1.WebRTC 实现 Android 传屏 demo
2.VB 关于系统托盘显示数字

WebRTC 实现 Android 传屏 demo

       WebRTC是一项实时通讯技术，允许网络应用或站点在浏览器之间不借助中间媒介实现点对点的连接，传输视频流、音频流或其他任意数据。在Android平台上集成WebRTC框架，可以实现强大的北京企业培训系统源码音视频传输功能，只需简洁的代码即可。

       为了实现Android平台的WebRTC demo，并实现两端局域网传屏功能，我们需要搭建相关环境和配置。首先，通过导入WebRTC官方的aar包，方便地引入官方提供的so与java层sdk代码。若需要自行编译aar，可以参考官方源码中的脚本生成本地aar或发布到maven仓库。

       在使用PeerConnectionFactory之前，必须进行全局初始化与资源加载，通过调用静态方法initialize()并传入InitializationOptions进行配置。完成初始化后，可以创建PeerConnectionFactory实例，这个工厂类在后续的github android项目源码音视频采集、编解码等操作中扮演重要角色。通过Builder模式进行初始化，方便设置编解码器。

       创建PeerConnection对象是点对点连接的起点，它可以从远端获取音视频流等数据。在创建之前，可以通过RTCConfiguration对连接进行详细配置。同时，通过Factory创建音视频数据源，如AudioSource和VideoSource，mfc 网页源码下载但数据来源需在外部实现，如从音频设备捕获或通过特定接口获取视频流。

       对于视频流，WebRTC提供了多种获取方式，如ScreenCapturerAndroid、CameraCapturer和FileVideoCapturer。通过startCapture()方法开始获取数据，并通过CapturerObserver进行回调。创建VideoTrack和AudioTrack后，通过PeerConnection添加到连接中，仿站长下载 源码以便生成包含相应媒体信息的SDP。

       建立信令服务器是交换SDP信息的关键步骤。对于局域网场景，可直接使用java Socket实现TCPChannelClient。在进行媒体协商前，需要交换编解码器、传输协议等信息，确保双方支持后，连接才能成功建立。

       媒体协商过程包括创建Offer和Answer SDP，pdf417 源码由呼叫方发起Offer请求，被呼叫方接收并创建Answer回复。当协商成功后，PeerConnection会尝试进行连接，优先选择host方式实现内网间连通。

       在点对点连接建立后，开始获取音视频流数据。通过onAddStream()回调接收远端的MediaStream对象，其中包含AudioTracks与VideoTracks。通过addSink()与SurfaceViewRenderer绑定，展示远端视频流。

       在WebRTC中，JavaAudioDeviceModule用于实现音视频的录制与播放，底层采用AudioRecord和AudioTrack。创建PeerConnectionFactory时设置AudioDeviceModule即可。

       DataChannel专门用于传输音视频流外的数据，如实时文字聊天、文件传输等。通过DataChannel.send()方法相互发送数据，onMessage()回调获取远端发送的数据。DataChannel的创建方式包括In-band与Out-of-band协商，后者在绑定ID一致时更为简便。

VB 关于系统托盘显示数字

       把数字0-9做成.

       0-9的直接显,或用拉伸(难看点)

       >的用隐藏的控件拼合所需再另存成图(抓图代码)调用.

       一个导向,明白了就行

       select Case的确是不够意思......:)

       ------------------------------------

       -3-3

       合成嘛,还是不给代码:P

       你会在image中画东西吧?在界面上输出文字做个什么定位的没问题吧?,让他们重叠没问题吧? 屏幕截图会不会?(CaptureWindow函数以及CreateBitmapPicture函数,ExtractIcon函数).

