C# : Properties and Serialization

Protected by mikecogh, on Flickr
Protected, a photo by mikecogh on Flickr.

Does your app serialize (on IS or for wire-travelling) model entities to JSON/XML? Did you come across a scenario where you want to ensure that a property is, though serialize-able but should not be settable from the code? For example ID property. Your model class creates this ID internally and it also gets serialized. For it being serialize-able, it is required that the properly is public, but then you expose it to other parts of code as well and make it vulnerable for accidental edits. EditorBrowsableAttribute is not the solution here because of two reasons; one it does not work with the code inside your project, second if it did work, it’s still only hiding from IntelliSense and not stopping you from setting the property in code.
I tackle this scenario in my Nokia Lumia app by having a super-class PersistentEntity and then derive all model classes from PersistentEntity class.
ClassDiagram
PersistentEntity has two properties related to serialization – WriteState and ReadState which are of PersistencyStates enumeration type. PersistencyStates enum has following members – None, WritePending, Queued (because all serialization takes place on BG thread), Writing, Written, Read, and Reading. In case of serializing an entity, as soon as any changes made to the object, the object goes in WritePending, and from there it changes state from Queued to Writing, to Written state. Every other property in derived class which needs to be exposed for serialization only, ensures that in setter sets the value SavingState is “Saving”. If it is not, throw an invalid operation exception with proper message. Let’s have a look at the code.

PersistencyStates enumerator:

    public enum PersistencyStates
    {
        None, WritePending, Queued, Writing, Written, Reading, Read
    }

This is the super class PersistentEntity:

   public class PersistentEntity : ISerializable
    {
        [NonSerialized] //for Silverlight this is IgnoreDataMember attribute
        public PersistencyStates WriteState { get; private set; }
        [NonSerialized] //for Silverlight this is IgnoreDataMember attribute
        public PersistencyStates ReadState { get; private set; }

        #region serialization related methods
        [OnDeserializing]
        public void OnDeSerializingEntity(StreamingContext context)
        {
            this.WriteState = PersistencyStates.Writing;
        }
        [OnDeserialized]
        public void OnDeSerializedEntity(StreamingContext context)
        {
            this.WriteState = PersistencyStates.Written;
            //do something else if required
            this.WriteState = PersistencyStates.None;
        }
        [OnSerializing]
        public void OnSerializingEntity(StreamingContext context)
        {
            this.ReadState = PersistencyStates.Reading;
        }
        [OnSerialized]
        public void OnSerializedEntity(StreamingContext context)
        {
            this.ReadState = PersistencyStates.Read;
        }
        #endregion //serialization related methods


        public void GetObjectData(SerializationInfo info, StreamingContext context)
        {
            //do nothing;
        }
    }

This is the derived class TestEntity have a property ID which is ensured to update only while serialization:

   class TestEntity : PersistentEntity
    {
        private Guid _id = Guid.NewGuid();
        public Guid ID 
        {
            get 
            {
                return _id;
            }
            set
            {
                if (this.WriteState == PersistencyStates.Writing)
                {
                    _id = value;
                }
                else
                {
                    throw new InvalidOperationException("Cannot set ID from outside", new Exception("MyCompany.MVVM.Model.TestEntity.ID has public setter for the purpose of serialization only. Not designed to be set from outside of the class."))
                }
            }
        }
    }

I hope I could make the intent and implementation clear.

C# Extension: Random Pastel Colors

C# Extension: Random Pastel Colors

In last post we wrote extension method to get complementary color of a given color. In this post we will write some more extension methods to get colors. Co-incidentally India is totally covered in colors because this is the Holi week.
If you want to have a dynamic feel to your app (or some part of your app) you could fill it with random colors. Let’s write following extension methods which return random color with parameterized control over what type of color output you need:

  • Color.GetRandom – This method returns a random color.
  • Color.GetRandom(Brightness Control) – This method returns a random color between given brightness.
  • Color.GetRandomShade – This returns a random color of the Color’s shade.
  • Color.GetRandomShade(Brightness Control) – It returns a random color of given color between given brightness.
  • Color.GetPastelShade() – Returns a pastel shade of given color.

Let’s code.
We will utilize the same code from our last post and extend the ColorExtensions class. To implement aforesaid methods, add following code to the said class

