Optimizing images usage in .NET – part 1

Using image is an integral part of GUI application but I have found very little resources on it's resource consumption and how I can optimize it. The goal of this post is exactly that, in part 1 I will show the performance impact and in part 2 I will propose an optimization.
I'm going to consider only the memory usage as CPU performance is generally insignificant.
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HTML Renderer

I'm very happy to release another update for the project, I believe I'm getting very close to remove the 'Beta' tag from it.
This update has many fixes for complex layout and tables to handle much more complex htmls, better support for style sheet loading (see below), context menu, embedded videos and finally fixing the support for preformatted text!
I have dropped support for 'Bridge' object (see below) which can be a breaking change if used, it quite easy to replace it's use with events as can be seen in the demo application. Hopefully this will be the last version that has breaking changes.
For next version (v1.5) I'm planning to rewrite the object model (CssBox monster) and core parsing engine to significantly improve performance, especially the memory allocations that can pretty bad now for large htmls. Of course I will continue to fix bugs and add support for features as requested by the community.
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Using T4 Templates for caching image resources

In my project I'm doing a lot of native UI rendering1, soon I will blog on why.
Naturally I have many images to render using DrawImage methods, that requires an Image instance.
There are couple of ways to load an image but the best2 and easies option is using a Resource File, just dragging and dropping the images into the resource designer will add the file to the project and generate a nice static property by the name of the file in the static class generated by the name of the resource file.
The problem is that each time image resource property is called a new image instance is created with the requested image, so if the same image is used in multiple places3 it will be loaded multiple times in memory4.
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International keyboard layout handling

In the Outlook add-in project I'm working on there is a feature that if the users enters '@' character in the body of mail editor window a dropdown popup will show with some options.
Because this feature is on Outlook window we implemented the feature by capturing keyboard events1 and waiting for "shift + 2" keycode. We check for "shift + 2" because the captured windows keyboard message contains keycode and not the actual character.
In a beta phase an European client reported that this functionality doesn't work, a quick session with the client revealed he used European keyboard layout, something new to me as I used to US keyboard layout.
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HTML Renderer

I'm happy to release another update to Html Renderer project.
This release is a result of integration of the Html Renderer in actual commercial project with complex html and stylesheet (more than 400 different styles), still not perfect but much closer to WebBrowser control rendering I'm replacing.
My next big step is to add support for images so stay tuned.
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HTML Renderer

This is the first major release of my contribution to the project, the focus of this release is on:
1. Refactor the code for clearer, simpler and more powerful API (work in progress).
2. Improve simple html layout to be more compatible with WinForms WebBrowser control.
3. Add text selection with copy capability.
Following the changes list there is a deeper explanation to some of the changes.
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Setting HTML and plain text formatting to clipboard

Working on adding text selection and copy-paste to HTML Renderer I wanted to add rich text copy capability.
My first thought was to use Clipboard.SetText method with TextDataFormat.Html but to my surprise it just didn’t work. Turning to Google I finally found this post, harder to find than what I expected, that explained what needs to be done.
Apparently when setting html text you need to provide a header with additional information to what fragment of the html you actually want to paste while being able to provide additional styling around it:
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