Delphi 中组件的定位提示
Positioning Hints for Components in Delphi
使用 Delphi XE6，我正在创建一个类似 TdateTimePicker 的控件，但出于几个原因，我使用了一个 TButtonedEdit，其中有一个 TMonthCalendar "embedded"。完整的准系统演示是：
单击右键时显示月历（with Style=WS_POPUP），我已经按照需要进行操作，当做出选择，用户导航离开，ESCapes 等
unit DateEditBare1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.ImgList, Vcl.ComCtrls, Vcl.StdCtrls,
CommCtrl;
type
TespMonthCalendar = class(TMonthCalendar)
procedure DoCloseUp(Sender: TObject);
private
FDroppedDown: boolean;
FManagerHandle: HWND; // just a convenience to avoid having to assume its in the owner
procedure CNNotify(var Message: TWMNotify); message CN_NOTIFY;
procedure SetWindowDIMs;
protected
procedure CreateParams(var Params: TCreateParams); override;
procedure CreateWnd; override;
procedure KeyDown(var Key: Word; Shift: TShiftState); override;
procedure WMActivate(var Msg: TWMActivate); message WM_ACTIVATE;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
end;
TespDateEdit = class(TButtonedEdit)
private
FMonthCalendar: TespMonthCalendar;
procedure DoRightButtonClick(Sender: TObject);
protected
procedure CreateWnd; override;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
public
constructor Create(AOwner:TComponent); override;
property MonthCalendar: TespMonthCalendar read FMonthCalendar write FMonthCalendar;
end;
TfrmDateEditBare1 = class(TForm)
Edit1: TEdit;
procedure FormCreate(Sender: TObject);
private
espDateEdit1: TespDateEdit;
public
end;
var
frmDateEditBare1: TfrmDateEditBare1;
implementation
{$R *.dfm}
var
_espdateEdit_ImageList: TImageList=nil;
//------------------------------------------------------------------------------
function MakeImageList(const ResNames: array of String): TImageList;
var
ResBmp: TBitmap;
I: Integer;
begin
{ Create an image list. }
_espdateEdit_ImageList := TImageList.Create(nil);
_espdateEdit_ImageList.Width := 24;
_espdateEdit_ImageList.Height := 16;
Result := _espdateEdit_ImageList;
for I := 0 to Length(ResNames) - 1 do
begin
ResBmp := TBitmap.Create();
try
{ Try to load the bitmap from the resource. }
try
//ResBmp.LoadFromResourceName(HInstance, ResNames[I]);
ResBmp.SetSize(24,16);
ResBmp.Transparent := true;
except
ResBmp.Free();
Result.Free();
Exit;
end;
Result.Add(ResBmp, nil);
finally
ResBmp.Free;
end;
end;
end;
// Aowner is ignored for now
function GetImageList: TImageList;
begin
if _espdateEdit_ImageList = nil then
result := MakeImageList(['CalendarDrop', 'CalendarDropShifted'])
else
result := _espdateEdit_ImageList;
end;
//------------------------------------------------------------------------------
procedure TfrmDateEditBare1.FormCreate(Sender: TObject);
begin
espDateEdit1:= TespDateEdit.Create(self);
espDateEdit1.Parent := self;
espDateEdit1.left := 100;
espDateEdit1.top := 100;
espDateEdit1.Visible := true;
end;
//------------------------------------------------------------------------------
{ TespMonthCalendar }
procedure TespMonthCalendar.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if Message.HintInfo.HintControl=Self then
begin
Message.HintInfo.HintPos := self.ClientToScreen(Point(0, self.Height + 1));
Message.HintInfo.HideTimeout := 1000;
// Message.HintInfo.ReshowTimeout := 1500; // setting this does not help
end;
end;
procedure TespMonthCalendar.CreateParams(var Params: TCreateParams);
begin
inherited CreateParams(Params);
with Params do
begin
Style := WS_POPUP;
WindowClass.Style := WindowClass.Style or CS_SAVEBITS ;
if CheckWin32Version(5, 1) then
WindowClass.Style := WindowClass.style or CS_DROPSHADOW;
end;
end;
procedure TespMonthCalendar.CreateWnd;
begin
inherited;
// Get/set the dimensions of the calendar
SetWindowDIMs;
end;
procedure TespMonthCalendar.SetWindowDIMs;
var
ReqRect: TRect;
MaxTodayWidth: Integer;
begin
FillChar(ReqRect, SizeOf(TRect), 0);
// get required rect
Win32Check(MonthCal_GetMinReqRect(Handle, ReqRect));
