Fix bug [b2dd3b4fe8] (text-11a.41 sometimes hangs) by reworking how the

<<WidgetViewSync>> event is handled.

1 files changed, 57 insertions, 20 deletions

diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index 8d60754..5903dfb 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -497,13 +497,15 @@ static TkTextDispChunk *baseCharChunkPtr = NULL;
  *				different character might be under the mouse
  *				cursor now). Need to recompute the current
  *				character before the next redisplay.
+ * OUT_OF_SYNC                  1 means that the last <<WidgetViewSync>> event had
+ *                              value 0, indicating that the widget is out of sync.
  */
 
 #define DINFO_OUT_OF_DATE	1
 #define REDRAW_PENDING		2
 #define REDRAW_BORDERS		4
 #define REPICK_NEEDED		8
-
+#define OUT_OF_SYNC             16
 /*
  * Action values for FreeDLines:
  *
@@ -681,7 +683,7 @@ TkTextCreateDInfo(
     dInfoPtr->scanTotalYScroll = 0;
     dInfoPtr->scanMarkY = 0;
     dInfoPtr->dLinesInvalidated = 0;
-    dInfoPtr->flags = DINFO_OUT_OF_DATE;
+    dInfoPtr->flags = 0;
     dInfoPtr->topPixelOffset = 0;
     dInfoPtr->newTopPixelOffset = 0;
     dInfoPtr->currentMetricUpdateLine = -1;
@@ -3070,10 +3072,13 @@ AsyncUpdateLineMetrics(
 	 * We have looped over all lines, so we're done. We must release our
 	 * refCount on the widget (the timer token was already set to NULL
 	 * above). If there is a registered aftersync command, run that first.
+	 * Cancel any pending idle task which would try to run the command
+	 * after the afterSyncCmd pointer had been set to NULL.
 	 */
 
         if (textPtr->afterSyncCmd) {
             int code;
+	    Tcl_CancelIdleCall(TkTextRunAfterSyncCmd, textPtr);
             Tcl_Preserve((ClientData) textPtr->interp);
             code = Tcl_EvalObjEx(textPtr->interp, textPtr->afterSyncCmd,
                     TCL_EVAL_GLOBAL);
@@ -3091,7 +3096,6 @@ AsyncUpdateLineMetrics(
          * with its internal data (actually it will be after the next trip
          * through the event loop, because the widget redraws at idle-time).
          */
-
         GenerateWidgetViewSyncEvent(textPtr, 1);
 
 	if (textPtr->refCount-- <= 1) {
@@ -3115,8 +3119,14 @@ AsyncUpdateLineMetrics(
  * GenerateWidgetViewSyncEvent --
  *
  *      Send the <<WidgetViewSync>> event related to the text widget
- *      line metrics asynchronous update.
- *      This is equivalent to:
+ *      line metrics asynchronous update.  These events should only
+ *      be sent when the sync status has changed.  So this function
+ *      compares the requested state with the state saved in the
+ *      TkText structure, and only generates the event if they are
+ *      different.  This means that it is safe to call this function
+ *      at any time when the state is known.
+ *
+ *      If an event is sent, the effect is equivalent to:
  *         event generate $textWidget <<WidgetViewSync>> -data $s
  *      where $s is the sync status: true (when the widget view is in
  *      sync with its internal data) or false (when it is not).
@@ -3132,9 +3142,12 @@ AsyncUpdateLineMetrics(
 
 static void
 GenerateWidgetViewSyncEvent(
-    TkText *textPtr,		/* Information about text widget. */
-    Bool InSync)                /* true if in sync, false otherwise */
+    TkText *textPtr,	  /* Information about text widget. */
+    Bool InSync)          /* true if becoming in sync, false otherwise */
 {
+    Bool NewSyncState = (InSync != 0); /* ensure 0 or 1 value */
+    Bool OldSyncState = !(textPtr->dInfoPtr->flags & OUT_OF_SYNC);
+    
     /*
      * OSX 10.14 needs to be told to display the window when the Text Widget
      * is in sync.  (That is, to run DisplayText inside of the drawRect
@@ -3147,8 +3160,15 @@ GenerateWidgetViewSyncEvent(
 	FORCE_DISPLAY(textPtr->tkwin);
     }
 
-    TkSendVirtualEvent(textPtr->tkwin, "WidgetViewSync",
-        Tcl_NewBooleanObj(InSync));
+    if (NewSyncState != OldSyncState) {
+	if (NewSyncState) {
+	    textPtr->dInfoPtr->flags &= ~OUT_OF_SYNC;
+	} else {
+	    textPtr->dInfoPtr->flags |= OUT_OF_SYNC;
+	}
+        TkSendVirtualEvent(textPtr->tkwin, "WidgetViewSync",
+                           Tcl_NewBooleanObj(NewSyncState));
+    }
 }
 