        static Random randomizer = new Random();
        /// <summary>
        /// Returns a pastel shade of the color
        /// </summary>
        /// <param name="source">Source  color</param>
        /// <returns></returns>
        public static Color GetPastelShade(this Color source)
        {
            return (generateColor(source, true, new HSB { H = 0, S = 0.2d, B = 255 }, new HSB { H = 360, S = 0.5d, B = 255 }));
        }
        /// <summary>
        /// Returns a random color
        /// </summary>
        /// <param name="source">Ignored(Use RandomShade to get a shade of given color)</param>
        /// <returns></returns>
        public static Color GetRandom(this Color source)
        {
            return (generateColor(source, false, new HSB { H = 0, S = 0, B = 0 }, new HSB { H = 360, S = 1, B = 255 }));
        }
        /// <summary>
        /// Returns a random color within a brightness boundry
        /// </summary>
        /// <param name="source">Ignored (Use GetRandomShade to get a random shade of the color)</param>
        /// <param name="minBrightness">A valued from 0.0 to 1.0, 0 is darkest and 1 is lightest</param>
        /// <param name="minBrightness">A valued from 0.0 to 1.0</param>
        /// <returns></returns>
        public static Color GetRandom(this Color source, double minBrightness, double maxBrightness)
        {
            if (minBrightness >= 0 && maxBrightness <= 1)
            {
                return (generateColor(source, false, new HSB { H = 0, S = 1 * minBrightness, B = 255 }, new HSB { H = 360, S = 1 * maxBrightness, B = 255 }));
            }
            else
            {
                throw new ArgumentOutOfRangeException();
            }
        }
        /// <summary>
        /// Returns a random shade of the color
        /// </summary>
        /// <param name="source">Base color for the returned shade</param>
        /// <returns></returns>
        public static Color GetRandomShade(this Color source)
        {
            return (generateColor(source, true, new HSB { H = 0, S = 1, B = 0 }, new HSB { H = 360, S = 1, B = 255 }));
        }
        /// <summary>
        /// Returns a random color within a brightness boundry
        /// </summary>
        /// <param name="source">Base color for the returned shade</param>
        /// <param name="minBrightness">A valued from 0.0 to 1.0, 0 is brightest and 1 is lightest</param>
        /// <param name="minBrightness">A valued from 0.0 to 1.0</param>
        /// <returns></returns>
        public static Color GetRandomShade(this Color source, double minBrightness, double maxBrightness)
        {
            if (minBrightness >= 0 && maxBrightness <= 1)
            {
            return (generateColor(source, true, new HSB { H = 0, S = 1 * minBrightness, B = 255 }, new HSB { H = 360, S = 1 * maxBrightness, B = 255 }));
            }
            else
            {
                throw new ArgumentOutOfRangeException();
            }
        }
        /// <summary>
        /// Process parameters and returns a color
        /// </summary>
        /// <param name="source">Color source</param>
        /// <param name="isaShadeOfSource">Should source be used to generate the new color</param>
        /// <param name="min">Minimum range for HSB</param>
        /// <param name="max">Maximum range for HSB</param>
        /// <returns></returns>
        private static Color generateColor(Color source, bool isaShadeOfSource, HSB min, HSB max)
        {
            HSB hsbValues = ConvertToHSB(new RGB { R = source.R, G = source.G, B = source.B });
            double h_double = randomizer.NextDouble();
            double s_double = randomizer.NextDouble();
            double b_double = randomizer.NextDouble();
            if (max.B - min.B == 0) b_double = 0; //do not change Brightness
            if(isaShadeOfSource)
            {
                min.H = hsbValues.H;
                max.H = hsbValues.H;
                h_double = 0;
            }
            hsbValues = new HSB
            {
                H = Convert.ToDouble(randomizer.Next(Convert.ToInt32(min.H), Convert.ToInt32(max.H))) + h_double,
                S = Convert.ToDouble((randomizer.Next(Convert.ToInt32(min.S * 100), Convert.ToInt32(max.S * 100)))/100d),
                B = Convert.ToDouble(randomizer.Next(Convert.ToInt32(min.B), Convert.ToInt32(max.B))) + b_double
            };
            Debug.WriteLine("H:{0} | S:{1} | B:{2} [Min_S:{3} | Max_S{4}]", hsbValues.H,_hsbValues.S,_hsbValues.B, min.S, max.S) ;
            RGB rgbvalues = ConvertToRGB(_hsbValues);
            return new Color { A = source.A, R = (byte)_rgbvalues.R, G = (byte)_rgbvalues.G, B = (byte)_rgbvalues.B };
        }

You could call these methods like so:

Color randomPurplishPastel = Colors.Purple.GetPastelShade();

Here is an example :

My app uses random colors pretty extensively:

Avirall Time Suite | Nokia Lumia 1520

Holi hai!!!

C# Extension: Complementary Color

C# Extension: Complementary Color

In the image above blue & orange are complementary colors, green and red are complementary colors, purple and yellow are complementary colors, etc. The formula is; two colors, placed exactly opposite to each other on color wheel are complementary. You use complementary color combination to highlight a particular item in your design. For example, if most part of your screen has blue color, for important elements on the screen you would choose orange color. Photographers and painters know about importance of complementary color in making their paintings and photographs beautiful:

Complementary Colors by OneEighteen, on Flickr
Complementary Colors, a photo by OneEighteen on Flickr.

In case your app design is dynamic which gives control to the user to choose a dominant color in your app, e.g. background color, you would want to know the contrast color of the chosen color on-the-fly. Particularly in Windows Phone apps, if you incorporate user selected accent color in app design, for some important elements you might need contrast color. For example, in following screenshot of my app, the accent color on the phone is magenta and the color of the hands, auto generated in code, is green.

