Delphi 2010 新增功能之: 手势编程[4] - 关于 OnGesture 事件过程的参数

OnGesture 事件中的 const EventInfo: TGestureEventInfo; 参数主要用于识别手势信息;

前面用过 EventInfo.GestureID, 还有 EventInfo.Location 给出了手势动作的起点坐标, 测试代码:

---

procedure TForm1.FormGesture(Sender: TObject;

  const EventInfo: TGestureEventInfo; var Handled: Boolean);

begin

  ShowMessage(Format('X:%d; Y:%d', [EventInfo.Location.X, EventInfo.Location.Y]));

end;


 
   

EventInfo 是个结构, 里面还有更多信息; 在没有触摸屏的情况下, 其它有可能都用不上了.

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OnGesture 事件中还有一个 var 参数 Handled: Boolean;

Handled 过来的值是 False, 我们一般可以写上一句 Handled := True;

如果 Handled = False 这个触摸动作将继续向上层控件去寻找相应.

首先应该知道, 现在包括窗体在内的诸多控件都有了 GestureManager 属性和 OnGesture 事件...

譬如我们在 Panel 和其窗体上同时设置了手势, 就可以看到 Handled 参数的作用.

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测试代码文件:

---

unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, GestureMgr, ExtCtrls;



type

  TForm1 = class(TForm)

    GestureManager1: TGestureManager;

    Panel1: TPanel;

    procedure FormCreate(Sender: TObject);

    procedure FormGesture(Sender: TObject; const EventInfo: TGestureEventInfo;

      var Handled: Boolean);

    procedure Panel1Gesture(Sender: TObject; const EventInfo: TGestureEventInfo;

      var Handled: Boolean);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.FormCreate(Sender: TObject);

begin

  Self.Touch.GestureManager := GestureManager1;

  Panel1.Touch.GestureManager := GestureManager1;

end;



procedure TForm1.FormGesture(Sender: TObject;

  const EventInfo: TGestureEventInfo; var Handled: Boolean);

begin

  ShowMessage(Sender.ClassName);

end;



procedure TForm1.Panel1Gesture(Sender: TObject;

  const EventInfo: TGestureEventInfo; var Handled: Boolean);

begin

  Handled := True; {可以把这句注释掉再试}

  ShowMessage(Sender.ClassName);

end;



end.


 
   

窗体文件:

object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 206

  ClientWidth = 339

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  OnCreate = FormCreate

  OnGesture = FormGesture

  PixelsPerInch = 96

  TextHeight = 13

  object Panel1: TPanel

    Left = 128

    Top = 16

    Width = 185

    Height = 121

    Caption = 'Panel1'

    TabOrder = 0

    OnGesture = Panel1Gesture

  end

  object GestureManager1: TGestureManager

    Left = 56

    Top = 104

  end

end