Why the antialising is not applied correctly?

[EricOuellet2]

I wonder if I do something wrong of there is a bug.
Please look at the result obtained from simple modifications of you example: TextExample (attached image).

Code:

namespace WriteableBitmapEx.TextExample
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            this.SizeChanged += MainWindow_SizeChanged;
        }

        private void MainWindow_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            if (this.IsVisible)
                Draw();
        }

         WriteableBitmap bmp;

        private void Draw()
        {
            // double DIP = GetDpi(this);

            // var bmp = LoadFromFile("Assets/Overlays/19.jpg");
            var parent = UiUtility.GetVisualParent(imgMain);
            DependencyObject doParent = VisualTreeHelper.GetParent(imgMain);

            int height = (int)parent.ActualHeight;
            int width = (int)parent.ActualWidth;
            var bmp = BitmapFactory.New(width, height);

            System.Windows.Media.FormattedText formattedText;
            {
                System.Windows.FontStyle fontStyle = FontStyles.Normal;
                FontWeight fontWeight = FontWeights.Medium;

                var Text = "Now supports text!";

                var FontSize = 80;

                // var Font = new FontFamily("Sans MS");
                var Font = new FontFamily("Arial");

                // Create the formatted text based on the properties set.
                formattedText = new FormattedText(Text, CultureInfo.CurrentUICulture, FlowDirection.LeftToRight, new Typeface("Arial"), FontSize, Brushes.Black); // This brush does not matter since we use the geometry of the text.                    

                // var t = new PixelsPerDip();        
            }

            bmp.DrawTextAa(formattedText, 0, 100, Colors.Black, 7);
            bmp.FillText(formattedText, 0, 100, Colors.Red);

            int[] points = { 10, 450, 60, 480, 120, 440, 180, 495, 250, 450 };
            bmp.DrawPolylineAa(points, Colors.Yellow, 7);

            imgMain.Source = bmp;
            // bmp.DrawTextAa()

        }

        public static WriteableBitmap LoadFromFile(string fileName)
        {
            using (var fileStream = File.OpenRead(fileName))
            {
                var wb = BitmapFactory.FromStream(fileStream);
                return wb;
            }
        }
    }
}

[epsi1on]

i had same problem as in #35
I think we should first understand the code and then fix the bug our self.

[EricOuellet2]

OK, thanks. It's been a while. I do not have the knowledge to fix that myself.

[epsi1on]

As I remember if you clear the bitmap before draw with some solid colors, with alpha = 255 (no transparency) this problem will not happen. it only happen when drawing AA line on a transparent image. Not sure, so check it yourself.
Thanks