表面上是label，实际上也是Memo

来源：互联网发布：mysql 数据不重复编辑：程序博客网时间：2024/05/17 03:16

在项目中，需要这么一个控件：

平常状态就像一个label，当鼠标双击后得到focus后处于可编辑状态
失去焦点后恢复到一开始的平常状态

这样的控件感觉好多软件都有，主要用于图形界面上的文本框，不过我找啊找都没有找到，只好自己写一个了：

一：基本原理

利用一个label控件和一个memo控件模拟得到。memo控件开始时候隐藏当鼠标双击label时候，显示并修改memo的位置和大小，并将label的caption赋给memo的Text.最后，当memo失去焦点时候，隐藏memo。

二：难点

当编辑memo时候，点击其它区域时候，也应恢复到平常状态。由于不是焦点的转移，OnExit事件并不能捕获。最后的解决方法是利用捕获CM_MOUSELEAVE、WM_KILLFOCUS消息，在CM_MOUSELEAVE中SetCapture，并在OnMouseDown事件中判断鼠标的位置，如果在控件外则::SetFocus(NULL);，WM_KILLFOCUS中做隐藏memo等善后事务。

三：使用方法

1、添加组件（TNoteLabel、TFloatMemo）

2、在Form上放置若干个TNoteLabel和一个TFloatMemo即可，并将TNoteLabel的EditMemo属性设置为TFloatMemo。或者在程序中动态赋也可以。

四：实现代码

呵呵，列出来大家参考，如有需要改进之处，请指正(email:wu_07@sina.com)

//---------------------------------------------------------------------------

#ifndef FloatMemoH
#define FloatMemoH
//---------------------------------------------------------------------------
#include
#include
#include
#include
//---------------------------------------------------------------------------
class PACKAGE TFloatMemo : public TMemo
{
private:
TNotifyEvent fOnMouseLeave ;
TNotifyEvent fOnLoseFocus;
MESSAGE void __fastcall CMMouseLeave(TMessage &Msg);
MESSAGE void __fastcall WMKillFocus(TMessage &Msg);
protected:

virtual void __fastcall Loaded(void);
public:
__fastcall TFloatMemo(TComponent* Owner);
bool b;
__published:

BEGIN_MESSAGE_MAP
MESSAGE_HANDLER(CM_MOUSELEAVE, TMessage, CMMouseLeave)
MESSAGE_HANDLER(WM_KILLFOCUS,TMessage,WMKillFocus)
END_MESSAGE_MAP(TControl)
__property Classes::TNotifyEvent OnMouseLeave= {read=fOnMouseLeave, write=fOnMouseLeave};
__property Classes::TNotifyEvent OnLoseFocus= {read=fOnLoseFocus, write=fOnLoseFocus};

};
//---------------------------------------------------------------------------
#endif

//---------------------------------------------------------------------------

#include

#pragma hdrstop

#include "FloatMemo.h"
#pragma package(smart_init)
//---------------------------------------------------------------------------
// ValidCtrCheck is used to assure that the components created do not have
// any pure virtual functions.
//

static inline void ValidCtrCheck(TFloatMemo *)
{
new TFloatMemo(NULL);
}
//---------------------------------------------------------------------------
__fastcall TFloatMemo::TFloatMemo(TComponent* Owner)
: TMemo(Owner)
{

}
//---------------------------------------------------------------------------
namespace Floatmemo
{
void __fastcall PACKAGE Register()
{
TComponentClass classes[1] = {__classid(TFloatMemo)};
RegisterComponents("Additional", classes, 0);
}
}
//---------------------------------------------------------------------------
void __fastcall TFloatMemo::Loaded(void)
{
this->Ctl3D =false;
this->Visible =false;
this->Cursor =crArrow;
}
//---------------------------------------------------------------------------
void __fastcall TFloatMemo::CMMouseLeave(TMessage &Msg)
{

TMemo::Dispatch(&Msg);
if (fOnMouseLeave) fOnMouseLeave(this);

}
//---------------------------------------------------------------------------
void __fastcall TFloatMemo::WMKillFocus(TMessage &Msg)
{
TMemo::Dispatch(&Msg);
if (fOnLoseFocus) fOnLoseFocus(this);
}
//---------------------------------------------------------------------------

