[pygobject] [gi-demos] added rotate text demo

[John Palmieri <johnp src gnome org>]

commit ad5d3fccff9433e2dadac89d731dac5cafb0eac3
Author: John (J5) Palmieri <johnp redhat com>
Date:   Thu Feb 17 19:46:49 2011 -0500

    [gi-demos] added rotate text demo
    
    * needs some Pango Attr fixes to be 100% done, See FIXME

 demos/gtk-demo/demos/rotatedtext.py |  196 +++++++++++++++++++++++++++++++++++
 1 files changed, 196 insertions(+), 0 deletions(-)
---
diff --git a/demos/gtk-demo/demos/rotatedtext.py b/demos/gtk-demo/demos/rotatedtext.py
new file mode 100644
index 0000000..30d606c
--- /dev/null
+++ b/demos/gtk-demo/demos/rotatedtext.py
@@ -0,0 +1,196 @@
+#!/usr/bin/env python
+# coding=utf-8
+# -*- Mode: Python; py-indent-offset: 4 -*-
+# vim: tabstop=4 shiftwidth=4 expandtab
+#
+# Copyright (C) 2010 Red Hat, Inc., John (J5) Palmieri <johnp redhat com>
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
+# USA
+
+title = "Rotated Text"
+description = """This demo shows how to use PangoCairo to draw rotated and transformed text.  The right pane shows a rotated GtkLabel widget.
+In both cases, a custom PangoCairo shape renderer is installed to draw a red heard using cairo drawing operations instead of the Unicode heart character.
+"""
+
+from gi.repository import Gtk, Pango, PangoCairo, Gdk
+import cairo
+import sys
+import math
+
+# Python 2 and 3 handle UTF8 differently
+if sys.version_info < (3, 0):
+    BYTES_TEXT = "I \xe2\x99\xa5 GTK+"
+    UTF8_TEXT = unicode(BYTES_TEXT, 'UTF-8')
+    BYTES_HEART = "\xe2\x99\xa5"
+    HEART = unicode(BYTES_HEART, 'UTF-8')
+else:
+    UTF8_TEXT = "I â?¥ GTK+"
+    BYTES_TEXT = bytes(UTF8_TEXT)
+    HEART = "â?¥"
+    BYTES_HEART = bytes(HEART)
+
+class RotatedTextApp:
+    RADIUS = 150
+    N_WORDS = 5
+    FONT = "Serif 18"
+
+    def __init__(self):
+    
+        white = Gdk.RGBA()
+        white.red = 1.0
+        white.green = 1.0
+        white.blue = 1.0
+        white.alpha = 1.0
+        
+        self.window = Gtk.Window(title="Rotated Text")
+        self.window.set_default_size(4 * self.RADIUS, 2 * self.RADIUS)
+        self.window.connect('destroy', Gtk.main_quit)
+
+        box = Gtk.HBox()
+        box.set_homogeneous(True)
+        self.window.add(box)
+        
+        # add a drawing area
+        da = Gtk.DrawingArea()
+        box.add(da)
+
+        # override the background color from the theme
+        da.override_background_color(0, white)
+
+        da.connect('draw', self.rotated_text_draw)
+
+        label = Gtk.Label(UTF8_TEXT)
+        box.add(label)
+        label.set_angle(45)
+
+        # Setup some fancy stuff on the label
+        layout = label.get_layout()
+        
+        PangoCairo.context_set_shape_renderer(layout.get_context(),
+                                              self.fancy_shape_renderer,
+                                              None)
+        attrs = self.create_fancy_attr_list_for_layout(layout)
+        label.set_attributes(attrs)
+
+        self.window.show_all()
+
+    def fancy_shape_renderer(self, cairo_ctx, attr, do_path):
+        x, y = cairo_ctx.get_current_point()
+        cairo_ctx.translate(x, y)
+
+        cairo_ctx.scale(float(attr.inc_rect.width) / Pango.SCALE,
+                        float(attr.inc_rect.height) / Pango.SCALE)
+
+        if int(attr.data) == 0x2665: # U+2665 BLACK HEART SUIT
+            cairo_ctx.move_to(0.5, 0.0)
+            cairo_ctx.line_to(0.9, -0.4)
+            cairo_ctx.curve_to(1.1, -0.8, 0.5, -0.9, 0.5, -0.5)
+            cairo_ctx.curve_to(0.5, -0.9, -0.1, -0.8, 0.1, -0.4)
+            cairo_ctx.close_path()
+
+        if not do_path:
