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#!/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 math
UTF8_TEXT = u"I ♥ GTK"
HEART = u"♥"
BYTES_TEXT = UTF8_TEXT.encode("utf-8")
BYTES_HEART = HEART.encode("utf-8")
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(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
# Set fancy shape attributes for all hearts
attrs = Pango.AttrList()
# FIXME: attr_shape_new_with_data isn't introspectable
'''
ink_rect = logical_rect
p = BYTES_TEXT.find(BYTES_HEART)
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):
RotatedTextApp()
Gtk.main()
if __name__ == '__main__':
main()
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