QSQIn1020Small

This extension method of Color class returns the contrast color:
(HSB and RGB conversion code courtesy, Yi-Lun Luo)

namespace MyCompany.AwesomeExtensions.MediaHelpers
{
    public static class ColorExtensions
    {
        static Random randomizer = new Random();
        public static Color GetContrast(this Color source, bool preserveOpacity)
        {
            Color inputColor = source;
            //if RGB values are close to each other by a diff less than 10%, then if RGB values are lighter side, decrease the blue by 50% (eventually it will increase in conversion below), if RBB values are on darker side, decrease yellow by about 50% (it will increase in conversion)
            byte avgColorValue = (byte)((source.R + source.G + source.B) / 3);
            int diff_r = Math.Abs(source.R - avgColorValue);
            int diff_g = Math.Abs(source.G - avgColorValue);
            int diff_b = Math.Abs(source.B - avgColorValue);
            if (diff_r < 20 && diff_g < 20 && diff_b < 20) //The color is a shade of gray
            {
                if (avgColorValue < 123) //color is dark
                {
                    inputColor.B = 220;
                    inputColor.G = 230;
                    inputColor.R = 50;
                }
                else
                {
                    inputColor.R = 255;
                    inputColor.G = 255;
                    inputColor.B = 50;
                }
            }
            byte sourceAlphaValue = source.A;
            if (!preserveOpacity)
            {
                sourceAlphaValue = Math.Max(source.A, (byte)127); //We don't want contrast color to be more than 50% transparent ever.
            }
            RGB rgb = new RGB { R = inputColor.R, G = inputColor.G, B = inputColor.B };
            HSB hsb = ConvertToHSB(_rgb);
            hsb.H = hsb.H < 180 ! hsb.H + 180 : hsb.H - 180;
            //hsb.B = isColorDark ? 240 : 50; //Added to create dark on light, and light on dark
            rgb = ConvertToRGB(_hsb);
            return new Color { A = sourceAlphaValue, R = rgb.R, G = (byte)rgb.G, B = (byte)rgb.B };
        }
        internal static RGB ConvertToRGB(HSB hsb)
        {
            // By: <a href="http://blogs.msdn.com/b/codefx/archive/2012/02/09/create-a-color-picker-for-windows-phone.aspx" title="MSDN" target="_blank">Yi-Lun Luo</a>
            double chroma = hsb.S * hsb.B;
            double hue2 = hsb.H / 60;
            double x = chroma * (1 - Math.Abs(hue2 % 2 - 1));
            double r1 = 0d;
            double g1 = 0d;
            double b1 = 0d;
            if (hue2 >= 0 && hue2 < 1)
            {
                r1 = chroma;
                g1 = x;
            }
            else if (hue2 >= 1 && hue2 < 2)
            {
                r1 = x;
                g1 = chroma;
            }
            else if (hue2 >= 2 && hue2 < 3)
            {
                g1 = chroma;
                b1 = x;
            }
            else if (hue2 >= 3 && hue2 < 4)
            {
                g1 = x;
                b1 = chroma;
            }
            else if (hue2 >= 4 && hue2 < 5)
            {
                r1 = x;
                b1 = chroma;
            }
            else if (hue2 >= 5 && hue2 <= 6)
            {
                r1 = chroma;
                b1 = x;
            }
            double m = hsb.B - chroma;
            return new RGB()
            {
                R = r1 + m,
                G = g1 + m,
                B = b1 + m
            };
        }
        internal static HSB ConvertToHSB(RGB rgb)
        {
           // By: <a href="http://blogs.msdn.com/b/codefx/archive/2012/02/09/create-a-color-picker-for-windows-phone.aspx" title="MSDN" target="_blank">Yi-Lun Luo</a>
            double r = rgb.R;
            double g = rgb.G;
            double b = rgb.B;

            double max = Max(r, g, b);
            double min = Min(r, g, b);
            double chroma = max - min;
            double hue2 = 0d;
            if (chroma != 0)
            {
                if (max == r)
                {
                    hue2 = (g - b) / chroma;
                }
                else if (max == g)
                {
                    hue2 = (b - r) / chroma + 2;
                }
                else
                {
                    hue2 = (r - g) / chroma + 4;
                }
            }
            double hue = hue2 * 60;
            if (hue < 0)
            {
                hue += 360;
            }
            double brightness = max;
            double saturation = 0;
            if (chroma != 0)
            {
                saturation = chroma / brightness;
            }
            return new HSB()
            {
                H = hue,
                S = saturation,
                B = brightness
            };
        }
        private static double Max(double d1, double d2, double d3)
        {
            if (d1 > d2)
            {
                return Math.Max(d1, d3);
            }
            return Math.Max(d2, d3);
        }
        private static double Min(double d1, double d2, double d3)
        {
            if (d1 < d2)
            {
                return Math.Min(d1, d3);
            }
            return Math.Min(d2, d3);
        }
        internal struct RGB
        {
            internal double R;
            internal double G;
            internal double B;
        }
        internal struct HSB
        {
            internal double H;
            internal double S;
            internal double B;
        }
    }
}

Get working code from my GitHub repository (POCs).

XAML|C# Step By Step : UserControl – Wait Spinner

Waiting by moonux, on Flickr
Waiting, a photo by moonux on Flickr.

