1 files changed, 124 insertions, 0 deletions
diff --git a/PIL/GimpGradientFile.py b/PIL/GimpGradientFile.py
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+#
+# Python Imaging Library
+# $Id: GimpGradientFile.py 2134 2004-10-06 08:55:20Z fredrik $
+#
+# stuff to read (and render) GIMP gradient files
+#
+# History:
+#       97-08-23 fl     Created
+#
+# Copyright (c) Secret Labs AB 1997.
+# Copyright (c) Fredrik Lundh 1997.
+#
+# See the README file for information on usage and redistribution.
+#
+
+from math import pi, log, sin, sqrt
+import string
+
+# --------------------------------------------------------------------
+# Stuff to translate curve segments to palette values (derived from
+# the corresponding code in GIMP, written by Federico Mena Quintero.
+# See the GIMP distribution for more information.)
+#
+
+EPSILON = 1e-10
+
+def linear(middle, pos):
+    if pos <= middle:
+        if middle < EPSILON:
+            return 0.0
+        else:
+            return 0.5 * pos / middle
+    else:
+        pos = pos - middle
+        middle = 1.0 - middle
+        if middle < EPSILON:
+            return 1.0
+        else:
+            return 0.5 + 0.5 * pos / middle
+
+def curved(middle, pos):
+    return pos ** (log(0.5) / log(max(middle, EPSILON)))
+
+def sine(middle, pos):
+    return (sin((-pi / 2.0) + pi * linear(middle, pos)) + 1.0) / 2.0
+
+def sphere_increasing(middle, pos):
+    return sqrt(1.0 - (linear(middle, pos) - 1.0) ** 2)
+
+def sphere_decreasing(middle, pos):
+    return 1.0 - sqrt(1.0 - linear(middle, pos) ** 2)
+
+SEGMENTS = [ linear, curved, sine, sphere_increasing, sphere_decreasing ]
+
+class GradientFile:
+
+    gradient = None
+
+    def getpalette(self, entries = 256):
+
+        palette = []
+
+        ix = 0
+        x0, x1, xm, rgb0, rgb1, segment = self.gradient[ix]
+
+        for i in range(entries):
+
+            x = i / float(entries-1)
+
+            while x1 < x:
+                ix = ix + 1
+                x0, x1, xm, rgb0, rgb1, segment = self.gradient[ix]
+
+            w = x1 - x0
+
+            if w < EPSILON:
+                scale = segment(0.5, 0.5)
+            else:
+                scale = segment((xm - x0) / w, (x - x0) / w)
+
+            # expand to RGBA
+            r = chr(int(255 * ((rgb1[0] - rgb0[0]) * scale + rgb0[0]) + 0.5))
+            g = chr(int(255 * ((rgb1[1] - rgb0[1]) * scale + rgb0[1]) + 0.5))
+            b = chr(int(255 * ((rgb1[2] - rgb0[2]) * scale + rgb0[2]) + 0.5))
+            a = chr(int(255 * ((rgb1[3] - rgb0[3]) * scale + rgb0[3]) + 0.5))
+
+            # add to palette
+            palette.append(r + g + b + a)
+
+        return string.join(palette, ""), "RGBA"
+
+##
+# File handler for GIMP's gradient format.
+
+class GimpGradientFile(GradientFile):
+
+    def __init__(self, fp):
+
+        if fp.readline()[:13] != "GIMP Gradient":
+            raise SyntaxError, "not a GIMP gradient file"
+
+        count = int(fp.readline())
+
+        gradient = []
+
+        for i in range(count):
+
+            s = string.split(fp.readline())
+            w = map(float, s[:11])
+
+            x0, x1  = w[0], w[2]
+            xm      = w[1]
+            rgb0    = w[3:7]
+            rgb1    = w[7:11]
+
+            segment = SEGMENTS[int(s[11])]
+            cspace  = int(s[12])
+
+            if cspace != 0:
+                raise IOError, "cannot handle HSV colour space"
+
+            gradient.append((x0, x1, xm, rgb0, rgb1, segment))
+
+        self.gradient = gradient