Question

我在表单中有一个TListView组件。它很长，我希望用户能够滚动它，如果鼠标在组件上方并滚动滚轮。我没有为TListView对象找到任何OnMouseWheel，OnMouseWheelDown或OnMouseWheelUp事件。我怎么能这样做？

此致 evilone

Answer 1

这是我的代码：

type
  TMyListView = class(TListView)
  protected
    function DoMouseWheelDown(Shift: TShiftState; MousePos: TPoint): Boolean; override;
    function DoMouseWheelUp(Shift: TShiftState; MousePos: TPoint): Boolean; override;
  end;

type    
  TMouseWheelDirection = (mwdUp, mwdDown);

function GenericMouseWheel(Handle: HWND; Shift: TShiftState; WheelDirection: TMouseWheelDirection): Boolean;
var
  i, ScrollCount, Direction: Integer;
  Paging: Boolean;
begin
  Result := ModifierKeyState(Shift)=[];//only respond to un-modified wheel actions
  if Result then begin
    Paging := DWORD(Mouse.WheelScrollLines)=WHEEL_PAGESCROLL;
    ScrollCount := Mouse.WheelScrollLines;
    case WheelDirection of
    mwdUp:
      if Paging then begin
        Direction := SB_PAGEUP;
        ScrollCount := 1;
      end else begin
        Direction := SB_LINEUP;
      end;
    mwdDown:
      if Paging then begin
        Direction := SB_PAGEDOWN;
        ScrollCount := 1;
      end else begin
        Direction := SB_LINEDOWN;
      end;
    end;
    for i := 1 to ScrollCount do begin
      SendMessage(Handle, WM_VSCROLL, Direction, 0);
    end;
  end;
end;

function TMyListView.DoMouseWheelDown(Shift: TShiftState; MousePos: TPoint): Boolean;
begin
  //don't call inherited
  Result := GenericMouseWheel(Handle, Shift, mwdDown);
end;

function TMyListView.DoMouseWheelUp(Shift: TShiftState; MousePos: TPoint): Boolean;
begin
  //don't call inherited
  Result := GenericMouseWheel(Handle, Shift, mwdUp);
end;

GenericMouseWheel非常漂亮。它适用于任何带垂直滚动条的控件。我将它用于树视图，列表视图，列表框，备忘录，丰富的编辑等。

您将错过我的ModifierKeyState例程，但您可以用自己的方法替换检查未更改滚轮事件。你想要这样做的原因是，例如，CTRL +鼠标滚轮意味着缩放而不是滚动。

对于它的价值，它看起来像这样：

type
  TModifierKey = ssShift..ssCtrl;
  TModifierKeyState = set of TModifierKey;

function ModifierKeyState(Shift: TShiftState): TModifierKeyState;
const
  AllModifierKeys = [low(TModifierKey)..high(TModifierKey)];
begin
  Result := AllModifierKeys*Shift;
end;

TListView和鼠标滚轮滚动

1 个答案: