silverlight：手写板/涂鸦/墨迹/InkPresenter示例程序

这种应用现在已经比较常见了，比如论坛回贴中的手写功能，IM聊天中的个性化手写文字，个性签名等，在Silverlight中要实现该功能其实非常简单，只要一个InkPresenter控件即可

使用要点:

1.要合理设置裁剪区，否则手写时可能笔划会写到你不希望出现的地方.
2.处理好MouseLeftButtonDown,MouseMove,LostMouseCapture这三个事件.

演示代码：

前端Xaml部分:

by 菩提树下的杨过 http://yjmyzz.cnblogs.com/

后端代码：

by 菩提树下的杨过 http://yjmyzz.cnblogs.com/

using System.Windows;
using System.Windows.Controls;
using System.Collections.Generic;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Windows.Browser;
using System.Windows.Media.Imaging;
using System.IO;
using FluxJpeg.Core;

namespace InkPresenterTest
{
    public partial class Page : UserControl
    {
        Stroke _drawStroke;

        List<FillColor> lstFillColor;
        List<SizeData> lstSizeData;
        List<OpacityData> lstOpacityData;

        bool _isLoaded = false;

        public Page()
        {
            InitializeComponent();

            //初始化数据
            lstFillColor = new List<FillColor>() {
                new FillColor(){ Color = new SolidColorBrush(Colors.Black), Name="黑色"},
                new FillColor(){ Color = new SolidColorBrush(Colors.Red), Name="红色"},
                new FillColor(){ Color = new SolidColorBrush(Colors.Blue), Name="蓝色"},
                new FillColor(){ Color = new SolidColorBrush(Colors.Green),Name="绿色"},
                new FillColor(){ Color = new SolidColorBrush(Colors.Magenta), Name="洋红"},
                new FillColor(){ Color = new SolidColorBrush(Colors.Orange), Name="橙色"},
            };

            lstSizeData = new List<SizeData>()
            {
                new SizeData(){ Size=1.0},
                new SizeData(){ Size=3.0},
                new SizeData(){ Size=5.0},
                new SizeData(){ Size=7.0},
                new SizeData(){ Size=9.0},
                new SizeData(){ Size=11.0},
                new SizeData(){ Size=13.0},
                new SizeData(){ Size=15.0}

            };

            lstOpacityData = new List<OpacityData>(){
                new OpacityData(){ Value=0.1},
                new OpacityData(){ Value=0.2},
                new OpacityData(){ Value=0.3},
                new OpacityData(){ Value=0.4},
                new OpacityData(){ Value=0.5},
                new OpacityData(){ Value=0.6},
                new OpacityData(){ Value=0.7},
                new OpacityData(){ Value=0.8},
                new OpacityData(){ Value=0.9},
                new OpacityData(){ Value=1.0}
            };

            this.Loaded += new RoutedEventHandler(Page_Loaded);
        }

        void Page_Loaded(object sender, RoutedEventArgs e)
        {
            this.cboColor.ItemsSource = lstFillColor;
            this.cboColor.SelectedIndex = 0;

            this.cboOutlineColor.ItemsSource = lstFillColor;
            this.cboOutlineColor.SelectedIndex = 0;

            this.cboWidth.ItemsSource = lstSizeData;
            this.cboWidth.SelectedIndex = 0;

            this.cboHeight.ItemsSource = lstSizeData;
            this.cboHeight.SelectedIndex = 0;

            this.cboOpactiy.ItemsSource = lstOpacityData;
            this.cboOpactiy.SelectedIndex = 5;

            _isLoaded = true;
        }

        private void OnMouseLeftButtonDown(object sender, MouseEventArgs e)
        {
            ink.CaptureMouse();
            StylusPointCollection MyStylusPointCollection = new StylusPointCollection();
            MyStylusPointCollection.Add(e.StylusDevice.GetStylusPoints(ink));
            _drawStroke = new Stroke(MyStylusPointCollection);
            _drawStroke.DrawingAttributes.Color = (cboColor.SelectedItem as FillColor).Color.Color;
            _drawStroke.DrawingAttributes.OutlineColor = (this.cboOutlineColor.SelectedItem as FillColor).Color.Color;
            _drawStroke.DrawingAttributes.Width = (this.cboWidth.SelectedItem as SizeData).Size;
            _drawStroke.DrawingAttributes.Height = (this.cboHeight.SelectedItem as SizeData).Size;
            //_drawStroke.SetValue(OpacityProperty, (this.cboOpactiy.SelectedItem as OpacityData).Value);
            ink.Strokes.Add(_drawStroke);
            ink.Opacity = (cboOpactiy.SelectedItem as OpacityData).Value;
        }

        private void OnMouseMove(object sender, MouseEventArgs e)
        {
            if (_drawStroke != null)
            {
                _drawStroke.StylusPoints.Add(e.StylusDevice.GetStylusPoints(ink));
            }
        }

        private void OnLostMouseCapture(object sender, MouseEventArgs e)
        {
            _drawStroke = null;
        }

