fix to text widget yview bug

2 files changed, 20 insertions, 6 deletions

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