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Java Forum / Virtual Machine / May 2005Interfacing with applet
I am running WinXP and have a win32 application which is monitoring IE (running a java applet). I want to extract info rendered by a java applet. I can find the window's handle, but don't know quite how to get at the info in the sunawtcanvas. Are there any examples which illustrate this? When an applet updates its java.applet.canvas, does the JVM call native Windows API to display text on a screen, or does it position the fonts on the canvas (what I think). When the applet needs memory, does jvm do some sort of malloc via a direct call to a C run-time lib? In general, does the JVM directly call the Win32 API or does it have its own interface? I was reading the JNI documentation, but can't make sense of enough of this. Any sites which discuss this topic. I understand that the java API does most of what the Win32 api does. But how does the JVM actually render an image. It must talk to the hardware at some point, in order to display the image. It must have some rudimentary understanding of a windows handle and the graphics drivers, as well as limits on it size and bitdepths. >I am running WinXP and have a win32 application which is monitoring IE > (running a java applet). [quoted text clipped - 9 lines] > I was reading the JNI documentation, but can't make sense of enough of > this. Any sites which discuss this topic. Of course you can always look in the SCSL sources how everything is done. I have my Win32 application and IE running a java applet. My application gets the hWnd of IE and its children hWnd's . Using spy++ you can see this hierarchy as IEFrame ->WorkerW --->WorkerW ----->msctls status bar32 ----->Shell DocObjectViewer ------->Internet Explorer_Server --------->JavaPluginControlwindow ----------->java.plugin.viewer.IExplorerEmbeddedFrame ------------->sunawtcanvas --------------->sunawtcanvas Does anyone know why MS's IE has two sunawtcanvas's. My guess is that the first one of these is the sunawtcomponent. Is that true? Given the sunawtcanvas HWND, can I ----------subclass.cpp------------ int subclass( HWND& hWndSunAwtCanvas2) { // jobject graphics; int iRc=0; #ifdef _USEJVM try { JavaVM *jvm; jsize mySize; jint status = JNI_GetCreatedJavaVMs( &jvm, mySize, &mySize); if (JNI_ERR==status) { OutputDebugString("failed in JNI_CreateJavaVM\n"); iRc=-5; } else { JNIEnv* env ; jint status2 = JNI_GetDefaultJavaVMInitArgs((void**)&env); if (JNI_ERR==status2) { OutputDebugString("failed in JNI_GetDefaultJavaVMInitArgs\n"); iRc=-9; } else { JAWT awt; jobject canvas=(jobject) hWndSunAwtCanvas2; // Get the AWT awt.version = JAWT_VERSION_1_4; jboolean result; result = JAWT_GetAWT(env, &awt);// need to get the awt from IE, not your local version if (result == JNI_FALSE){ OutputDebugString("AWT Not Found\n"); iRc=-8; } else { JAWT_DrawingSurface* ds; JavaVMOption options[1]; JavaVMInitArgs vm_args; //JNIEnv_ myJNIEnv;// need to init this?? memset( &vm_args, 0, sizeof(vm_args)); vm_args.version = JNI_VERSION_1_4; vm_args.nOptions = 1; vm_args.options = options; // Get the drawing surface ds = awt.GetDrawingSurface(env, canvas); if (ds == NULL){ OutputDebugString("NULL drawing surface\n"); iRc=-3; } else { jint lock; // Lock the drawing surface lock = ds->Lock(ds); if ((lock & JAWT_LOCK_ERROR) != 0){ OutputDebugString("Error locking surface\n"); iRc=-2; } else { //try JAWT_DrawingSurfaceInfo* dsi; // Get the drawing surface info dsi = ds->GetDrawingSurfaceInfo(ds); if (dsi == NULL){ OutputDebugString("Error getting surface info\n"); iRc=-6; } else { JAWT_Win32DrawingSurfaceInfo* dsi_win; // Get the platform-specific drawing info dsi_win = (JAWT_Win32DrawingSurfaceInfo*)dsi->platformInfo; if (dsi_win == NULL){ OutputDebugString("Error getting platform-specific drawing info\n"); iRc=-7; } else { ////////////////////////////// // !!! DO PAINTING HERE !!! // ////////////////////////////// //dsi_win. //jint ret = reinterpret_cast<jint>(dsiwin->hwnd); if (hWndSunAwtCanvas2==dsi_win->hwnd) { playDIB3(dsi_win->hwnd); } else{ OutputDebugString("Error dsi_win->hwnd\n"); }// // Free the drawing surface info ds->FreeDrawingSurfaceInfo(dsi); }// // // Unlock the drawing surface ds->Unlock(ds); } }// // Free the drawing surface awt.FreeDrawingSurface(ds); }// jvm->DetachCurrentThread(); } }//JAWT_GetAWT }//JNI_CreateJavaVM } catch(...){ OutputDebugString("Exception caught\n"); throw; } return iRc; } ------------eof---------------------- Now, I want to subclass the java applet through the use of JNI like this example from sun's jni. ----------------------WindowUtil.java import java.awt.*; import javax.swing.*; public class WindowUtil extends Canvas { static { System.load("c:\\mylib.dll"); } public native void flashInTaskBar(Component c, boolean flash); public void flash(final JFrame frame, final int intratime, final int intertime, final int count) { new Thread(new Runnable() { public void run() { try { // flash on and off each time for(int i=0; i<count; i++) { flashInTaskBar(frame,true); Thread.sleep(intratime); flashInTaskBar(frame,true); Thread.sleep(intertime); } // turn the flash off flashInTaskBar(frame,false); } catch (Exception ex) { System.out.println(ex.getMessage()); } }}).start(); } } ------------eof---------------------- ----------myutil.c --------------------- JNIEXPORT void JNICALL Java_flash_WindowUtil_flashInTaskBar (JNIEnv *env, jobject canvas, jobject component, jboolean flash) { JAWT awt; JAWT_DrawingSurface* ds; JAWT_DrawingSurfaceInfo* dsi; JAWT_Win32DrawingSurfaceInfo* dsi_win; jboolean result; jint lock; // Get the AWT awt.version = JAWT_VERSION_1_3; result = JAWT_GetAWT(env, &awt); assert(result != JNI_FALSE); // Get the drawing surface ds = awt.GetDrawingSurface(env, component); if(ds == NULL) return; // Lock the drawing surface lock = ds->Lock(ds); assert((lock & JAWT_LOCK_ERROR) == 0); // Get the drawing surface info dsi = ds->GetDrawingSurfaceInfo(ds); // Get the platform-specific drawing info dsi_win = (JAWT_Win32DrawingSurfaceInfo*)dsi->platformInfo; FlashWindow(dsi_win->hwnd, flash); // Free the drawing surface info ds->FreeDrawingSurfaceInfo(dsi); // Unlock the drawing surface ds->Unlock(ds); // Free the drawing surface awt.FreeDrawingSurface(ds); } ------------eof---------------------- Will this approach let me get into the java model and extract the info being typed on the screen. Any comments or suggestions on how to read info from a java applet, which is one over which I have no control? also see http://msdn.microsoft.com/library/periodic/period00/hood0200.htm http://java.sys-con.com/read/48177.htm http://www.codeproject.com apihijack subhook 1) Does anyone know how to get to the Sun supplied ActiveX control which contains the jvm? 2) Another approach is to intercept the communications between the java applet and IE. Does anyone know how to do this? > I have my Win32 application and IE running a java applet. My > application gets the hWnd of IE and its children hWnd's . Using spy++ [quoted text clipped - 217 lines] > > subhook Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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