// get max today string width
MaxTodayWidth := MonthCal_GetMaxTodayWidth(Handle);
// adjust rect width to fit today string
if MaxTodayWidth > ReqRect.Right then
ReqRect.Right := MaxTodayWidth;
// set new height & width
Width := ReqRect.Right ;
Height:= ReqRect.Bottom ;
end; (* SetWindowDIMs *)
procedure TespMonthCalendar.CNNotify(var Message: TWMNotify);
begin
// hand off control of the selection to the boss i.e. the espDateEdit that I belong to
// skip for demo ... just closeup
if ( Message.NMHdr^.code = MCN_SELECT) then
DoCloseUp(self);
inherited;
end; (*CNNotify*)
procedure TespMonthCalendar.KeyDown(var Key: Word; Shift: TShiftState);
begin
if Key = VK_ESCAPE then
begin
Key := 0;
DoCloseUp(self);
end
else
inherited KeyDown(Key, Shift);
end;
procedure TespMonthCalendar.WMActivate(var Msg: TWMActivate);
begin
if (Msg.Active <> WA_INACTIVE) then
// tell form to paint itself as though it still has focus (as we are no outside the form with POPUP)
SendMessage(screen.ActiveForm.Handle, WM_NCACTIVATE, WPARAM(True), -1)
else
DoCloseUp(self);
inherited;
end;
procedure TespMonthCalendar.DoCloseUp(Sender: TObject);
begin
if FDroppedDown then
begin
FDroppedDown := false;
Hide;
// put focus back on dateedit so that checking is done if we leave here to go on to another control
SendMessage(FManagerHandle, WM_ACTIVATE, WPARAM(True), -1); // less assumptions this way
end;
end;
//------------------------------------------------------------------------------
{ TespDateEdit }
procedure TespDateEdit.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if Message.HintInfo.HintControl=Self then
Message.HintInfo.HintPos := self.ClientToScreen(Point(0, 21));
end;
constructor TespDateEdit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
if not(csDesigning in ComponentState) then
begin
FmonthCalendar := TespMonthCalendar.Create(self);
self.hint := 'DUMMY HINT for Edit Box';
FMonthCalendar.Hint := 'Select required Date,' + ^M^J + 'or ESCape to close the calendar.';
FMonthCalendar.ShowHint := true;
end;
Width := 100;
Height := 21;
Images := GetImageList;
Text := ''; // FormatdateTime('dd/mm/yy', Date); // not for demo
ShowHint := True;
DoubleBuffered := true; // reduces flicker when passing thru and within control
RightButton.ImageIndex := 0;
RightButton.PressedImageIndex := 1;
RightButton.Visible := True;
OnRightButtonClick := DoRightButtonClick;
end;
procedure TespDateEdit.CreateWnd;
var
P: TWinControl;
begin
inherited CreateWnd;
if not(csDesigning in ComponentState) then
begin
FMonthCalendar.left := -900;
P := self.Parent;
while (P <> nil ) and not ( P is TCustomForm ) do
P := P.parent;
FmonthCalendar.Parent := P; // ie form (or the topmost non nil entry in the tree)
FmonthCalendar.FManagerHandle := self.Handle;
FMonthCalendar.Hide;
FmonthCalendar.OnExit := FmonthCalendar.DoCloseUp;
end;
end;
procedure TespDateEdit.DoRightButtonClick(Sender: TObject);
var
dt: Tdate;
TopLeft: TPoint;
Rect: TRect;
begin
if FmonthCalendar.FdroppedDown then
begin
FMonthCalendar.DoCloseUp(nil);
exit;
end;
// load non-zero date into calendar as the selected date ... skip for demo
TopLeft := self.ClientToScreen(Point(0, 0)); // i.e. screen co-ords of top left of edit box
monthCalendar.left := TopLeft.X - 3 ; // shift a poopsie to line up visually
monthCalendar.Top := TopLeft.Y + self.Height - 2;
// only move it if it exceeds screen bounds ... skip this for demo
FmonthCalendar.FDroppedDown := true;
MonthCal_SetCurrentView(FmonthCalendar.handle, MCMV_MONTH);
FmonthCalendar.Show;
// showing is not enough - need to grab focus to get kbd events happening on the calendar
FmonthCalendar.SetFocus;
inherited OnRightButtonClick;
end;
//------------------------------------------------------------------------------
initialization
finalization
FreeAndNil(_espdateEdit_ImageList);
end.
