Quick search

Table Of Contents

Source code for kivy.uix.image

'''
Image
=====

The :class:`Image` widget is used to display an image::

    wimg = Image(source='mylogo.png')

Asynchronous Loading
--------------------

To load an image asynchronously (for example from an external webserver), use
the :class:`AsyncImage` subclass::

    aimg = AsyncImage(source='http://mywebsite.com/logo.png')

This can be useful as it prevents your application from waiting until the image
is loaded. If you want to display large images or retrieve them from URL's,
using :class:`AsyncImage` will allow these resources to be retrieved on a
background thread without blocking your application.

Alignment
---------

By default, the image is centered and fits inside the widget bounding box.
If you don't want that, you can set `allow_stretch` to True and `keep_ratio`
to False.

You can also inherit from Image and create your own style. For example, if you
want your image to be greater than the size of your widget, you could do::

    class FullImage(Image):
        pass

And in your kivy language file::

    <-FullImage>:
        canvas:
            Color:
                rgb: (1, 1, 1)
            Rectangle:
                texture: self.texture
                size: self.width + 20, self.height + 20
                pos: self.x - 10, self.y - 10

'''
__all__ = ('Image', 'AsyncImage')

from kivy.uix.widget import Widget
from kivy.core.image import Image as CoreImage
from kivy.resources import resource_find
from kivy.properties import StringProperty, ObjectProperty, ListProperty, \
    AliasProperty, BooleanProperty, NumericProperty
from kivy.logger import Logger
from kivy.compat import PY2

