From 9c5f4049da417ed02b8a48adcc61ff8f88bfce2e Mon Sep 17 00:00:00 2001
From: vincentdarley <vincentdarley>
Date: Wed, 7 Jan 2004 16:28:23 +0000
Subject: fix to text widget yview bug

---
 ChangeLog             |  7 +++++++
 generic/tkTextBTree.c | 10 +++++++---
 generic/tkTextDisp.c  | 16 +++++++++++++---
 tests/text.test       | 20 +++++++++++++++++++-
 4 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 489682b..8ff3d56 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2004-01-07  Vince Darley <vincentdarley@users.sourceforge.net>
 
+	* generic/tkTextDisp.c:
+	* generic/tkTextBTree.c:
+	* tests/text.test: fixed crashing [Bug 872299] in yview code,
+	and added tests and better error checking in the B-tree.
+	
+2004-01-07  Vince Darley <vincentdarley@users.sourceforge.net>
+
 	* generic/tkTextIndex.c:
 	* tests/textIndex.test: fixed bug in which 'wordstart' and 
 	'wordend' were not utf-8 aware (they haven't been changed since
diff --git a/generic/tkTextBTree.c b/generic/tkTextBTree.c
index b2db5aa..8ac05ea 100644
--- a/generic/tkTextBTree.c
+++ b/generic/tkTextBTree.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkTextBTree.c,v 1.11 2003/12/15 11:51:06 vincentdarley Exp $
+ * RCS: @(#) $Id: tkTextBTree.c,v 1.12 2004/01/07 16:28:23 vincentdarley Exp $
  */
 
 #include "tkInt.h"
@@ -1002,6 +1002,10 @@ TkBTreeFindPixelLine(tree, pixels, pixelOffset)
 	return NULL;
     }
 
+    if (nodePtr->numPixels == 0) {
+	panic("TkBTreeFindPixelLine called with empty window");
+    }
+    
     /*
      * Work down through levels of the tree until a node is found at
      * level 0.
@@ -1012,7 +1016,7 @@ TkBTreeFindPixelLine(tree, pixels, pixelOffset)
 		nodePtr->numPixels <= pixelsLeft;
 		nodePtr = nodePtr->nextPtr) {
 	    if (nodePtr == NULL) {
-		panic("TkBTreeFindLine ran out of nodes");
+		panic("TkBTreeFindPixelLine ran out of nodes");
 	    }
 	    pixelsLeft -= nodePtr->numPixels;
 	}
@@ -1026,7 +1030,7 @@ TkBTreeFindPixelLine(tree, pixels, pixelOffset)
 	    linePtr->pixelHeight < pixelsLeft;
 	    linePtr = linePtr->nextPtr) {
 	if (linePtr == NULL) {
-	    panic("TkBTreeFindLine ran out of lines");
+	    panic("TkBTreeFindPixelLine ran out of lines");
 	}
 	pixelsLeft -= linePtr->pixelHeight;
     }
diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index 1fbf4cf..9cab7f8 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -13,7 +13,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkTextDisp.c,v 1.38 2003/12/15 11:51:06 vincentdarley Exp $
+ * RCS: @(#) $Id: tkTextDisp.c,v 1.39 2004/01/07 16:28:23 vincentdarley Exp $
  */
 
 #include "tkPort.h"
@@ -5193,14 +5193,23 @@ TkTextYviewCmd(textPtr, interp, objc, objv)
     switch (type) {
 	case TKTEXT_SCROLL_ERROR:
 	    return TCL_ERROR;
-	case TKTEXT_SCROLL_MOVETO:
+	case TKTEXT_SCROLL_MOVETO: {
+	    int numPixels = TkBTreeNumPixels(textPtr->tree);
+	    if (numPixels == 0) {
+		/* 
+		 * If the window is totally empty no scrolling is
+		 * needed, and the TkTextMakePixelIndex call
+		 * below will fail.
+		 */
+		break;
+	    }
 	    if (fraction > 1.0) {
 		fraction = 1.0;
 	    }
 	    if (fraction < 0) {
 		fraction = 0;
 	    }
-	    fraction *= (TkBTreeNumPixels(textPtr->tree)-1);
+	    fraction *= (numPixels - 1);
 	    /*
 	     * This function returns the number of pixels by which the
 	     * given line should overlap the top of the visible screen.
@@ -5211,6 +5220,7 @@ TkTextYviewCmd(textPtr, interp, objc, objv)
 		    (int) (0.5 + fraction), &index);
 	    TkTextSetYView(textPtr, &index, pixels);
 	    break;
+	}
 	case TKTEXT_SCROLL_PAGES: {
 	    /*
 	     * Scroll up or down by screenfuls.  Actually, use the
diff --git a/tests/text.test b/tests/text.test
index bf7314b..1672138 100644
--- a/tests/text.test
+++ b/tests/text.test
@@ -6,7 +6,7 @@
 # Copyright (c) 1998-1999 by Scriptics Corporation.
 # All rights reserved.
 #
-# RCS: @(#) $Id: text.test,v 1.27 2003/12/05 17:19:06 vincentdarley Exp $
+# RCS: @(#) $Id: text.test,v 1.28 2004/01/07 16:28:45 vincentdarley Exp $
 
 package require tcltest 2.1
 eval tcltest::configure $argv
@@ -2929,6 +2929,24 @@ test text-27.4 {tabs - must be positive and must be increasing} {
     set result 1
 } {1}
 
+test text-28.0 {repeated insert and scroll} {
+    foreach subcmd {
+	{moveto 1}
+	{scroll 1 pages}
+	{scroll 100 pixels}
+	{scroll 10 units}
+    } {
+	destroy .t
+	pack [text .t]
+	for {set i 0} {$i < 30} {incr i} {
+	    .t insert end "blabla\n"
+	    eval .t yview $subcmd
+	}
+    }
+    # This test must simply not crash to succeed
+    set result 1
+} {1}
+
 deleteWindows
 option clear
 
-- 
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