[pygobject] [gi-demos] add images demo

[John Palmieri <johnp src gnome org>]

commit 9ac11c3c3b1c0399c85ece57c0983ed60d419d7a
Author: John (J5) Palmieri <johnp redhat com>
Date:   Thu Feb 17 17:25:00 2011 -0500

    [gi-demos] add images demo
    
     * needs annotation fix from GdkPixbuf for ImageLoader to work

 demos/gtk-demo/demos/images.py |  311 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 311 insertions(+), 0 deletions(-)
---
diff --git a/demos/gtk-demo/demos/images.py b/demos/gtk-demo/demos/images.py
new file mode 100644
index 0000000..cf5b113
--- /dev/null
+++ b/demos/gtk-demo/demos/images.py
@@ -0,0 +1,311 @@
+#!/usr/bin/env python
+# -*- 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 = "Images"
+description = """GtkImage is used to display an image; the image can be in a number of formats. Typically, you load an image into a GdkPixbuf, then display the pixbuf.
+This demo code shows some of the more obscure cases, in the simple case a call to gtk_image_new_from_file() is all you need.
+"""
+
+from gi.repository import Gtk, Gdk, GdkPixbuf, GLib, Gio, GObject
+import os
+import math
+from os import path
+
+class ImagesApp:
+    def __init__(self):
+        self.pixbuf_loader = None
+        self.image_stream = None
+
+        self.window = Gtk.Window(title="Images")
+        self.window.connect('destroy', self.cleanup_cb)
+        self.window.set_border_width(8)
+
+        vbox = Gtk.VBox(spacing=8)
+        vbox.set_border_width(8)
+        self.window.add(vbox)        
+
+        label = Gtk.Label()
+        label.set_markup('<u>Image loaded from file</u>')
+        vbox.pack_start(label, False, False, 0)
+
+        frame = Gtk.Frame()
+        frame.set_shadow_type(Gtk.ShadowType.IN)
+        
+        # The alignment keeps the frame from growing when users resize
+        # the window
+        align = Gtk.Alignment(xalign=0.5, 
+                              yalign=0.5, 
+                              xscale=0, 
+                              yscale=0)
+        align.add(frame)
+        vbox.pack_start(align, False, False, 0)
+
+        self.base_path = 'data'
+        if not path.isdir(self.base_path):
+            self.base_path = path.join('demos', self.base_path)
+   
+        try:
+            img_path = path.join(self.base_path, 'gtk-logo-rgb.gif')
+            pixbuf = GdkPixbuf.Pixbuf.new_from_file(img_path)
+        except GLib.Error as e:
+            dialog = Gtk.MessageDialog(self.window,
+                                       Gtk.DialogFlags.DESTROY_WITH_PARENT,
+                                       Gtk.MessageType.ERROR,
+                                       Gtk.ButtonsType.CLOSE,
+                                       e.message)
+ 
+            dialog.show()
+            dialog.connect('response', lambda x,y: dialog.destroy())
+
+        image = Gtk.Image.new_from_pixbuf(pixbuf)
+        frame.add(image)
+
+        # Animation
+
+        label = Gtk.Label()
+        label.set_markup('<u>Animation loaded from file</u>')
+        vbox.pack_start(label, False, False, 0)
+
+        frame = Gtk.Frame()
+        frame.set_shadow_type(Gtk.ShadowType.IN)
+        
+        # The alignment keeps the frame from growing when users resize
+        # the window
+        align = Gtk.Alignment(xalign=0.5, 
+                              yalign=0.5, 
+                              xscale=0, 
+                              yscale=0)
+        align.add(frame)
+        vbox.pack_start(align, False, False, 0)
+
+        img_path = path.join(self.base_path, 'floppybuddy.gif')
+        image = Gtk.Image.new_from_file(img_path)
+        frame.add(image)
+
+        # Symbolic icon
+
+        label = Gtk.Label()
+        label.set_markup('<u>Symbolic themed icon</u>')
+        vbox.pack_start(label, False, False, 0)
+
+        frame = Gtk.Frame()
+        frame.set_shadow_type(Gtk.ShadowType.IN)
+        
+        # The alignment keeps the frame from growing when users resize
+        # the window
+        align = Gtk.Alignment(xalign=0.5, 
+                              yalign=0.5, 
+                              xscale=0, 
+                              yscale=0)
+        align.add(frame)
+        vbox.pack_start(align, False, False, 0)
+
+        gicon = Gio.ThemedIcon.new_with_default_fallbacks('battery-caution-charging-symbolic')
+        image = Gtk.Image.new_from_gicon(gicon, Gtk.IconSize.DIALOG)
+        frame.add(image)
+
+        # progressive
+
+        label = Gtk.Label()
+        label.set_markup('<u>Progressive image loading</u>')
+        vbox.pack_start(label, False, False, 0)
+
+        frame = Gtk.Frame()
+        frame.set_shadow_type(Gtk.ShadowType.IN)
+        
+        # The alignment keeps the frame from growing when users resize
+        # the window
+        align = Gtk.Alignment(xalign=0.5, 
+                              yalign=0.5, 
+                              xscale=0, 
+                              yscale=0)
+        align.add(frame)
+        vbox.pack_start(align, False, False, 0)
+
+        image = Gtk.Image.new_from_pixbuf(None)
+        frame.add(image)
+
+        self.start_progressive_loading(image)
+
+        # Sensistivity control
+        button = Gtk.ToggleButton(label='_Insensitive')
+        button.connect('toggled', self.toggle_sensitivity_cb, vbox)
+        vbox.pack_start(button, False, False, 0)
+
+        self.window.show_all()
+
+    def toggle_sensitivity_cb(self, button, container):
+        widget_list = container.get_children()
+        for w in widget_list:
+            if w != button:
+                w.set_sensitive(not button.get_active())
+
+        return True
+
+    def progressive_timeout(self, image):
+        # This shows off fully-paranoid error handling, so looks scary.
+        # You could factor out the error handling code into a nice separate
+        # function to make things nicer.
+
+        if self.image_stream:
