How can I stream to a wxImage?

Nintendofreak88 · Post by **Nintendofreak88** » Mon May 09, 2005 9:51 pm

I've looked at the image example and it shows streaming, but here's my problem. I'd like to do the stream reading into the wxImage myself because I want to have a progress bar (for loading very large images) and a cancel button while loading. When I pass a wxFileInputStream to wxImage::Load, it loads the thing by itself, and I have no time to display the progrmess bar, etc. Any ideas on how I might go about this? Is there soem way I can manually stream into a wxImage or wxBitmap? Thanks.

travfar · Post by **travfar** » Mon May 09, 2005 10:44 pm

You could try writing your own wxImageHandler but I have no idea how.

Nintendofreak88 · Post by **Nintendofreak88** » Mon May 09, 2005 11:28 pm

Well isn't there a way wxWidgets has built in to do that...? I've only been using it for a few months, and I probably couldn't write one even if I tried...

eco · Post by **eco** » Tue May 10, 2005 1:10 am

You might be able to derive a new class from wxFileInputStream and update the progress bar from there. It probably wouldn't cover the time needed to decompress the image but at least you'd get the file load progress.

Nintendofreak88 · Post by **Nintendofreak88** » Tue May 10, 2005 1:39 am

So should I overload the wxInputStream::Read method or the wxStreamBase::OnSysRead method? Also if I were to overload it how could i call the wxFileInputStream's version of the method from my new method?

eco · Post by **eco** » Tue May 10, 2005 6:41 am

I'm not sure, I've never done it. Has anyone on the board derived from wxFileInputStream and would like to share their insight?

Post by **upCASE** » Tue May 10, 2005 6:56 am

Hi!

Nintendofreak88 wrote:So should I overload the wxInputStream::Read method or the wxStreamBase::OnSysRead method? Also if I were to overload it how could i call the wxFileInputStream's version of the method from my new method?

I just had a look at the code and I'd say that you should overload the wxStreamBase::OnSysRead() method as it is declared as a pure virtual function for wxInputStream and gets called by wxInputStream::Read() internaly.
As for the second question: Call the "normal" version of the methods with a wxFileInputStream:: prefix. So for calling wxFileInputStreams Ok() method use wxFileInputStream::Ok().

Nintendofreak88 · Post by **Nintendofreak88** » Tue May 10, 2005 12:07 pm

That worked perfectly! Thanks everyone!