F6 Team

今天介紹如何利用WebClient來下載圖片

並且加上進度資訊,讓使用者了解下載進度

WebClientDownload.xaml

<UserControl x:Class="SilverlightApplication1.WebClientDownload" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="400" Height="300" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid x:Name="LayoutRoot" Background="White"> <Grid.RowDefinitions> <RowDefinition Height="0.09*"/> <RowDefinition Height="0.17*"/> <RowDefinition Height="0.74*"/> </Grid.RowDefinitions> <Canvas Canvas.Top="70" Grid.RowSpan="3"> <Rectangle x:Name="progressRectangle" Canvas.Left="96" Height="10" Width="0" Fill="Maroon" Canvas.Top="42" /> <Rectangle Canvas.Top ="42" Canvas.Left="96" Height="10" Width="200" StrokeThickness="1" Stroke="Black" /> <TextBlock x:Name="progressText" Canvas.Top="36.545" Canvas.Left="302" Text="0%" FontSize="12" /> </Canvas> <Button HorizontalAlignment="Left" Margin="23,8,0,16" Width="67" Grid.Row="1" Content="Download" x:Name="btnDownload" Click="btnDownload_Click"/> <Image Margin="8.5,8.5,8,8" Grid.Row="2" x:Name="img"/> </Grid> </UserControl>

WebClientDownload.xaml.cs

using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Windows.Media.Imaging; using System.Windows.Resources; namespace SilverlightApplication1 { public partial class WebClientDownload : UserControl { WebClient wc = null; public WebClientDownload() { InitializeComponent(); wc = new WebClient(); wc.DownloadProgressChanged += new DownloadProgressChangedEventHandler(wc_DownloadProgressChanged); wc.OpenReadCompleted += new OpenReadCompletedEventHandler(wc_OpenReadCompleted); } //進度 void wc_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e) { progressText.Text = e.ProgressPercentage.ToString(); progressRectangle.Width = (double)e.ProgressPercentage*2; } //下載完成,載入圖片 void wc_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { if (e.Error != null) { return; } BitmapImage bi = new BitmapImage(); bi.SetSource(e.Result); img.Source = bi; } private void btnDownload_Click(object sender, RoutedEventArgs e) { //檔案放在ClientBin的上層 wc.OpenReadAsync(new Uri("../YY.jpg", UriKind.Relative)); } } }

執行結果：

 

參考網址：

http://msdn.microsoft.com/en-us/library/cc189021(vs.95).aspx

http://msdn.microsoft.com/zh-tw/library/cc190632(VS.95).aspx