现在，我想为编辑框和 TMonthCalendar 添加单独的提示，但我想确保显示的提示不会遮挡相关控件。
对于编辑框，我已经成功拦截了CM_HINTSHOW消息，我设置了HintInfo.HintPos来实现。到目前为止，还不错。
问题 1：更新：我现在显示了。最初我将提示文本设置为包含管道字符，这样我就可以使用 TCustomHint。删除管道字符，导致提示显示。 但是 此提示不会自行隐藏，它会在 TmonthCalendar 显示时一直显示在屏幕上。我怎样才能做到 "self hide"?
问题 2：如果我对任一控件使用 TCustomHint，则 CMHintShow 过程永远不会触发。那么，如果我确实想使用 TCustomHint 来获得它提供的额外控制，这将如何改变定位策略？
（而且我不希望在 "application" 级别进行任何操作，例如通过 OnShowHint - 它必须特定于这些控件）
正如问题的评论中所确定的那样，提示不会无限期地停留在屏幕上，但实际上一旦隐藏就会不断重新显示。
原因是，VCL 假定提示控件是子 window，那是因为它 Parent 属性 不是 nil。对于问题中的代码，虽然月历 floats 通过将其突变为弹出窗口 window，但就 VCL 所知，其父级仍然是表单它。这会导致Application 的ActivateHint 过程中提示矩形的计算出错。另一方面，应用程序的 HintMouseMessage 过程不关心控件是否为父控件。然后会发生什么，虽然你没有在控件上移动鼠标指针，但 VCL 推断鼠标指针连续离开提示边界然后重新进入。
这里是问题的简化重现：
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.StdCtrls;
type
TPanel = class(vcl.extctrls.TPanel)
protected
procedure CreateParams(var Params: TCreateParams); override;
end;
TForm1 = class(TForm)
Button1: TButton;
Panel1: TPanel;
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
{ TPanel }
procedure TPanel.CreateParams(var Params: TCreateParams);
begin
inherited;
Params.Style := WS_POPUPWINDOW or WS_THICKFRAME;
end;
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
begin
Button1.Hint := 'Button1';
Panel1.Hint := 'Panel1';
ShowHint := True;
Application.HintHidePause := 1000;
Left := 0;
Top := 0;
Panel1.ParentBackground := False;
Panel1.Left := 0;
Panel1.Height := 50;
Panel1.Top := Top + Height;
end;
end.
上述代码中，按钮的提示超时会隐藏，而面板的提示在隐藏后重新显示。我特意将 windows 定位到它们的位置，以便您可以在激活提示时观察指针位置的意义。如果您从下方将鼠标指针输入面板，提示将只显示一次然后隐藏。但是，如果您从上方进入面板，就会发现问题。
修复很简单，您可以在 CM_HINTSHOW 消息处理程序中修改提示矩形。由于控件是浮动的，因此不需要复杂的计算。相应地修改了复制案例，其中也修复了问题中的日历：
type
TPanel = class(vcl.extctrls.TPanel)
protected
procedure CreateParams(var Params: TCreateParams); override;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
end;
TForm1 = class(TForm)
...
