Solved

How can I change the height of a listview header, part2

Posted on 2010-09-15
6
1,455 Views
Last Modified: 2012-05-10
Hi,

I have asked this question before and received good solutions.
I have tried them all, except for one solution there I got stuck.
I wanted to try Espasquier's solution:

http://www.experts-exchange.com/Programming/Languages/Pascal/Delphi/Q_26471490.html
(the last post)

So I have put the code that Espasquier posted in my component.
And then tried to check it out by calling it dynamicly:

procedure TMainForm.Button1Click(Sender: TObject);
var
  MyListv: PkListv;
  MyListCol : TListColumn;
begin
  MyListv:= PkListv.Create(Self);
  MyListv.Parent := self;
  MyListv.Align := alTop;
  MyListv.Height := 300;
  MyListv.ViewStyle := vsReport;
  MyListv.GridLines := True;
  MyListv.ColumnClick := False;  
// MyListv.Caption:=IntToStr(MyListv.HeaderHeight);  <=============
  MyListv.HeaderHeight:=40;
  MyListCol := MyListv.Columns.Add;
  MyListCol.Alignment := taLeftJustify;
  MyListCol.Width := 150;
  MyListCol.Caption := 'Naam';
end;

But I get an error at line where I have put the arrow:

[Pascal Error] Main.pas(49): E2362 Cannot access protected symbol TControl.Caption

What do I do wrong?

Peter
My component:

unit PkListView;

interface

uses
  SysUtils, Classes, Controls, ComCtrls, Windows;

type
  PkListv = class(TListView)
  private
    { Private declarations }
  protected
    { Protected declarations }
   FHeaderHandle: HWND;
   function GetHeaderHeight:Integer;
   procedure SetHeaderHeight(h:Integer);
  public
    { Public declarations }
    constructor Create(AOwner: TComponent);
    destructor Destroy();
  published
    { Published declarations }
   property HeaderHeight:Integer read GetHeaderHeight write SetHeaderHeight;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [PkListv]);
end;

{ PkListv }

const
  LVM_FIRST = $1000;
  LVM_GETHEADER = LVM_FIRST + 31;

constructor PkListv.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);

end;

destructor PkListv.Destroy;
begin
  inherited;
end;

function PkListv.GetHeaderHeight: Integer;
Var
  Rc:TRect;
begin
 Result:=0;
 FHeaderHandle:=SendMessage(Handle, LVM_GETHEADER, 0, 0);
 If GetWindowRect(FHeaderHandle, rc)
  Then Result := rc.Bottom - rc.Top
end;

procedure PkListv.SetHeaderHeight(h: Integer);
begin
 FHeaderHandle:=SendMessage(Handle, LVM_GETHEADER, 0, 0);
 SetWindowPos( FHeaderHandle, 0 , 0, 0, Width, h, 0 );
 InvalidateRect(FHeaderHandle,nil,True);
end;

end.

Open in new window

0
Comment
Question by:peterkiers
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
6 Comments
 
LVL 25

Expert Comment

by:epasquier
ID: 33680585
that line is useless, in my example it is the form caption that I set to the headerHeight converted
delete it and run !
0
 
LVL 1

Author Comment

by:peterkiers
ID: 33680781
You mean this:

  MainForm.Caption:=IntToStr(MyListv.HeaderHeight);
  MyListv.HeaderHeight:=20;

After running it I get a number 0 in the caption of the mainform!

P
0
 
LVL 1

Author Comment

by:peterkiers
ID: 33680816
Even only with this line:

  MyListv.HeaderHeight:=20;

its not working.



0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
LVL 25

Accepted Solution

by:
epasquier earned 500 total points
ID: 33681113
can you try to change the Header Height on another event than the one that creates the LV ? I'm not sure that the Header window is created at this moment, and if so the Get/Set functions cannot work.
0
 
LVL 1

Author Comment

by:peterkiers
ID: 33681205
Yes, it works now, I have installed my component and called for it with a button.
And it works great. Just one little question remains:

If i resize the columns, the height of the header will be set to normal.
Is there something I could do about that, to prevent it. So I set the
header to 28, and I resize the columns that the header stays at 28.

P.
0
 
LVL 25

Expert Comment

by:epasquier
ID: 33682728
That is the problem, TListView has not been written to be easily subclassed.

A lot of such issues could be fixed by taking the TCustomList view code, and make the modification right from there. But as I told you in your first post, TListView sucks (both Microsoft implementation and Delphi wrapping) so it is better to take some replacements components from guys who spent years already to make their own improved versions
0

Featured Post

[Live Webinar] The Cloud Skills Gap

As Cloud technologies come of age, business leaders grapple with the impact it has on their team's skills and the gap associated with the use of a cloud platform.

Join experts from 451 Research and Concerto Cloud Services on July 27th where we will examine fact and fiction.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…
If you’ve ever visited a web page and noticed a cool font that you really liked the look of, but couldn’t figure out which font it was so that you could use it for your own work, then this video is for you! In this Micro Tutorial, you'll learn yo…
Suggested Courses
Course of the Month8 days, 19 hours left to enroll

615 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question