Something is cooking in the background? Do not forget to inform your user. A modern, flat, light weight, wait spinner is an animated and prominent way to inform user about running background processes (you would not have long running processes on the UI thread, right? See how to effectively free up UI). You would choose to show this control in that area of the screen to which the information, related to which the BG work is taking place – loading/processing etc, belongs. You may have multiple information points on screen for which background work is running.

For this step-by-step we will create this example:

A practical example of implementation of this spinner is this panorama app there are two wait spinners being used, one in Quick Stopwatch pano, and other in Recent pano. When data related to Quick stopwatch is loading, the wait spinner shows beside the title “Quick”, and when data related to Recent is loading, the wait spinner shows near the pano title “Recent”. This way user is informed about which section of the app is doing something in the background.

WaitSpinnerExample

Don’t have this app on your Windows Phone? Visit here

Let’s go through step-by-step of creating a WaitSpinner UserControl and using it in a page.

Step 1 : Create Solution and Project

  1. Create a project in VS with the name “WaitSpinner”. The solution gets created automatically.
  2. Right click on the solution in Solution Explorer, and choose “Add”>”New Project”.
  3. Select Class Library type project and name it “XAMLControls”.

Step 2 : Create UserControl

  1. Right click on XAMLControls and select “Add”>”New item”.
  2. Choose User Control and name it “UCWaitSpinner”.
  3. A new UCWaitSpinner.xaml and its code behind is created.

Step 3 : Open in Blend

Right click on UCWaitSpinner.xaml and choose to open in Blend. Depending on the version of Visual Studio the view you get might be a little different, but most of the UI will be similar. You will get something like this:
01_OpenUCInBlend

Step 4 : Change the type of Layout control

Change the type of Layout from Grid to ViewBox.
02_ChangeLayoutType

Step 5 : Add a new Grid to Layout ViewBox

  1. Choose Grid from control and right click and drag in XAML design view area.
  2. Update Layout properties; Height and Width to 50, HorizontalAlignment and VerticalAlignment to Stretch.

03_AddGridToLayoutRoot

Step 6 : Add Outer border

  1. Choose Ellipse tool from Toolbox and create a circle in the design area. Don’t worry about size and fill at this point.
  2. Make sure Ellipse is selected.
  3. In Properties.Brushes;
    • Set Fill to “No Brush”.
    • Set Stroke to “PhoneForegroundBrush”.
  4. In Layout section;
    • Set HorizontalAlignment to stretch.
    • Set VerticalAlignment to stretch.
    • Set all margins to 0.

04_CreateACircle

Step 7 : Add axis for hands

  1. Choose Ellipse tool from Toolbox again and create a circle in the middle of XAML design. Don’t bother about size at this point.
  2. Make sure this ellipse is selected.
  3. In Properties.Brushes;
    • Set Fill to “PhoneForegroundBrush”.
    • Set Stroke to “No Brush”.
  4. In Layout section;
    • Set Width and Height to 5.
    • Set HorizontalAlignment to center.
    • Set VerticalAlignment to center.
    • Set all margins to 0.

05_CreateAxisForHands

Step 8 : Add minute and hour hands

  1. Choose Rectangle tool from Toolbox and create a rectangle in the design area. Don’t worry about size and placement at this point.
  2. Rename the [Rectangle] to “MinuteHand”.
  3. Make sure you have MinuteHand selected.
  4. In Properties.Brushes;
    • Set Fill to “PhoneForegroundBrush”.
    • Set Stroke to “No Brush”.
  5. In Layout section;
    • Set Width to 2 and Height to 20.
    • Set HorizontalAlignment to Center.
    • Set VerticalAlignment to Bottom.
    • Set Bottom margin to 25 and all others to 0.
  6. In Properties.Transform;
    • Select Center Point tab.
    • Set X to 0.5.
    • Set Y to 1.
  7. Copy and paste “MinuteHand” control and name it “HourHand”. Keep everything same and change only the Properties.Layout.Height to 13.

06_CreateMinuteHand

Step 9 : Create Storyboard for moving hands

  1. In Objects and Timeline, click on “+” sign to add a new storyboard.
  2. Name the storyboard as “MoveHands”.

07_CreateStoryBoard

Step 10 : Create animation for minute hand

  1. In timeline window slide the marker to 3 second.
  2. Select MinuteHand control.
  3. In Properties.Transform select Rotate tab and set Angle property to 1440.

07b_CreateStoryBoard

Step 11 : Create animation for hour hand

  1. Select HourHand control.
  2. In Properties.Transform select Rotate tab and set Angle property to 360.
  3. c. In timeline windows click on play button to see hands are rotating properly (Hour hand completes 1 rotation and minute hand completes 4 rotations in 3 seconds).

