Qt: speed improvement for QTextEdit text insertions when it contains < or > chars. part of issue #22715

git-svn-id: trunk@38367 -

lcl/interfaces/qt/qtprivate.pp

@@ -412,6 +412,20 @@ end;
 procedure TQtMemoStrings.Insert(Index: integer; const S: string);
 var
   W: WideString;
+  QtCursor: QTextCursorH;
+
+
+  function WorkaroundNeeded: Boolean;
+  var
+    HaveLt: Boolean;
+    HaveGt: Boolean;
+    S1: String;
+  begin
+    HaveLt := System.Pos('<', S) > 0;
+    HaveGt := System.Pos('>', S) > 0;
+    Result := HaveLt or HaveGt;
+  end;
+
 begin
   if FTextChanged then InternalUpdate;
   if Index < 0 then Index := 0;
@@ -423,18 +437,16 @@ begin
   if Index <= FStringList.Count then
   begin
     FStringList.Insert(Index, S);
-    // to fix #22715 we must use slower insertLine(). Rewriting
+    if (TQtTextEdit(FOwner.Handle).getBlockCount - Index <= 1) then
-    // handle from QTextEdit to QPlainTextEdit should fix speed.
-    // Currently we are missing Text alignment in QPlainTextEdit class,
-    // so that's why it's not rewritten yet.
-    if (Index < FStringList.Count - 1) and
-      (TQtTextEdit(FOwner.Handle).getBlockCount - Index <= 1) then
     begin
-      if (System.Pos('<', S) > 0) or (System.Pos('>',S) > 0) then
+      // workaround for qt richtext parser bug. issues #17170 and #22715
+      if WorkaroundNeeded then
       begin
-        // workaround for qt richtext parser bug
         W := GetUTF8String(S);
-        TQtTextEdit(FOwner.Handle).insertLine(Index, W);
+        if (Index >= FStringList.Count - 1) then
+          TQtTextEdit(FOwner.Handle).appendLine(W)
+        else
+          TQtTextEdit(FOwner.Handle).insertLine(Index, W);
       end else
       begin
         // append is much faster in case when we add strings

lcl/interfaces/qt/qtwidgets.pas

@@ -818,6 +818,7 @@ type
     function getSelectionStart: Integer;
     function getSelectionEnd: Integer;
     function getSelectionLength: Integer;
+    procedure appendLine(AText: WideString);
     procedure insertLine(const AIndex: integer; AText: WideString);
     function isUndoAvailable: Boolean;
     procedure removeLine(const AIndex: integer);
@@ -8129,6 +8130,29 @@ begin
   {$note implement TQtTextEdit.setMaxLength}
 end;
 
+procedure TQtTextEdit.appendLine(AText: WideString);
+var
+  QtCursor: QTextCursorH;
+  WrapMode: QTextEditLineWrapMode;
+begin
+  WrapMode := QTextEdit_lineWrapMode(QTextEditH(Widget));
+  {we must remove wrapping to get correct line !}
+  setLineWrapMode(QTextEditNoWrap);
+  QtCursor := QTextCursor_create();
+  try
+    QTextEdit_textCursor(QTextEditH(Widget), QtCursor);
+    QTextCursor_beginEditBlock(QtCursor);
+    QTextCursor_movePosition(QtCursor, QTextCursorEnd,
+        QTextCursorMoveAnchor, 1);
+    QTextCursor_insertBlock(QtCursor);
+    QTextCursor_endEditBlock(QtCursor);
+    QTextEdit_insertPlainText(QTextEditH(Widget), @AText);
+  finally
+    QTextCursor_destroy(QtCursor);
+    setLineWrapMode(WrapMode);
+  end;
+end;
+
 procedure TQtTextEdit.insertLine(const AIndex: integer; AText: WideString);
 var
   QtCursor: QTextCursorH;
@@ -8141,15 +8165,33 @@ begin
   try
     QTextEdit_textCursor(QTextEditH(Widget), QtCursor);
     QTextCursor_beginEditBlock(QtCursor);
-    QTextCursor_movePosition(QtCursor, QTextCursorStart,
+    // QTextCursor slowness
-      QTextCursorMoveAnchor, 1);
+    // https://bugreports.qt-project.org/browse/QTBUG-3554
-    QTextCursor_movePosition(QtCursor, QTextCursorStartOfLine,
+    // differentiate append vs. insert issue #22715
-      QTextCursorMoveAnchor, 1);
+    if AIndex >= FList.Count - 1 then
+    begin
+      QTextCursor_movePosition(QtCursor, QTextCursorEnd,
+        QTextCursorMoveAnchor, 1);
+      QTextCursor_insertBlock(QtCursor);
+    end else
+    begin
+      QTextCursor_movePosition(QtCursor, QTextCursorStart,
+        QTextCursorMoveAnchor, 1);
+      QTextCursor_movePosition(QtCursor, QTextCursorStartOfLine,
+        QTextCursorMoveAnchor, 1);
+    end;
+
     QTextCursor_movePosition(QtCursor, QTextCursorDown,
       QTextCursorMoveAnchor, AIndex);
-    QTextCursor_insertBlock(QtCursor);
+    // QTextCursor slowness
-    QTextCursor_movePosition(QtCursor, QTextCursorUp,
+    // https://bugreports.qt-project.org/browse/QTBUG-3554
-      QTextCursorMoveAnchor, 1);
+    // differentiate append vs. insert issue #22715
+    if AIndex < FList.Count - 1 then
+    begin
+      QTextCursor_insertBlock(QtCursor);
+      QTextCursor_movePosition(QtCursor, QTextCursorUp,
+        QTextCursorMoveAnchor, 1);
+    end;
     QTextCursor_insertText(QtCursor, @AText);
     QTextCursor_endEditBlock(QtCursor);
   finally