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src/calibre/ebooks/pdf/render/gradients.py

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+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+from future_builtins import map
+
+from PyQt4.Qt import (QPointF)
+
+from calibre.ebooks.pdf.render.common import Stream
+
+def generate_linear_gradient_shader(gradient, page_rect, is_transparent=False):
+    pass
+
+class LinearGradient(Stream):
+
+    def __init__(self, brush, matrix, pixel_page_width, pixel_page_height):
+        is_opaque = brush.isOpaque()
+        gradient = brush.gradient()
+        inv = matrix.inverted()[0]
+
+        page_rect = tuple(map(inv.map, (
+            QPointF(0, 0), QPointF(pixel_page_width, 0), QPointF(0, pixel_page_height),
+            QPointF(pixel_page_width, pixel_page_height))))
+
+        shader = generate_linear_gradient_shader(gradient, page_rect)
+        alpha_shader = None
+        if not is_opaque:
+            alpha_shader = generate_linear_gradient_shader(gradient, page_rect, True)
+
+        shader, alpha_shader
+
+