//---------------------------------------------------------------------------

#ifndef NoteLabelH
#define NoteLabelH
//---------------------------------------------------------------------------
#include
#include
#include
#include
#include "FloatMemo.h"
//---------------------------------------------------------------------------
class PACKAGE TNoteLabel : public TCustomLabel
{
private:
TFloatMemo * fEditMemo;
void __fastcall SetEditMemo(TFloatMemo* Memo);
DYNAMIC void __fastcall DblClick(void);
void __fastcall EditMemoMouseLeave(TObject *Sender);
void __fastcall EditMemoMouseUp(TObject *Sender,TMouseButton Button, TShiftState Shift, int X, int Y);
void __fastcall EditMemoLoseFocus(TObject *Sender);
protected:
void __fastcall Paint(void);
virtual void __fastcall Loaded(void);
MESSAGE void __fastcall WMSetText(TMessage &Msg);
public:
__fastcall TNoteLabel(TComponent* Owner);
__published:
__property TFloatMemo *EditMemo={read=fEditMemo,write=SetEditMemo};
__property Align = {default=0};
__property Alignment = {default=0};
__property Anchors = {default=3};
__property AutoSize = {default=0};
__property BiDiMode ;
__property Caption ;
__property Color = {default=-2147483643};
__property Constraints ;
__property DragCursor = {default=-12};
__property DragKind = {default=0};
__property DragMode = {default=0};
__property Enabled = {default=1};
__property FocusControl ;
__property Font ;
__property ParentBiDiMode = {default=1};
__property ParentColor = {default=1};
__property ParentFont = {default=1};
__property ParentShowHint = {default=1};
__property PopupMenu ;
__property ShowAccelChar = {default=1};
__property ShowHint ;
__property Transparent = {default=0};
__property Layout = {default=0};
__property Visible = {default=1};
__property WordWrap = {default=0};
__property OnClick ;
__property OnContextPopup ;
__property OnDblClick ;
__property OnDragDrop ;
__property OnDragOver ;
__property OnEndDock ;
__property OnEndDrag ;
__property OnMouseDown ;
__property OnMouseMove ;
__property OnMouseUp ;
__property OnMouseEnter ;
__property OnMouseLeave ;
__property OnStartDock ;
__property OnStartDrag ;

BEGIN_MESSAGE_MAP
MESSAGE_HANDLER(WM_SETTEXT, TMessage, WMSetText)
END_MESSAGE_MAP(TControl)

};
//---------------------------------------------------------------------------
#endif

//---------------------------------------------------------------------------

#include

#pragma hdrstop

#include "NoteLabel.h"
#pragma package(smart_init)
/* Standard DrawText flags */
#define LV_ML_DT_FLAGS (DT_TOP | DT_NOPREFIX | DT_EDITCONTROL | DT_CENTER | DT_WORDBREAK | DT_WORD_ELLIPSIS | DT_END_ELLIPSIS)
#define LV_FL_DT_FLAGS (DT_TOP | DT_NOPREFIX | DT_EDITCONTROL | DT_CENTER | DT_WORDBREAK | DT_NOCLIP)
#define LV_SL_DT_FLAGS (DT_TOP | DT_EDITCONTROL | DT_SINGLELINE | DT_WORD_ELLIPSIS | DT_END_ELLIPSIS)

//---------------------------------------------------------------------------
// ValidCtrCheck is used to assure that the components created do not have
// any pure virtual functions.
//

static inline void ValidCtrCheck(TNoteLabel *)
{
new TNoteLabel(NULL);
}
//---------------------------------------------------------------------------
__fastcall TNoteLabel::TNoteLabel(TComponent* Owner)
: TCustomLabel(Owner)
{
AutoSize =false;
}
//---------------------------------------------------------------------------
namespace Notelabel
{
void __fastcall PACKAGE Register()
{
TComponentClass classes[1] = {__classid(TNoteLabel)};
RegisterComponents("Additional", classes, 0);
}
}
//---------------------------------------------------------------------------

void __fastcall TNoteLabel::Paint(void)
{
Canvas->Font =Font;
Canvas->Brush->Color =Color;
if (Transparent)
SetBkMode(Canvas->Handle,TRANSPARENT);
else
{
SetBkMode(Canvas->Handle,OPAQUE);
Canvas->FillRect(Rect(0, 0, Width, Height));
}
DrawTextEx(Canvas->Handle, Caption.c_str(), Caption.Length(), &Rect(0, 0, Width
, Height),LV_ML_DT_FLAGS,NULL);
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::WMSetText(TMessage &Msg)
{
TControl::Dispatch(&Msg);
Invalidate();
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::SetEditMemo(TFloatMemo* Memo)
{
fEditMemo = Memo;
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::DblClick()
{
if (fEditMemo!=NULL)
{

fEditMemo->OnMouseUp = EditMemoMouseUp;
fEditMemo->OnMouseLeave = EditMemoMouseLeave;
fEditMemo->OnLoseFocus = EditMemoLoseFocus;
fEditMemo->BoundsRect = BoundsRect;
fEditMemo->Text = Caption;
fEditMemo->Show();
::SetFocus(fEditMemo->Handle);
fEditMemo->SelectAll();
}
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::Loaded()
{
//
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::EditMemoLoseFocus(TObject *Sender)
{
TMemo* Ctl=dynamic_cast(Sender);
if (Ctl==0) return ;
Ctl->Hide();
Caption = Ctl->Text;
}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::EditMemoMouseLeave(TObject *Sender)
{
TWinControl* Ctl=dynamic_cast(Sender);
if (Ctl==0) return ;
if (GetCapture()!=Ctl->Handle) SetCapture(Ctl->Handle);

}
//---------------------------------------------------------------------------
void __fastcall TNoteLabel::EditMemoMouseUp(TObject *Sender,TMouseButton Button, TShiftState Shift, int X, int Y)
{
TWinControl* Ctl=dynamic_cast(Sender);
if (Ctl==0) return;
if(!PtInRect(&Rect(0,0,Ctl->Width,Ctl->Height),Point(X,Y)))
{
ReleaseCapture();
::SetFocus(NULL);
}
}

//---------------------------------------------------------------------------