macOS: fixed crash when running in WebSwing (issue #826; regression i…

…n 3.4)

CHANGELOG.md

@@ -22,6 +22,7 @@ FlatLaf Change Log
   incompatible native library) and to test whether native methods can be invoked
   (some security software allows loading native library but blocks method
   invocation).
+- macOS: Fixed crash when running in WebSwing. (issue #826; regression in 3.4)
 
 
 ## 3.4

flatlaf-natives/flatlaf-natives-macos/src/main/headers/JNIUtils.h

@@ -42,5 +42,5 @@
 
 
 jclass findClass( JNIEnv *env, const char* className, bool globalRef );
-jfieldID getFieldID( JNIEnv *env, const char* className, const char* fieldName, const char* fieldSignature, bool staticField );
+jfieldID getFieldID( JNIEnv *env, jclass cls, const char* fieldName, const char* fieldSignature, bool staticField );
 jmethodID getMethodID( JNIEnv *env, jclass cls, const char* methodName, const char* methodSignature, bool staticMethod );

flatlaf-natives/flatlaf-natives-macos/src/main/objcpp/JNIUtils.mm

@@ -38,18 +38,17 @@ jclass findClass( JNIEnv *env, const char* className, bool globalRef ) {
 	return cls;
 }
 
-jfieldID getFieldID( JNIEnv *env, const char* className, const char* fieldName, const char* fieldSignature, bool staticField ) {
-//	NSLog( @"getFieldID %s %s %s", className, fieldName, fieldSignature );
+jfieldID getFieldID( JNIEnv *env, jclass cls, const char* fieldName, const char* fieldSignature, bool staticField ) {
+//	NSLog( @"getFieldID %s %s", fieldName, fieldSignature );
 
-	jclass cls = findClass( env, className, false );
 	if( cls == NULL )
 		return NULL;
 
 	jfieldID fieldID = staticField
 		? env->GetStaticFieldID( cls, fieldName, fieldSignature )
 		: env->GetFieldID( cls, fieldName, fieldSignature );
 	if( fieldID == NULL ) {
-		NSLog( @"FlatLaf: failed to lookup field '%s' of type '%s' in class '%s'", fieldName, fieldSignature, className );
+		NSLog( @"FlatLaf: failed to lookup field '%s' of type '%s'", fieldName, fieldSignature );
 		env->ExceptionDescribe(); // print stack trace
 		env->ExceptionClear();
 		return NULL;

flatlaf-natives/flatlaf-natives-macos/src/main/objcpp/MacWindow.mm

@@ -52,21 +52,27 @@ @implementation WindowData
 	if( window == NULL )
 		return NULL;
 
+	// initialize class IDs (done only once because variables are static)
+	static jclass lwWindowPeerClass = findClass( env, "sun/lwawt/LWWindowPeer", true );
+	static jclass cfRetainedResourceClass = findClass( env, "sun/lwawt/macosx/CFRetainedResource", true );
+	if( lwWindowPeerClass == NULL || cfRetainedResourceClass == NULL )
+		return NULL;
+
 	// initialize field IDs (done only once because variables are static)
-	static jfieldID peerID = getFieldID( env, "java/awt/Component", "peer", "Ljava/awt/peer/ComponentPeer;", false );
-	static jfieldID platformWindowID = getFieldID( env, "sun/lwawt/LWWindowPeer", "platformWindow", "Lsun/lwawt/PlatformWindow;", false );
-	static jfieldID ptrID = getFieldID( env, "sun/lwawt/macosx/CFRetainedResource", "ptr", "J", false );
+	static jfieldID peerID = getFieldID( env, findClass( env, "java/awt/Component", false ), "peer", "Ljava/awt/peer/ComponentPeer;", false );
+	static jfieldID platformWindowID = getFieldID( env, lwWindowPeerClass, "platformWindow", "Lsun/lwawt/PlatformWindow;", false );
+	static jfieldID ptrID = getFieldID( env, cfRetainedResourceClass, "ptr", "J", false );
 	if( peerID == NULL || platformWindowID == NULL || ptrID == NULL )
 		return NULL;
 
 	// get field java.awt.Component.peer
 	jobject peer = env->GetObjectField( window, peerID );
-	if( peer == NULL )
+	if( peer == NULL || !env->IsInstanceOf( peer, lwWindowPeerClass ) )
 		return NULL;
 
 	// get field sun.lwawt.LWWindowPeer.platformWindow
 	jobject platformWindow = env->GetObjectField( peer, platformWindowID );
-	if( platformWindow == NULL )
+	if( platformWindow == NULL || !env->IsInstanceOf( platformWindow, cfRetainedResourceClass ) )
 		return NULL;
 
 	// get field sun.lwawt.macosx.CFRetainedResource.ptr