/******************************************************************************* * Copyright (c) 2000, 2012 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation *******************************************************************************/ package org.eclipse.swt.internal; import java.lang.reflect.*; import java.util.function.*; import org.eclipse.swt.*; /** * Instances of this class represent entry points into Java * which can be invoked from operating system level callback * routines. *
* IMPORTANT: A callback is only valid when invoked on the
* thread which created it. The results are undefined (and
* typically bad) when a callback is passed out to the
* operating system (or other code) in such a way that the
* callback is called from a different thread.
*/
public class Callback {
Object object;
String method, signature;
int argCount;
long address, errorResult;
boolean isStatic, isArrayBased;
static final boolean is32Bit = C.PTR_SIZEOF == 4 ? true : false;
static final String PTR_SIGNATURE = is32Bit ? "I" : "J"; //$NON-NLS-1$ //$NON-NLS-2$
static final String SIGNATURE_0 = getSignature(0);
static final String SIGNATURE_1 = getSignature(1);
static final String SIGNATURE_2 = getSignature(2);
static final String SIGNATURE_3 = getSignature(3);
static final String SIGNATURE_4 = getSignature(4);
static final String SIGNATURE_N = "(["+PTR_SIGNATURE+")"+PTR_SIGNATURE; //$NON-NLS-1$ //$NON-NLS-2$
/**
* Constructs a new instance of this class given an object
* to send the message to, a string naming the method to
* invoke and an argument count. Note that, if the object
* is an instance of Class
it is assumed that
* the method is a static method on that class.
*
*
Note, do not use this if the method arguments have a double, as arguments will be
* shifted/corrupted. See Bug 510538. Instead use the following constructor:
* Callback (Object, String, Type, Type [])
Class
* it is assumed that the method is a static method on that
* class.
*
* Note, do not use this if the method arguments have a double, as arguments will be
* shifted/corrupted. See Bug 510538. Instead use the following constructor:
* Callback (Object, String, Type, Type [])
true
if the arguments should be passed in an array and false otherwise
*/
public Callback (Object object, String method, int argCount, boolean isArrayBased) {
this (object, method, argCount, isArrayBased, 0);
}
/**
* Constructs a new instance of this class given an object
* to send the message to, a string naming the method to
* invoke, an argument count, a flag indicating whether
* or not the arguments will be passed in an array and a value
* to return when an exception happens. Note that, if
* the object is an instance of Class
* it is assumed that the method is a static method on that
* class.
*
* Note, do not use this if the method arguments have a double, as arguments will be
* shifted/corrupted. See Bug 510538. Instead use the following constructor:
* Callback (Object, String, Type, Type [])
true
if the arguments should be passed in an array and false otherwise
* @param errorResult the return value if the java code throws an exception
*/
public Callback (Object object, String method, int argCount, boolean isArrayBased, long errorResult) {
/* Set the callback fields */
this.object = object;
this.method = method;
this.argCount = argCount;
this.isStatic = object instanceof Class;
this.isArrayBased = isArrayBased;
this.errorResult = errorResult;
/* Inline the common cases */
if (isArrayBased) {
signature = SIGNATURE_N;
} else {
switch (argCount) {
case 0: signature = SIGNATURE_0; break; //$NON-NLS-1$
case 1: signature = SIGNATURE_1; break; //$NON-NLS-1$
case 2: signature = SIGNATURE_2; break; //$NON-NLS-1$
case 3: signature = SIGNATURE_3; break; //$NON-NLS-1$
case 4: signature = SIGNATURE_4; break; //$NON-NLS-1$
default:
signature = getSignature(argCount);
}
}
/* Bind the address */
address = bind (this, object, method, signature, argCount, isStatic, isArrayBased, errorResult);
}
/**
* Register the java method to be a C callback. * I.e, C will be able to make a call to this java method directly (through callback.c)
* *The other constructors hard-code int/long into the method signature:
* long method (long ...)
* Which is suitable for int/long and pointers.
* This constructor is used if you need to use a different return/argument type, e.g double. See Bug 510538
Note: *
Class
it is assumed that
* the method is a static method on that class. long /*int*/
The following types are supported:
*
For example if you want to link the following method:
* void myMethod(long /*int*/ arg1, double arg2)
* Then you would call this callback like:
* Callback (this, "myMethod", void.class, new Type []{long.class, double.class});
*
void.class, long.class, double.class
* @param arguments specify the list of arguments like new Type [] {long.class, double.class }
*/
public Callback (Object object, String method, Type returnType, Type [] arguments) {
/* Set the callback fields */
this.object = object;
this.method = method;
this.argCount = arguments != null ? arguments.length : 0;
this.isStatic = object instanceof Class;
this.isArrayBased = false;
this.errorResult = 0;
Function * Note: This should not be called by application code. *
* * @return the entry count * * @since 2.1 */ public static native int getEntryCount (); static String getSignature(int argCount) { String signature = "("; //$NON-NLS-1$ for (int i = 0; i < argCount; i++) signature += PTR_SIGNATURE; signature += ")" + PTR_SIGNATURE; //$NON-NLS-1$ return signature; } /** * Indicates whether or not callbacks which are triggered at the * native level should cause the messages described by the matching *Callback
objects to be invoked. This method is used
* to safely shut down SWT when it is run within environments
* which can generate spurious events.
* * Note: This should not be called by application code. *
* * @param enable true if callbacks should be invoked */ public static final native synchronized void setEnabled (boolean enable); /** * Returns whether or not callbacks which are triggered at the * native level should cause the messages described by the matching *Callback
objects to be invoked. This method is used
* to safely shut down SWT when it is run within environments
* which can generate spurious events.
* * Note: This should not be called by application code. *
* * @return true if callbacks should not be invoked */ public static final native synchronized boolean getEnabled (); /** * This might be called directly from native code in environments * which can generate spurious events. Check before removing it. * * @deprecated * * @param ignore true if callbacks should not be invoked */ @Deprecated static final void ignoreCallbacks (boolean ignore) { setEnabled (!ignore); } /** * Immediately wipes out all native level state associated * with all callbacks. ** WARNING: This operation is extremely dangerous, * and should never be performed by application code. *
*/ public static final native synchronized void reset (); /** * Releases the native level resources associated with the callback. * * @see #dispose */ static final native synchronized void unbind (Callback callback); }