how to port DrawingBrush stuff from WPF to WinUI 3?

Hi @Mahdi Hosseini ,

Welcome to Microsoft Q&A!

I'll share my solution here, it may not be elegant enough.

1. Install System.Drawing.Common in NuGet Manager, use Graphics.DrawString to draw text.
2. Rotate the image.
3. Use the image in ImageBrush , fill it in a layout.

<?xml version="1.0" encoding="utf-8"?>
<Window
    x:Class="Winui3WaterMark.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Winui3WaterMark"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center" BorderBrush="Black" BorderThickness="1">
        <Rectangle x:Name="rectangle" Height="500" Width="500">
            <Rectangle.Fill>
                <ImageBrush ImageSource="{x:Bind imgTest.Source}" Stretch="None"/>
            </Rectangle.Fill>
        </Rectangle>
    </StackPanel>
</Window>

using ABI.Windows.Foundation;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Controls.Primitives;
using Microsoft.UI.Xaml.Data;
using Microsoft.UI.Xaml.Input;
using Microsoft.UI.Xaml.Media;
using Microsoft.UI.Xaml.Media.Imaging;
using Microsoft.UI.Xaml.Navigation;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Reflection.Metadata;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;

// To learn more about WinUI, the WinUI project structure,
// and more about our project templates, see: http://aka.ms/winui-project-info.

namespace Winui3WaterMark
{
    /// <summary>
    /// An empty window that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainWindow : Window
    {
        public Microsoft.UI.Xaml.Controls.Image imgTest;
        public MainWindow()
        {
            this.InitializeComponent();

            imgTest=new Microsoft.UI.Xaml.Controls.Image();

            var bmp = ConvertTextToImage("WaterMark", "Calibri", 10, Color.Empty, Color.HotPink, 1000, 2000);

            BitmapImage bitmapImage = new BitmapImage();

            using (MemoryStream stream = new MemoryStream())
            {
      
                bmp.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
                stream.Position = 0;
                bitmapImage.SetSource(stream.AsRandomAccessStream());
            }
            imgTest.Source = bitmapImage;
        }
    
        public Bitmap ConvertTextToImage(string txt, string fontname, int fontsize, Color bgcolor, Color fcolor, int width, int Height)
        {
            Bitmap bmp = new Bitmap(width, Height);

            //a way to get the width of string
            SizeF size;
            using (System.Drawing.Graphics graphics = System.Drawing.Graphics.FromImage(new Bitmap(1, 1)))
            {
                 size = graphics.MeasureString(txt, new Font(fontname, fontsize, FontStyle.Regular, GraphicsUnit.Point));
            }

            //draw text
            using (Graphics graphics = Graphics.FromImage(bmp))
            {

                Font font = new Font(fontname, fontsize);

                //In order to avoid blank areas after rotation, expand the drawing range
                graphics.FillRectangle(new SolidBrush(bgcolor), -size.Width, -font.Height, width+2*size.Width, Height+2*font.Height);

                for (int i = 0; i < Height/ font.Height; i++) 
                {
                    for (int j = -2; j< width/ size.Width; j++ ) 
                    {
                        graphics.DrawString(txt, font, new SolidBrush(fcolor), j* size.Width, i * font.Height);
                    }
                   
                }   
               
                graphics.Flush();
                font.Dispose();
                graphics.Dispose();

            }

            //rotate the bitmap
            Bitmap returnBitmap = new Bitmap(bmp.Width, bmp.Height);

            using (Graphics g = Graphics.FromImage(returnBitmap))
            {
                g.TranslateTransform((float)bmp.Width / 2, (float)bmp.Height / 2);
                g.RotateTransform(15);
                g.TranslateTransform(-(float)bmp.Width / 2, -(float)bmp.Height / 2);
                g.DrawImage(bmp, new System.Drawing.Point(0, 0));
            }

            return returnBitmap;
        }

       
    }
}

Thank you.

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