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# Copyright (C) 2008, One Laptop per Child
# Author: Sayamindu Dasgupta <sayamindu@laptop.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import cairo
from gi.repository import Gtk
from gi.repository import Gdk
from gi.repository import GdkPixbuf
from gi.repository import GObject
ZOOM_STEP = 0.05
ZOOM_MAX = 4
ZOOM_MIN = 0.05
def _surface_from_file(file_location, ctx):
pixbuf = GdkPixbuf.Pixbuf.new_from_file(file_location)
surface = ctx.get_target().create_similar(
cairo.CONTENT_COLOR_ALPHA, pixbuf.get_width(),
pixbuf.get_height())
ctx_surface = cairo.Context(surface)
Gdk.cairo_set_source_pixbuf(ctx_surface, pixbuf, 0, 0)
ctx_surface.paint()
return surface
class ImageViewer(Gtk.DrawingArea):
def __init__(self):
Gtk.DrawingArea.__init__(self)
self._file_location = None
self._surface = None
self._zoom = None
self.connect('draw', self.__draw_cb)
def set_file_location(self, file_location):
self._file_location = file_location
self.queue_draw()
def set_zoom(self, zoom):
self._zoom = zoom
self.queue_draw()
def get_zoom(self):
return self._zoom
def zoom_in(self):
if self._zoom + ZOOM_STEP > ZOOM_MAX:
return
self._zoom += ZOOM_STEP
self.queue_draw()
def zoom_out(self):
if self._zoom - ZOOM_STEP < ZOOM_MIN:
return
self._zoom -= ZOOM_MIN
self.queue_draw()
def zoom_to_fit(self):
# This tries to figure out a best fit model
# If the image can fit in, we show it in 1:1,
# in any other case we show it in a fit to screen way
parent_allocation = self.get_parent().get_allocation()
parent_width = parent_allocation.width
parent_height = parent_allocation.height
surface_width = self._surface.get_width()
surface_height = self._surface.get_height()
if parent_width < surface_width or parent_height < surface_height:
# Image is larger than allocated size
self._zoom = min(parent_width * 1.0 / surface_width,
parent_height * 1.0 / surface_height)
else:
self._zoom = 1.0
self.queue_draw()
def zoom_equal(self):
self._zoom = 1
self.queue_draw()
def __draw_cb(self, widget, ctx):
# If the image surface is not set, it reads it from the file
# location. If the file location is not set yet, it just
# returns.
if self._surface is None:
if self._file_location is None:
return
self._surface = _surface_from_file(self._file_location, ctx)
if self._zoom is None:
self.zoom_to_fit()
# FIXME investigate
ctx.set_antialias(cairo.ANTIALIAS_NONE)
# Scale and center the image according to the current zoom.
scaled_width = int(self._surface.get_width() * self._zoom)
scaled_height = int(self._surface.get_height() * self._zoom)
parent_allocation = self.get_parent().get_allocation()
parent_width = parent_allocation.width
parent_height = parent_allocation.height
x_offset = (parent_width * 1.0 - scaled_width) / 2
y_offset = (parent_height * 1.0 - scaled_height) / 2
ctx.translate(x_offset, y_offset)
ctx.scale(self._zoom, self._zoom)
ctx.set_source_surface(self._surface, 0, 0)
# FIXME investigate
ctx.get_source().set_filter(cairo.FILTER_NEAREST)
ctx.paint()
if __name__ == '__main__':
import sys
window = Gtk.Window()
window.connect("destroy", Gtk.main_quit)
view = ImageViewer()
view.set_file_location(sys.argv[1])
window.add(view)
view.show()
window.set_size_request(800, 600)
window.show()
Gtk.main()
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