I’ve just released Catfood Earth for Android. It’s my second app created with Xamarin’s excellent toolkit. Being able to develop in C# allowed me to reuse a lot of code from the Windows version of Catfood Earth. The Android version doesn’t include all the same layers (yet) but it’s got the main ones – daytime (twelve different satellite images included, based on NASA’s Blue Marble Next Generation but with some special processing to make them look better), nighttime (city lights, shaded to show nighttime and the terminator between day and night) and a clouds layer that is downloaded every three hours.
My main worry had been that this would suck the phone battery dry, but after a fair amount of optimization it doesn’t even register on the battery consumption list. Grab it now from Google Play ($3.99, Android 2.2 or better).
Here’s how to share a picture to Facebook, Twitter and so forth from MonoDroid:
A fun mix of Java and C#. The directory got me to start with so check to see if the ExternalCacheDir is available and if not fall back to the internal CacheDir. Frustratingly Facebook doesn’t pick up on the text associated with an image regardless of the intent ExtraWhatever specified.
I’ve just released a WebCam app for Android. It’s based on WebCamSaver but allows you to control the webcam – you tap the edges of the screen to pan, pinch to zoom in and out. A fun little time waster.
This is the first app I’ve released using Xamarin’s MonoDroid framework. This integrates nicely into Visual Studio and allows you to program an Android app in C#. This is fantastic for productivity and code reuse and I enjoyed the process a lot more than previous work I’ve done in Java / Eclipse. The main drawback is that the framework adds around 5MB (significant for mobile) and the documentation isn’t always the best, especially when you search for something and find out you’ve been dumped into iOS reference material. Digging around the sample code and cross-referencing the official Android documentation helps a lot. I’m going to take a stab at something a little more ambitious next…
I’ve just released a small update to Catfood.Shapefile. Stephan Stapel, who implemented PolyLineM support, has contributed a patch that improves the class hierarchy. CodePlex user originSH suggested supporting the ACE driver for 64-bit systems. I’ve added a constructor overload that allows you to use predefined Jet and ACE connection strings or provide your own templates if necessary. Thanks to Stephan and originSH.
Catfood.Shapefile is a .NET library for enumerating ESRI shapefiles. I originally wrote the library to help me build some complex layers in Catfood Earth. Since then it’s picked up thousands of users and some really valuable suggestions and patches from the CodePlex community. I’m very glad a took a couple of hours to open source the library back in 2009.
I’ve just moved ITHCWY comments over to Disqus. BlogEngine.NET now supports Disqus out of the box, but doesn’t export comments to anything that Disqus is willing to eat. I’ve knocked up a quick converter that takes a full BlogML export from BlogEngine.NET (and at least in theory any other source of BlogML) and converts the comments to WXR. You can import the WXR file under the Generic option in Disqus.
The tool is a Windows console application that takes two parameters, the BlogML import file and the WXR output, i.e.:
BlogMLtoDisqus.exe C:\BlogML.xml C:\ForDisqus.wxr
It isn’t fancy and there is no error checking so it will either work or die horribly. If the latter, leave a comment and I’ll try to fix it for you.
Here are two scenarios where merged ResourceDictionary objects are the way forward.
I’m working on a WPF project that needs to be single instance. Heaven forbid that the WPF team should pollute the purity of their framework with support for this kind of thing (or NotifyIcon support but that’s another story) so I’m using the code recommended by Arik Poznanski: WPF Single Instance Application. I like this because it both enforces a single instance and provides an interface that reports the command line passed to any attempt to launch another instance.
An issue with using this code is that you need to write a Main function and so App.xaml is set to Page instead of Application Definition. Once you’ve done this the program works fine but the Visual Studio designer fails to load resources in UserControls (and in Windows containing those UserControls).
The fix is to factor all of the application level resources out into a separate ResourceDictionary (i.e. MergedResources.xaml). Once you’ve done this merge the new ResourceDictionary into App.xaml as follows:
Next, in each Window or UserControl reference the same ResourceDictionary:
The designer will now be able to find the correct resources for each UserControl and Window.
The second scenario is factoring resources and other Xaml into a DLL. To pull resources in from a referenced assembly you just need to use a Pack Uri when merging in the remote ResourceDictionary:
If you’re putting Windows and UserControls in the DLL use exactly the same approach to reference the resources using ResourceDictionary.MergedDictionaries and you’ll get designer support for these as well.