+            try:
+                buf = self.image_stream.read(256)
+            except IOError as e:
+                dialog = Gtk.MessageDialog(self.window,
+                                           Gtk.DialogFlags.DESTROY_WITH_PARENT,
+                                           Gtk.MessageType.ERROR,
+                                           Gtk.ButtonsType.CLOSE,
+                                           "Failure reading image file 'alphatest.png': %s" %str(e))
+
+                self.image_stream.close()
+                self.image_stream = None
+                self.load_timeout = 0
+
+                dialog.show()
+                dialog.connect('response', lambda x,y: dialog.destroy())
+
+                return False # uninstall the timeout
+
+            try:
+                self.pixbuf_loader.write(buf)
+            except GLib.Error as e:
+                dialog = Gtk.MessageDialog(self.window,
+                                           Gtk.DialogFlags.DESTROY_WITH_PARENT,
+                                           Gtk.MessageType.ERROR,
+                                           Gtk.ButtonsType.CLOSE,
+                                           e.message)
+
+                self.image_stream.close()
+                self.image_stream = None
+                self.load_timeout = 0
+    
+                dialog.show()
+                dialog.connect('response', lambda x,y: dialog.destroy())
+
+                return False # uninstall the timeout
+
+            if len(buf) < 256: # eof
+                self.image_stream.close()
+                self.image_stream = None
+
+                # Errors can happen on close, e.g. if the image
+                # file was truncated we'll know on close that
+                # it was incomplete.
+                try:
+                   self.pixbuf_loader.close()
+                except GLib.Error as e:
+                    dialog = Gtk.MessageDialog(self.window,
+                                               Gtk.DialogFlags.DESTROY_WITH_PARENT,
+                                               Gtk.MessageType.ERROR,
+                                               Gtk.ButtonsType.CLOSE,
+                                               'Failed to load image: %s' % e.message)
+
+                    self.load_timeout = 0
+    
+                    dialog.show()
+                    dialog.connect('response', lambda x,y: dialog.destroy())
+
+                    return False # uninstall the timeout
+        else:
+            img_path = path.join(self.base_path, 'alphatest.png')
+            try:
+                self.image_stream = open(img_path, 'rb')
+            except IOError as e:
+                dialog = Gtk.MessageDialog(self.window,
+                                           Gtk.DialogFlags.DESTROY_WITH_PARENT,
+                                           Gtk.MessageType.ERROR,
+                                           Gtk.ButtonsType.CLOSE,
+                                           str(e))
+                self.load_timeout = 0
+                dialog.show()
+                dialog.connect('response', lambda x,y: dialog.destroy())
+
+                return False # uninstall the timeout
+
+            if self.pixbuf_loader:
+                try:
+                    self.pixbuf_loader.close()
+                except GLib.Error:
+                    pass
+                self.pixbuf_loader = None
+
+            self.pixbuf_loader = GdkPixbuf.PixbufLoader()
+
+            self.pixbuf_loader.connect('area-prepared',
+                                       self.progressive_prepared_callback, 
+                                       image)
+      
+            self.pixbuf_loader.connect('area-updated',
+                                       self.progressive_updated_callback, 
+                                       image)
+        # leave timeout installed
+        return True
+
+    def progressive_prepared_callback(self, loader, image):
+        pixbuf = loader.get_pixbuf()
+        # Avoid displaying random memory contents, since the pixbuf
+        # isn't filled in yet.
+        pixbuf.fill(0xaaaaaaff)
+        image.set_from_pixbuf(pixbuf)
+
+    def progressive_updated_callback(self, loader, x, y, width, height, image):       
+        # We know the pixbuf inside the GtkImage has changed, but the image
+        # itself doesn't know this; so queue a redraw.  If we wanted to be
+        # really efficient, we could use a drawing area or something
+        # instead of a GtkImage, so we could control the exact position of
+        # the pixbuf on the display, then we could queue a draw for only
+        # the updated area of the image.
+        image.queue_draw()
+
+    def start_progressive_loading(self, image):
+        # This is obviously totally contrived (we slow down loading
+        # on purpose to show how incremental loading works).
+        # The real purpose of incremental loading is the case where
+        # you are reading data from a slow source such as the network.
+        # The timeout simply simulates a slow data source by inserting
+        # pauses in the reading process.
+
+        self.load_timeout = Gdk.threads_add_timeout(150,
+                                                    GLib.PRIORITY_DEFAULT_IDLE,
+                                                    self.progressive_timeout,
+                                                    image)
+
+    def cleanup_cb(self, widget):
+        if self.load_timeout:
+            GObject.source_remove(self.load_timeout)
+
+        if self.pixbuf_loader:
+            try:
+                self.pixbuf_loader.close()
+            except GLib.Error:
+                pass
+
+        if self.image_stream:
+            self.image_stream.close()
+
+        Gtk.main_quit()
+            
+def main(demoapp=None):
+    app = ImagesApp()
+    Gtk.main()
+
+if __name__ == '__main__':
+    main()