Windows 8 Photo Retouching

capturephoto.cs

        private async void CapturePhoto_Click(object sender, RoutedEventArgs e)
        {
            var dialog = new Windows.Media.Capture.CameraCaptureUI();
            photo = await dialog.CaptureFileAsync(Windows.Media.Capture.CameraCaptureUIMode.Photo);

            if (photo != null)
            {
                IRandomAccessStream stream = await photo.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
                image = new BitmapImage();
                image.SetSource(stream);
                PhotoHolder.Source = image;
            }
        }

grayscale.cs

        private void BWConverstion_Click(object sender, RoutedEventArgs e)
        {
            if (photo != null)
            {
                bitmap = new WriteableBitmap(image);
                var stream = bitmap.PixelBuffer.AsStream();
                
                byte[] buffer = new byte[(int)stream.Length];
                int c = stream.Read(buffer, 0, (int)stream.Length);

                buffer = BlackWhiteConversion(buffer);
                
                stream.Seek(0, System.IO.SeekOrigin.Begin);
                stream.Write(buffer, 0, buffer.Length);
                bitmap.Invalidate();

                PhotoHolder.Source = bitmap;
            }
        }

        private byte[] BlackWhiteConversion(byte[] buffer)
        {
            for (int i = 0; i < buffer.Length; i += 4)
            {
                byte r = buffer[i];
                byte g = buffer[i + 1];
                byte b = buffer[i + 2];
                byte gray = (byte)Math.Round(.299 * r + .587 * g + .114 * b);
                buffer[i] = buffer[i + 1] = buffer[i + 2] = gray;
            }
            return buffer;
        }

invert.cs

        private void Invert_Click(object sender, RoutedEventArgs e)
        {
            if (image != null)
            {
                bitmap = new WriteableBitmap(image);
                var stream = bitmap.PixelBuffer.AsStream();

                byte[] buffer = new byte[(int)stream.Length];
                int c = stream.Read(buffer, 0, (int)stream.Length);

                if (c > 0)
                {
                    for (int i = 0; i < buffer.Length; i += 4)
                    {
                        buffer[i] = (byte)(255 - buffer[i]);
                        buffer[i + 1] = (byte)(255 - buffer[i + 1]);
                        buffer[i + 2] = (byte)(255 - buffer[i + 2]);
                    }
                }

                stream.Seek(0, System.IO.SeekOrigin.Begin);
                stream.Write(buffer, 0, buffer.Length);
                bitmap.Invalidate();

                PhotoHolder.Source = bitmap;
            }
        }

mainpage.xaml

    <UserControl.Resources>
        <Style TargetType="Button">
            <Setter Property="Margin" Value="10,50,0,0"></Setter>
            <Setter Property="Width" Value="150"></Setter>
        </Style>
        
        <Style x:Key="AppButton" TargetType="Button">
            <Setter Property="BorderBrush" Value="Transparent"></Setter>
            <Setter Property="Margin" Value="0,0,10,15"></Setter>
        </Style>
    </UserControl.Resources>
    
    <Grid x:Name="LayoutRoot" Background="#FF0C0C0C">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200"></ColumnDefinition>
            <ColumnDefinition Width="*"></ColumnDefinition>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="80"></RowDefinition>
        </Grid.RowDefinitions>
        <StackPanel>
            <Button x:Name="BWConverstion" Click="BWConverstion_Click" Content="Black and White"></Button>
            <Button x:Name="Invert" Click="Invert_Click" Content="Invert"></Button>
        </StackPanel>
        <Border Grid.Column="1" Margin="50,50,0,0" BorderBrush="White" BorderThickness="2">
            <Image x:Name="PhotoHolder"></Image>
        </Border>
        <ApplicationBar Grid.Row="1" Grid.ColumnSpan="2">
            <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Margin="0,0,25,0">
                <Button x:Name="CapturePhoto" Click="CapturePhoto_Click" Style="{StaticResource AppButton}">
                    <Image Source="/Icons/Camera.png"></Image>
                </Button>
                <Button x:Name="OpenPhoto" Click="OpenPhoto_Click" Style="{StaticResource AppButton}">
                    <Image Source="/Icons/Open.png"></Image>
                </Button>
                <Button x:Name="SavePhoto" Click="SavePhoto_Click" Style="{StaticResource AppButton}">
                    <Image Source="/Icons/Save.png"></Image>
                </Button>
            </StackPanel>
        </ApplicationBar>
    </Grid>

openfile.cs

        async void OpenPhoto_Click(object sender, RoutedEventArgs e)
        {
            FileOpenPicker openPicker = new FileOpenPicker();
            openPicker.ViewMode = PickerViewMode.Thumbnail;
            openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
            openPicker.FileTypeFilter.Add(".jpg");
            openPicker.FileTypeFilter.Add(".jpeg");
            openPicker.FileTypeFilter.Add(".png");
            StorageFile file = await openPicker.PickSingleFileAsync();

            if (file != null)
            {
                photo = file;
                IRandomAccessStream stream = await photo.OpenAsync(Windows.Storage.FileAccessMode.ReadWrite);
                image = new BitmapImage();
                image.SetSource(stream);
                PhotoHolder.Source = image;
            }
        }

saveimage.cs

        async void SavePhoto_Click(object sender, RoutedEventArgs e)
        {
            if (photo != null)
            {
                if (bitmap == null)
                {
                    bitmap = new WriteableBitmap(image);
                }
                FileSavePicker picker = new FileSavePicker();
                picker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
                picker.FileTypeChoices.Add("PNG", new List<string>() { ".png" });
                picker.DefaultFileExtension = ".png";
                picker.SuggestedFileName = "photo";
                StorageFile savedFile = await picker.PickSaveFileAsync();

                if (savedFile != null)
                {
                    IRandomAccessStream output = await savedFile.OpenAsync(FileAccessMode.ReadWrite);
                    BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, output);

                    var stream = bitmap.PixelBuffer.AsStream();
                    byte[] buffer = new byte[(int)stream.Length];
                    int c = stream.Read(buffer, 0, (int)stream.Length);

                    encoder.SetPixelData(BitmapPixelFormat.Rgba8, BitmapAlphaMode.Straight, (uint)bitmap.PixelWidth, (uint)bitmap.PixelHeight,
                        96.0, 96.0, buffer);
                    await encoder.FlushAsync();
                    output.GetOutputStreamAt(0).FlushAsync().Start();
                }
            }
        }