       ----------------------

       下面转一段截图文章

       ---------------------

       大家知道在VB下利用API函数Bitblt可以将屏幕或者窗口上的图象拷贝到VB中的PictureBox对象中,但是如果简单的利用PictureBox的SavePicture函数来保存图象，会发现什么也保存不了。这篇文章就是介绍如何捕获并利用Windows下的OLE API函数保存图象。

        首先来看源程序，首先建立一个新的工程文件，然后在Form1中加入5个CommandButton对象和一个PictureBox对象，然后在Form1中加入以下代码：

       Option Explicit

       Option Base 0

       Private Type PALETTEENTRY

        peRed As Byte

        peGreen As Byte

        peBlue As Byte

        peFlags As Byte

       End Type

       Private Type LOGPALETTE

        palVersion As Integer

        palNumEntries As Integer

        palPalEntry() As PALETTEENTRY

       End Type

       Private Type GUID

        Data1 As Long

        Data2 As Integer

        Data3 As Integer

        Data4(7) As Byte

       End Type

       Private Const RASTERCAPS As Long =

       Private Const RC_PALETTE As Long = &H

       Private Const SIZEPALETTE As Long =

       Private Type RECT

        Left As Long

        Top As Long

        Right As Long

        Bottom As Long

       End Type

       Private Declare Function CreateCompatibleDC Lib "GDI" (ByVal hDC As Long) As Long

       Private Declare Function CreateCompatibleBitmap Lib "GDI" (ByVal hDC As Long, _

        ByVal nWidth As Long, ByVal nHeight As Long) As Long

       Private Declare Function GetDeviceCaps Lib "GDI" (ByVal hDC As Long, ByVal _

        iCapabilitiy As Long) As Long

       Private Declare Function GetSystemPaletteEntries Lib "GDI" (ByVal hDC As Long, _

        ByVal wStartIndex As Long, ByVal wNumEntries As Long, lpPaletteEntries _

        As PALETTEENTRY) As Long

       Private Declare Function CreatePalette Lib "GDI" (lpLogPalette As LOGPALETTE) _

        As Long

       Private Declare Function SelectObject Lib "GDI" (ByVal hDC As Long, ByVal hObject _

        As Long) As Long

       Private Declare Function BitBlt Lib "GDI" (ByVal hDCDest As Long, ByVal XDest As _

        Long, ByVal YDest As Long, ByVal nWidth As Long, ByVal nHeight As Long, _

        ByVal hDCSrc As Long, ByVal XSrc As Long, ByVal YSrc As Long, ByVal dwRop _

        As Long) As Long

       Private Declare Function DeleteDC Lib "GDI" (ByVal hDC As Long) As Long

       Private Declare Function GetForegroundWindow Lib "USER" () As Long

       Private Declare Function SelectPalette Lib "GDI" (ByVal hDC As Long, ByVal hPalette _

        As Long, ByVal bForceBackground As Long) As Long

       Private Declare Function RealizePalette Lib "GDI" (ByVal hDC As Long) As Long

       Private Declare Function GetWindowDC Lib "USER" (ByVal hWnd As Long) As Long

       Private Declare Function GetDC Lib "USER" (ByVal hWnd As Long) As Long

       Private Declare Function GetWindowRect Lib "USER" (ByVal hWnd As Long, lpRect As _

        RECT) As Long

       Private Declare Function ReleaseDC Lib "USER" (ByVal hWnd As Long, ByVal hDC As _

        Long) As Long

       Private Declare Function GetDesktopWindow Lib "USER" () As Long

       Private Type PicBmp

        Size As Long

        Type As Long

        hBmp As Long

        hPal As Long

        Reserved As Long

       End Type

       Private Declare Function OleCreatePictureIndirect Lib "olepro.dll" (PicDesc As _

        PicBmp, RefIID As GUID, ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long

       '捕捉整个屏幕

       Private Sub Command1_Click()

        Set Picture1.Picture = CaptureScreen()

       End Sub

       '在两秒钟后捕捉当前的活动窗口

       Private Sub Command2_Click()

        MsgBox "当你关闭这个对话框两秒钟之后程序会捕捉处于活动状态的窗口."

