From f0e7b98adcaa0890c60fdf84c8e9753f8f903a53 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Thu, 19 Nov 2015 20:46:40 +0000
Subject: First test-implementation of "$t yupdate -command <command>". TODO:
 more testcases and documentation

---
 generic/tkText.c     | 37 +++++++++++++++++++++++++++++--------
 generic/tkText.h     |  1 +
 generic/tkTextDisp.c | 13 ++++++++++++-
 tests/textDisp.test  | 18 ++++++++++++++++++
 4 files changed, 60 insertions(+), 9 deletions(-)

diff --git a/generic/tkText.c b/generic/tkText.c
index 5c7f187..2c4d54c 100644
--- a/generic/tkText.c
+++ b/generic/tkText.c
@@ -1508,14 +1508,31 @@ TextWidgetObjCmd(
 	result = TkTextXviewCmd(textPtr, interp, objc, objv);
 	break;
     case TEXT_YUPDATE: {
-        if (objc != 2) {
-            Tcl_WrongNumArgs(interp, 2, objv, NULL);
-            result = TCL_ERROR;
-            goto done;
-        }
-        TkTextUpdateLineMetrics(textPtr, 1,
-                TkBTreeNumLines(textPtr->sharedTextPtr->tree, textPtr), -1);
-        break;
+	    if ((objc == 4) && !strncmp(Tcl_GetString(objv[2]), "-command", objv[3]->length)) {
+		    Tcl_Obj *cmd = objv[3];
+		    Tcl_IncrRefCount(cmd);
+		    if (TkTextPendingyupdate(textPtr)) {
+			if (textPtr->linesUpdatedCmd) {
+			    Tcl_DecrRefCount(textPtr->linesUpdatedCmd);
+			}
+			textPtr->linesUpdatedCmd = cmd;
+		    } else {
+			result = Tcl_EvalObjEx(interp, cmd, TCL_EVAL_GLOBAL);
+			Tcl_DecrRefCount(cmd);
+		    }
+		    break;
+		} else if (objc != 2) {
+		    Tcl_WrongNumArgs(interp, 2, objv, "?-command command?");
+		    result = TCL_ERROR;
+		    goto done;
+		}
+		if (textPtr->linesUpdatedCmd) {
+		    Tcl_DecrRefCount(textPtr->linesUpdatedCmd);
+		}
+		textPtr->linesUpdatedCmd = NULL;
+		TkTextUpdateLineMetrics(textPtr, 1,
+			TkBTreeNumLines(textPtr->sharedTextPtr->tree, textPtr), -1);
+	break;
     }
     case TEXT_YVIEW:
 	result = TkTextYviewCmd(textPtr, interp, objc, objv);
@@ -1993,6 +2010,10 @@ DestroyText(
     textPtr->tkwin = NULL;
     textPtr->refCount--;
     Tcl_DeleteCommandFromToken(textPtr->interp, textPtr->widgetCmd);
+    if (textPtr->linesUpdatedCmd != 0){
+	Tcl_DecrRefCount(textPtr->linesUpdatedCmd);
+	textPtr->linesUpdatedCmd = 0;
+    }
     if (textPtr->refCount == 0) {
 	ckfree((char *) textPtr);
     }
diff --git a/generic/tkText.h b/generic/tkText.h
index 2d1bcaa..192ab12 100644
--- a/generic/tkText.h
+++ b/generic/tkText.h
@@ -782,6 +782,7 @@ typedef struct TkText {
 				 * statements. */
     int autoSeparators;		/* Non-zero means the separators will be
 				 * inserted automatically. */
+    Tcl_Obj *linesUpdatedCmd; /* Command to be executed when lines are up to date */
 } TkText;
 
 /*
diff --git a/generic/tkTextDisp.c b/generic/tkTextDisp.c
index ff90520..d31d2f3 100644
--- a/generic/tkTextDisp.c
+++ b/generic/tkTextDisp.c
@@ -2942,9 +2942,20 @@ 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).
+	 * above). If there is a registered command, run that first.
 	 */
 
+	if (textPtr->linesUpdatedCmd != NULL) {
+		Tcl_Preserve((ClientData)textPtr->interp);
+	    int code = Tcl_EvalObjEx(textPtr->interp, textPtr->linesUpdatedCmd, TCL_EVAL_GLOBAL);
+		if (code != TCL_OK && code != TCL_CONTINUE
+			&& code != TCL_BREAK) {
+		    Tcl_AddErrorInfo(textPtr->interp, "\n    (text yupdate)");
+		    Tcl_BackgroundError(textPtr->interp);
+		}
+		Tcl_Release((ClientData)textPtr->interp);
+	}
+
 	textPtr->refCount--;
 	if (textPtr->refCount == 0) {
 	    ckfree((char *) textPtr);
diff --git a/tests/textDisp.test b/tests/textDisp.test
index 4c88b38..f2b176c 100644
--- a/tests/textDisp.test
+++ b/tests/textDisp.test
@@ -4191,6 +4191,24 @@ test textDisp-34.1 {Line heights recalculation problem: bug 2677890} -setup {
     destroy .t1
 } -result {0}
 
+test textDisp-34.2 {text yupdate syntax} -body {
+} -body {
+    pack [text .t1] -expand 1 -fill both
+    .t1 yupdate foo
+} -cleanup {
+    destroy .t1
+} -returnCodes 1 -result {wrong # args: should be ".t1 yupdate ?-command command?"}
+
+test textDisp-34.3 {text yupdate syntax} -body {
+} -body {
+    set ::x 0
+    pack [text .t1] -expand 1 -fill both
+    .t1 yupdate -command [list set ::x 1]
+    set ::x
+} -cleanup {
+    destroy .t1
+} -result {1}
+
 deleteWindows
 option clear
 
-- 
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