Пример компонента "HotSpot"

Вот пример HotSpot-компонента, основанного на TPanel (небольшая переделка). Управляя событиями MouseDown и MouseUp можно получить эффект резинового контура.

unit Newpanel;

interface
Uses WinTypes, Classes, Controls, StdCtrls, ExtCtrls;

Type
tHotSpotClickEvent = Procedure ( Sender : tObject; Button : tMouseButton; Shift : tShiftState ) Of Object;
TNewPanel = Class ( tPanel ) Private

fHotSpotClick : tHotSpotClickEvent; fHotSpot      : tRect; fInHotSpot    : Boolean;
Function GetHotSpotTop : Word; Function GetHotSpotLeft : Word; Function GetHotSpotWidth : Word; Function GetHotSpotHeight : Word;
Procedure SetHotSpotTop ( Value : Word ); Procedure SetHotSpotLeft ( Value : Word ); Procedure SetHotSpotWidth ( Value : Word ); Procedure SetHotSpotHeight ( Value : Word ); Protected Procedure Paint; override; Procedure MouseDown ( Button : tMouseButton; Shift : tShiftState; X, Y : Integer ); override; Procedure MouseUp   ( Button : tMouseButton; Shift : tShiftState; X, Y : Integer ); override; Public Procedure Click; override;
Property HotSpot : tRect Read fHotSpot Write fHotSpot; Published Property hsTop : Word Read GetHotSpotTop Write SetHotSpotTop; Property hsLeft : Word Read GetHotSpotLeft Write SetHotSpotLeft; Property hsWidth : Word Read GetHotSpotWidth Write SetHotSpotWidth; Property hsHeight : Word Read GetHotSpotHeight Write SetHotSpotHeight;
Property OnHotSpot : tHotSpotClickEvent Read fHotSpotClick Write fHotSpotClick; End;
Procedure Register;
implementation
Uses WinProcs, Graphics;

Procedure Register;
Begin
RegisterComponents('Custom',[TNewPanel]); End;

Procedure TNewPanel.MouseDown ( Button : tMouseButton;
Shift : tShiftState; X, Y   : Integer ); Begin
If PtInRect ( fHotSpot, Point ( X, Y ) ) And Assigned ( fHotSpotClick ) Then fInHotSpot := True; Inherited MouseDown ( Button, Shift, X, Y ); End;

Procedure TNewPanel.MouseUp ( Button : tMouseButton;
Shift : tShiftState; X, Y   : Integer ); Begin
Inherited MouseUp ( Button, Shift, X, Y );
If fInHotSpot Then Begin If Assigned ( fHotSpotClick ) Then fHotSpotClick ( Self, Button, Shift ); fInHotSpot := False; End; End;

Procedure TNewPanel.Click;
Begin
If Not fInHotSpot Then Inherited Click; End;

Procedure TNewPanel.Paint;
Var
OldStyle : tPenStyle; Begin
Inherited Paint;
If csDesigning in ComponentState Then Begin OldStyle := Canvas.Pen.Style; Canvas.Pen.Style := psDash; Canvas.Rectangle ( HotSpot.Left, HotSpot.Top, HotSpot.Right, HotSpot.Bottom ); Canvas.Pen.Style := OldStyle; End; End;

Procedure TNewPanel.SetHotSpotTop ( Value : Word );
Begin
fHotSpot.Bottom := fHotSpot.Bottom + Value - fHotSpot.Top; fHotSpot.Top := Value; Paint; End;

Procedure TNewPanel.SetHotSpotLeft ( Value : Word );
Begin
fHotSpot.Right := fHotSpot.Right + Value - fHotSpot.Left; fHotSpot.Left := Value; Paint; End;

Procedure TNewPanel.SetHotSpotWidth ( Value : Word );
Begin
fHotSpot.Right := fHotSpot.Left + Value; Paint; End;

Procedure TNewPanel.SetHotSpotHeight ( Value : Word );
Begin
fHotSpot.Bottom := fHotSpot.Top + Value; Paint; End;

Function TNewPanel.GetHotSpotTop : Word;
Begin
Result := fHotSpot.Top End;

Function TNewPanel.GetHotSpotLeft : Word;
Begin
Result := fHotSpot.Left; End;

Function TNewPanel.GetHotSpotWidth : Word;
Begin
Result := fHotSpot.Right - fHotSpot.Left; End;

Function TNewPanel.GetHotSpotHeight : Word;
Begin
Result := fHotSpot.Bottom - fHotSpot.Top; End;

End.

Надеюсь, с моей помощью вы найдете правильное направление,
Robert Wittig [000547]

Содержание раздела