        '等待两秒钟

        Dim EndTime As Date

        EndTime = DateAdd("s", 2, Now)

        Do Until Now > EndTime

        DoEvents

        Loop

        Set Picture1.Picture = CaptureActiveWindow()

        Me.SetFocus

       End Sub

       Private Sub Command3_Click()

        Set Picture1.Picture = Nothing

       End Sub

       Public Function CreateBitmapPicture(ByVal hBmp As Long, ByVal hPal As Long) As Picture

        Dim r As Long

        Dim Pic As PicBmp

        Dim IPic As IPicture

        Dim IID_IDispatch As GUID

        '填充IDispatch界面

        With IID_IDispatch

        .Data1 = &H

        .Data4(0) = &HC0

        .Data4(7) = &H

        End With

        '填充Pic

        With Pic

        .Size = Len(Pic) ' Pic结构长度

        .Type = vbPicTypeBitmap ' 图象类型

        .hBmp = hBmp ' 位图句柄

        .hPal = hPal ' 调色板句柄

        End With

        '建立Picture图象

        r = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)

        '返回Picture对象

        Set CreateBitmapPicture = IPic

       End Function

       Public Function CaptureWindow(ByVal hWndSrc As Long, ByVal Client As Boolean, ByVal _

        LeftSrc As Long, ByVal TopSrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc _

        As Long) As Picture

        Dim hDCMemory As Long

        Dim hBmp As Long

        Dim hBmpPrev As Long

        Dim r As Long

        Dim hDCSrc As Long

        Dim hPal As Long

        Dim hPalPrev As Long

        Dim RasterCapsScrn As Long

        Dim HasPaletteScrn As Long

        Dim PaletteSizeScrn As Long

        Dim LogPal As LOGPALETTE

        If Client Then

        hDCSrc = GetDC(hWndSrc)

        Else

        hDCSrc = GetWindowDC(hWndSrc)

        End If

        hDCMemory = CreateCompatibleDC(hDCSrc)

        hBmp = CreateCompatibleBitmap(hDCSrc, WidthSrc, HeightSrc)

        hBmpPrev = SelectObject(hDCMemory, hBmp)

        '获得屏幕属性

        RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS)

        HasPaletteScrn = RasterCapsScrn And RC_PALETTE

        PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE)

        '如果屏幕对象有调色板则获得屏幕调色板

        If HasPaletteScrn And (PaletteSizeScrn = ) Then

        '建立屏幕调色板的拷贝

        LogPal.palVersion = &H

        LogPal.palNumEntries =

        r = GetSystemPaletteEntries(hDCSrc, 0, , LogPal.palPalEntry(0))

        hPal = CreatePalette(LogPal)

        '将新建立的调色板选如建立的内存绘图句柄中

        hPalPrev = SelectPalette(hDCMemory, hPal, 0)

        r = RealizePalette(hDCMemory)

        End If

        '拷贝图象

        r = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hDCSrc, LeftSrc, TopSrc, vbSrcCopy)

        hBmp = SelectObject(hDCMemory, hBmpPrev)

        If HasPaletteScrn And (PaletteSizeScrn = ) Then

        hPal = SelectPalette(hDCMemory, hPalPrev, 0)

        End If

        '释放资源

        r = DeleteDC(hDCMemory)

        r = ReleaseDC(hWndSrc, hDCSrc)

        Set CaptureWindow = CreateBitmapPicture(hBmp, hPal)

       End Function

       'capturescreen函数捕捉整个屏幕图象

       Public Function CaptureScreen() As Picture

        Dim hWndScreen As Long

        '获得桌面的窗口句柄

        hWndScreen = GetDesktopWindow()

        Set CaptureScreen = CaptureWindow(hWndScreen, False, 0, 0, Screen.Width _

        \ Screen.TwipsPerPixelX, Screen.Height \ Screen.TwipsPerPixelY)

