delphi – 不支持vcl样式的标签页的关闭按钮

procedure TFormMain.PageControlCloseButtonDrawTab(Control: TCustomTabControl;
  TabIndex: Integer; const Rect: TRect; Active: Boolean);
var
  CloseBtnSize: Integer;
  PageControl: TPageControl;
  TabCaption: TPoint;
  CloseBtnRect: TRect;
  CloseBtnDrawState: Cardinal;
  CloseBtnDrawDetails: TThemedElementDetails;
begin
  PageControl := Control as TPageControl;

  if InRange(TabIndex,Length(FCloseButtonsRect) - 1) then
  begin
    CloseBtnSize := 14;
    TabCaption.Y := Rect.Top + 3;

    if Active then
    begin
      CloseBtnRect.Top := Rect.Top + 4;
      CloseBtnRect.Right := Rect.Right - 5;
      TabCaption.X := Rect.Left + 6;
    end
    else
    begin
      CloseBtnRect.Top := Rect.Top + 3;
      CloseBtnRect.Right := Rect.Right - 5;
      TabCaption.X := Rect.Left + 3;
    end;

    CloseBtnRect.Bottom := CloseBtnRect.Top + CloseBtnSize;
    CloseBtnRect.Left := CloseBtnRect.Right - CloseBtnSize;
    FCloseButtonsRect[TabIndex] := CloseBtnRect;

    PageControl.Canvas.FillRect(Rect);
    PageControl.Canvas.TextOut(TabCaption.X,TabCaption.Y,PageControl.Pages[TabIndex].Caption);

    if not UseThemes then
    begin
      if (FCloseButtonMouseDownIndex = TabIndex) and FCloseButtonShowPushed then
        CloseBtnDrawState := DFCS_CAPTIONCLOSE + DFCS_PUSHED
      else
        CloseBtnDrawState := DFCS_CAPTIONCLOSE;

      Winapi.Windows.DrawFrameControl(PageControl.Canvas.Handle,FCloseButtonsRect[TabIndex],DFC_CAPTION,CloseBtnDrawState);
    end
    else
    begin
      Dec(FCloseButtonsRect[TabIndex].Left);

      if (FCloseButtonMouseDownIndex = TabIndex) and FCloseButtonShowPushed then
        CloseBtnDrawDetails := StyleServices.GetElementDetails(twCloseButtonPushed)
      else
        CloseBtnDrawDetails := StyleServices.GetElementDetails(twCloseButtonNormal);

      StyleServices.DrawElement(PageControl.Canvas.Handle,CloseBtnDrawDetails,FCloseButtonsRect[TabIndex]);
    end;
  end;
end;

如果您使用的是vcl样式,则必须编写一个vcl样式钩子以在选项卡控件中绘制一个关闭按钮,查看 Vcl.Styles.ColorTabs单元(在这些文章 Creating colorful tabsheets with the VCL Styles,Added border to TTabColorControlStyleHook中介绍)以了解您需要什么写一个这样的样式钩子.除了在选项卡中绘制按钮的代码之外,您必须处理WM_MOUSEMOVE和WM_LBUTTONUP消息(在样式挂钩中)以更改按钮的状态(正常,热)并检测关闭按钮中的单击.

如果你在实现样式钩子时遇到问题,请告诉我在这里发布一个完整的解决方案.

UPDATE

我刚刚写了这个简单的样式钩子来为标签页中的关闭按钮添加suport.

