c# – 在Windows 8 Pro Tablet中使用WinAPI引发AccessViolationException

我正在尝试使用Magnification API为32位 Windows 8 Pro平板电脑编写一个可访问性应用程序.应用程序可以完全放大和缩小全屏,但是当放大时,点击事件会发送到未屏幕屏幕的错误位置,因此用户不能直接触摸他所看到的内容.

为了解决这个问题,我试过MagSetInputTransform(fSetInputTransform,rcSource,rcDest).它适用于64位Windows 8桌面,但是当我在平板电脑上测试时,我会收到以下错误：

System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
   at GTZoom.WinAPIMethods.MagSetInputTransform(Boolean fEnabled,RECT prcSource,RECT prcDest)
   at GTZoom.ZoomControl.SetInput(IntPtr hwndDlg,Boolean fSetInputTransform) in c:\Users\AlpayK\Desktop\GTMagnify\GTMagnify\ZoomControl.cs:line 113
   at GTZoom.ZoomControl.trackBar1_Scroll(Object sender,EventArgs e) in c:\Users\AlpayK\Desktop\GTMagnify\GTMagnify\ZoomControl.cs:line 37
   at System.Windows.Forms.TrackBar.OnScroll(EventArgs e)
   at System.Windows.Forms.TrackBar.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd,Int32 msg,IntPtr wparam,IntPtr lparam)

当我尝试编译x86目标平台的项目并在64位机器下测试时,获得了完全相同的错误.

总结一下

Target platform x64 -> Tested under 64bit Windows 8 Desktop    OK
Target platform x86 -> Tested under 64bit Windows 8 Desktop    ERROR
Target platform x64 -> Tested under 64bit Windows 8 Tablet     ERROR
Target platform x86 -> Tested under 32bit Windows 8 Tablet     ERROR ?

如何在32位Windows 8平板电脑中使用此WinAPI功能？

EDIT1

这是产生错误的方法：

void SetInput(IntPtr hwndDlg,bool fSetInputTransform)
        {
            bool fContinue = true;

            RECT rcSource = new RECT();
            RECT rcDest = new RECT();

            // MagSetInputTransform() is used to adjust pen and touch input to account for the current magnification.
            // The "Source" and "Destination" rectangles supplied to MagSetInputTransform() are from the perspective
            // of the currently magnified visuals. The source rectangle is the portion of the screen that is 
            // currently being magnified,and the destination rectangle is the area on the screen which shows the 
            // magnified results.

            // If we're setting an input transform,base the transform on the current fullscreen magnification.
            if (fSetInputTransform)
            {
                // Assume here the touch and pen input is going to the primary monitor.
                rcDest.Right = screenWidth;
                rcDest.Bottom = screenHeight;

                float magnificationFactor = 0;
                int xOffset = 0;
                int yOffset = 0;

                // Get the currently active magnification.
                if (WinAPIMethods.MagGetFullscreenTransform(ref magnificationFactor,ref xOffset,ref yOffset))
                {
                    // Determine the area of the screen being magnified.
                    rcSource.Left = xOffset;
                    rcSource.Top = yOffset;
                    rcSource.Right = rcSource.Left + (int)(rcDest.Right / magnificationFactor);
                    rcSource.Bottom = rcSource.Top + (int)(rcDest.Bottom / magnificationFactor);
                }
                else
                {
                    // An unexpected error occurred trying to get the current magnification.
                    fContinue = false;
                }
            }

            if (fContinue)
            {
                // Now set the input transform as required.
                if (!WinAPIMethods.MagSetInputTransform(fSetInputTransform,rcDest))
                {
                    MessageBox.Show("Err");
                }
            }
        }

EDIT2

以下是pinvoke签名：

[DllImport("Magnification.dll",CallingConvention = CallingConvention.StdCall)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool MagGetFullscreenTransform(ref float magLevel,ref int xOffset,ref int yOffset);

[DllImport("Magnification.dll",CallingConvention = CallingConvention.StdCall)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool MagSetInputTransform(bool fEnabled,RECT prcDest);

而this是我的RECT架构如何.

解决方法

WinAPIMethods.MagSetInputTransform(fSetInputTransform,rcDest)
WinAPIMethods.MagSetInputTransform(fSetInputTransform,ref rcSource,ref rcDest)

和pinvoke

public static extern bool MagSetInputTransform(bool fEnabled,RECT prcDest);
public static extern bool MagSetInputTransform(bool fEnabled,ref RECT prcSource,ref RECT prcDest);

MagSetInputTransform采用LPRECT,而不是RECT

我不能解释为什么它在一台机器上工作.