+            cairo_ctx.set_source_rgb(1.0, 0.0, 0.0)
+            cairo_ctx.fill()
+
+    def create_fancy_attr_list_for_layout(self, layout):
+        pango_ctx = layout.get_context()
+        metrics = pango_ctx.get_metrics(layout.get_font_description(),
+                                        None)
+        ascent = metrics.get_ascent()
+        
+        logical_rect = Pango.Rectangle()
+        logical_rect.x = 0
+        logical_rect.width = ascent
+        logical_rect.y = -ascent
+        logical_rect.height = ascent
+
+        ink_rect = logical_rect
+
+        # Set fancy shape attributes for all hearts
+        attrs = Pango.AttrList()
+        p = BYTES_TEXT.find(BYTES_HEART)
+
+        # FIXME: attr_shape_new_with_data isn't introspectable
+        '''
+        while (p != -1):
+            attr = Pango.attr_shape_new_with_data(ink_rect,
+                                                  logical_rect,
+                                                  ord(HEART),
+                                                  None)
+            attr.start_index = p
+            attr.end_index = p + len(BYTES_HEART)
+            p = UTF8_TEXT.find(HEART, attr.end_index)
+
+        attrs.insert(attr)
+        '''
+        return attrs
+        
+    def rotated_text_draw (self, da, cairo_ctx):
+        # Create a cairo context and set up a transformation matrix so that the user
+        # space coordinates for the centered square where we draw are [-RADIUS, RADIUS],
+        # [-RADIUS, RADIUS].
+        # We first center, then change the scale.
+        width = da.get_allocated_width()
+        height = da.get_allocated_height()
+        device_radius = min(width, height) / 2.0
+        cairo_ctx.translate(
+                   device_radius + (width - 2 * device_radius) / 2,
+                   device_radius + (height - 2 * device_radius) / 2)
+        cairo_ctx.scale(device_radius / self.RADIUS, 
+                        device_radius / self.RADIUS)
+
+        # Create a subtle gradient source and use it.
+        pattern = cairo.LinearGradient(-self.RADIUS, -self.RADIUS, 
+                                        self.RADIUS,  self.RADIUS)
+        pattern.add_color_stop_rgb(0.0, 0.5, 0.0, 0.0)
+        pattern.add_color_stop_rgb(1.0, 0.0, 0.0, 0.5)
+        cairo_ctx.set_source(pattern)
+
+        # Create a PangoContext and set up our shape renderer
+        context = da.create_pango_context()
+        PangoCairo.context_set_shape_renderer(context,
+                                               self.fancy_shape_renderer,
+                                               None)
+
+        # Create a PangoLayout, set the text, font, and attributes */
+        layout = Pango.Layout(context=context)
+        layout.set_text(UTF8_TEXT, -1)
+        desc = Pango.FontDescription(self.FONT)
+        layout.set_font_description(desc)
+
+        attrs = self.create_fancy_attr_list_for_layout(layout)
+        layout.set_attributes(attrs)
+
+        # Draw the layout N_WORDS times in a circle */
+        for i in range(self.N_WORDS):
+            # Inform Pango to re-layout the text with the new transformation matrix
+            PangoCairo.update_layout(cairo_ctx, layout)
+    
+            width, height = layout.get_pixel_size()
+            cairo_ctx.move_to(-width / 2, -self.RADIUS * 0.9)
+            PangoCairo.show_layout(cairo_ctx, layout)
+
+            # Rotate for the next turn
+            cairo_ctx.rotate(math.pi*2 / self.N_WORDS)
+  
+        return False
+
+def main(demoapp=None):
+    app = RotatedTextApp()
+    Gtk.main()
+
+if __name__ == '__main__':
+    main()