{
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
}
{
Frage:
Wie kann ich herausfinden, wenn in einer TListView eine Spaltengröße
verändert wird? OnResize wird ja nur dann ausgelöst, wenn sich die Größe
der TListView ändert.
Antwort:
Ein OnColumnResize Ereignis kann mit ein wenig Arbeit einer TListView
hinzugefügt werden. Installiere die PBExListview Komponente,
welche von der TListView abgeleitet ist.
Die Komponente besitzt 3 neue Ereignisse:
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.
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