Silverlight缩略图生成(使用WriteableBitmap类)

来源：互联网发布：淘宝代购怎么开店编辑：程序博客网时间：2024/05/28 18:43

前段時間，一直因為silverlight生成縮略圖而飽受困擾。

雖然聽說過WriteableBitmap這個類，能生成縮略圖。也曾百度上面粗略看過，一直沒找到合適的生成縮略圖的辦法。

今天，再次試過，終于成功。下面貼出代碼，實際的向大家說明一下，縮略圖是如何生成的。

/// <summary>/// 生成縮略圖/// </summary>/// <param name="bitmap">要轉換的位圖</param>/// <returns>返回WriteableBitmap</returns>public WriteableBitmap RenderThumbnail(BitmapImage bitmap){Image img = new Image();img.Width = 150;img.Height = 150;img.Source = bitmap;WriteableBitmap Wimg = new WriteableBitmap(img,null);Wimg.Invalidate();return Wimg;}

下面展示一個示例：

<UserControl x:Class="SilverlightTest.MainPage"    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"    mc:Ignorable="d"    d:DesignHeight="300" d:DesignWidth="400">    <Grid x:Name="LayoutRoot" Background="White">        <Grid.RowDefinitions>            <RowDefinition></RowDefinition>            <RowDefinition></RowDefinition>        </Grid.RowDefinitions>        <Image x:Name="TestImg1" Grid.Row="0" Source="/SilverlightTest;component/Images/20120229_reg_page1_09.jpg" Stretch="None"></Image>        <Image x:Name="TestImg"  Grid.Row="1" Source="/SilverlightTest;component/Images/20120229_reg_page1_09.jpg" Stretch="None"></Image>        <TextBlock x:Name="txt" Grid.Row="1" VerticalAlignment="Bottom" HorizontalAlignment="Center"></TextBlock>    </Grid></UserControl>

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;namespace SilverlightTest{public partial class MainPage : UserControl{public MainPage(){InitializeComponent();BitmapImage bmap = TestImg.Source as BitmapImage;WriteableBitmap wimg = this.RenderThumbnail(bmap);TestImg.Source = wimg;txt.Text ="原圖大小為：" +bmap.PixelWidth + "Px;縮略圖寬度為：" + wimg.PixelWidth+"Px";}/// <summary>/// 生成縮略圖/// </summary>/// <param name="bitmap">要轉換的位圖</param>/// <returns>返回WriteableBitmap</returns>public WriteableBitmap RenderThumbnail(BitmapImage bitmap){Image img = new Image();img.Width = 150;img.Height = 150;img.Source = bitmap;WriteableBitmap Wimg = new WriteableBitmap(img,null);Wimg.Invalidate();return Wimg;}}}

請看如下效果：

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