Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.11/site-packages/PIL/GimpGradientFile.py: 26%

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 

27TYPE_CHECKING = False 

28if TYPE_CHECKING: 

29 from collections.abc import Callable 

30 from typing import IO 

31 

32EPSILON = 1e-10 

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

34 

35 

36def linear(middle: float, pos: float) -> float: 

37 if pos <= middle: 

38 if middle < EPSILON: 

39 return 0.0 

40 else: 

41 return 0.5 * pos / middle 

42 else: 

43 pos = pos - middle 

44 middle = 1.0 - middle 

45 if middle < EPSILON: 

46 return 1.0 

47 else: 

48 return 0.5 + 0.5 * pos / middle 

49 

50 

51def curved(middle: float, pos: float) -> float: 

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

53 

54 

55def sine(middle: float, pos: float) -> float: 

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

57 

58 

59def sphere_increasing(middle: float, pos: float) -> float: 

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

61 

62 

63def sphere_decreasing(middle: float, pos: float) -> float: 

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

65 

66 

67SEGMENTS = [linear, curved, sine, sphere_increasing, sphere_decreasing] 

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

69 

70 

71class GradientFile: 

72 gradient: ( 

73 list[ 

74 tuple[ 

75 float, 

76 float, 

77 float, 

78 list[float], 

79 list[float], 

80 Callable[[float, float], float], 

81 ] 

82 ] 

83 | None 

84 ) = None 

85 

86 def getpalette(self, entries: int = 256) -> tuple[bytes, str]: 

87 assert self.gradient is not None 

88 palette = [] 

89 

90 ix = 0 

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

92 

93 for i in range(entries): 

94 x = i / (entries - 1) 

95 

96 while x1 < x: 

97 ix += 1 

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

99 

100 w = x1 - x0 

101 

102 if w < EPSILON: 

103 scale = segment(0.5, 0.5) 

104 else: 

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

106 

107 # expand to RGBA 

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

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

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

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

112 

113 # add to palette 

114 palette.append(r + g + b + a) 

115 

116 return b"".join(palette), "RGBA" 

117 

118 

119class GimpGradientFile(GradientFile): 

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

121 

122 def __init__(self, fp: IO[bytes]) -> None: 

123 if not fp.readline().startswith(b"GIMP Gradient"): 

124 msg = "not a GIMP gradient file" 

125 raise SyntaxError(msg) 

126 

127 line = fp.readline() 

128 

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

130 if line.startswith(b"Name: "): 

131 line = fp.readline().strip() 

132 

133 count = int(line) 

134 

135 self.gradient = [] 

136 

137 for i in range(count): 

138 s = fp.readline().split() 

139 w = [float(x) for x in s[:11]] 

140 

141 x0, x1 = w[0], w[2] 

142 xm = w[1] 

143 rgb0 = w[3:7] 

144 rgb1 = w[7:11] 

145 

146 segment = SEGMENTS[int(s[11])] 

147 cspace = int(s[12]) 

148 

149 if cspace != 0: 

150 msg = "cannot handle HSV colour space" 

151 raise OSError(msg) 

152 

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