通过listview中的点击项将图像加载到imageviewer时，我得到了鬼图像

Question

问题：如何删除残像？

详情： 我使用的是delphi xe10。我正在制作简单的imageview应用程序。 电脑规格：I7 6700HQ，Ram16G。 Windows10,64位。

我在表单上设置了Opendialog，ImageViewer，ListView，Button。没有更改默认名称导致它进行测试。

以下是该程序的程序。 1.单击按钮设置目录。 2.然后我可以在Listview的目录中看到文件名 3.单击列表视图中的项目。 4.可以在ImageViewer中看到图像

运作良好。但残像仍然像马赛克。所以，我试过了

image1.free;
image1.canvas.free;
image1.bitmap.free;

最后，添加以下代码。但是没有用。

if Assigned(ImageViewer1.Bitmap) then
begin
ImageViewer1.Bitmap.Clear(0);
end;

我需要尝试更多的东西吗？

这是我的完整代码。

unit app4VIew;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes,
  System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs,
  FMX.ListView.Types, FMX.ListView.Appearances, FMX.ListView.Adapters.Base,
  FMX.Controls.Presentation, FMX.StdCtrls, FMX.ListView, FMX.Layouts,
  FMX.ExtCtrls, FMX.Objects;

type
  TForm1 = class(TForm)
    ListView1: TListView;
    SpeedButton1: TSpeedButton;
    OpenDialog1: TOpenDialog;
    ImageViewer1: TImageViewer;
    procedure SpeedButton1Click(Sender: TObject);
    procedure ListView1ItemClick(const Sender: TObject;
      const AItem: TListViewItem);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  chosenDirectory: string;
  SR: TsearchRec;
  Litem: TListViewItem;

implementation

{$R *.fmx}



{ In the form There are Opendialog, ImageViewer, ListView. *}


//when click item in listview, imagefile appear in
procedure TForm1.ListView1ItemClick(const Sender: TObject;
  const AItem: TListViewItem);
var
  Image1: TBitmap;

begin
  //if already imageviewer1.bitmap assigned then free it for initializing imageviewer
  //Question1: I suppose it make easy memory load or some conflict. Just feeling. Am I right?
    if Assigned(ImageViewer1.Bitmap) then
    begin
    ImageViewer1.Bitmap.Clear(0);
    end;

  //Question2: There is afterimage look like mosaic. Why? I freed image before load.
  try
    Image1 := TBitmap.CreateFromFile(chosenDirectory + '\' + ListView1.Items
      [ListView1.Selected.Index].Text);
    Image1.Resize(round(ImageViewer1.Width)-100, round(ImageViewer1.Canvas.Height)-100);
    ImageViewer1.Bitmap.Assign(Image1);
  finally
    Image1.Free;
  end;
end;


//List files in selected directory to Listview
procedure TForm1.SpeedButton1Click(Sender: TObject);
var
  Res: Integer; // count number of files

begin
  if SelectDirectory('Select a directory', 'C:\', chosenDirectory) then
  begin
    //find file in the Directry and assign the result to SR
    Res := FindFirst(chosenDirectory + '\*.*', faAnyFile, SR);
    if Res = 0 then
      repeat
        //and give the result SR to ListView as Itrm as SR.name
        Litem := ListView1.Items.Add();
        Litem.Text := SR.Name;
      until FindNext(SR) <> 0;
    FindClose(SR);
  end;

end;

end.