# delayed imports
Loader = None


[docs]class Image(Widget): '''Image class, see module documentation for more information. ''' source = StringProperty(None) '''Filename / source of your image. :attr:`source` is a :class:`~kivy.properties.StringProperty` and defaults to None. ''' texture = ObjectProperty(None, allownone=True) '''Texture object of the image. The texture represents the original, loaded image texture. It is stretched and positioned during rendering according to the :attr:`allow_stretch` and :attr:`keep_ratio` properties. Depending of the texture creation, the value will be a :class:`~kivy.graphics.texture.Texture` or a :class:`~kivy.graphics.texture.TextureRegion` object. :attr:`texture` is an :class:`~kivy.properties.ObjectProperty` and defaults to None. ''' texture_size = ListProperty([0, 0]) '''Texture size of the image. This represents the original, loaded image texture size. .. warning:: The texture size is set after the texture property. So if you listen to the change on :attr:`texture`, the property texture_size will not be up-to-date. Use self.texture.size instead. ''' def get_image_ratio(self): if self.texture: return self.texture.width / float(self.texture.height) return 1. mipmap = BooleanProperty(False) '''Indicate if you want OpenGL mipmapping to be applied to the texture. Read :ref:`mipmap` for more information. .. versionadded:: 1.0.7 :attr:`mipmap` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' image_ratio = AliasProperty(get_image_ratio, None, bind=('texture', )) '''Ratio of the image (width / float(height). :attr:`image_ratio` is an :class:`~kivy.properties.AliasProperty` and is read-only. ''' color = ListProperty([1, 1, 1, 1]) '''Image color, in the format (r, g, b, a). This attribute can be used to 'tint' an image. Be careful: if the source image is not gray/white, the color will not really work as expected. .. versionadded:: 1.0.6 :attr:`color` is a :class:`~kivy.properties.ListProperty` and defaults to [1, 1, 1, 1]. ''' allow_stretch = BooleanProperty(False) '''If True, the normalized image size will be maximized to fit in the image box. Otherwise, if the box is too tall, the image will not be stretched more than 1:1 pixels. .. versionadded:: 1.0.7 :attr:`allow_stretch` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' keep_ratio = BooleanProperty(True) '''If False along with allow_stretch being True, the normalized image size will be maximized to fit in the image box and ignores the aspect ratio of the image. Otherwise, if the box is too tall, the image will not be stretched more than 1:1 pixels. .. versionadded:: 1.0.8 :attr:`keep_ratio` is a :class:`~kivy.properties.BooleanProperty` and defaults to True. ''' keep_data = BooleanProperty(False) '''If True, the underlaying _coreimage will store the raw image data. This is useful when performing pixel based collision detection. .. versionadded:: 1.3.0 :attr:`keep_data` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' anim_delay = NumericProperty(.25) '''Delay the animation if the image is sequenced (like an animated gif). If anim_delay is set to -1, the animation will be stopped. .. versionadded:: 1.0.8 :attr:`anim_delay` is a :class:`~kivy.properties.NumericProperty` and defaults to 0.25 (4 FPS). ''' anim_loop = NumericProperty(0) '''Number of loops to play then stop animating. 0 means keep animating. .. versionadded:: 1.9.0 :attr:`anim_loop` is a :class:`~kivy.properties.NumericProperty` and defaults to 0. ''' nocache = BooleanProperty(False) '''If this property is set True, the image will not be added to the internal cache. The cache will simply ignore any calls trying to append the core image. .. versionadded:: 1.6.0 :attr:`nocache` is a :class:`~kivy.properties.BooleanProperty` and defaults to False. ''' def get_norm_image_size(self): if not self.texture: return self.size ratio = self.image_ratio w, h = self.size tw, th = self.texture.size # ensure that the width is always maximized to the containter width if self.allow_stretch: if not self.keep_ratio: return w, h iw = w else: iw = min(w, tw) # calculate the appropriate height ih = iw / ratio # if the height is too higher, take the height of the container # and calculate appropriate width. no need to test further. :) if ih > h: if self.allow_stretch: ih = h else: ih = min(h, th) iw = ih * ratio return iw, ih norm_image_size = AliasProperty(get_norm_image_size, None, bind=( 'texture', 'size', 'image_ratio', 'allow_stretch')) '''Normalized image size within the widget box. This size will always fit the widget size and will preserve the image ratio. :attr:`norm_image_size` is an :class:`~kivy.properties.AliasProperty` and is read-only. ''' def __init__(self, **kwargs): self._coreimage = None self._loops = 0 super(Image, self).__init__(**kwargs) fbind = self.fbind update = self.texture_update fbind('source', update) fbind('mipmap', update) if self.source: update() self.on_anim_delay(self, kwargs.get('anim_delay', .25)) def texture_update(self, *largs): if not self.source: self.texture = None else: filename = resource_find(self.source) self._loops = 0 if filename is None: return Logger.error('Image: Error reading file {filename}'. format(filename=self.source)) mipmap = self.mipmap if self._coreimage is not None: self._coreimage.unbind(on_texture=self._on_tex_change) try: if PY2 and isinstance(filename, str): filename = filename.decode('utf-8') self._coreimage = ci = CoreImage(filename, mipmap=mipmap, anim_delay=self.anim_delay, keep_data=self.keep_data, nocache=self.nocache) except: Logger.error('Image: Error loading texture {filename}'. format(filename=self.source)) self._coreimage = ci = None if ci: ci.bind(on_texture=self._on_tex_change) self.texture = ci.texture def on_anim_delay(self, instance, value): self._loop = 0 if self._coreimage is None: return self._coreimage.anim_delay = value if value < 0: self._coreimage.anim_reset(False) def on_texture(self, instance, value): if value is not None: self.texture_size = list(value.size) def _on_tex_change(self, *largs): # update texture from core image self.texture = self._coreimage.texture ci = self._coreimage if self.anim_loop and ci._anim_index == len(ci._image.textures) - 1: self._loops += 1 if self.anim_loop == self._loops: ci.anim_reset(False) self._loops = 0
[docs] def reload(self): '''Reload image from disk. This facilitates re-loading of images from disk in case the image content changes. .. versionadded:: 1.3.0 Usage:: im = Image(source = '1.jpg') # -- do something -- im.reload() # image will be re-loaded from disk ''' try: self._coreimage.remove_from_cache() except AttributeError: pass oldsource = self.source self.source = '' self.source = oldsource
def on_nocache(self, *args): if self.nocache and self._coreimage: self._coreimage.remove_from_cache() self._coreimage._nocache = True
[docs]class AsyncImage(Image): '''Asynchronous Image class. See the module documentation for more information. .. note:: The AsyncImage is a specialized form of the Image class. You may want to refer to the :mod:`~kivy.loader` documentation and in particular, the :class:`~kivy.loader.ProxyImage` for more detail on how to handle events around asynchronous image loading. ''' __events__ = ('on_error', 'on_load') def __init__(self, **kwargs): self._coreimage = None super(AsyncImage, self).__init__(**kwargs) global Loader if not Loader: from kivy.loader import Loader self.fbind('source', self._load_source) if self.source: self._load_source() self.on_anim_delay(self, kwargs.get('anim_delay', .25)) def _load_source(self, *args): source = self.source if not source: if self._coreimage is not None: self._coreimage.unbind(on_texture=self._on_tex_change) self._coreimage.unbind(on_load=self._on_source_load) self.texture = None self._coreimage = None else: if not self.is_uri(source): source = resource_find(source) self._coreimage = image = Loader.image(source, nocache=self.nocache, mipmap=self.mipmap, anim_delay=self.anim_delay) image.bind(on_load=self._on_source_load) image.bind(on_error=self._on_source_error) image.bind(on_texture=self._on_tex_change) self.texture = image.texture def _on_source_load(self, value): image = self._coreimage.image if not image: return self.texture = image.texture self.dispatch('on_load') def _on_source_error(self, instance, error=None): self.dispatch('on_error', error) def on_error(self, error): pass def on_load(self, *args): pass def is_uri(self, filename): proto = filename.split('://', 1)[0] return proto in ('http', 'https', 'ftp', 'smb') def _on_tex_change(self, *largs): if self._coreimage: self.texture = self._coreimage.texture def texture_update(self, *largs): pass