        private void btnClear_Click(object sender, System.Windows.RoutedEventArgs e)
        {
            ink.Strokes.Clear();
        }

        private void cboOpactiy_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
        {
            if (_isLoaded)
            {
                ink.Opacity = (cboOpactiy.SelectedItem as OpacityData).Value;
            }
        }

        private void btnToogleBg_Click(object sender, RoutedEventArgs e)
        {
            Button btn = (sender as Button);
            if (btn.Content.ToString() == "隐藏背景图")
            {
                imgBg.Visibility = Visibility.Collapsed;
                btn.Content = "显示背景图";
            }
            else
            {
                imgBg.Visibility = Visibility.Visible;
                btn.Content = "隐藏背景图";
            }
        }

        private void btnToogleBgRect_Click(object sender, RoutedEventArgs e)
        {
            Button btn = (sender as Button);
            if (btn.Content.ToString() == "隐藏背景色")
            {
                this.rectBg.Visibility = Visibility.Collapsed;
                btn.Content = "显示背景色";
            }
            else
            {
                rectBg.Visibility = Visibility.Visible;
                btn.Content = "隐藏背景色";
            }
        }

        private void TextBlock_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            HtmlPage.Window.Navigate(new System.Uri("http://yjmyzz.cnblogs.com/"), "_blank");
        }

        private void btnSave_Click(object sender, RoutedEventArgs e)
        {
            // 创建一个WriteableBitmap并且把需要呈现位图的元素赋值给WriteableBitmap
            WriteableBitmap wb = new WriteableBitmap(inkC, null);

            // 创建一个Image元素来承载位图
            System.Windows.Controls.Image image = new System.Windows.Controls.Image();
            image.Height = 120;
            image.Margin = new Thickness(5);
            image.Source = wb;

            // 将Image元素放入容器控件中
            thumbs.Children.Add(image);

            ScreenshotViewer.ScrollToHorizontalOffset(ScreenshotViewer.ExtentWidth);

        }

        private void btnClearSave_Click(object sender, RoutedEventArgs e)
        {
            thumbs.Children.Clear();
        }

        private void btnSaveLocal_Click(object sender, RoutedEventArgs e)
        {
            WriteableBitmap wb = new WriteableBitmap(inkC, null);

            if (wb != null)
            {
                SaveFileDialog saveDlg = new SaveFileDialog();
                saveDlg.Filter = "JPEG Files (*.jpeg)|*.jpeg";
                saveDlg.DefaultExt = ".jpeg";

                if (saveDlg.ShowDialog().Value)
                {
                    using (Stream fs = saveDlg.OpenFile())
                    {
                        SaveToFile(wb, fs);
                        MessageBox.Show(string.Format("文件已经保存至“{0}”",saveDlg.SafeFileName));
                    }
                }
            }

        }

        private void SaveToFile(WriteableBitmap bitmap, Stream fs)
        {
            int width = bitmap.PixelWidth;
            int height = bitmap.PixelHeight;
            int bands = 3;
            byte[][,] raster = new byte[bands][,];

            for (int i = 0; i < bands; i++)
            {
                raster[i] = new byte[width, height];
            }

            for (int row = 0; row < height; row++)
            {
                for (int column = 0; column < width; column++)
                {
                    int pixel = bitmap.Pixels[width * row + column];
                    raster[0][column, row] = (byte)(pixel >> 16);
                    raster[1][column, row] = (byte)(pixel >> 8);
                    raster[2][column, row] = (byte)pixel;
                }

            }

            FluxJpeg.Core.ColorModel model = new FluxJpeg.Core.ColorModel { colorspace = FluxJpeg.Core.ColorSpace.RGB };
            FluxJpeg.Core.Image img = new FluxJpeg.Core.Image(model, raster);

            //Encode the Image as a JPEG
            MemoryStream stream = new MemoryStream();
            FluxJpeg.Core.Encoder.JpegEncoder encoder = new FluxJpeg.Core.Encoder.JpegEncoder(img, 100, stream);
            encoder.Encode();

            //Back to the start
            stream.Seek(0, SeekOrigin.Begin);

            //Get teh Bytes and write them to the stream
            byte[] binaryData = new byte[stream.Length];
            long bytesRead = stream.Read(binaryData, 0, (int)stream.Length);
            fs.Write(binaryData, 0, binaryData.Length);
        }

    }

    public class FillColor
    {
        public SolidColorBrush Color { set; get; }
        public string Name { set; get; }
    }

    public class SizeData
    {
        public double Size { set; get; }
    }

    public class OpacityData
    {
        public double Value { set; get; }
    }
}

源代码下载地址: https://files.cnblogs.com/yjmyzz/InkPresenterTest.rar

对Flash感兴趣的朋友，做为对比，也可以看下Flash/Flex学习笔记(14)：制作涂鸦板

转载请注明来自菩提树下的杨过 http://www.cnblogs.com/yjmyzz/archive/2010/01/14/1647636.html

注：里面用到了一个开源的组件FJCore

作者：菩提树下的杨过
出处：http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。