How does WinRT handle BitmapImage and Image memory

Question

I am new to programming Windows Store Apps with C# and I am trying to understand how image memory is handled. My app is very simple:

1) it references a bitmap from a file using a Windows.UI.Xaml.Media.Imaging.BitmapImage object and then uses that as the Source for a Windows.UI.Xaml.Controls.Image object. In my case the image on disk has larger dimensions than what is being displayed on screen so it is being scaled by the system.

My question is how does WinRT handle the memory for the image? I used the vmmap tool and I see in the Mapped File section there is an entry for my image file. I guess this means that the raw bytes for this file are fully loaded into memory. Since this is a JPG these bytes must be decoded into pixel bytes. It seems from my tests that setting the UriSource of the BitmapImage doesn't actually cause any processing to take place since it takes 0 ms and that instead there is some lazy loading going on.

So the questions are: Which object is dominator of the the uncompressed unscaled pixel data? What object is the dominator for the scaled pixel data that gets drawn on screen? Are there tools that can easily show me this? In the Java world I use the Eclipse memory analyzer tool. I tried using PerfView but the results make no sense to me, it seems the tool was meant for analyzing performance.

UPDATE:

At the BUILD conference the team discussed the Windows Performance Toolkit. I never heard anyone mention PerfView so I believe that WPT is the latest and greatest tool for analyzing memory and performance, here is a link:

http://msdn.microsoft.com/en-us/performance/cc825801.aspx

Answer 1

A short answer is most likely "optimally". Not being a smartass, there are just a lot of different systems out there. One mentioned hardware acceleration, you can also consider number of cores, display memory, disk speed, monitor bit depth and resolution, the list goes on and on.