07c_CreateStoryBoard

Step 11B : Follow me on Twitter 😀

Step 12 : Review XAML code

Close Blend and go back to XAML view of UCWaitSpinner in VS. You should see following XAML code:

<UserControl x:Class="XAMLControls.UCWaitSpinner"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    d:DesignHeight="480" d:DesignWidth="480">
	<UserControl.Resources>
		<Storyboard x:Name="MoveHands">
			<DoubleAnimation Duration="0:0:3" To="360" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.Rotation)" Storyboard.TargetName="HourHand" d:IsOptimized="True"/>
			<DoubleAnimation Duration="0:0:3" To="1440" Storyboard.TargetProperty="(UIElement.RenderTransform).(CompositeTransform.Rotation)" Storyboard.TargetName="MinuteHand" d:IsOptimized="True"/>
		</Storyboard>
    </UserControl.Resources>

    <Viewbox x:Name="LayoutRoot">
    	<Grid Width="50" Height="50">
    		<Ellipse Margin="0">
    			<Ellipse.Stroke>
    				<SolidColorBrush Color="{StaticResource PhoneForegroundColor}"/>
    			</Ellipse.Stroke>
    		</Ellipse>
    		<Ellipse Margin="0" Width="4" Height="4" HorizontalAlignment="Center" VerticalAlignment="Center">
    			<Ellipse.Fill>
    				<SolidColorBrush Color="{StaticResource PhoneForegroundColor}"/>
    			</Ellipse.Fill>
    		</Ellipse>
    		<Rectangle x:Name="MinuteHand" Height="20" Margin="0,0,0,25" Width="2" StrokeThickness="0" HorizontalAlignment="Center" VerticalAlignment="Bottom" RenderTransformOrigin="0.5,1">
    			<Rectangle.RenderTransform>
    				<CompositeTransform/>
    			</Rectangle.RenderTransform>
    			<Rectangle.Fill>
    				<SolidColorBrush Color="{StaticResource PhoneContrastBackgroundColor}"/>
    			</Rectangle.Fill>
    		</Rectangle>
    		<Rectangle x:Name="HourHand" Height="13" Margin="0,0,0,25" Width="2" StrokeThickness="0" HorizontalAlignment="Center" VerticalAlignment="Bottom" RenderTransformOrigin="0.5,1">
    			<Rectangle.RenderTransform>
    				<CompositeTransform/>
    			</Rectangle.RenderTransform>
    			<Rectangle.Fill>
    				<SolidColorBrush Color="{StaticResource PhoneContrastBackgroundColor}"/>
    			</Rectangle.Fill>
    		</Rectangle>
    	</Grid>
    </Viewbox>
</UserControl>

Step 13 : Add appear disappear animations

Add AppearClock and DisappearClock animations just below MoveHands inside UserControl.Resource, like so:

        <Storyboard x:Name="AppearClock">
            <DoubleAnimation Duration="0:0:0.3" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="LayoutRoot" d:IsOptimized="True"/>
        </Storyboard>
        <Storyboard x:Name="DisappearClock">
            <DoubleAnimation Duration="0:0:2" To="0" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="LayoutRoot" d:IsOptimized="True"/>
        </Storyboard>

Step 14 : Update code behind

Open code behind UCWaitSpinner.xaml.cs and add following lines to its constructor:

        public UCWaitSpinner()
        {
            InitializeComponent();
            MoveHands.RepeatBehavior = RepeatBehavior.Forever;
            LayoutRoot.Opacity = 0d;
            DisappearClock.Completed += (object sender, EventArgs e) => { MoveHands.Stop(); };
        }

Step 15 : Add start functionality

Add a public Start method to the class:

        public void Start()
        {
            MoveHands.Stop();
            AppearClock.Begin();
            MoveHands.Begin();
        }

Step 16 : Add stop functionality

Add a public Stop methods to the class:

        public void Stop()
        {
            DisappearClock.Begin();
        }

Step 17 : Build

Build XAMLControls project. If your project builds properly you should see UCWaitSpinner listed in your Toolbox in XAML Controls.

Step 18 : Add spinner to form

Open MainPage.xaml from the main project WaitSpinner and drag UCWaitSpinner from the Toolbox to the page. Open MainPage.xaml in code view and your will find the newly added control in ContentPanel:

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
                <my:UCWaitSpinner/>
        </Grid>

Step 19 : Edit control properties

In MainPage.xaml name UCWaitSpinner control as “waitSpinner”, add Height and Width properties with a value of 120 in both, and wrap the control in a StackPanel:

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <StackPanel>
                <my:UCWaitSpinner x:Name="waitSpinner" Height="120" Width="120" />
            </StackPanel>
        </Grid>

Step 20 : Add buttons to control test

Add two buttons, just below WaitSpinner, Start and Stop with Click handlers to control WaitSpinner:

        <my:UCWaitSpinner x:Name="waitSpinner" Height="120" Width="120" />
        <Button x:Name="buttonStart" Content="Start" Click="buttonStart_Click"/>
        <Button x:Name="buttonStop" Content="Stop"  Click="buttonStop_Click"/>

Step 21 : Write code in click handlers

Open MainPage.xaml.cs and call Start and Stop of WaitSpinner in buttons’ click handlers:

        private void buttonStart_Click(object sender, RoutedEventArgs e)
        {
            waitSpinner.Start();
        }

        private void buttonStop_Click(object sender, RoutedEventArgs e)
        {
            waitSpinner.Stop();
        }

You can run your code and click on Start button to start spinner. Click on Stop button and spinner will slowly fade out.

