Accessing Java Access Bridge from C#
Using PInvoke, I can talk to the Access Bridge and connect to GUI events. When I get an event, I can get at the accessibility information, but when I return from the event handler, I get an AccessViolationException. Here's the code:
[DllImport("WindowsAccessBridge.dll")]
private externstaticvoid Windows_run();
[DllImport("WindowsAccessBridge.dll")]
private externstaticvoid setMouseClickedFP(MouseClickedDelegate fp);
[DllImport("WindowsAccessBridge.dll")]
private externstaticvoid releaseJavaObject(System.Int32 vmID, IntPtr javaObject);
[DllImport("WindowsAccessBridge.dll")]
private externstaticvoid getVersionInfo(System.Int32 vmID, out VersionInfo v);
delegatevoid MouseClickedDelegate(System.Int32 vmID, IntPtr jevent, IntPtr ac);
static MouseClickedDelegate mcd;// so delegate won't get gc'd
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct VersionInfo{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
string VMversion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
string bridgeJavaClassVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
string bridgeJavaDLLVersion;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 256)]
string bridgeWinDLLVersion;
}
privatestatic VersionInfo vi =new VersionInfo();
privatevoid button1_Click(object sender, EventArgs e)
{
Windows_run();
mcd =new MouseClickedDelegate(HandleMouseClicked);
setMouseClickedFP(mcd);
}
staticvoid HandleMouseClicked(System.Int32 vmID, IntPtr jevent, IntPtr ac){
getVersionInfo(vmID, out vi);
releaseJavaObject(vmID, ac);
releaseJavaObject(vmID, jevent);
}
If I put a breakpoint in the event handler, I get the version information just fine, and the releaseJavaObject calls both work. However, if I then continue, I get an AccessViolationException which points back to the Application.Run call in Main.
Strangely, if I define the event handler without parameters, it all works fine, although the event isn't terribly useful that way. This is probably something simple staring me in the face. What am I missing here?
