#!/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 # # 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()