Let’s see the example code to integrate the control with background processes.

Make following changes to MainPage.xaml’s ContentPanel control:

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <StackPanel>
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition/>
                        <ColumnDefinition/>
                    </Grid.ColumnDefinitions>
                    <TextBlock Grid.Column="0" x:Name="textBlockSeconds" Text="..."/>
                    <my:UCWaitSpinner Grid.Column="1" x:Name="waitSpinner2" Height="90" Width="90" />
                </Grid>
                <my:UCWaitSpinner x:Name="waitSpinner" Height="120" Width="120" />
                <Button x:Name="buttonStart" Content="Start" Click="buttonStart_Click"/>
                <Button x:Name="buttonStop" Content="Stop"  Click="buttonStop_Click"/>
                <Button x:Name="buttonBackground" Content="Background" Click="buttonBackground_Click"/>
            </StackPanel>
        </Grid>

And add following code to the code behind MainPage.xaml.cs:

    public partial class MainPage : PhoneApplicationPage
    {
        // Constructor
        Thread bgThread;
        public MainPage()
        {
            InitializeComponent();
            bgThread = new Thread(new ThreadStart(() => 
            {
                Dispatcher.BeginInvoke(new Action(() => { waitSpinner2.Start(); }));
                for (int cnt = 0; cnt < 5; cnt++)
                {
                    Dispatcher.BeginInvoke(new Action(() => { textBlockSeconds.Text = string.Format("Step - {0}/4", cnt); }));
                    Thread.CurrentThread.Join(2000);
                }
                Dispatcher.BeginInvoke(new Action(() => { waitSpinner2.Stop(); }));
            }));
        }

        private void buttonStart_Click(object sender, RoutedEventArgs e)
        {
            waitSpinner.Start();
        }

        private void buttonStop_Click(object sender, RoutedEventArgs e)
        {
            waitSpinner.Stop();
        }

        private void buttonBackground_Click(object sender, RoutedEventArgs e)
        {
            buttonBackground.IsEnabled = false;
            bgThread.Start();
        }
    }

F5. You should see something like this:

Download entire code here.

C#|XAML : ListBox – Search, Filter, and Highlight (3/3)

Highlight colors. by pasukaru76, on Flickr
Highlight colors., a photo by pasukaru76 on Flickr.

In part 1  and part 2 we set up our ListBox and search TextBox in MainPage.XAML and filtered the list on-the-fly for the text entered in the text box. To see search/filter/highlight code in action in a published app, you can download my app for free.

After having filtered the list, in this post we will add code to highlight the searched text in each field of the items. The highlighted text will be in current accent color on the device, italicized, and underlined.

Let’s open MainPage.xaml.cs and add two new fields at MainPage class level:

        EventHandler _listBoxItemsRearrangedHandler;
        bool    _trapListBoxLayoutUpdate = true;

…and in the constructor initialize the handler:

            _listBoxItemsRearrangedHandler = new EventHandler(listBoxItems_Rearranged);

In the private method prepareFilteredList, we created in Part 2, set the _trapListBoxLayoutUpdate flag and also start listening to LayoutUpdated event of listBoxTextItems:

            _trapListBoxLayoutUpdate = true;
            listBoxTextItems.LayoutUpdated -= new EventHandler(_listBoxItemsRearrangedHandler);
            listBoxTextItems.LayoutUpdated += new EventHandler(_listBoxItemsRearrangedHandler);

Add following two methods for the core highlighting logic:

        void listBoxItems_Rearranged(object sender, EventArgs e)
        {
            if (_trapListBoxLayoutUpdate)
            {
                foreach (var ob in listBoxTextItems.Items)
                {
                    ListBoxItem lbi = listBoxTextItems.ItemContainerGenerator.ContainerFromItem(ob) as ListBoxItem;
                    if (lbi != null)
                    {
                        IEnumerable<TextBlock> _allTextBlocks = ViewHelpers.GetChildrenByType<TextBlock>(VisualTreeHelper.GetChild(lbi, 0));
                        foreach (TextBlock _txtBlock in _allTextBlocks)
                        {
                            if (
                                (
                                _txtBlock.Name == "templateTextBlockName" ||
                                _txtBlock.Name == "templateTextBlockNote" ||
                                _txtBlock.Name == "templateTextBlockAdd"
                                ) &&
                                _txtBlock.Text.ToUpper().Contains(textBoxSearch.Text.ToUpper())
                                )
                            {
                                HightlightText(_txtBlock, textBoxSearch.Text);
                            }
                        }
                    }
                }
                _trapListBoxLayoutUpdate = false;
            }
        }
        public static void HightlightText(TextBlock textBlockTarget, string highlightedText)
        {

            string Text = textBlockTarget.Text;
            textBlockTarget.Inlines.Clear();
            int _indexOfHighlightedTextInTarget = Text.ToUpper().IndexOf(highlightedText.ToUpper());
            Color highlightColor = (Color)Application.Current.Resources["PhoneAccentColor"];
            Run r = new Run();
            r.Text = Text.Substring(0, _indexOfHighlightedTextInTarget);
            textBlockTarget.Inlines.Add(r);


            r = new Run();
            r.Text = highlightedText;
            r.FontWeight = FontWeights.Bold;
            r.FontStyle = FontStyles.Italic;
            r.TextDecorations = TextDecorations.Underline;
            r.Foreground = new SolidColorBrush(highlightColor);
            textBlockTarget.Inlines.Add(r);

            r = new Run();
            r.Text = Text.Substring(_indexOfHighlightedTextInTarget + highlightedText.Length, Text.Length - (_indexOfHighlightedTextInTarget + highlightedText.Length));
            textBlockTarget.Inlines.Add(r);
        }