{ TPanel }
procedure TPanel.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if (GetAncestor(Handle, GA_ROOT) = Handle) and Assigned(Parent) then
Message.HintInfo.CursorRect := Rect(0, 0, Width, Height);
end;
至于问题 2，自定义提示 window 不幸的是似乎没有设计 position-able。提示 window 是本地创建的，没有巧妙的方法来获取它或以任何其他方式指定它的位置。我能想到的唯一方法是覆盖自定义提示的一种绘制方法，该方法将提示 window 作为参数公开。所以我们可以在收到绘制消息后立即重新定位提示 window。
这是一个工作示例（对于普通（非浮动）控件）：
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
type
TMyCustomHint = class(TCustomHint)
private
FControl: TControl;
public
procedure NCPaintHint(HintWindow: TCustomHintWindow; DC: HDC); override;
end;
procedure TMyCustomHint.NCPaintHint(HintWindow: TCustomHintWindow; DC: HDC);
var
Pt: TPoint;
begin
Pt := FControl.ClientToScreen(Point(0, 0));
SetWindowPos(HintWindow.Handle, 0, Pt.X, Pt.Y + FControl.Height, 0, 0,
SWP_NOSIZE or SWP_NOZORDER or SWP_NOACTIVATE);
inherited;
end;
//--------
procedure TForm1.FormCreate(Sender: TObject);
begin
ShowHint := True;
Button1.Hint := 'button1 hint';
Button1.CustomHint := TMyCustomHint.Create(Self);
TMyCustomHint(Button1.CustomHint).FControl := Button1;
end;
end.
使用 Delphi XE6，我正在创建一个类似 TdateTimePicker 的控件，但出于几个原因，我使用了一个 TButtonedEdit，其中有一个 TMonthCalendar "embedded"。完整的准系统演示是：
单击右键时显示月历（with Style=WS_POPUP），我已经按照需要进行操作，当做出选择，用户导航离开，ESCapes 等
unit DateEditBare1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.ImgList, Vcl.ComCtrls, Vcl.StdCtrls,
CommCtrl;
type
TespMonthCalendar = class(TMonthCalendar)
procedure DoCloseUp(Sender: TObject);
private
FDroppedDown: boolean;
FManagerHandle: HWND; // just a convenience to avoid having to assume its in the owner
procedure CNNotify(var Message: TWMNotify); message CN_NOTIFY;
procedure SetWindowDIMs;
protected
procedure CreateParams(var Params: TCreateParams); override;
procedure CreateWnd; override;
procedure KeyDown(var Key: Word; Shift: TShiftState); override;
procedure WMActivate(var Msg: TWMActivate); message WM_ACTIVATE;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
end;
TespDateEdit = class(TButtonedEdit)
private
FMonthCalendar: TespMonthCalendar;
procedure DoRightButtonClick(Sender: TObject);
protected
procedure CreateWnd; override;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
public
constructor Create(AOwner:TComponent); override;
property MonthCalendar: TespMonthCalendar read FMonthCalendar write FMonthCalendar;
end;
TfrmDateEditBare1 = class(TForm)
Edit1: TEdit;
procedure FormCreate(Sender: TObject);
private
espDateEdit1: TespDateEdit;
public
end;
var
frmDateEditBare1: TfrmDateEditBare1;
implementation
{$R *.dfm}
var
_espdateEdit_ImageList: TImageList=nil;
//------------------------------------------------------------------------------
function MakeImageList(const ResNames: array of String): TImageList;
var
ResBmp: TBitmap;
I: Integer;
begin
{ Create an image list. }
_espdateEdit_ImageList := TImageList.Create(nil);
_espdateEdit_ImageList.Width := 24;
_espdateEdit_ImageList.Height := 16;
Result := _espdateEdit_ImageList;
