fixed tab interpretation inconsistency

3 files changed, 77 insertions, 33 deletions

diff --git a/ChangeLog b/ChangeLog
index e9fb2a8..6abbb11 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2003-11-15  Vince Darley <vincentdarley@users.sourceforge.net>
+
+	* generic/tkTextDisp.c: 
+	* tests/textDisp.test: fixes to one more old Tk [Bug 422411]
+	this time concerning inconsistent tab interpretation.
+	
 2003-11-14  Joe English  <jenglish@users.sourceforge.net>
 	* doc/text.n: Fix markup errors.
 
diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index 7e6713b..040c907 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 1.30 2003/11/15 02:49:36 vincentdarley Exp $
+ * RCS: @(#) $Id: tkTextDisp.c,v 1.31 2003/11/15 12:47:15 vincentdarley Exp $
  */
 
 #include "tkPort.h"
@@ -429,8 +429,8 @@ static void		YScrollByLines _ANSI_ARGS_((TkText *textPtr,
 static void		YScrollByPixels _ANSI_ARGS_((TkText *textPtr,
 			    int offset));
 static int		SizeOfTab _ANSI_ARGS_((TkText *textPtr,
-			    TkTextTabArray *tabArrayPtr, int index, int x,
-			    int maxX));
+			    TkTextTabArray *tabArrayPtr, int *indexPtr, 
+			    int x, int maxX));
 static void		TextInvalidateRegion _ANSI_ARGS_((TkText *textPtr,
 			    TkRegion region));
 static int              TextCalculateDisplayLineHeight _ANSI_ARGS_((
@@ -1239,9 +1239,8 @@ LayoutDLine(textPtr, indexPtr)
 		AdjustForTab(textPtr, tabArrayPtr, tabIndex, tabChunkPtr);
 		x = chunkPtr->x + chunkPtr->width;
 	    }
-	    tabIndex++;
 	    tabChunkPtr = chunkPtr;
-	    tabSize = SizeOfTab(textPtr, tabArrayPtr, tabIndex, x, maxX);
+	    tabSize = SizeOfTab(textPtr, tabArrayPtr, &tabIndex, x, maxX);
 	    if ((maxX >= 0) && (tabSize >= maxX - x)) {
 		break;
 	    }
@@ -6663,10 +6662,14 @@ AdjustForTab(textPtr, tabArrayPtr, index, chunkPtr)
  *
  * Results:
  *	The return value is the minimum number of pixels that will
- *	be occupied by the index'th tab of tabArrayPtr, assuming that
+ *	be occupied by the next tab of tabArrayPtr, assuming that
  *	the current position on the line is x and the end of the
- *	line is maxX.  For numeric tabs, this is a conservative
- *	estimate.  The return value is always >= 0.
+ *	line is maxX.  The 'next tab' is determined by a combination
+ *	of the current position (x) which it must be equal to or
+ *	beyond, and the tab count in indexPtr.
+ *	
+ *	For numeric tabs, this is a conservative estimate.  The return
+ *	value is always >= 0.
  *
  * Side effects:
  *	None.
@@ -6675,45 +6678,70 @@ AdjustForTab(textPtr, tabArrayPtr, index, chunkPtr)
  */
 
 static int
-SizeOfTab(textPtr, tabArrayPtr, index, x, maxX)
+SizeOfTab(textPtr, tabArrayPtr, indexPtr, x, maxX)
     TkText *textPtr;			/* Information about the text widget as
 					 * a whole. */
     TkTextTabArray *tabArrayPtr;	/* Information about the tab stops
 					 * that apply to this line.  NULL
 					 * means use default tabbing (every
 					 * 8 chars.) */
-    int index;				/* Index of current tab stop. */
-    int x;				/* Current x-location in line. Only
-					 * used if tabArrayPtr == NULL. */
+    int *indexPtr;			/* Contains index of previous tab 
+                  			 * stop, will be updated to
+                  			 * reflect the number of stops
+                  			 * used. */
+    int x;				/* Current x-location in line. */
     int maxX;				/* X-location of pixel just past the
 					 * right edge of the line. */
 {
-    int tabX, prev, result, spaceWidth;
+    int tabX, prev, result, index, spaceWidth;
     TkTextTabAlign alignment;
-
+    
     if ((tabArrayPtr == NULL) || (tabArrayPtr->numTabs == 0)) {
 	tabX = NextTabStop(textPtr->tkfont, x, 0);
+	/* 
+	 * We used up one tab stop.
+	 */
+	*indexPtr = (*indexPtr)+1;
 	return tabX - x;
     }
-    if (index < tabArrayPtr->numTabs) {
-	tabX = tabArrayPtr->tabs[index].location;
-	alignment = tabArrayPtr->tabs[index].alignment;
-    } else {
-	/*
-	 * Ran out of tab stops;  compute a tab position by extrapolating
-	 * from the last two tab positions.
-	 */
 
