TListView 和鼠标滚轮滚动

Question

我在表单中有一个 TListView 组件。它很长，如果鼠标悬停在组件上并且滚轮滚动，我希望用户能够滚动它。我没有找到 TListView 对象的任何 OnMouseWheel、OnMouseWheelDown 或 OnMouseWheelUp 事件。我该怎么做？

问候， 恶人

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。它适用于任何带有垂直滚动条的控件。我将它与树视图、列表视图、列表框、备忘录、富编辑等一起使用。

你会错过我的ModifierKeyState 例程，但你可以用你自己的方法来检查车轮事件是否未被修改。您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;