F5 and when the form is up, type Bill in the text box. You will notice as you are typing list is filtering and the text being typed in the text box is getting highlighted in different fields of the items in the ListBox.

highlight

A more extensive implementation can be found in this app.

Hope you find this code useful.

Happy searching/filtering/highlighting 😀

C#|XAML : ListBox – Search, Filter, and Highlight (2/3)

Filter by Joe Edwards, on Flickr
Filter, a photo by Joe Edwards on Flickr.

In part 1 we set up our ListBox and search TextBox in MainPage.XAML. We also created the ViewModel class which will be shown in the ListBox. You can download my app for free which has the complete working filter/search/highlight function.

In this post we will add functionality to filter our ListBox items on the basis of text entered in TextBox. We will filter the list on the fly without any query. To achieve this we will utilize filter event of CollectionViewSource. We will also create a field in Profile class to concatenate different properties which are going to participate in search.

Add new property to Profile class like so:

        public string SearchText { get { return string.Format("{0}|{1}|{2}", Name, Address, Note); } }

Update the code behind MainPage.xaml.cs to add a filter event handler. This is how the complete code of MainPage class will look like:

    public partial class MainPage : PhoneApplicationPage
    {
        ObservableCollection<Profile> _infoList = new ObservableCollection<Profile>();
        FilterEventHandler _searchFilter;

        // Constructor
        public MainPage()
        {
            InitializeComponent();

            _infoList.Add(new Profile("A Kejriwal", "New Delhi, India", "I am common man A"));
            _infoList.Add(new Profile("Bill Gates", "Microsoft One", "I am not a common man"));
            _infoList.Add(new Profile("Bill Burr", "Comedy Central", "Don't say there is no reason"));
            _infoList.Add(new Profile("Kartavya Sharma", "Street dhimka", "What do you mean?"));
            _infoList.Add(new Profile("Louis CK", "HBO One Night", "Bill curses a lot in comedy"));
            _infoList.Add(new Profile("Sanjay Sharma", "Street falana", "What do you mean?"));
            _infoList.Add(new Profile("Z Kejriwal", "New Delhi, India", "Don't underestimate the power"));

            _searchFilter = new FilterEventHandler(onSearchResultsFiltering);

            textListViewSource.Source = null;
            textListViewSource.Source = _infoList;
            textListViewSource.Filter += _searchFilter;
            listBoxTextItems.DataContext = _infoList;
        }

        private void onSearchResultsFiltering(object sender, FilterEventArgs e)
        {
            Profile _info = e.Item as Profile;
            if (_info != null)
            {
                if (_info.SearchText.ToUpper().Contains(String.Format("{0}", textBoxSearch.Text).ToUpper()))
                {
                    e.Accepted = true;
                }
                else
                {
                    e.Accepted = false;
                }
            }
        }
    }

Next, we want our TextBox to initiate filtration of the ListBox items as soon as text is changed by user. To achieve this behavior, we will trap KeyUp event of TextBox. Let’s update XAML to add the event handler.

<TextBox Grid.Row="0" x:Name="textBoxSearch" KeyUp="textBoxSearch_KeyUp"/>

As we have the event handler code inserted by VS in the code behind, let’s update it to refresh our ListBox with latest filtered list:

        private void textBoxSearch_KeyUp(object sender, KeyEventArgs e)
        {
            Dispatcher.BeginInvoke(new Action(prepareFilteredList));
        }
        private void prepareFilteredList()
        {
            textListViewSource.View.Refresh();
        }

We are ready! F5. Type ‘Bill’ in TextBox. You will see that the list gets filtered on the fly, while you type. Filtered list should look like this :
FilteredList

In the next part of the series, we will see how to highlight the searched text in the fields in ListBox.

To be continued…(Part 3)

C#|XAML : ListBox – Search, Filter, and Highlight (1/3)

C#|XAML : ListBox – Search, Filter, and Highlight (1/3)

In this 3 part series we will go through c#/XAML code to setup Listbox with multiple rows of information having ability to search, filter and highlight the text in searched items. To see the actual running code of this ListBox in live app, you can check my app. The topics of different parts in this series are as follows:

  • Part 1: Set-up form with TextBox and ListBox with example model class
  • Part 2: Add search and filter ability
  • Part 3: Highlight searched text

Setup Test XAML Form

This is our default MainPage.XAML. We will add a TextBox control and a ListBox control to this page. TextBox control is where we will input the text to be searched in the ListBox items. ListBox will show items. Each item has three information fields. These fields are: Name, Address, and Note. Let’s first update the XAML created by Studio.