       End Function

       Public Function CaptureActiveWindow() As Picture

        Dim hWndActive As Long

        Dim r As Long

        Dim RectActive As RECT

        hWndActive = GetForegroundWindow()

        r = GetWindowRect(hWndActive, RectActive)

        Set CaptureActiveWindow = CaptureWindow(hWndActive, False, 0, 0, _

        RectActive.Right - RectActive.Left, RectActive.Bottom - RectActive.Top)

       End Function

       Public Sub PrintPictureToFitPage(Prn As Printer, Pic As Picture)

        Const vbHiMetric As Integer = 8

        Dim PicRatio As Double

        Dim PrnWidth As Double

        Dim PrnHeight As Double

        Dim PrnRatio As Double

        Dim PrnPicWidth As Double

        Dim PrnPicHeight As Double

        If Pic.Height >= Pic.Width Then

        Prn.Orientation = vbPRORPortrait

        Else

        Prn.Orientation = vbPRORLandscape

        End If

        PicRatio = Pic.Width / Pic.Height

        PrnWidth = Prn.ScaleX(Prn.ScaleWidth, Prn.ScaleMode, vbHiMetric)

        PrnHeight = Prn.ScaleY(Prn.ScaleHeight, Prn.ScaleMode, vbHiMetric)

        PrnRatio = PrnWidth / PrnHeight

        If PicRatio >= PrnRatio Then

        PrnPicWidth = Prn.ScaleX(PrnWidth, vbHiMetric, Prn.ScaleMode)

        PrnPicHeight = Prn.ScaleY(PrnWidth / PicRatio, vbHiMetric, Prn.ScaleMode)

        Else

        PrnPicHeight = Prn.ScaleY(PrnHeight, vbHiMetric, Prn.ScaleMode)

        PrnPicWidth = Prn.ScaleX(PrnHeight * PicRatio, vbHiMetric, Prn.ScaleMode)

        End If

        Prn.PaintPicture Pic, 0, 0, PrnPicWidth, PrnPicHeight

       End Sub

       Private Sub Command4_Click()

        CommonDialog1.DefaultExt = ".BMP"

        CommonDialog1.Filter = "Bitmap Image (*.bmp)|*.bmp"

        CommonDialog1.ShowSave

        If CommonDialog1.FileName <> "" Then

        SavePicture Picture1.Picture, CommonDialog1.FileName

        End If

       End Sub

       Private Sub Command5_Click()

        PrintPictureToFitPage Printer, Picture1.Picture

        Printer.EndDoc

       End Sub

       Private Sub Form_Load()

        Command1.Caption = "捕捉整个屏幕"

        Command2.Caption = "两秒钟后捕捉活动窗口"

        Command3.Caption = "清除图象"

        Command4.Caption = "保存图象"

        Command5.Caption = "打印图象"

       End Sub

        运行程序，点击command1或者Command2就可以捕捉成个屏幕或者窗口到Picture1中，然后点击Command4或者Command5就可以保存或打印图象。

        上面的程序中最重要的是CaptureWindow函数以及CreateBitmapPicture函数，CaptureWindow函数建立与要捕捉的窗口的绘图设备（Device Context）句柄相兼容的绘图设备（Device Context）句柄，然后建立相应的调色板，最后将绘图设备（Device Context）中的图象拷贝到一个hBitmap对象句柄中。CreateBitmapPicture函数则根据传递过来的hBitmap对象句柄和调色板句柄建立一个Picture对象。在将这个对象赋予PictureBox的Picture属性，然后就可以使用SavePicture函数来保存图象了。

        OleCreatePictureIndirect函数支持的不仅有BMP图象，同时也支持Ico图标，所以利用该函数和ExtractIcon函数也可以提取并保存Windows文件中的图标。有兴趣的读者可以到我的主页/~blackcat上下载源程序。