如何看两个形状是否重叠

Question

我正在尝试编写一个简单的firemonkey测试应用程序.

我有一个表单,有一个面板(align:= alClient).
表格上是2 TCircle.我已经设置了TCircle.Dragmode:= dmAutomatic.

我想拖动圆圈并在圆圈重叠时发生一些事情.
问题是:我没有在TCircle中看到任何称为重叠的方法,也没有看到一个名为重叠的事件.我已经尝试了所有的xxxxDrag事件,但这对我的测试没有帮助.

如何查看拖动的形状何时与另一个形状重叠？
我期待的一个DragOver,DragEnter事件检测这对我来说,但是这似乎并不如此.

当然在Firemonkey中必须有一些标准方法吗？

现在pas文件看起来像:

implementation

{$R *.fmx}

procedure TForm8.Circle1DragEnter(Sender: TObject; const Data: TDragObject;
  const Point: TPointF);
begin
  if Data.Source = Circle1 then Button1.Text:= 'DragEnter';

end;

procedure TForm8.Circle1DragOver(Sender: TObject; const Data: TDragObject;
  const Point: TPointF; var Accept: Boolean);
begin
  if (Data.Source = Circle2) then Button1.Text:= 'Circle2 drag';
end;

procedure TForm8.Circle2DragEnd(Sender: TObject);
begin
  Button1.Text:= 'DragEnd';
end;

procedure TForm8.Circle2DragEnter(Sender: TObject; const Data: TDragObject;
  const Point: TPointF);
begin
  Button1.Text:= 'DragEnter';
end;

procedure TForm8.Circle2DragLeave(Sender: TObject);
begin
  Button1.Text:= 'DragLeave';
end;

procedure TForm8.Circle2DragOver(Sender: TObject; const Data: TDragObject;
  const Point: TPointF; var Accept: Boolean);
begin
  if Data.Source = Circle2 then begin

    Button1.Text:= 'DragOver';
    Accept:= true;
  end;
end;

dfm看起来像这样:

object Form8: TForm8
  Left = 0
  Top = 0
  BiDiMode = bdLeftToRight
  Caption = 'Form8'
  ClientHeight = 603
  ClientWidth = 821
  Transparency = False
  Visible = False
  StyleLookup = 'backgroundstyle'
  object Panel1: TPanel
    Align = alClient
    Width = 821.000000000000000000
    Height = 603.000000000000000000
    TabOrder = 1
    object Button1: TButton
      Position.Point = '(16,16)'
      Width = 80.000000000000000000
      Height = 22.000000000000000000
      TabOrder = 1
      StaysPressed = False
      IsPressed = False
      Text = 'Button1'
    end
    object Circle1: TCircle
      DragMode = dmAutomatic
      Position.Point = '(248,120)'
      Width = 97.000000000000000000
      Height = 105.000000000000000000
      OnDragEnter = Circle1DragEnter
      OnDragOver = Circle1DragOver
    end
    object Circle2: TCircle
      DragMode = dmAutomatic
      Position.Point = '(168,280)'
      Width = 81.000000000000000000
      Height = 65.000000000000000000
      OnDragEnter = Circle2DragEnter
      OnDragLeave = Circle2DragLeave
      OnDragOver = Circle2DragOver
      OnDragEnd = Circle2DragEnd
    end
  end
end

Answer 1

一般问题很难并且称为碰撞检测 - 您可以谷歌这个术语来找到相关的算法.

圆碰撞检测的特殊情况很简单 - 只需计算圆心之间的距离即可.如果获得的距离小于圆的半径之和,则圆重叠.