.5) / log(max(middle, EPSILON))) 

48 

49 

50def sine(middle, pos): 

51 return (sin((-pi / 2.0) + pi * linear(middle, pos)) + 1.0) / 2.0 

52 

53 

54def sphere_increasing(middle, pos): 

55 return sqrt(1.0 - (linear(middle, pos) - 1.0) ** 2) 

56 

57 

58def sphere_decreasing(middle, pos): 

59 return 1.0 - sqrt(1.0 - linear(middle, pos) ** 2) 

60 

61 

62SEGMENTS = [linear, curved, sine, sphere_increasing, sphere_decreasing] 

63"""""" # Enable auto-doc for data member 

64 

65 

66class GradientFile: 

67 gradient = None 

68 

69 def getpalette(self, entries=256): 

70 palette = [] 

71 

72 ix = 0 

73 x0, x1, xm, rgb0, rgb1, segment = self.gradient[ix] 

74 

75 for i in range(entries): 

76 x = i / (entries - 1) 

77 

78 while x1 < x: 

79 ix += 1 

80 x0, x1, xm, rgb0, rgb1, segment = self.gradient[ix] 

81 

82 w = x1 - x0 

83 

84 if w < EPSILON: 

85 scale = segment(0.5, 0.5) 

86 else: 

87 scale = segment((xm - x0) / w, (x - x0) / w) 

88 

89 # expand to RGBA 

90 r = o8(int(255 * ((rgb1[0] - rgb0[0]) * scale + rgb0[0]) + 0.5)) 

91 g = o8(int(255 * ((rgb1[1] - rgb0[1]) * scale + rgb0[1]) + 0.5)) 

92 b = o8(int(255 * ((rgb1[2] - rgb0[2]) * scale + rgb0[2]) + 0.5)) 

93 a = o8(int(255 * ((rgb1[3] - rgb0[3]) * scale + rgb0[3]) + 0.5)) 

94 

95 # add to palette 

96 palette.append(r + g + b + a) 

97 

98 return b"".join(palette), "RGBA" 

99 

100 

101class GimpGradientFile(GradientFile): 

102 """File handler for GIMP's gradient format.""" 

103 

104 def __init__(self, fp): 

105 if fp.readline()[:13] != b"GIMP Gradient": 

106 msg = "not a GIMP gradient file" 

107 raise SyntaxError(msg) 

108 

109 line = fp.readline() 

110 

111 # GIMP 1.2 gradient files don't contain a name, but GIMP 1.3 files do 

112 if line.startswith(b"Name: "): 

113 line = fp.readline().strip() 

114 

115 count = int(line) 

116 

117 gradient = [] 

118 

119 for i in range(count): 

120 s = fp.readline().split() 

121 w = [float(x) for x in s[:11]] 

122 

123 x0, x1 = w[0], w[2] 

124 xm = w[1] 

125 rgb0 = w[3:7] 

126 rgb1 = w[7:11] 

127 

128 segment = SEGMENTS[int(s[11])] 

129 cspace = int(s[12]) 

130 

131 if cspace != 0: 

132 msg = "cannot handle HSV colour space" 

133 raise OSError(msg) 

134 

135 gradient.append((x0, x1, xm, rgb0, rgb1, segment)) 

136 

137 self.gradient = gradient