uses
  Vcl.Styles,Vcl.Themes;

type
  TTabControlStyleHookBtnClose = class(TTabControlStyleHook)
  private
    FHotIndex       : Integer;
    FWidthModified  : Boolean;
    procedure WMMouseMove(var Message: TMessage); message WM_MOUSEMOVE;
    procedure WMLButtonUp(var Message: TWMMouse); message WM_LBUTTONUP;
    function GetButtonCloseRect(Index: Integer):TRect;
  strict protected
    procedure DrawTab(Canvas: TCanvas; Index: Integer); override;
    procedure MouseEnter; override;
    procedure MouseLeave; override;
  public
    constructor Create(AControl: TWinControl); override;
  end;

constructor TTabControlStyleHookBtnClose.Create(AControl: TWinControl);
begin
  inherited;
  FHotIndex:=-1;
  FWidthModified:=False;
end;

procedure TTabControlStyleHookBtnClose.DrawTab(Canvas: TCanvas; Index: Integer);
var
  Details : TThemedElementDetails;
  ButtonR : TRect;
  FButtonState: TThemedWindow;
begin
  inherited;

  if (FHotIndex>=0) and (Index=FHotIndex) then
   FButtonState := twSmallCloseButtonHot
  else
  if Index = TabIndex then
   FButtonState := twSmallCloseButtonNormal
  else
   FButtonState := twSmallCloseButtonDisabled;

  Details := StyleServices.GetElementDetails(FButtonState);

  ButtonR:= GetButtonCloseRect(Index);
  if ButtonR.Bottom - ButtonR.Top > 0 then
   StyleServices.DrawElement(Canvas.Handle,Details,ButtonR);
end;

procedure TTabControlStyleHookBtnClose.WMLButtonUp(var Message: TWMMouse);
Var
  LPoint : TPoint;
  LIndex : Integer;
begin
  LPoint:=Message.Pos;
  for LIndex := 0 to TabCount-1 do
   if PtInRect(GetButtonCloseRect(LIndex),LPoint) then
   begin
      if Control is TPageControl then
      begin
        TPageControl(Control).Pages[LIndex].Parent:=nil;
        TPageControl(Control).Pages[LIndex].Free;
      end;
      break;
   end;
end;

procedure TTabControlStyleHookBtnClose.WMMouseMove(var Message: TMessage);
Var
  LPoint : TPoint;
  LIndex : Integer;
  LHotIndex : Integer;
begin
  inherited;
  LHotIndex:=-1;
  LPoint:=TWMMouseMove(Message).Pos;
  for LIndex := 0 to TabCount-1 do
   if PtInRect(GetButtonCloseRect(LIndex),LPoint) then
   begin
      LHotIndex:=LIndex;
      break;
   end;

   if (FHotIndex<>LHotIndex) then
   begin
     FHotIndex:=LHotIndex;
     Invalidate;
   end;
end;

function TTabControlStyleHookBtnClose.GetButtonCloseRect(Index: Integer): TRect;
var
  FButtonState: TThemedWindow;
  Details : TThemedElementDetails;
  R,ButtonR : TRect;
begin
  R := TabRect[Index];
  if R.Left < 0 then Exit;

  if TabPosition in [tpTop,tpBottom] then
  begin
    if Index = TabIndex then
      InflateRect(R,2);
  end
  else
  if Index = TabIndex then
    Dec(R.Left,2)
  else
    Dec(R.Right,2);

  Result := R;
  FButtonState := twSmallCloseButtonNormal;

  Details := StyleServices.GetElementDetails(FButtonState);
  if not StyleServices.GetElementContentRect(0,Result,ButtonR) then
    ButtonR := Rect(0,0);

  Result.Left :=Result.Right - (ButtonR.Width) - 5;
  Result.Width:=ButtonR.Width;
end;

procedure TTabControlStyleHookBtnClose.MouseEnter;
begin
  inherited;
  FHotIndex := -1;
end;

procedure TTabControlStyleHookBtnClose.MouseLeave;
begin
  inherited;
  if FHotIndex >= 0 then
  begin
    FHotIndex := -1;
    Invalidate;
  end;
end;

以这种方式注册

TStyleManager.Engine.RegisterStyleHook(TCustomTabControl,TTabControlStyleHookBtnClose);
  TStyleManager.Engine.RegisterStyleHook(TTabControl,TTabControlStyleHookBtnClose);

这是一个演示