From 7f867fb33052b69eedbb7979b9ada1dd478c176d Mon Sep 17 00:00:00 2001
From: "fvogelnew1@free.fr" <fvogel>
Date: Sun, 25 Jan 2015 13:55:34 +0000
Subject: Fixed disappearing cursor when moving up one line at the boundary of
 elided lines. Factorized the code again in the process, using function
 IsStartOfNotMergedLine when possible.

---
 generic/tkTextDisp.c | 14 +++++---------
 tests/textDisp.test  | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index 34202bd..e21b76b 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -4668,12 +4668,11 @@ TextChanged(
      */
 
     rounded = *index1Ptr;
-    do {
-        rounded.byteIndex = 0;
+    rounded.byteIndex = 0;
+    notBegin = 0;
+    while (!IsStartOfNotMergedLine(textPtr, &rounded) && notBegin) {
         notBegin = !TkTextIndexBackBytes(textPtr, &rounded, 1, &rounded);
-    } while (TkTextIsElided(textPtr, &rounded, NULL) && notBegin);
-    if (notBegin) {
-        TkTextIndexForwBytes(textPtr, &rounded, 1, &rounded);
+        rounded.byteIndex = 0;
     }
 
     /*
@@ -4703,14 +4702,11 @@ TextChanged(
         }
         rounded.linePtr = linePtr;
         rounded.byteIndex = 0;
-        TkTextIndexBackBytes(textPtr, &rounded, 1, &rounded);
-    } while (TkTextIsElided(textPtr, &rounded, NULL));
+    } while (!IsStartOfNotMergedLine(textPtr, &rounded));
 
     if (linePtr == NULL) {
         lastPtr = NULL;
     } else {
-        TkTextIndexForwBytes(textPtr, &rounded, 1, &rounded);
-
         /*
          * 'rounded' now points to the start of a display line as well as the
          * start of a logical line not merged with its previous line, and
diff --git a/tests/textDisp.test b/tests/textDisp.test
index 44a45b2..12a20c6 100644
--- a/tests/textDisp.test
+++ b/tests/textDisp.test
@@ -1152,6 +1152,41 @@ test textDisp-8.11 {TkTextChanged, scrollbar notification when changes are off-s
     .t configure -yscrollcommand ""
     set scrollInfo
 } {0.0 0.625}
+test textDisp-8.12 {TkTextChanged, moving the insert cursor redraws only past and new lines} {
+    .t delete 1.0 end
+    .t configure -wrap none
+    for {set i 1} {$i < 25} {incr i} {
+        .t insert end "Line $i Line $i\n"
+    }
+    .t tag add hidden 5.0 8.0
+    .t tag configure hidden -elide true
+    .t mark set insert 9.0
+    update
+    .t mark set insert 8.0        ; # up one line
+    update
+    set res [list $tk_textRedraw]
+    .t mark set insert 12.2       ; # in the visible text
+    update
+    lappend res $tk_textRedraw
+    .t mark set insert 6.5        ; # in the hidden text
+    update
+    lappend res $tk_textRedraw
+    .t mark set insert 3.5        ; # in the visible text again
+    update
+    lappend res $tk_textRedraw
+    .t mark set insert 3.8        ; # within the same line
+    update
+    lappend res $tk_textRedraw
+    # This last one is tricky: correct result really is {2.0 3.0} when
+    # calling .t mark set insert, two calls to TkTextChanged are done:
+    # (a) to redraw the line of the past position of the cursor
+    # (b) to redraw the line of the new position of the cursor
+    # During (a) the display line showing the cursor gets unlinked,
+    # which leads TkTextChanged in (b) to schedule a redraw starting
+    # one line _before_ the line containing the insert cursor. This is
+    # because during (b) findDLine cannot return the display line the
+    # cursor is in since this display line was just unlinked in (a).
+} {{8.0 9.0} {8.0 12.0} {8.0 12.0} {3.0 8.0} {2.0 3.0}}
 
 test textDisp-9.1 {TkTextRedrawTag} {
     .t configure -wrap char
-- 
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