Category Archives: Universal Windows Platform

Frame Rate counters on by Default for Windows UWP Emulators

Something that I spotted today (mainly because my app got ‘notes’ during its submission to the store) is the frame rate counter that is on by default for UWP apps. These are the small numbers down the right hand side of the screen:

framerate1

Your app will pass if you submit screenshots with these, but they don’t look good and, as I said, you get ‘Notes’.

To remove them, search you project for this line:

this.DebugSettings.EnableFrameRateCounter = true;

And just comment it out. If you need to see it then you can simply re-enable it when you’ve taken the screenshot.

framerate3

Huzaar!

(the app in question can be found Here

Deleting Files in a Storage Folder Using UWP

Just a little helper method that I used in a recent project to delete files, given a particular name, and excluding a provided list of files:

        internal static async Task DeleteTempFiles(ObservableCollection<StorageFile> exceptionFiles, StorageFolder folder, string fileNameStartsWith)
        {
            var files = (await folder.GetFilesAsync())
                .Where(p => p.DisplayName.StartsWith(fileNameStartsWith)
                && !exceptionFiles.Any(e => e.DisplayName == p.DisplayName));            

            foreach(var file in files)
            {
                await file.DeleteAsync(StorageDeleteOption.Default);                
            }
        }

You can call it like this:

	await FileHelper.DeleteTempFiles(Files, KnownFolders.PicturesLibrary, "_tmpFile");

It will delete all files in the Pictures folder starting with _tmpFile, and exclude anything in the Files collection.

InkCanvas

Pointlessly Long Introduction (feel free to skip)

Some time ago, in a previous job, I was asked to add spell checking to a WPF textbox. I did some research as to how to do that, and came to the conclusion that the only way was using MS Word automation. I must have spent a good three or four hours writing code that interrogated Word and performed spell checking. It wasn’t until I got to auto correct that one of my searches threw up a property on the text box: “SpellCheck.IsEnabled”.

(At the time of writing) I recently attended a developer conference, and at it, I was shown a control called InkCanvas! Having recently spent a considerable amount of time trying to use a Canvas for drawing, I felt like I’d just found the SpellCheck.IsEnabled property again.

Using the InkCanvas Control

In comparison to the Canvas, the InkCanvas basically works out of the box. If you use the InkToolbar with it, you’ll get some errors, but they aren’t actually errors; for example:

1>C:\Program Files (x86)\MSBuild\14.0\bin\Microsoft.Common.CurrentVersion.targets(2048,5): warning MSB3781: The SDK “InkToolbarControl, Version=0.3.2” depends on the following SDK(s) “Microsoft.VCLibs, version=14.0”, which have not been added to the project or were not found. Please ensure that you add these dependencies to your project or you may experience runtime issues. You can add dependencies to your project through the Reference Manager.

Here’s the XAML that I used to get it working. Don’t be phased by the fact that x:Bind doesn’t seem to resolve.

            <InkCanvas x:Name="drawInkCanvas">                    
            </InkCanvas>
            <inkTools:InkToolbar TargetInkCanvas="{x:Bind drawInkCanvas}" 
                                PenColor="#FFE61021" 
                                VerticalAlignment="Top" HorizontalAlignment="Right"/>

Enabling Input

I found only one thing that caused confusion, and it took a while to solve. Basically, the above XAML doesn’t allow you to actually draw anything; you need this:

        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            base.OnNavigatedTo(e);

            drawInkCanvas.InkPresenter.InputDeviceTypes =
                Windows.UI.Core.CoreInputDeviceTypes.Mouse |
                Windows.UI.Core.CoreInputDeviceTypes.Pen |
                Windows.UI.Core.CoreInputDeviceTypes.Touch;

        }

Saving the Image

To save what you’ve drawn, you can use something similar to this code:

            if (canvas != null && canvas.InkPresenter.StrokeContainer.GetStrokes().Count > 0)
            {
                if (file != null)
                {
                    using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
                    {
                        await canvas.InkPresenter.StrokeContainer.SaveAsync(stream);
                    }
                }
                Clear(canvas);
            }