图片文件的转换、加载及缩放显示

xaml文件代码

<Window x:Class="ImageShowDemo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:s="clr-namespace:System;assembly=mscorlib"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <s:Boolean x:Key="True">True</s:Boolean>
        <s:Boolean x:Key="False">False</s:Boolean>
    </Window.Resources>
    <!--只有鼠标在Image控件上时，才会触发MouseWheel事件，因为Grid.Background默认为null
        将Background设为不为null时，即可在Grid范围触发MouseWheel事件-->
    <Grid MouseWheel="Grid_MouseWheel" Background="Transparent">
        <Grid.RowDefinitions>
            <RowDefinition Height="9*"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <!--Image无Background属性-->
        <Image x:Name="image" Width="auto" Height="auto" Source="{Binding buffer}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        <Border Grid.Row="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" BorderBrush="Blue" BorderThickness="1">
            <TextBlock Text="测试测试测试测试测试测试测试测试测试测试测试" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        </Border>
    </Grid>
</Window>

　　对应的xmal.cs文件代码：

using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
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;

namespace ImageShowDemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public byte[] buffer;

        public MainWindow()
        {
            InitializeComponent();
            OpenFileDialog dialog = new OpenFileDialog() { Filter = string.Format("{0}|*.jpg;*.png;*.jpeg", "图片文件") };
            if ((bool)dialog.ShowDialog())
            {
                buffer = FileToByteArray(dialog.FileName);
                this.image.Source = ByteArrayToBitmapImage(buffer);
            }
        }
　　　　 #region WPF Image控件 Source,byte[],BitmapImage相互转换
        /// <summary>
        /// 文件转换为byte[]
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        private byte[] FileToByteArray(string filePath)
        {
            FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);
            try
            {
                byte[] buffer = new byte[fs.Length];
                fs.Read(buffer, 0, (int)fs.Length);
                return buffer;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                return null;
            }
            finally
            {
                if (fs != null)
                    fs.Close();
            }
        }

        /// <summary>
        /// byte[]转换为BitmapImage
        /// </summary>
        /// <param name="byteArray"></param>
        /// <returns></returns>
        private BitmapImage ByteArrayToBitmapImage(byte[] byteArray)
        {
            BitmapImage bmp = null;
            try
            {
                bmp = new BitmapImage();
                bmp.BeginInit();
                bmp.StreamSource = new MemoryStream(byteArray);
                bmp.EndInit();
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                bmp = null;
            }
            return bmp;
        }
        /// <summary>
        /// BitmapImage转换为byte[]
        /// </summary>
        /// <param name="bmp"></param>
        /// <returns></returns>
        private byte[] BitmapImageToByteArray(BitmapImage bmp)
        {
            byte[] byteArray = null;
            Stream sMarket = bmp.StreamSource;
            try
            {
                if (sMarket != null && sMarket.Length > 0)
                {
                    // Position位于Stream的末尾，需手动置为0，否则下面读取到的长度为0
                    sMarket.Position = 0;
                    using (BinaryReader br = new BinaryReader(sMarket))
                    {
                        byteArray = br.ReadBytes((int)sMarket.Length);
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                sMarket.Close();
            }
            return byteArray;
        }
        #endregion
　　　　  /// <summary>
        /// 通过滚动鼠标滚轮对图片进行缩放显示
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Grid_MouseWheel(object sender, MouseWheelEventArgs e)
        {
            Matrix m = image.RenderTransform.Value;
            Point p = new Point(image.ActualWidth / 2, image.ActualHeight / 2);
            if (e.Delta > 0)
            {
                m.ScaleAtPrepend(1.1, 1.1, p.X, p.Y);
            }
            else
            {
                m.ScaleAtPrepend(1 / 1.1, 1 / 1.1, p.X, p.Y);
            }
            image.RenderTransform = new MatrixTransform(m);
        }
    }
}