地图控件GMAP.NET

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深入理解最强桌面地图控件GMAP.NET --- 街景地图(StreetView)

很久没有更新博客了，今天无事把GMAP.NET的代码又重新翻了翻，看到了街景地图的例子。

街景地图是谷歌最早提出来的，我不知道谷歌的街景地图是如何实现的，在这个例子中，运用了WPF 3D的原理，对街景地图进行了简单的实现，在我看来更像是全景地图（PanoramaViewer)。先看看实现的效果，在本地运行代码的时候，鼠标拖动后整个图像是可以360旋转的，这里是张静态图片而已。

View Code

2. 图片的组织和加载

Window1.xaml则承担了图片的组织和加载工作，和大部分图片加载一样，也是先尝试从本地加载，本地没有，则从网上下载。这里的图片是由许多

小块组成的，看看图片文件夹的结构就清楚了。最后这些图片组成RenderTargetBitmap,赋给前面提到的PanoramaImage。

View Code

using System;
using System.ComponentModel;
using System.IO;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace Demo.StreetView
{
/// <summary>
/// Interaction logic for Window1.xaml
/// </summary>
public partial class Window1 : Window
{
BackgroundWorker loader = new BackgroundWorker();
StackPanel buff = new StackPanel();

public Window1()
{
InitializeComponent();
Viewer.MouseLeftButtonDown += Viewer_MouseLeftButtonDown;
Viewer.MouseMove += Viewer_MouseMove;

buff.Orientation = Orientation.Vertical;

// removes white lines between tiles!
SetValue(RenderOptions.EdgeModeProperty, EdgeMode.Aliased);

loader.DoWork += loader_DoWork;
loader.ProgressChanged += loader_ProgressChanged;
loader.RunWorkerCompleted += loader_RunWorkerCompleted;
loader.WorkerReportsProgress = true;
}

void loader_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
buff.UpdateLayout();

Canvas canvas = new Canvas();
canvas.Children.Add(buff);
canvas.Width = 512 * 13;
canvas.Height = 512 * 7;

canvas.UpdateLayout();

canvas.Measure(new Size((int)canvas.Width, (int)canvas.Height));
canvas.Arrange(new Rect(new Size((int)canvas.Width, (int)canvas.Height)));
int Height = ((int)(canvas.ActualHeight));
int Width = ((int)(canvas.ActualWidth));

RenderTargetBitmap _RenderTargetBitmap = new RenderTargetBitmap(Width, Height, 96, 96, PixelFormats.Pbgra32);
_RenderTargetBitmap.Render(buff);

Image img = new Image();
img.Source = _RenderTargetBitmap;

Viewer.PanoramaImage = _RenderTargetBitmap;

Title = "Demo.StreetView, enjoy! ;}";
}

Vector RotationVector = new Vector();
Point DownPoint = new Point();
void Viewer_MouseMove(object sender, MouseEventArgs e)
{
if(e.LeftButton == MouseButtonState.Released)
return;
Vector Offset = Point.Subtract(e.GetPosition(Viewer), DownPoint) * 0.25;

Viewer.RotationY = RotationVector.Y + Offset.X;
Viewer.RotationX = RotationVector.X - Offset.Y;
}

void Viewer_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DownPoint = e.GetPosition(Viewer);
RotationVector.X = Viewer.RotationX;
RotationVector.Y = Viewer.RotationY;
Cursor = Cursors.SizeAll;
}

private void Viewer_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
Cursor = Cursors.Arrow;
}

void loader_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
if(e.ProgressPercentage == 100)
{
Pass p = e.UserState as Pass;

Title = "Demo.StreetView, please wait on first time loading: " + p.X + "|" + p.Y + " of 13";
Image i = new Image();

i.Source = p.src;
(buff.Children[buff.Children.Count - 1] as StackPanel).Children.Add(i);
}
else if(e.ProgressPercentage == 0)
{
Title = "Demo.StreetView, please wait on first time loading: zooming...";

