在.NET平台使用Google Earth COM API示例(02)

准备工作与注意事项同前一篇文章，现在我们来关注一些高级的内容。

本文将涉及到两个方面的内容。

1.跨平台调用，在C#中使用Windows API(从dll导入的函数)

2.将GE渲染窗口嵌入到C#的WinForm窗体中

第一部分，跨平台调用的代码

// Windows API调用using System;using System.Collections.Generic;using System.Text;using System.Runtime.InteropServices;namespace GEDemo2{    public class NativeMethods    {        [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]        public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, UInt32 uflags);        [DllImport("user32.dll", CharSet = CharSet.Auto)]        public static extern IntPtr PostMessage(int hWnd, int msg, int wParam, int lParam);        #region 预定义        public static readonly IntPtr   HWND_BOTTOM =          new IntPtr(1);        public static readonly IntPtr   HWND_NOTOPMOST = new IntPtr(-2);        public static readonly IntPtr   HWND_TOP =                   new IntPtr(0);        public static readonly IntPtr   HWND_TOPMOST =       new IntPtr(-1);        public static readonly UInt32 SWP_NOSIZE =                           1U;        public static readonly UInt32 SWP_NOMOVE =                        2U;        public static readonly UInt32 SWP_NOZORDER =                    4U;        public static readonly UInt32 SWP_NOREDRAW =                   8U;        public static readonly UInt32 SWP_NOACTIVATE =                16U;        public static readonly UInt32 SWP_FRAMECHANGED =         32U;        public static readonly UInt32 SWP_SHOWWINDOW =           64U;        public static readonly UInt32 SWP_HIDEWINDOW =            128U;        public static readonly UInt32 SWP_NOCOPYBITS =               256U;        public static readonly UInt32 SWP_NOOWNERZORDER =    512U;        public static readonly UInt32 SWP_NOSENDCHANGING = 1024U;        #endregion        public delegate int EnumWindowsProc(IntPtr hwnd, int lParam);        [DllImport("user32", CharSet = CharSet.Auto)]        public extern static IntPtr GetParent(IntPtr hWnd);        [DllImport("user32", CharSet = CharSet.Auto)]        public extern static bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);        [DllImport("user32", CharSet = CharSet.Auto)]        public extern static IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);        [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]        public static extern IntPtr GetWindow(IntPtr hWnd, int uCmd);        public static int GW_CHILD = 5;        public static int GW_HWNDNEXT = 2;    }}

这部分代码被称作"NativeMethods"，其中的一些method将会在第二部分中被引用

第二部分，窗体嵌入

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;using EARTHLib;namespace GEDemo2{    public partial class GEDemo2 : Form    {        static readonly Int32 WM_QUIT = 0x0012;        private IntPtr GEHMainWnd = (IntPtr)0;        private IntPtr GEHRenderWnd = (IntPtr)0;        private ApplicationGE GEApp;        public GEDemo2()        {            InitializeComponent();        }        //重写OnLoad比实现Form_Load更高效        protected override void OnLoad(EventArgs e)        {            base.OnLoad(e);            //启动GoogleEarth实例            GEApp = new ApplicationGE();            GEHMainWnd = (IntPtr)GEApp.GetMainHwnd();            //隐藏GoogleEarth主窗口            NativeMethods.SetWindowPos(GEHMainWnd, NativeMethods.HWND_BOTTOM,                0, 0, 0, 0,                NativeMethods.SWP_NOSIZE | NativeMethods.SWP_HIDEWINDOW);            GEHRenderWnd = (IntPtr)GEApp.GetRenderHwnd();            //将渲染窗口嵌入到主窗体            NativeMethods.MoveWindow(GEHRenderWnd, 0, 0, this.Width, this.Height, true);            NativeMethods.SetParent(GEHRenderWnd, this.Handle);        }        protected override void OnClosing(CancelEventArgs e)        {            base.OnClosing(e);            //关闭窗口            NativeMethods.PostMessage((int)GEHMainWnd, WM_QUIT, 0, 0);        }    }}

这部分就是主窗体的（非设计部分）的全部代码，运行结果如下

现在只是实现了第一部分（窗体嵌入），稍后将会陆续完善。敬请关注本博。

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