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Loading large file in a TRichEdit

Posted on 2014-04-08
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Last Modified: 2014-04-09
Hi all this question is related this one: http://www.experts-exchange.com/Programming/Languages/Pascal/Delphi/Q_28407456.html#a39986818

I thought the problem was the StringList but the bottleneck is TRichEdit. The file is very fastly loaded in the StringList but it takes a long time to be loaded in TRichEdit and when it is loaded it freezes the program. I use TRichEdit because I have a piece of code which allows me to use a different font color for certain words.
In my case, I highlight all non existent paths to allow the user to edit them accordingly to his system.

How can solve this problem?
Thanks in advance
Marco
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Question by:Marco Gasi
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9 Comments
 
LVL 46

Accepted Solution

by:
aikimark earned 2000 total points
ID: 39987055
I can offer this work-around.  Use a listbox control and use custom drawing to do your highlighting.  When the user clicks on a listbox item, you move that selected item into an edit control.  Update the listbox item after the user has finished editing.

a code example is in this article:
http://delphi.about.com/cs/adptips2002/a/bltip0602_4.htm
0
 
LVL 31

Author Comment

by:Marco Gasi
ID: 39987167
Okay, aikimark, Listbox is very fast! But I still have an issue with the OwnerDraw event. Here's my code:

procedure TfrmIncorrectPaths.lbxRegFileDrawItem(Control: TWinControl;
  Index: Integer; Rect: TRect; State: TOwnerDrawState);
var
  myColor: TColor;
  myBrush: TBrush;
  rx: TPerlRegEx;
  I: Integer;
begin
  myBrush := TBrush.Create;
  try
    rx := TPerlRegEx.Create;
    try
      with (Control as TListBox).Canvas do
      begin
          rx.Options := [preCaseLess,preExtended];
          rx.RegEx := '\b[a-z]:\\                    # Drive'#10 +
                      '(?:[^\\/:*?"<>|\r\n]+\\)*     # Folder'#10 +
                      '[^\\/:*?"<>|\r\n]*            # File';
          rx.Subject := lbxRegFile.Items[Index];
          if rx.Match then
          begin
            if (not DirectoryExists(ExtractFilePath(rx.MatchedText))) then
              myColor := clYellow
            else
              myColor := clWhite;
          end;
        myBrush.Style := bsSolid;
        myBrush.Color := myColor;
        Winapi.Windows.FillRect(handle, Rect, myBrush.Handle) ;
        Brush.Style := bsClear;
        TextOut(Rect.Left, Rect.Top,
                 (Control as TListBox).Items[Index]) ;
      end;
    finally
      rx.Free;
    end;
  finally
    MyBrush.Free;
  end;
end;

Open in new window


It correctly draws a yellow background for non existent directories (it highlights the whole item instead of the directory string only but I can accept it), but all the rest is black! It's sure because I don't understand brush tecniques: can you help me?
0
 
LVL 46

Expert Comment

by:aikimark
ID: 39987339
The only difference I notice between your code and the article's code is
Winapi.Windows.FillRect()
vs.
Windows.FillRect()

What version of Delphi are you using?
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LVL 31

Author Comment

by:Marco Gasi
ID: 39987846
XE3. If I only use Windows.FillRect I get 'Undeclared identifier: Windows' error when I try to compile.
0
 
LVL 31

Author Comment

by:Marco Gasi
ID: 39987918
Solved. The working code is the following:

procedure TfrmIncorrectPaths.lbxRegFileDrawItem(Control: TWinControl;
  Index: Integer; Rect: TRect; State: TOwnerDrawState);
var
  myColor: TColor;
  myBrush: TBrush;
  rx: TPerlRegEx;
  I: Integer;
begin
  myBrush := TBrush.Create;
  try
    rx := TPerlRegEx.Create;
    try
      rx.Options := [preCaseLess,preExtended];
      rx.RegEx := '\b[a-z]:\\                    # Drive'#10 +
                  '(?:[^\\/:*?"<>|\r\n]+\\)*     # Folder'#10 +
                  '[^\\/:*?"<>|\r\n]*            # File';
      rx.Subject := lbxRegFile.Items[Index];
      if rx.Match then
      begin
        if (not DirectoryExists(ExtractFilePath(rx.MatchedText))) then
          myColor := clYellow
        else
          myColor := clWhite;
      end
      else
        myColor := clWhite;
      with (Control as TListBox).Canvas do
      begin
        myBrush.Style := bsSolid;
        myBrush.Color := myColor;
        Winapi.Windows.FillRect(handle, Rect, myBrush.Handle) ;
        Brush.Style := bsClear;
        TextOut(Rect.Left, Rect.Top,
                 (Control as TListBox).Items[Index]) ;
      end;
    finally
      rx.Free;
    end;
  finally
    MyBrush.Free;
  end;
end;

Open in new window


Thanks
0
 
LVL 31

Author Closing Comment

by:Marco Gasi
ID: 39987919
Thank you so mutch!
0
 
LVL 46

Expert Comment

by:aikimark
ID: 39988447
You're welcome.

Ah.  I see the problem now as well.  Thanks for posting the fixed/correct code. I missed the default white color being lost.  Maybe it is only a style difference, but you might try the following structure to see if it is faster than the else clause.
      myColor := clWhite;
      if rx.Match then
        if (not DirectoryExists(ExtractFilePath(rx.MatchedText))) then
          myColor := clYellow;

Open in new window

0
 
LVL 46

Expert Comment

by:aikimark
ID: 39988471
Note: I edited my comment, tweaking the code for simplicity.
0
 
LVL 31

Author Comment

by:Marco Gasi
ID: 39988581
Okay, I'll try it. Yhank you for this further help. Please, if you can take a look at the other quesiton: http://www.experts-exchange.com/Programming/Languages/Pascal/Delphi/Q_28408505.html
Cheers
0

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