Перехват изменения размера колонки в TListView

Code:

{

Question:

How do I capture a column resize event in TListView, the OnResize

only works when the ListView is changed?

Answer:

The event can be added with a bit of work. See the custom TListview derivative

below. It has 3 new events:

OnColumnResize, OnBeginColumnResize, OnEndColumnResize

}

unit PBExListview;

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.