for I := 0 to Length(ResNames) - 1 do
begin
ResBmp := TBitmap.Create();
try
{ Try to load the bitmap from the resource. }
try
//ResBmp.LoadFromResourceName(HInstance, ResNames[I]);
ResBmp.SetSize(24,16);
ResBmp.Transparent := true;
except
ResBmp.Free();
Result.Free();
Exit;
end;
Result.Add(ResBmp, nil);
finally
ResBmp.Free;
end;
end;
end;
// Aowner is ignored for now
function GetImageList: TImageList;
begin
if _espdateEdit_ImageList = nil then
result := MakeImageList(['CalendarDrop', 'CalendarDropShifted'])
else
result := _espdateEdit_ImageList;
end;
//------------------------------------------------------------------------------
procedure TfrmDateEditBare1.FormCreate(Sender: TObject);
begin
espDateEdit1:= TespDateEdit.Create(self);
espDateEdit1.Parent := self;
espDateEdit1.left := 100;
espDateEdit1.top := 100;
espDateEdit1.Visible := true;
end;
//------------------------------------------------------------------------------
{ TespMonthCalendar }
procedure TespMonthCalendar.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if Message.HintInfo.HintControl=Self then
begin
Message.HintInfo.HintPos := self.ClientToScreen(Point(0, self.Height + 1));
Message.HintInfo.HideTimeout := 1000;
// Message.HintInfo.ReshowTimeout := 1500; // setting this does not help
end;
end;
procedure TespMonthCalendar.CreateParams(var Params: TCreateParams);
begin
inherited CreateParams(Params);
with Params do
begin
Style := WS_POPUP;
WindowClass.Style := WindowClass.Style or CS_SAVEBITS ;
if CheckWin32Version(5, 1) then
WindowClass.Style := WindowClass.style or CS_DROPSHADOW;
end;
end;
procedure TespMonthCalendar.CreateWnd;
begin
inherited;
// Get/set the dimensions of the calendar
SetWindowDIMs;
end;
procedure TespMonthCalendar.SetWindowDIMs;
var
ReqRect: TRect;
MaxTodayWidth: Integer;
begin
FillChar(ReqRect, SizeOf(TRect), 0);
// get required rect
Win32Check(MonthCal_GetMinReqRect(Handle, ReqRect));
// get max today string width
MaxTodayWidth := MonthCal_GetMaxTodayWidth(Handle);
// adjust rect width to fit today string
if MaxTodayWidth > ReqRect.Right then
ReqRect.Right := MaxTodayWidth;
// set new height & width
Width := ReqRect.Right ;
Height:= ReqRect.Bottom ;
end; (* SetWindowDIMs *)
procedure TespMonthCalendar.CNNotify(var Message: TWMNotify);
begin
// hand off control of the selection to the boss i.e. the espDateEdit that I belong to
// skip for demo ... just closeup
if ( Message.NMHdr^.code = MCN_SELECT) then
DoCloseUp(self);
inherited;
end; (*CNNotify*)
procedure TespMonthCalendar.KeyDown(var Key: Word; Shift: TShiftState);
begin
if Key = VK_ESCAPE then
begin
Key := 0;
DoCloseUp(self);
end
else
inherited KeyDown(Key, Shift);
end;
procedure TespMonthCalendar.WMActivate(var Msg: TWMActivate);
begin
if (Msg.Active <> WA_INACTIVE) then
// tell form to paint itself as though it still has focus (as we are no outside the form with POPUP)
SendMessage(screen.ActiveForm.Handle, WM_NCACTIVATE, WPARAM(True), -1)
else
DoCloseUp(self);
inherited;
end;
