gnome-devel-docs 3.8.1-1 / usr / share / help / gl / gnome-devel-demos / image.py.page

<?xml version="1.0" encoding="utf-8"?>
<page xmlns="http://projectmallard.org/1.0/" xmlns:xi="http://www.w3.org/2001/XInclude" type="guide" style="task" id="image.py" xml:lang="gl">
  <info>
    <title type="text">Image (Python)</title>
    <link type="guide" xref="beginner.py#display-widgets"/>
    <link type="seealso" xref="properties.py"/>
    <link type="next" xref="strings.py"/>
    <revision version="0.2" date="2012-06-14" status="draft"/>

    <credit type="author copyright">
      <name>Marta Maria Casetti</name>
      <email>mmcasetti@gmail.com</email>
      <years>2012</years>
    </credit>

    <desc>A widget displaying an image</desc>
  
    <mal:credit xmlns:mal="http://projectmallard.org/1.0/" type="translator copyright">
      <mal:name>Fran Dieguez</mal:name>
      <mal:email>frandieguez@gnome.org</mal:email>
      <mal:years>2012-2013.</mal:years>
    </mal:credit>
  </info>

  <title>Image</title>
  <media type="image" mime="image/png" src="media/image.png"/>
  <p>This GtkApplication displays an image file from the current directory.</p>

  <note><p>
    If the image file is not loaded successfully, the image will contain a "broken image" icon.  The <file>filename.png</file> needs to be in the current directory for this code to work.
  </p></note>

  <links type="section"/>

  <section id="code">
  <title>Código usado para xerar este exemplo</title>

  <code mime="text/x-python" style="numbered">from gi.repository import Gtk
import sys

class MyWindow(Gtk.ApplicationWindow):
    # create a window
    def __init__(self, app):
        Gtk.Window.__init__(self, title="Welcome to GNOME", application=app)
        self.set_default_size(300, 300)

        # create an image
        image = Gtk.Image()
        # set the content of the image as the file filename.png
        image.set_from_file("gnome-image.png")
        # add the image to the window
        self.add(image)

class MyApplication(Gtk.Application):
    def __init__(self):
        Gtk.Application.__init__(self)

    def do_activate(self):
        win = MyWindow(self)
        win.show_all()

    def do_startup(self):
        Gtk.Application.do_startup(self)

app = MyApplication()
exit_status = app.run(sys.argv)
sys.exit(exit_status)
</code>

  <p>Another way to obtain what we have in the example is to create the image as an instance of another class and add it to the instance of <code>MyWindow</code> in the <code>do_activate(self)</code> method:</p>
      <code mime="text/x-python">
# a class to create a window
class MyWindow(Gtk.ApplicationWindow):
    def __init__(self, app):
        Gtk.Window.__init__(self, title="Welcome to GNOME", application=app)
        self.set_default_size(300, 300)

# a class to create an image
class MyImage(Gtk.Image):
    def __init__(self):
        Gtk.Image.__init__(self)
        self.set_from_file("gnome-image.png")

class MyApplication(Gtk.Application):
    def __init__(self):
        Gtk.Application.__init__(self)

    def do_activate(self):
        # create an instance of MyWindow
        win = MyWindow(self)
        # create an instance of MyImage and add it to the window
        win.add(MyImage())
        # show the window and everything on it
        win.show_all()</code>
  </section>

  <section id="methods">
  <title>Useful methods for an Image widget</title>

  <list>
    <item><p>To set a stock icon as image, you can use <code>set_from_stock(stock_id, size)</code> where <code>stock_id</code> is a stock icon such as <code>Gtk.STOCK_ABOUT</code> (more can be found at <link href="http://developer.gnome.org/gtk3/unstable/gtk3-Stock-Items">Stock Items</link>, with the caveat that they should be modified as above) and <code>size</code> is a stock icon size to be chosen from <code>Gtk.IconSize.INVALID, Gtk.IconSize.MENU, Gtk.IconSize.SMALL_TOOLBAR, Gtk.IconSize.LARGE_TOOLBAR, Gtk.IconSize.BUTTON, Gtk.IconSize.DND, Gtk.IconSize.DIALOG</code>.</p></item>
    <item><p>You can also use <code>set_from_icon_name(icon_name, size)</code>, where <code>icon_name</code> is a stock icon name such as <code>"gtk-about"</code> (more can be found as above) and <code>size</code> is as above.</p></item>
    <item><p>To load an image over a network use <code>set_from_pixbuf(pixbuf)</code>, where <code>pixbuf</code> is a <link href="http://developer.gnome.org/gdk-pixbuf/unstable//index.html">GdkPixbuf</link>.</p>
    <code mime="text/python">
from gi.repository import Gtk
from gi.repository import GdkPixbuf
import sys

class MyWindow(Gtk.ApplicationWindow):
    # create a window
    def __init__(self, app):
        Gtk.Window.__init__(self, title="Welcome to GNOME", application=app)
        self.set_default_size(300, 300)

        # create a pixbuf from file filename="gnome-image.png", with width=32
        # and height=64 amd boolean preserve_aspect_ratio=False.
        pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_scale("gnome-image.png", 64, 128, False)

        # create an image
        image = Gtk.Image()
        # set the content of the image as the pixbuf
        image.set_from_pixbuf(pixbuf)
        # add the image to the window
        self.add(image)</code>
    <p>If <code>preserve_aspect_ratio=True</code> we can use <code>new_from_file_at_size(filename, width, height)</code>. If <code>width</code> or <code>height</code> is <code>-1</code>, it is not constrained.</p>
    <p>For loading from an input stream, see <code>new_from_stream()</code> and <code>new_from_stream_at_scale()</code> in the documentation</p>
    </item>
  </list>
  </section>

  <section id="references">
  <title>API References</title>
  <p>Neste exemplo empregaremos o seguinte:</p>
  <list>
    <item><p><link href="http://developer.gnome.org/gtk3/unstable/GtkImage.html">GtkImage</link></p></item>
    <item><p><link href="http://developer.gnome.org/gtk3/unstable/GtkWindow.html">GtkWindow</link></p></item>
  </list>
  </section>
</page>