8151925: Font reference improvements

Reviewed-by: prr, serb, skoivu

src/windows/native/sun/windows/awt_Font.cpp

@@ -256,7 +256,7 @@ AwtFont* AwtFont::Create(JNIEnv *env, jobject font, jint angle, jfloat awScale)
 
     AwtFont* awtFont = NULL;
     jobjectArray compFont = NULL;
-    int cfnum;
+    int cfnum = 0;
 
     try {
         if (env->EnsureLocalCapacity(3) < 0)
@@ -264,7 +264,9 @@ AwtFont* AwtFont::Create(JNIEnv *env, jobject font, jint angle, jfloat awScale)
 
         if (IsMultiFont(env, font)) {
             compFont = GetComponentFonts(env, font);
-            cfnum = env->GetArrayLength(compFont);
+            if (compFont != NULL) {
+                cfnum = env->GetArrayLength(compFont);
+            }
         } else {
             compFont = NULL;
             cfnum = 0;
@@ -614,7 +616,9 @@ int AwtFont::getFontDescriptorNumber(JNIEnv *env, jobject font,
 
     if (IsMultiFont(env, font)) {
         array = GetComponentFonts(env, font);
-        num = env->GetArrayLength(array);
+        if (array != NULL) {
+            num = env->GetArrayLength(array);
+        }
     } else {
         array = NULL;
         num = 0;
@@ -672,14 +676,16 @@ SIZE  AwtFont::DrawStringSize_sub(jstring str, HDC hDC,
 
     if (IsMultiFont(env, font)) {
         jobject peer = env->CallObjectMethod(font, AwtFont::peerMID);
-        array =  (jobjectArray)(env->CallObjectMethod(
-        peer, AwtFont::makeConvertedMultiFontStringMID, str));
-        DASSERT(!safe_ExceptionOccurred(env));
+        if (peer != NULL) {
+            array = (jobjectArray)(env->CallObjectMethod(
+            peer, AwtFont::makeConvertedMultiFontStringMID, str));
+            DASSERT(!safe_ExceptionOccurred(env));
 
-        if (array != NULL) {
-            arrayLength = env->GetArrayLength(array);
+            if (array != NULL) {
+                arrayLength = env->GetArrayLength(array);
+            }
+            env->DeleteLocalRef(peer);
         }
-        env->DeleteLocalRef(peer);
     } else {
         array = NULL;
         arrayLength = 0;

src/windows/native/sun/windows/awt_Font.h

@@ -230,11 +230,14 @@ public:
     INLINE static jobjectArray GetComponentFonts(JNIEnv *env,
                                                      jobject font) {
       jobject platformFont = env->CallObjectMethod(font, AwtFont::peerMID);
-      jobjectArray result =
-          (jobjectArray)(env->GetObjectField(platformFont,
-                                             AwtFont::componentFontsID));
-      env->DeleteLocalRef(platformFont);
-      return result;
+      if (platformFont != NULL) {
+          jobjectArray result =
+              (jobjectArray)(env->GetObjectField(platformFont,
+                                                 AwtFont::componentFontsID));
+          env->DeleteLocalRef(platformFont);
+          return result;
+      }
+      return NULL;
     }
 
    /*