delphi – 如何在Trectangle的画布上绘画

我需要一个可点击的控件,我可以根据自己的需要量身定制.从Delphi文档中我收集到了TRectangle会做的事情.我需要以编程方式创建我的TRectangles,因此我创建了一个Form,一个Panel和一个Button(参见下面的代码).由于TRectangle是通过TControl的TShape派生的,我测试了是否可以使用PaintTo在TRectangle Canvas上绘制,使用自己的画布.我构造的TRectF是在假设绘画相对于TRectangle的Canvas的情况下创建的,因此需要偏移(0,0).然而,矩形被绘制在Form的位置(0,0)！没有注意到我所做的Fill和Stroke属性的变化.

我接下来尝试了FillRect并再次使用相同的结果,尽管使用了正确的填充.虽然调用来自Trectangle变量.Canvas.FillRect,它总是相对于树中的最高父节点,绕过TRectangle和TPanel.我一直认为绘画是相对于Canvas所属的TControl的坐标.

这是错的还是TRectangle有什么特别之处？在TRectangle上有更好的绘画方式吗？

unit rect_test_main;

interface

uses
  System.SysUtils,System.Types,System.UITypes,System.Classes,System.Variants,FMX.Types,FMX.Controls,FMX.Forms,FMX.Graphics,FMX.Dialogs,FMX.StdCtrls,FMX.Objects;

type
   TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;

    procedure Button1Click (Sender: TObject);
    procedure FormCreate (Sender: TObject);

   protected
      FR: TRectangle;

   public
      procedure draw_paintto (rect: TRectangle);
      procedure draw_rect (rect: TRectangle);
      procedure draw_fill (rect: TRectangle);
      procedure draw (surface: TControl);
   end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

procedure TForm1.FormCreate (Sender: TObject);
begin
   FR := Trectangle.Create (Panel1);
   FR.Parent := Panel1;
   FR.Canvas.BeginScene;
   FR.Canvas.Fill.Color := TAlphaColors.Black;
   FR.Canvas.Stroke.Color := TAlphaColors.Green;
   FR.SetBounds (200,200,50,300);
   FR.OnClick := Button1Click;
   FR.Canvas.EndScene;
end; // FormCreate //

procedure TForm1.Button1Click (Sender: TObject);
begin
   draw_fill (FR);
end;

procedure TForm1.draw_paintto (rect: TRectangle);
var
   r: TRectF;
begin
   FR.Canvas.BeginScene;
   FR.Canvas.Fill.Color := TAlphaColors.Black;
   FR.Canvas.Stroke.Color := TAlphaColors.Green;
   FR.Canvas.Stroke.Thickness := 10;
   r := rect.ShapeRect;
//   r := TRectF.Create (TPointF.Create (FR.Position.X - 10,FR.Position.Y - 10),FR.Width,FR.Height);
   FR.PaintTo (FR.Canvas,r,FR.Parent);
   FR.Canvas.EndScene;
end; // draw_paintto //

procedure TForm1.draw_fill (rect: TRectangle);
var
   r: TRectF;
begin
   FR.Canvas.BeginScene;
   FR.Canvas.Fill.Color := TAlphaColors.Black;
   FR.Canvas.Stroke.Color := TAlphaColors.Green;
   FR.Canvas.Stroke.Thickness := 10;
   r := TRectF.Create (TPointF.Create (FR.Position.X,FR.Position.Y),FR.Height);
   FR.Canvas.FillRect (r,AllCorners,1);
   FR.Canvas.EndScene;
end; // draw_fill //

Key: TRectangle;
...
Key.Fill.Color := TAlphaColors.White;
Key.Fill.Kind := TBrushKind.bkSolid; // and not Key.Canvas.Fill ...
Key.Stroke.Thickness := 1;
Key.Stroke.Color := TAlphaColors.Darkgray;
Key.Paint;