From a79485f8c2bf84f0140b479959ffea2362a72b88 Mon Sep 17 00:00:00 2001
From: Anthony Thibault <ajt@hyperlogic.org>
Date: Sat, 1 Oct 2016 13:37:42 -0700
Subject: [PATCH] Fix for crash bug in web entities

Guard against nullptrs in RenderableWebEntitItem and WebEntityAPIHelper.
These pointers can go null if the webEntity is deleted on the main thread.
Also, the backing offscreen qml surface can be destroyed if the webEntity has not been rendered for 30 seconds
due to frustum culling.
---
 .../src/RenderableWebEntityItem.cpp           | 70 +++++++++++--------
 1 file changed, 42 insertions(+), 28 deletions(-)

diff --git a/libraries/entities-renderer/src/RenderableWebEntityItem.cpp b/libraries/entities-renderer/src/RenderableWebEntityItem.cpp
index 1c177cffc4..86bce87ba2 100644
--- a/libraries/entities-renderer/src/RenderableWebEntityItem.cpp
+++ b/libraries/entities-renderer/src/RenderableWebEntityItem.cpp
@@ -58,9 +58,13 @@ void WebEntityAPIHelper::emitWebEvent(const QVariant& message) {
     } else {
         // special case to handle raising and lowering the virtual keyboard
         if (message.type() == QVariant::String && message.toString() == "_RAISE_KEYBOARD" && _renderableWebEntityItem) {
-            _renderableWebEntityItem->setKeyboardRaised(true);
+            if (_renderableWebEntityItem) {
+                _renderableWebEntityItem->setKeyboardRaised(true);
+            }
         } else if (message.type() == QVariant::String && message.toString() == "_LOWER_KEYBOARD" && _renderableWebEntityItem) {
-            _renderableWebEntityItem->setKeyboardRaised(false);
+            if (_renderableWebEntityItem) {
+                _renderableWebEntityItem->setKeyboardRaised(false);
+            }
         } else {
             emit webEventReceived(message);
         }
@@ -343,7 +347,7 @@ void RenderableWebEntityItem::destroyWebSurface() {
 
         // The lifetime of the QML surface MUST be managed by the main thread
         // Additionally, we MUST use local variables copied by value, rather than
-        // member variables, since they would implicitly refer to a this that 
+        // member variables, since they would implicitly refer to a this that
         // is no longer valid
         auto webSurface = _webSurface;
         AbstractViewStateInterface::instance()->postLambdaEvent([webSurface] {
@@ -388,35 +392,40 @@ static bool equals(const QByteArray& byteArray, const uint8_t* ptr) {
 }
 
 void RenderableWebEntityItem::synthesizeKeyPress(QString key) {
-    auto utf8Key = key.toUtf8();
+    auto eventHandler = getEventHandler();
+    if (eventHandler) {
+        auto utf8Key = key.toUtf8();
 
-    int scanCode = (int)utf8Key[0];
-    QString keyString = key;
-    if (equals(utf8Key, UPWARDS_WHITE_ARROW_FROM_BAR) || equals(utf8Key, ASTERISIM) ||
-        equals(utf8Key, (uint8_t*)PUNCTUATION_STRING) || equals(utf8Key, (uint8_t*)ALPHABET_STRING)) {
-        return;  // ignore
-    } else if (equals(utf8Key, LEFT_ARROW)) {
-        scanCode = Qt::Key_Backspace;
-        keyString = "\x08";
-    } else if (equals(utf8Key, RETURN_SYMBOL)) {
-        scanCode = Qt::Key_Return;
-        keyString = "\x0d";
-    } else if (equals(utf8Key, LEFTWARD_WHITE_ARROW)) {
-        scanCode = Qt::Key_Left;
-        keyString = "";
-    } else if (equals(utf8Key, RIGHTWARD_WHITE_ARROW)) {
-        scanCode = Qt::Key_Right;
-        keyString = "";
+        int scanCode = (int)utf8Key[0];
+        QString keyString = key;
+        if (equals(utf8Key, UPWARDS_WHITE_ARROW_FROM_BAR) || equals(utf8Key, ASTERISIM) ||
+            equals(utf8Key, (uint8_t*)PUNCTUATION_STRING) || equals(utf8Key, (uint8_t*)ALPHABET_STRING)) {
+            return;  // ignore
+        } else if (equals(utf8Key, LEFT_ARROW)) {
+            scanCode = Qt::Key_Backspace;
+            keyString = "\x08";
+        } else if (equals(utf8Key, RETURN_SYMBOL)) {
+            scanCode = Qt::Key_Return;
+            keyString = "\x0d";
+        } else if (equals(utf8Key, LEFTWARD_WHITE_ARROW)) {
+            scanCode = Qt::Key_Left;
+            keyString = "";
+        } else if (equals(utf8Key, RIGHTWARD_WHITE_ARROW)) {
+            scanCode = Qt::Key_Right;
+            keyString = "";
+        }
+
+        QKeyEvent* pressEvent = new QKeyEvent(QEvent::KeyPress, scanCode, Qt::NoModifier, keyString);
+        QKeyEvent* releaseEvent = new QKeyEvent(QEvent::KeyRelease, scanCode, Qt::NoModifier, keyString);
+        QCoreApplication::postEvent(eventHandler, pressEvent);
+        QCoreApplication::postEvent(eventHandler, releaseEvent);
     }
-
-    QKeyEvent* pressEvent = new QKeyEvent(QEvent::KeyPress, scanCode, Qt::NoModifier, keyString);
-    QKeyEvent* releaseEvent = new QKeyEvent(QEvent::KeyRelease, scanCode, Qt::NoModifier, keyString);
-    QCoreApplication::postEvent(getEventHandler(), pressEvent);
-    QCoreApplication::postEvent(getEventHandler(), releaseEvent);
 }
 
 void RenderableWebEntityItem::emitScriptEvent(const QVariant& message) {
-    _webEntityAPIHelper->emitScriptEvent(message);
+    if (_webEntityAPIHelper) {
+        _webEntityAPIHelper->emitScriptEvent(message);
+    }
 }
 
 void RenderableWebEntityItem::setKeyboardRaised(bool raised) {
@@ -424,5 +433,10 @@ void RenderableWebEntityItem::setKeyboardRaised(bool raised) {
     // raise the keyboard only while in HMD mode and it's being requested.
     bool value = AbstractViewStateInterface::instance()->isHMDMode() && raised;
 
-    _webSurface->getRootItem()->setProperty("keyboardRaised", QVariant(value));
+    if (_webSurface) {
+        auto rootItem = _webSurface->getRootItem();
+        if (rootItem) {
+            rootItem->setProperty("keyboardRaised", QVariant(value));
+        }
+    }
 }