Comments on: WriteableBitmap pixel format in Silverlight 3

By: agaace

agaace — Sat, 19 Sep 2009 20:14:53 +0000

Thank you so so much for saving my life! I spent last 2 hours wondering what I was doing wrong, because I was SURE it was using ARGB (otherwise it would be explained in samples or in the doc, right?).

By: Bill Bartmann

Bill Bartmann — Thu, 03 Sep 2009 17:37:55 +0000

Excellent site, keep up the good work

By: Conker

Conker — Tue, 21 Jul 2009 17:59:18 +0000

Found it on other forum, when researching bad performance :

do not use WriteableBitmap.PixelWidth/PixelHeight property in pixel rendering cycle, it cost too much time.

// set _pwidth=bitmap.PixelWidth in constructor
public void SetPixel(int x, int y, int color)
{
var index = (_pwidth * (y – 1)) + x;
frontBuffer[index] = color;
}

Mog Liang
Microsoft Online Community Support

By: Rene

Rene — Fri, 17 Jul 2009 08:30:38 +0000

I used Bill’s methods, optimized them a bit and packed them into a static class as extension methods, which is downloadable here http://kodierer.blogspot.com/2009/07/writeablebitmap-extension-methods.html
You can also find a code snippet on how to use it there.

By: Ben

Ben — Fri, 17 Jul 2009 05:13:49 +0000

Neat article! Just one thing: maybe I’m too old school, those divisions look scary to me. Perhaps we can have one “alpha / 255d” instead of three (though I’m not too sure if that is going to make any difference in 2009)…

Regards,
Ben.

By: Bill Reiss

Bill Reiss — Thu, 16 Jul 2009 20:07:33 +0000

Fallon,

Thanks yeah I guess I should have tested the code, I usually do but didn’t this time. The samples have been updated based on your suggestion.

Bill

By: Fallon Massey

Fallon Massey — Thu, 16 Jul 2009 18:53:53 +0000

You probably should change:

void SetPixel(WriteableBitmap b, int row, int col, byte alpha,
byte r, byte g, byte b)

to:

void SetPixel(WriteableBitmap bm, int row, int col, byte alpha,
byte r, byte g, byte b)

Otherwise, THANKS!!!

By: DotNetShoutout

DotNetShoutout — Thu, 16 Jul 2009 07:08:26 +0000

WriteableBitmap pixel format in Silverlight 3 | Silverlight Games 101…

Thank you for submitting this cool story – Trackback from DotNetShoutout…

By: Rene

Rene — Thu, 16 Jul 2009 06:15:52 +0000

Thanks for sharing this great info.

By: Daniel Vogt

Daniel Vogt — Thu, 16 Jul 2009 05:41:41 +0000

Thanks for sharing this finding. I think I can use it for making the background black-and-white while showing a child window.