On 08/07/2010 12:28, Jan-Philip Gehrcke wrote:
Thanks for your comment, Michael.
I found the explanation in the docs:
http://msdn.microsoft.com/en-us/library/ms619201(v=VS.95).aspx
The default setting is `BitmapCreateOptions.DelayCreation`
-> "Causes a BitmapSource object to delay initialization until it is
necessary. This is useful when dealing with collections of images.
This is the default value of the BitmapImage.CreateOptions property in
Silverlight."
Now, I change this to `BitmapCreateOptions.None` and add the callbacks
before assigning the URI:
Great - glad you got it sorted.
Michael
def load_and_show(self):
self.bi = BitmapImage()
self.bi.CreateOptions = BitmapCreateOptions.None;
self.bi.ImageOpened += self.successfully_loaded_now_show
self.bi.ImageFailed += self.load_failed
self.bi.UriSource = Uri(self.abspath, UriKind.Absolute)
def successfully_loaded_now_show(self, s, e):
self.xaml_main_image.Source = self.bi
This works as expected.
Jan-Philip
On 07.07.2010 18:49, Michael Foord wrote:
On 06/07/2010 15:59, Jan-Philip Gehrcke wrote:
Hello,
I don't know if this is more an IronPython (2.6.1) issue than a
Silverlight (4) issue, but I hope that I am talking to the right
audience again (thank you for the great answers last time).
I've created an `Image` class managing images based on
System.Windows.Media.Imaging.BitmapImage. My method
`image_instance.load_and_show()` should load the image from a given
URI and then show it in an XAML <image /> element. The important
thing is that the showing part should only happen after it is sure
that the image has loaded correctly. To control this, I use the
BitmapImage.ImageOpened event. This is the relevant part of the code
from my `Image` class:
def load_and_show(self):
self.bi = BitmapImage(Uri(self.abspath, UriKind.Absolute))
self.bi.ImageOpened += self.successfully_loaded_now_show
self.bi.ImageFailed += self.load_failed
#self.xaml_main_image.Source = self.bi # LINE A
def successfully_loaded_now_show(self, s, e):
debug("image loaded: %s" % s.UriSource) # LINE B
self.xaml_main_image.Source = self.bi # LINE C
def load_failed(self, s, e):
debug("image load failed") # LINE D
If the code is like shown above and I do
`image_instance.show_and_load()`, nothing happens. More exactly,
LINE B, C, and D are not reached. It is like *neither the event
ImageOpened nor ImageFailed is toggled*.
It seems likely then that the image is not opened or downloaded until
you set it as the source on an image. Does the code behave
differently if you write it in C#?
If you set the bitmapimage as the image source does the event then
fire correctly? If so perhaps create the image control but only add
it to the visual tree once the bitmap has loaded.
Michael
If I re-activate (or un-outcomment =)) LINE A, the callbacks
magically work properly, i.e. after calling
`image_instance.show_and_load()` the image shows up in the UI
(either via LINE A or C), and LINE B is definitely reached (or LINE
D in case of a wrong URI).
The point is that I don't want LINE A, because showing the image
should happen in a more controlled manner. What's the problem in my
approach, why are the callbacks not called?
Thank you in advance,
Jan-Philip Gehrcke
--
http://gehrcke.de
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