wpf图片查看器，支持鼠标滚动缩放拖拽

最近项目需要，要用到一个图片查看器，类似于windows自带的图片查看器那样，鼠标滚动可以缩放，可以拖拽图片，于是就写了这个简单的图片查看器。

前台代码：

<Window x:Class="PictureViewer.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

        AllowDrop="True"

        Title="图片查看器" Height="" Width="" Loaded="Window_Loaded"

        SizeChanged="Window_SizeChanged" DragEnter="Window_DragEnter" Drop="Window_Drop">

    <Grid x:Name="mainGrid">

        <Grid.Resources>

            <TransformGroup x:Key="TfGroup">

                <ScaleTransform ScaleX="" ScaleY=""/>

                <TranslateTransform X="" Y=""/>

            </TransformGroup>

        </Grid.Resources>

        <Grid.RowDefinitions>

            <RowDefinition Height=""></RowDefinition>

            <RowDefinition Height="*"></RowDefinition>

        </Grid.RowDefinitions>

        <Button Grid.Row="" Width="" Height="" Cursor="Hand" Background="Transparent" BorderThickness="" Content="打开图片" Click="OpenImg_Click" x:Name="OpenImg" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="20,0,0,0"/>

        <Label Content="缩放倍数：" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="130,0,0,0"/>

        <TextBox x:Name="txtMinSize" Width="" Height="" VerticalContentAlignment="Center" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="200,0,0,0" TextChanged="txtMinSize_TextChanged" Text="0.1"/>

        <Label Content="--" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="240,0,0,0"/>

        <TextBox x:Name="txtMaxSize" Width="" Height="" VerticalContentAlignment="Center" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="260,0,0,0" TextChanged="txtMaxSize_TextChanged" Text=""/>

        <ScrollViewer x:Name="mainScrollv" HorizontalAlignment="Center" VerticalAlignment="Center" HorizontalScrollBarVisibility="Disabled"

                      VerticalScrollBarVisibility="Disabled" Cursor="SizeAll" Margin="" Focusable="False" Grid.Row="">

            <ContentControl MouseLeftButtonDown="ContentControl_MouseLeftButtonDown"

                            MouseLeftButtonUp="ContentControl_MouseLeftButtonUp"

                            MouseMove="ContentControl_MouseMove"

                            MouseWheel="ContentControl_MouseWheel"

                            HorizontalAlignment="Center" VerticalAlignment="Center">

                <Image x:Name="IMG" Margin="" RenderTransform="{StaticResource TfGroup}" RenderOptions.BitmapScalingMode="NearestNeighbor"/>

            </ContentControl>

        </ScrollViewer>

    </Grid>

</Window>

代码解析：

　　通过一个定义一个TransformGroup，通过Key绑定到图片控件中，并且里面使用ScaleTransform实现缩放（scaleX是水平方向的缩放倍数，现默认为1倍，即无缩放，scaleY同理），TranslateTransform实现平移（鼠标拖动，X为水平方向的偏移量，Y为垂直方向的偏移量）。

　　另通过一个ContentControl控件摆放图片控件，并为控件绑定各种事件（鼠标点下、抬起、拖动、滚动），图片控件的RenderOptions.BitmapscalingMode="NearestNeighbor"属性用于优化图片变换过程，防止出现图片移动或缩放模糊。

后台代码：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

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 PictureViewer

{

    /// <summary>

    /// MainWindow.xaml 的交互逻辑

    /// </summary>

    public partial class MainWindow : Window

    {

        public MainWindow()

        {

            InitializeComponent();

        }

        private bool mouseDown;

        private Point mouseXY;

        private double min = 0.1, max = 3.0;//最小/最大放大倍数

        private void Domousemove(ContentControl img, MouseEventArgs e)

        {

            if (e.LeftButton != MouseButtonState.Pressed)

            {

                return;