Replace the default “ContentPanel” control with following Grid:

        <Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
            <Grid.RowDefinitions>
                <RowDefinition Height="80"></RowDefinition>
                <RowDefinition Height="*"></RowDefinition>
            </Grid.RowDefinitions>
            <TextBox Grid.Row="0" x:Name="textBoxSearch" KeyUp="textBoxSearch_KeyUp"/>
            <ListBox Grid.Row="1" x:Name="listBoxTextItems"></ListBox>
        </Grid>

Create ViewModel Class

The class which feeds data to the ListBox is Profile and contains three basic properties : Name, Address, and Note. For the sake of keeping this example simple, let’s write this class in the code-behind, MainPage.xaml.cs (please note, in real world, ViewModel classes do not go in the code-behinds and they usually have mechanism to broadcast change messages to UI. To keep the focus on the subject in hand, we are only writing just the essential code).

    public class Profile
    {
        public string Name { get; set; }
        public string Address { get; set; }
        public string Note { get; set; }
        public Profile(string name, string add, string note)
        {
            Name = name;
            Address = add;
            Note = note;
        }
    }

Create List and connect View and ViewModel

Let’s first update MainPage.XAML to add CollectionViewSource to its resources and bind it to the ListBox. We need CollectionViewSource to filter our data in the view.

    <phone:PhoneApplicationPage.Resources>
        <CollectionViewSource x:Name="textListViewSource">
        </CollectionViewSource>
    </phone:PhoneApplicationPage.Resources>

Update the ListBox definition to add the CollectionViewSource:

            <ListBox Grid.Row="1" x:Name="listBoxTextItems" ItemsSource="{Binding Source={StaticResource textListViewSource}}">

We also want our ListBox to show these items in different sizes and colors so that three different rows in each item can be differentiated visually. So, we will add a visual template for ListItem and assign it to the ListBox.

The style definition will go in the Resources section:

        <Style x:Key="styleInfoTextListBox" TargetType="ListBoxItem">
            <Setter Property="HorizontalAlignment" Value="Left" />
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ListBoxItem">
                        <Grid x:Name="gridDataTemplate" Margin="15,5,5,5">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="Auto"/>
                                <RowDefinition Height="Auto"/>
                            </Grid.RowDefinitions>
                            <TextBlock Grid.Row="0" x:Name="templateTextBlockName" Text="{Binding Name}" FontFamily="Segoe WP Black" FontSize="{StaticResource PhoneFontSizeExtraLarge}" Foreground="White"/>
                            <TextBlock Grid.Row="1" x:Name="templateTextBlockAdd" Text="{Binding Address}" FontFamily="Segoe WP" FontSize="{StaticResource PhoneFontSizeLarge}" Foreground="White" Opacity="0.8"/>
                            <TextBlock Grid.Row="2" x:Name="templateTextBlockNote" Text="{Binding Note}" FontFamily="Segoe WP Light" FontSize="{StaticResource PhoneFontSizeNormal}" Foreground="White" Opacity="0.8"/>
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>

Update the ListBox definition one last time to apply the style on ListItems to add the CollectionViewSource:

<ListBox Grid.Row="1" x:Name="listBoxTextItems" ItemsSource="{Binding Source={StaticResource textListViewSource}}" ItemContainerStyle="{StaticResource styleInfoTextListBox}">

Our ListBox is ready to show the data. Now let’s switch back to MainPage.xaml.cs. We will create an ObservableCollection of Profile type and add some example data to it. We will write this code in MainPage.xaml.cs. Also in the constructor of our page we will set CollectionViewSource’s source and ListBox’s DataContext to connect our list with the data. Our MainPage.xaml.cs will look like this:

    public partial class MainPage : PhoneApplicationPage
    {
        ObservableCollection<Profile> _infoList = new ObservableCollection<Profile>();
        // Constructor
        public MainPage()
        {
            InitializeComponent();

            _infoList.Add(new Profile("A Kejriwal", "New Delhi, India", "I am common man A"));
            _infoList.Add(new Profile("Bill Gates", "One Microsoft, Redmond", "I am not a common man"));
            _infoList.Add(new Profile("Bill Burr", "Comedy Central", "Don't say there is no reason"));
            _infoList.Add(new Profile("Kartavya Sharma", "Street dhimka", "What do you mean?"));
            _infoList.Add(new Profile("Louis CK", "HBO One Night", "Bill curses a lot in comedy"));
            _infoList.Add(new Profile("Sanjay Sharma", "Street falana", "What do you mean?"));
            _infoList.Add(new Profile("Z Kejriwal", "New Delhi, India", "Don't underestimate the power"));

            textListViewSource.Source = _infoList;
            listBoxTextItems.DataContext = _infoList;
        }
    }

Let’s F5 our form. You should see this on your emulator:
List

In next post we will write code to respond to search query in TextBox and filter data in ListBox.

To be contd… Part 2