Firemonkey：Image.Bitmap.DrawLine 在 ipad 上不可见

Question

我正在 DelphiXE2 firemonkey 中为 IOS 构建一个应用程序。如果我在 Mac 上的 Xcode IPAD 模拟器中进行测试，我会看到该按钮。但是当我单击按钮时，看不到任何线条。为什么？

代码：（在表单上一个按钮和一个图像）

unit Unit3;

interface

uses
  SysUtils, Types, UITypes, Classes, Variants, FMX_Types, FMX_Controls, FMX_Forms,
  FMX_Dialogs, FMX_Objects;

type
  TForm3 = class(TForm)
    Image1: TImage;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form3: TForm3;

implementation

{$R *.lfm}

procedure TForm3.Button1Click(Sender: TObject);
var pt0,pt1 : TPointF;
begin
  pt0.Create(0,0);
  pt1.Create(200,200);
  with Image1.Bitmap do begin
    Canvas.Stroke.Color := $ffff0000 ;  // Red
    Canvas.BeginScene;

    Canvas.DrawLine(pt0,pt1,1);
    BitmapChanged;  // without this, no output
    Canvas.EndScene;
  end;

end;


procedure TForm3.FormCreate(Sender: TObject);
begin
  Image1.Bitmap := TBitmap.Create(200,200);
end;
end.

Answer 1

我认为应该是：

pt0 := TPointF.Create(0, 0);

Answer 2

试试这个

  pt0.X:=X;
  pt0.Y:=Y;
  pt1.X:=X+4;
  pt1.Y:=Y+4;
  with Image1.Bitmap do begin
    Canvas.Stroke.Color := $ffff0000 ;  // Red
    Canvas.Stroke.Kind := TBrushKind.bkSolid;
    Canvas.StrokeThickness:= 10;
    Canvas.BeginScene;
    Canvas.DrawLine(pt0,pt1,100);
    Canvas.EndScene;
  end;