WPF image via web url or uri

FredGrit發表於2024-10-02

The basic roadmap is to download web image at first ,

second convert it into memeorystream,

third assign the memorystream to bitmapimage as StreamSource.

//xaml
<Window x:Class="WpfApp2.MainWindow"
        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"
        xmlns:local="clr-namespace:WpfApp2"
        WindowState="Maximized"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Image x:Name="img"/>
    </Grid>
</Window>


//xaml.cs
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using static System.Net.Mime.MediaTypeNames;

namespace WpfApp2
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        static string url = "https://wx4.sinaimg.cn/mw690/007ucPXmgy1hteb8tr7gjj311x1kwhdt.jpg";
        public MainWindow()
        {
            InitializeComponent();
            //LoadWebImageSync();
            LoadWebImageAsync();
        }

        private void LoadWebImageSync()
        {
            WebClient client = new WebClient();
            var imgBytes = client.DownloadData(url);
            if(imgBytes!=null && imgBytes.Any())
            {
                BitmapImage bmi = new BitmapImage();
                bmi.BeginInit();
                MemoryStream ms = new MemoryStream(imgBytes);
                ms.Seek(0, SeekOrigin.Begin);
                bmi.StreamSource = ms;
                bmi.EndInit();
                img.Source = bmi;
            }
        }

        private void LoadWebImageAsync()
        {
            WebClient client = new WebClient();
            client.DownloadDataAsync(new Uri(url));
            client.DownloadDataCompleted += Client_DownloadDataCompleted;
        }

        private void Client_DownloadDataCompleted(object sender, DownloadDataCompletedEventArgs e)
        {
            var imgBytes = e.Result;
            if (imgBytes != null && imgBytes.Any())
            {
                MemoryStream stream = new MemoryStream(imgBytes);
                BitmapImage bmi = new BitmapImage();
                bmi.BeginInit();
                bmi.StreamSource = stream;
                bmi.EndInit();
                img.Source = bmi;
            }
        }
    }
}

Here I recommand the asynchronous method which will not block other thread.

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