procedure TespMonthCalendar.DoCloseUp(Sender: TObject);
begin
if FDroppedDown then
begin
FDroppedDown := false;
Hide;
// put focus back on dateedit so that checking is done if we leave here to go on to another control
SendMessage(FManagerHandle, WM_ACTIVATE, WPARAM(True), -1); // less assumptions this way
end;
end;
//------------------------------------------------------------------------------
{ TespDateEdit }
procedure TespDateEdit.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if Message.HintInfo.HintControl=Self then
Message.HintInfo.HintPos := self.ClientToScreen(Point(0, 21));
end;
constructor TespDateEdit.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
if not(csDesigning in ComponentState) then
begin
FmonthCalendar := TespMonthCalendar.Create(self);
self.hint := 'DUMMY HINT for Edit Box';
FMonthCalendar.Hint := 'Select required Date,' + ^M^J + 'or ESCape to close the calendar.';
FMonthCalendar.ShowHint := true;
end;
Width := 100;
Height := 21;
Images := GetImageList;
Text := ''; // FormatdateTime('dd/mm/yy', Date); // not for demo
ShowHint := True;
DoubleBuffered := true; // reduces flicker when passing thru and within control
RightButton.ImageIndex := 0;
RightButton.PressedImageIndex := 1;
RightButton.Visible := True;
OnRightButtonClick := DoRightButtonClick;
end;
procedure TespDateEdit.CreateWnd;
var
P: TWinControl;
begin
inherited CreateWnd;
if not(csDesigning in ComponentState) then
begin
FMonthCalendar.left := -900;
P := self.Parent;
while (P <> nil ) and not ( P is TCustomForm ) do
P := P.parent;
FmonthCalendar.Parent := P; // ie form (or the topmost non nil entry in the tree)
FmonthCalendar.FManagerHandle := self.Handle;
FMonthCalendar.Hide;
FmonthCalendar.OnExit := FmonthCalendar.DoCloseUp;
end;
end;
procedure TespDateEdit.DoRightButtonClick(Sender: TObject);
var
dt: Tdate;
TopLeft: TPoint;
Rect: TRect;
begin
if FmonthCalendar.FdroppedDown then
begin
FMonthCalendar.DoCloseUp(nil);
exit;
end;
// load non-zero date into calendar as the selected date ... skip for demo
TopLeft := self.ClientToScreen(Point(0, 0)); // i.e. screen co-ords of top left of edit box
monthCalendar.left := TopLeft.X - 3 ; // shift a poopsie to line up visually
monthCalendar.Top := TopLeft.Y + self.Height - 2;
// only move it if it exceeds screen bounds ... skip this for demo
FmonthCalendar.FDroppedDown := true;
MonthCal_SetCurrentView(FmonthCalendar.handle, MCMV_MONTH);
FmonthCalendar.Show;
// showing is not enough - need to grab focus to get kbd events happening on the calendar
FmonthCalendar.SetFocus;
inherited OnRightButtonClick;
end;
//------------------------------------------------------------------------------
initialization
finalization
FreeAndNil(_espdateEdit_ImageList);
end.
现在，我想为编辑框和 TMonthCalendar 添加单独的提示，但我想确保显示的提示不会遮挡相关控件。 对于编辑框，我已经成功拦截了CM_HINTSHOW消息，我设置了HintInfo.HintPos来实现。到目前为止，还不错。
问题 1：更新：我现在显示了。最初我将提示文本设置为包含管道字符，这样我就可以使用 TCustomHint。删除管道字符，导致提示显示。 但是 此提示不会自行隐藏，它会在 TmonthCalendar 显示时一直显示在屏幕上。我怎样才能做到 "self hide"?
