ListView - automatische Spaltenbreite-Anpassung abfangen

[ThoPos]

Hallo Eric,

ich habe mal in einem englischsprachigen Delphi-Forum (Quelle unbekannt) folgende Unit gefunden. Diese erweitert die Standard-Listview um die Events OnBeginColumnResize, OnColumnResize und OnEndColumnResize. Damit reagiere ich in meinen Programmen auf Änderungen der Spaltenbreiten.

Delphi-Quellcode:

unit ExListView;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
  Dialogs, ComCtrls;

type
  TLVColumnResizeEvent = procedure(Sender: TCustomListview;
    columnindex: Integer;
    columnwidth: Integer) of object;

  TPBExListview = class(TListview)

  private
    FBeginColumnResizeEvent : TLVColumnResizeEvent;
    FEndColumnResizeEvent   : TLVColumnResizeEvent;
    FColumnResizeEvent      : TLVColumnResizeEvent;

  protected
    procedure DoBeginColumnResize(columnindex, columnwidth: Integer); virtual;
    procedure DoEndColumnResize(columnindex, columnwidth: Integer); virtual;
    procedure DoColumnResize(columnindex, columnwidth: Integer); virtual;
    procedure WMNotify(var Msg: TWMNotify); message WM_NOTIFY;
    function  FindColumnIndex(pHeader: pNMHdr): Integer;
    function  FindColumnWidth(pHeader: pNMHdr): Integer;
    procedure CreateWnd; override;
  published
    property OnBeginColumnResize: TLVColumnResizeEvent read FBeginColumnResizeEvent write FBeginColumnResizeEvent;
    property OnEndColumnResize: TLVColumnResizeEvent read FEndColumnResizeEvent write FEndColumnResizeEvent;
    property OnColumnResize: TLVColumnResizeEvent read FColumnResizeEvent write FColumnResizeEvent;
  end;

procedure Register;

implementation

uses CommCtrl;

procedure Register;
begin
  RegisterComponents('PBGoodies', [TPBExListview]);
end;

procedure TPBExListview.DoBeginColumnResize(columnindex, columnwidth: Integer);
begin
  if Assigned(FBeginColumnResizeEvent) then
    FBeginColumnResizeEvent(Self, columnindex, columnwidth);
end;

procedure TPBExListview.DoEndColumnResize(columnindex, columnwidth: Integer);
begin
  if Assigned(FEndColumnResizeEvent) then
    FEndColumnResizeEvent(Self, columnindex, columnwidth);
end;

procedure TPBExListview.DoColumnResize(columnindex, columnwidth: Integer);
begin
  if Assigned(FColumnResizeEvent) then
    FColumnResizeEvent(Self, columnindex, columnwidth);
end;

function TPBExListview.FindColumnIndex(pHeader: pNMHdr): Integer;
var
  hwndHeader: HWND;
  iteminfo: THdItem;
  ItemIndex: Integer;
  buf: array [0..128] of Char;
begin
  Result := -1;
  hwndHeader := pHeader^.hwndFrom;
  ItemIndex := pHDNotify(pHeader)^.Item;
  FillChar(iteminfo, SizeOf(iteminfo), 0);
  iteminfo.Mask := HDI_TEXT;
  iteminfo.pszText := buf;
  iteminfo.cchTextMax := SizeOf(buf) - 1;
  Header_GetItem(hwndHeader, ItemIndex, iteminfo);
  if CompareStr(Columns[ItemIndex].Caption, iteminfo.pszText) = 0 then
    Result := ItemIndex
  else
  begin
    for ItemIndex := 0 to Columns.Count - 1 do
      if CompareStr(Columns[ItemIndex].Caption, iteminfo.pszText) = 0 then
      begin
        Result := ItemIndex;
        Break;
      end;
  end;
end;

procedure TPBExListview.WMNotify(var Msg: TWMNotify);
begin
  inherited;
  case Msg.NMHdr^.code of
    HDN_ENDTRACK:
      DoEndColumnResize(FindColumnIndex(Msg.NMHdr),
        FindColumnWidth(Msg.NMHdr));
    HDN_BEGINTRACK:
      DoBeginColumnResize(FindColumnIndex(Msg.NMHdr),
        FindColumnWidth(Msg.NMHdr));
    HDN_TRACK:
      DoColumnResize(FindColumnIndex(Msg.NMHdr),
        FindColumnWidth(Msg.NMHdr));
  end;
end;

procedure TPBExListview.CreateWnd;
var
  wnd: HWND;
begin
  inherited;
  wnd := GetWindow(Handle, GW_CHILD);
  SetWindowLong(wnd, GWL_STYLE,
    GetWindowLong(wnd, GWL_STYLE) and not HDS_FULLDRAG);
end;

function TPBExListview.FindColumnWidth(pHeader: pNMHdr): Integer;
begin
  Result := -1;
  if Assigned(PHDNotify(pHeader)^.pItem) and
    ((PHDNotify(pHeader)^.pItem^.mask and HDI_WIDTH) <> 0) then
    Result := PHDNotify(pHeader)^.pItem^.cxy;
end;

end.

Gruß
Thomas