StackPanel ph = new StackPanel();
ph.Orientation = Orientation.Horizontal;
buff.Children.Add(ph);
}
}

void loader_DoWork(object sender, DoWorkEventArgs e)
{
string panoId = "4fe6hEN9GJC6thoQBcgv0Q";
int zoom = 4;

//0, 1
//1, 2
//2, 4
//3, 7
//4, 13
//5, 26

for(int y = 0; y <= zoom + 1; y++)
{
loader.ReportProgress(0);

for(int x = 0; x < 13; x++)
{
Pass p = new Pass();
p.Y = y;
p.X = x;

string fl = "Tiles\\" + zoom + "\\" + panoId + "\\img_" + x + "_" + y + ".jpg";
string dr = System.IO.Path.GetDirectoryName(fl);
if(!Directory.Exists(dr))
{
Directory.CreateDirectory(dr);
}
if(!File.Exists(fl))
{
ImageSource src = Get(string.Format("http://cbk{0}.{5}/cbk?output=tile&panoid={1}&zoom={2}&x={3}&y={4}&cb_client=maps_sv", (x + 2 * y) % 3, panoId, zoom, x, y, GMap.NET.MapProviders.GoogleMapProvider.Instance.Server));
p.src = src;
SaveImg(src, fl);
}
else
{
using(Stream s = File.OpenRead(fl))
{
p.src = FromStream(s);
}
}

loader.ReportProgress(100, p);
}
}

GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
}

void SaveImg(ImageSource src, string file)
{
using(Stream s = File.OpenWrite(file))
{
JpegBitmapEncoder e = new JpegBitmapEncoder();
e.Frames.Add(BitmapFrame.Create(src as BitmapSource));
e.Save(s);
}
}

private void Window_Loaded(object sender, RoutedEventArgs e)
{
loader.RunWorkerAsync();
}

public Stream CopyStream(Stream inputStream)
{
const int readSize = 256;
byte[] buffer = new byte[readSize];
MemoryStream ms = new MemoryStream();

using(inputStream)
{
int count = inputStream.Read(buffer, 0, readSize);
while(count > 0)
{
ms.Write(buffer, 0, count);
count = inputStream.Read(buffer, 0, readSize);
}
}
buffer = null;
ms.Seek(0, SeekOrigin.Begin);
return ms;
}

ImageSource FromStream(Stream stream)
{
ImageSource ret = null;
if(stream != null)
{
{
// try png decoder
try
{
JpegBitmapDecoder bitmapDecoder = new JpegBitmapDecoder(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
ImageSource m = bitmapDecoder.Frames[0];

if(m != null)
{
ret = m;
}
}
catch
{
ret = null;
}

// try jpeg decoder
if(ret == null)
{
try
{
stream.Seek(0, SeekOrigin.Begin);

PngBitmapDecoder bitmapDecoder = new PngBitmapDecoder(stream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
ImageSource m = bitmapDecoder.Frames[0];

if(m != null)
{
ret = m;
}
}
catch
{
ret = null;
}
}
}
}
return ret;
}

ImageSource Get(string url)
{
ImageSource ret;

try
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.ServicePoint.ConnectionLimit = 50;
request.Proxy = WebRequest.DefaultWebProxy;

request.UserAgent = "Opera/9.62 (Windows NT 5.1; U; en) Presto/2.1.1";
request.Timeout = 10 * 1000;
request.ReadWriteTimeout = request.Timeout * 6;
request.Referer = string.Format("http://maps.{0}/", GMap.NET.MapProviders.GoogleMapProvider.Instance.Server);
request.KeepAlive = true;

using(HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
using(Stream responseStream = CopyStream(response.GetResponseStream()))
{
ret = FromStream(responseStream);
}
}
}
catch(Exception)
{
ret = null;
}
return ret;
}
}

class Pass
{
public ImageSource src;
public int Y;
public int X;
}
}

整个代码在http://code.google.com/p/ypmap/source/browse/可以看到。