问题 2：如果我对任一控件使用 TCustomHint，则 CMHintShow 过程永远不会触发。那么，如果我确实想使用 TCustomHint 来获得它提供的额外控制，这将如何改变定位策略？ （而且我不希望在 "application" 级别进行任何操作，例如通过 OnShowHint - 它必须特定于这些控件）
正如问题的评论中所确定的那样，提示不会无限期地停留在屏幕上，但实际上一旦隐藏就会不断重新显示。
原因是，VCL 假定提示控件是子 window，那是因为它 Parent 属性 不是 nil。对于问题中的代码，虽然月历 floats 通过将其突变为弹出窗口 window，但就 VCL 所知，其父级仍然是表单它。这会导致Application 的ActivateHint 过程中提示矩形的计算出错。另一方面，应用程序的 HintMouseMessage 过程不关心控件是否为父控件。然后会发生什么，虽然你没有在控件上移动鼠标指针，但 VCL 推断鼠标指针连续离开提示边界然后重新进入。
这里是问题的简化重现：
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.StdCtrls;
type
TPanel = class(vcl.extctrls.TPanel)
protected
procedure CreateParams(var Params: TCreateParams); override;
end;
TForm1 = class(TForm)
Button1: TButton;
Panel1: TPanel;
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
{ TPanel }
procedure TPanel.CreateParams(var Params: TCreateParams);
begin
inherited;
Params.Style := WS_POPUPWINDOW or WS_THICKFRAME;
end;
{ TForm1 }
procedure TForm1.FormCreate(Sender: TObject);
begin
Button1.Hint := 'Button1';
Panel1.Hint := 'Panel1';
ShowHint := True;
Application.HintHidePause := 1000;
Left := 0;
Top := 0;
Panel1.ParentBackground := False;
Panel1.Left := 0;
Panel1.Height := 50;
Panel1.Top := Top + Height;
end;
end.
上述代码中，按钮的提示超时会隐藏，而面板的提示在隐藏后重新显示。我特意将 windows 定位到它们的位置，以便您可以在激活提示时观察指针位置的意义。如果您从下方将鼠标指针输入面板，提示将只显示一次然后隐藏。但是，如果您从上方进入面板，就会发现问题。
修复很简单，您可以在 CM_HINTSHOW 消息处理程序中修改提示矩形。由于控件是浮动的，因此不需要复杂的计算。相应地修改了复制案例，其中也修复了问题中的日历：
type
TPanel = class(vcl.extctrls.TPanel)
protected
procedure CreateParams(var Params: TCreateParams); override;
procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
end;
TForm1 = class(TForm)
...
{ TPanel }
procedure TPanel.CMHintShow(var Message: TCMHintShow);
begin
inherited;
if (GetAncestor(Handle, GA_ROOT) = Handle) and Assigned(Parent) then
Message.HintInfo.CursorRect := Rect(0, 0, Width, Height);
end;
至于问题 2，自定义提示 window 不幸的是似乎没有设计 position-able。提示 window 是本地创建的，没有巧妙的方法来获取它或以任何其他方式指定它的位置。我能想到的唯一方法是覆盖自定义提示的一种绘制方法，该方法将提示 window 作为参数公开。所以我们可以在收到绘制消息后立即重新定位提示 window。
这是一个工作示例（对于普通（非浮动）控件）：
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ExtCtrls, Vcl.StdCtrls;
type
TForm1 = class(TForm)
Button1: TButton;
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
type
TMyCustomHint = class(TCustomHint)
private
FControl: TControl;
public
procedure NCPaintHint(HintWindow: TCustomHintWindow; DC: HDC); override;
end;
procedure TMyCustomHint.NCPaintHint(HintWindow: TCustomHintWindow; DC: HDC);
var
Pt: TPoint;
begin
Pt := FControl.ClientToScreen(Point(0, 0));
SetWindowPos(HintWindow.Handle, 0, Pt.X, Pt.Y + FControl.Height, 0, 0,
SWP_NOSIZE or SWP_NOZORDER or SWP_NOACTIVATE);
inherited;
end;
//--------
procedure TForm1.FormCreate(Sender: TObject);
begin
ShowHint := True;
Button1.Hint := 'button1 hint';
Button1.CustomHint := TMyCustomHint.Create(Self);
TMyCustomHint(Button1.CustomHint).FControl := Button1;
end;
end.