            }

            var group = IMG.FindResource("TfGroup") as TransformGroup;

            var transform = group.Children[] as TranslateTransform;

            var position = e.GetPosition(img);

            transform.X -= mouseXY.X - position.X;

            transform.Y -= mouseXY.Y - position.Y;

            mouseXY = position;

        }

        private void DowheelZoom(TransformGroup group, Point point, double delta)

        {

            var pointToContent = group.Inverse.Transform(point);

            var transform = group.Children[] as ScaleTransform;

            if (transform.ScaleX + delta < min) return;

            if (transform.ScaleX + delta > max) return;

            transform.ScaleX += delta;

            transform.ScaleY += delta;

            var transform1 = group.Children[] as TranslateTransform;

            transform1.X = - * ((pointToContent.X * transform.ScaleX) - point.X);

            transform1.Y = - * ((pointToContent.Y * transform.ScaleY) - point.Y);

        }

        private void ContentControl_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

        {

            var img = sender as ContentControl;

            if (img == null)

            {

                return;

            }

            img.CaptureMouse();

            mouseDown = true;

            mouseXY = e.GetPosition(img);

        }

        private void ContentControl_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)

        {

            var img = sender as ContentControl;

            if (img == null)

            {

                return;

            }

            img.ReleaseMouseCapture();

            mouseDown = false;

        }

        private void ContentControl_MouseMove(object sender, MouseEventArgs e)

        {

            var img = sender as ContentControl;

            if (img == null)

            {

                return;

            }

            if (mouseDown)

            {

                Domousemove(img, e);

            }

        }

        private void ContentControl_MouseWheel(object sender, MouseWheelEventArgs e)

        {

            var img = sender as ContentControl;

            if (img == null)

            {

                return;

            }

            var point = e.GetPosition(img);

            var group = IMG.FindResource("TfGroup") as TransformGroup;

            var delta = e.Delta * 0.001;

            DowheelZoom(group, point, delta);

        }

        private void OpenImg_Click(object sender, RoutedEventArgs e)

        {

            // 在WPF中， OpenFileDialog位于Microsoft.Win32名称空间

            Microsoft.Win32.OpenFileDialog dialog = new Microsoft.Win32.OpenFileDialog();

            dialog.Filter = "Files (*.png)|*.png|Files(*.jpg)|*.jpg";

            if (dialog.ShowDialog() == true)

            {

                //MessageBox.Show(dialog.FileName);

                this.IMG.Source = new BitmapImage(new Uri(dialog.FileName));

            }

        }

        private void Window_Loaded(object sender, RoutedEventArgs e)

        {

            setViewSize();

        }

        private void setViewSize()

        {

            mainScrollv.Width = this.ActualWidth;

            mainScrollv.Height = this.ActualHeight - ;

        }

        private void Window_SizeChanged(object sender, SizeChangedEventArgs e)

        {

            setViewSize();

        }

        private void txtMinSize_TextChanged(object sender, TextChangedEventArgs e)

        {

            this.min = double.Parse(txtMinSize.Text);

        }

        private void txtMaxSize_TextChanged(object sender, TextChangedEventArgs e)

        {

            this.max = double.Parse(txtMaxSize.Text);

        }

        private void Window_DragEnter(object sender, DragEventArgs e)

        {

            if (e.Data.GetDataPresent(DataFormats.FileDrop))

                e.Effects = DragDropEffects.Link;//WinForm中为e.Effect = DragDropEffects.Link

            else e.Effects = DragDropEffects.None;//WinFrom中为e.Effect = DragDropEffects.None

        }

        private void Window_Drop(object sender, DragEventArgs e)

        {

            string filename = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue().ToString();

            this.IMG.Source = new BitmapImage(new Uri(filename));

        }

    }

}

可将图片拖拽到窗口打开，Window_DragEnter里验证拖拽进来的文件是否可用，Window_Drop处理拖拽进来之后的事情

源码：http://files.cnblogs.com/files/huangli321456/PictureViewer.zip

代码参照：http://www.cnblogs.com/snake-hand/archive/2012/08/13/2636227.html

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