 /*
@@ -3191,6 +3211,9 @@ TkTextUpdateLineMetrics(
     TkTextLine *linePtr = NULL;
     int count = 0;
     int totalLines = TkBTreeNumLines(textPtr->sharedTextPtr->tree, textPtr);
+    int fullUpdateRequested = (lineNum == 0 &&
+                               endLine == totalLines &&
+                               doThisMuch == -1);
 
     if (totalLines == 0) {
 	/*
@@ -3201,6 +3224,7 @@ TkTextUpdateLineMetrics(
     }
 
     while (1) {
+
 	/*
 	 * Get a suitable line.
 	 */
@@ -3227,6 +3251,7 @@ TkTextUpdateLineMetrics(
 	     */
 
 	    if (textPtr->dInfoPtr->metricEpoch == -1 && lineNum == endLine) {
+
 		/*
 		 * We have looped over all lines, so we're done.
 		 */
@@ -3250,10 +3275,12 @@ TkTextUpdateLineMetrics(
 
 	    if (TkBTreeLinePixelEpoch(textPtr, linePtr)
 		    == textPtr->dInfoPtr->lineMetricUpdateEpoch) {
+
 		/*
 		 * This line is already up to date. That means there's nothing
 		 * to do here.
 		 */
+
 	    } else if (doThisMuch == -1) {
 		count += 8 * TkTextUpdateOneLine(textPtr, linePtr, 0,NULL,0);
 	    } else {
@@ -3275,6 +3302,7 @@ TkTextUpdateLineMetrics(
 		    indexPtr = &textPtr->dInfoPtr->metricIndex;
 		    pixelHeight = textPtr->dInfoPtr->metricPixelHeight;
 		} else {
+
 		    /*
 		     * We must reset the partial line height calculation data
 		     * here, so we don't use it when it is out of date.
@@ -3298,6 +3326,7 @@ TkTextUpdateLineMetrics(
 			pixelHeight, indexPtr, 1);
 
 		if (indexPtr->linePtr == linePtr) {
+
 		    /*
 		     * We didn't complete the logical line, because it
 		     * produced very many display lines, which must be because
@@ -3306,6 +3335,7 @@ TkTextUpdateLineMetrics(
 		     */
 
 		    if (pixelHeight == 0) {
+
 			/*
 			 * These have already been stored, unless we just
 			 * started the new line.
@@ -3327,6 +3357,7 @@ TkTextUpdateLineMetrics(
 		textPtr->dInfoPtr->metricEpoch = -1;
 	    }
 	} else {
+
 	    /*
 	     * We must never recalculate the height of the last artificial
 	     * line. It must stay at zero, and if we recalculate it, it will
@@ -3351,13 +3382,21 @@ TkTextUpdateLineMetrics(
 	}
     }
     if (doThisMuch == -1) {
+
 	/*
-	 * If we were requested to provide a full update, then also update the
-	 * scrollbar.
+	 * If we were requested to update the entire range, then also update
+	 * the scrollbar.
 	 */
 
 	GetYView(textPtr->interp, textPtr, 1);
     }
+    if (fullUpdateRequested) {
+        TextDInfo *dInfoPtr = textPtr->dInfoPtr;
+
+        dInfoPtr->lastMetricUpdateLine = lineNum;
+        dInfoPtr->currentMetricUpdateLine = lineNum;
+        GenerateWidgetViewSyncEvent(textPtr, 1);
+    }
     return lineNum;
 }
 
@@ -3526,8 +3565,12 @@ TextInvalidateLineMetrics(
 	textPtr->refCount++;
 	dInfoPtr->lineUpdateTimer = Tcl_CreateTimerHandler(1,
 		AsyncUpdateLineMetrics, textPtr);
-        GenerateWidgetViewSyncEvent(textPtr, 0);
     }
+
+    /*
+     * The widget is out of sync: send a <<WidgetViewSync>> event.
+     */
+    GenerateWidgetViewSyncEvent(textPtr, 0);
 }
 
 /*
@@ -5269,9 +5312,7 @@ TkTextRelayoutWindow(
 	    inSync = 0;
 	}
 
-	if (!inSync) {
-	    GenerateWidgetViewSyncEvent(textPtr, 0);
-	}
+        GenerateWidgetViewSyncEvent(textPtr, inSync);
     }
 }
 
@@ -6296,11 +6337,7 @@ TkTextPendingsync(
 {
     TextDInfo *dInfoPtr = textPtr->dInfoPtr;
 
-    return (
-        (!(dInfoPtr->flags & REDRAW_PENDING) &&
-	 (dInfoPtr->metricEpoch == -1) &&
-         (dInfoPtr->lastMetricUpdateLine == dInfoPtr->currentMetricUpdateLine)) ?
-        0 : 1);
+    return ((dInfoPtr->flags & OUT_OF_SYNC) != 0);
 }
 
 /*