WPF: When it's good it’s very, very good and when it’s bad it’s like sautéing your own eyeballs.
When you’re about to launch a process that will trigger an elevation prompt it’s polite to decorate it with the little UAC shield so the user knows what to expect. Of course there’s no such capability in WPF, and WPF controls have no handles so you can’t use SendMessage / BCM_SETSHIELD as with Windows Forms.
System.Drawing.SystemIcons.Shield seems promising, but it returns the wrong icon on Windows 7 (at least in .NET 4).
SHGetStockIconInfo will allow you to get the correct icon, but isn’t supported on Windows XP. I’ve just added the necessary interop signatures for SHGetStockIconInfo to pinvoke.net so I won’t duplicate that code here. Once you have the interop you can get the correct icon as a BitmapSource using the following code:
I've written an extension for BlogEngine.NET that automatically adds several different geographical tags to blog posts. I knocked this up for my Hikes blog. It might be useful for any blog where some of the posts are related to a real world location.
To get started download GeotagFromKML.zip (2.24 kb) and copy GeotagFromKML.cs to the App_Code\Extensions folder in your BlogEngine.NET instance.
The extension does two things. Firstly it looks for a link to a KML file when post is added or updated (it does this because each of my hike posts includes a Google Earth KML file for the hike). If a KML link is found then a paragraph is added to the post containing the longitude and latitude of the first coordinate in the KML file. The paragraph uses the Geo microformat. You can customize the text in settings for the extension. You can also regenerate by deleting the paragraph and saving the post.
The second function is to add ICBM and Geo Tag META tags when serving a post that contains the geotagged coordinates. You can take advantage of this without linking to a KML file, just include a location like this in your post:
Once you have geotagging up and running you might also want to add GeoURL to the list of ping services for your site.
Here's a frustrating WPF scenario — you use the ApplicationCommands class to add Cut, Copy and Paste commands to toolbar and then put a TextBox on another toolbar. Click in the TextBox and the commands remain disabled. WTF, WPF?
The problem is with focus scopes. Your window is a focus scope and so are any menus or toolbars. This has the desirable property of allowing commands to target the control you were in immediately before invoking the command. You want paste to target the text box you're editing, not the menu item or button you clicked to request the paste.
So far so good. The problem is that the commanding system isn't smart enough to target the control with keyboard focus if it's in a nested focus scope. Remember that the window itself is a focus scope so our TextBox in a ToolBar (also a focus scope) is nested and immune to commands from our menu or toolbar.
Here's a simple window that demonstrates the problem:
Ignore the PreviewCanExecute handler for now. If you run this window and click in the main TextBox the paste button and menu item are enabled. Click in the toolbar TextBox and pasting isn't an option. Well, Ctrl-V still works and there's a context menu but you know what I mean.
The problem can be fixed by adding a command binding for ApplicationCommands.Paste and handling the PreviewCanExecute event:
When the window loads we're making note of the focus scopes for the toolbar and menu. Then when PreviewCanExecute fires we check to see if the element with the keyboard focus is in a different focus scope (and also that the window doesn't have keyboard focus). We then set the CommandTarget for the menu item and button to the element that has keyboard focus.
A handler isn't required for CanExecute as the command will take care of this with respect to the new CommandTarget.
Run the window again and you'll see that the paste button is enabled for both of the TextBox controls. When you click the button (or menu item) our PreviewCanExecute handler ignores the new keyboard focus and the command is sent to the desired control.
One drawback of this approach is that keyboard focus isn't returned to the TextBox after the command executes. The CommandTarget remains in place so you can keep pasting and the command remains enabled but you lose the visual cue that lets you know where the target is. I haven't figured out a clean approach to this yet. When I do, I'll update this post. Better yet, if you've figured it out leave a comment.
I'm slowly converting a number of blogs from Blogger to BlogEngine.NET. The least fun part is dealing with the Blogger export file. For this blog I used a Powershell script but had problems with comments not exporting correctly and it was quite painful to fix everything up. Blogger allows you to export a copy of your blog using ATOM, however BlogEngine.NET (and other tools) speak BlogML.
I've just released a command line tool that takes the ATOM format Blogger export and converts it to BlogML. You can download Blogger2BlogML from GitHub. The tool uses .NET 4.0 (client profile) so you'll need to install this if you don't already have it. If you give Blogger2BlogML a try let me know how you get on.