-------- Original Message -------- Subject: Re: Calling Same Native method more than once. Date: Wed, 04 Aug 1999 10:46:06 -0400 From: Jacob Nikom <[EMAIL PROTECTED]> Reply-To: [EMAIL PROTECTED] Organization: MERL To: [EMAIL PROTECTED] References: <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> <[EMAIL PROTECTED]> Hi Nagaraj, I think it is better to see one time the working code than discuss how to do it. Here are the two files: one in Java and one in C which create animated color. The program runs on Linux and NT. You have to run it as application, not applet. Jacob Nikom =========Start of the JCMotion.java file =========== /* *<applet code=JCMotion width=200 height=200> *</applet> */ import javax.swing.*; import java.applet.*; import java.awt.*; import java.awt.event.*; import java.awt.image.*; // This applet creates a series of moving // lines by creating a memory image and cycling // its color palette. public class JCMotion extends JApplet implements Runnable, ActionListener { public native void imageGen(int[] intArr, int imageWidth, int ImageHeight, int squareSize); static { System.loadLibrary("Image_native"); } // variables come after system library protected Image cycledImage; // image after cycling protected Thread cycleThread = null; protected int delay = 10; // milliseconds between cycles protected static int squareSize = 10; protected static int imageWidth = 100; protected static int imageHeight = 100; // holding pixels in memory int intArr[]; public void init() { // Create space for the memory image intArr = new int[imageWidth * imageHeight]; // Now create the image imageGen(intArr, imageWidth, imageHeight, squareSize); // Create the cycled image cycledImage = createImage( new MemoryImageSource(imageWidth, imageHeight, intArr, 0, imageWidth)); } // Paint simply draws the cycled image public synchronized void paint(Graphics g) { // g.drawImage(cycledImage, 0, 0, this); g.drawImage(cycledImage, 0, 0, getWidth(), getHeight(), this); } // Flicker-free update public void update(Graphics g) { paint(g); } // Cycles the colors and creates a new cycled image. Uses media // tracker to ensure that the new image has been created before // trying to display. Otherwise, we can get bad flicker. public synchronized void doCycle() { // Flush clears out a loaded image without having to create a // while new one. cycledImage.flush(); // Generate new image imageGen(intArr, imageWidth, imageHeight, squareSize); // Create the cycled image cycledImage = createImage( new MemoryImageSource(imageWidth, imageHeight, intArr, 0, imageWidth)); // When we use waitForID on this image now, it will be regenerated. MediaTracker myTracker = new MediaTracker(this); myTracker.addImage(cycledImage, 0); try { // Cause the cycledImage to be regenerated if (!myTracker.waitForID(0, 1000)) { return; } } catch (Exception ignore) { } // Now that we have reloaded the cycled image, ask that it // be redrawn. repaint(); } // Typical threaded applet start and stop public void start() { if (cycleThread == null) { cycleThread = new Thread(this, "Cycle"); cycleThread.start(); } } public void stop() { cycleThread = null; } // Continually run public void run() { Thread myCurrentThread = Thread.currentThread(); while (cycleThread == myCurrentThread) { doCycle(); try { Thread.sleep(delay); } catch (Exception hell) { } } } public void actionPerformed(ActionEvent evt) { System.out.println("actionPerformed"); this.stop(); } /** * application entry point. create window and new set of * command-line arguments **/ public static void main (String args[]) { JFrame f = new JFrame ("Cycler"); JCMotion motion = new JCMotion(); motion.init (); f.setSize (imageWidth, imageHeight); f.getContentPane().add ("Center", motion); f.setVisible(true); f.addWindowListener(new WindowCloser()); motion.start (); } } class WindowCloser extends WindowAdapter { public void windowClosing(WindowEvent e) { Window win = e.getWindow(); win.setVisible(false); win.dispose(); System.exit(0); } } ==============End of the JCMotion.java file ============= =============Start of the Image_native.c file============= /* JCMotion.h generated by applying javah * on the Java class, and contains the * function declaration for the native method */ #include "JCMotion.h" /* used for printf */ #include "stdio.h" /* Signatures of several of these are in JCMotion.h */ static ii = 0; JNIEXPORT void JNICALL Java_JCMotion_imageGen( JNIEnv *env, jobject obj, jintArray intArr, jint imageWidth, jint imageHeight, jint squareSize ) { int i, j; int alpha, red, green, blue, index; jint* intArrElems = (*env)->GetIntArrayElements(env, intArr, 0); alpha = 255; index = 0; for (i = 0; i < imageHeight; i++) { for (j = 0; j < imageWidth; j++) { red = 255 - ii*2; green = j*2 + ii/2; blue = ii + j; intArrElems[index++] = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0); } } if ( ii >= imageWidth - squareSize) ii = 0; printf("imageGen: ii = %3d\n",ii); ii++; (*env)->ReleaseIntArrayElements(env, intArr, intArrElems, 0); } ================End of the Image_native.c file============== "Nagaraj S.B" wrote: > Jacob Nikom wrote: > > > > I don't think there is any limitations on the number of calls of C routine. > > I call my C routine from Java thousand times without any problem. Look > > for something else - memory problem of threads. Do you call your routine > > from the main tread or you created separate one? > I am calling it from the main. > Nagaraj > > > > Jacob > > > > "Nagaraj S.B" wrote: > > > > > Hi all, > > > Thanks for helping me in interfacing C with Java.I am facing a problem > > > in executing my program(java) which calls a 'C' function. > > > I am calling 'C' native method for every 10 secs in my 'java' program , > > > but after first loop, my program(java) exits by giving > > > SIGSEV 11* Segmentation violation ................. > > > How to call same native method for more than one time ?. > > > Thanks in advance, > > > -- > > > Nagaraj S.B. > > > Bells Softech Ltd,Bells House,1036, > > > 26th Main,4th 'T' Block, > > > Jayanagar, Banglore - 560 041.Ph.No.:6650084/33. > > > > > > ---------------------------------------------------------------------- > > > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > > > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] > > > > ---------------------------------------------------------------------- > > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] > > -- > Nagaraj S.B. > Bells Softech Ltd,Bells House,1036, > 26th Main,4th 'T' Block, > Jayanagar, Banglore - 560 041.Ph.No.:6650084/33. > > ---------------------------------------------------------------------- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] ---------------------------------------------------------------------- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