-	if (tabArrayPtr->numTabs > 1) {
-	    prev = tabArrayPtr->tabs[tabArrayPtr->numTabs-2].location;
+    index = *indexPtr;
+    do {
+	/* 
+	 * We were given the count before this tabs, so increment it
+	 * first.
+	 */
+	index++;
+	if (index < tabArrayPtr->numTabs) {
+	    tabX = tabArrayPtr->tabs[index].location;
+	    alignment = tabArrayPtr->tabs[index].alignment;
 	} else {
-	    prev = 0;
+	    /*
+	     * Ran out of tab stops;  compute a tab position by extrapolating
+	     * from the last two tab positions.
+	     */
+	    
+	    if (tabArrayPtr->numTabs > 1) {
+		prev = tabArrayPtr->tabs[tabArrayPtr->numTabs-2].location;
+	    } else {
+		prev = 0;
+	    }
+	    tabX = tabArrayPtr->tabs[tabArrayPtr->numTabs-1].location
+	      + (index + 1 - tabArrayPtr->numTabs)
+	      * (tabArrayPtr->tabs[tabArrayPtr->numTabs-1].location - prev);
+	    alignment = tabArrayPtr->tabs[tabArrayPtr->numTabs-1].alignment;
 	}
-	tabX = tabArrayPtr->tabs[tabArrayPtr->numTabs-1].location
-		+ (index + 1 - tabArrayPtr->numTabs)
-		* (tabArrayPtr->tabs[tabArrayPtr->numTabs-1].location - prev);
-	alignment = tabArrayPtr->tabs[tabArrayPtr->numTabs-1].alignment;
-    }
+	/* 
+	 * If this tab stop is before the current x position, then we
+	 * must obviously continue until we reach the text tab stop.
+	 */
+    } while (tabX < x);
+    
+    /* 
+     * Inform our caller of how many tab stops we've used up.
+     */
+    *indexPtr = index;
+    
     if (alignment == CENTER) {
 	/*
 	 * Be very careful in the arithmetic below, because maxX may
diff --git a/tests/textDisp.test b/tests/textDisp.test
index 30495b8..bb60912 100644
--- a/tests/textDisp.test
+++ b/tests/textDisp.test
@@ -6,7 +6,7 @@
 # Copyright (c) 1998-1999 by Scriptics Corporation.
 # All rights reserved.
 #
-# RCS: @(#) $Id: textDisp.test,v 1.18 2003/11/15 02:33:51 vincentdarley Exp $
+# RCS: @(#) $Id: textDisp.test,v 1.19 2003/11/15 12:47:15 vincentdarley Exp $
 
 package require tcltest 2.1
 eval tcltest::configure $argv
@@ -3089,7 +3089,16 @@ test textDisp-26.13 {AdjustForTab procedure, not enough space} {textfonts} {
     .t tag add x 1.0 end
     list [lindex [.t bbox 1.4] 0] [lindex [.t bbox 1.8] 0] \
 	    [lindex [.t bbox 1.12] 0] [lindex [.t bbox 1.16] 0]
-} [list 28 56 84 120]
+} [list 28 56 120 190]
+test textDisp-26.14 {AdjustForTab procedure, not enough space} {textfonts} {
+    .t delete 1.0 end
+    .t insert end "a \tb \tc \td \te \tf \tg\n"
+    .t insert end "Watch the \tX and the \t\t\tY\n"
+    .t tag configure moop -tabs [expr {8*$fixedWidth}]
+    .t insert end "Watch the \tX and the \t\t\tY\n" moop
+    list [lindex [.t bbox 2.11] 0] [lindex [.t bbox 2.24] 0] \
+	    [lindex [.t bbox 3.11] 0] [lindex [.t bbox 3.24] 0]
+} [list 112 56 112 56]
 
 .t configure -width 20 -bd 2 -highlightthickness 2 -relief sunken -tabs {} \
 	-wrap char
@@ -3145,7 +3154,8 @@ test textDisp-27.7 {SizeOfTab procedure, center alignment, wrap -none (potential
     .t insert 1.0 a\tb\tc\td\te\n012345678934567890a\tbb\tcc\tdd
     update
     .t bbox 2.24
-} [list 172 [expr {$fixedDiff + 18}] 7 $fixedHeight]
+} [list 200 [expr {$fixedDiff + 18}] 7 $fixedHeight]
+
 .t configure -wrap char -tabs {} -width 20
 update
 test textDisp-27.8 {SizeOfTab procedure, right alignment} {textfonts} {