如何创建特定区域的屏幕截图？

Question

我有代码接收之前在服务器端定义的特定区域，并在客户端的表单上创建一个洞。而不是这个，我想获取同一区域的屏幕截图，但最终结果中没有出现我的表单，就像普通的桌面截图一样，但在这种情况下，只会捕获这个小区域。

那么，我该如何调整下面的代码？

procedure TForm1.CS1Read(Sender: TObject; Socket: TCustomWinSocket);
var
  X1, X2, Y1, Y2: Integer;
  List: TStrings;
  FormRegion, HoleRegion: HRGN;
  StrCommand: String;
begin
  StrCommand := Socket.ReceiveText;

  if Pos('§', StrCommand) > 0 then
  begin
    List := TStringList.Create;
    try
      FormRegion := CreateRectRgn(0, 0, Form12.Width, Form12.Height);
      ExtractStrings(['§'], [], PChar(StrCommand), List);

      X1 := StrToIntDef(List[0], 0) - Form12.Left - 2;
      Y1 := StrToIntDef(List[1], 0) - Form12.Top - 2;
      X2 := StrToIntDef(List[2], 0) - Form12.Left - 2;
      Y2 := StrToIntDef(List[3], 0) - Form12.Top - 2;

      HoleRegion := CreateRectRgn(X1, Y1, X2, Y2);
      CombineRgn(FormRegion, FormRegion, HoleRegion, RGN_DIFF);
      SetWindowRgn(Form12.Handle, FormRegion, True);
    finally
      List.Free;
    end;
  end;
end;

Answer 1

我没有你所有的无关信息，但我可以向你展示如何将区域的内容捕获到位图中。当然，您需要适当调整坐标以满足您的需要。您可能想查看 GetRgnBox 以了解在组合它们之后如何获取整个区域的边界矩形。我的示例没有这样做，因为我只有一个区域。

该示例需要在窗体上使用两个 TButton 和一个 TImage。我已经调整了表单的大小并在代码中定位了三个组件，因此没有必要包含 DFM。但是，您需要将组件放在窗体上并连接事件处理程序。 :-)

单击 Button1 将在窗体上创建一个矩形区域，用红线的网格类型图案和一些文本填充它，只是为了定义该区域的位置。单击第二个按钮将在位图上绘制该区域内容的副本，并将该位图分配给图像控件。

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    // Region coords
    R: TRect;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

// Create the region (hole)
procedure TForm1.Button1Click(Sender: TObject);
var
  Region: HRGN;
begin
  Canvas.TextOut(R.Left + 60, R.Top + 60, 'Test text');
  Canvas.Brush.Style := bsCross;
  Canvas.Brush.Color := clRed;
  Region := CreateRectRgn(R.Left, R.Top, R.Right, R.Bottom);
  { 
    Note: Normally you'd want to check the result of the above API call
    and only proceed if it's not NULL (0). You'd also want to use a
    try..finally to make sure that the region was deleted properly.
    Omitted here because 
      a) This code was tested to work properly, and
      b) It's a demo app for doing something with the region and
         nothing else. If the call to create the region fails, the
         app is useless, and you'll close it anyway, which means
         the region will be automatically destroyed.
  }
  FillRgn(Canvas.Handle, Region, Canvas.Brush.Handle);
  DeleteObject(Region);
  Button2.Enabled := True;
end;

// Capture the region (hole) and display in the TImage.
procedure TForm1.Button2Click(Sender: TObject);
var
  Bmp: TBitmap;
begin
  Bmp := TBitmap.Create;
  try
    Bmp.SetSize(R.Right - R.Left, r.Bottom - R.Top);
    Bmp.Canvas.CopyRect(Rect(0, 0, Bmp.Width, Bmp.Height), Canvas, R);
    Image1.Picture.Assign(Bmp);
  finally
    Bmp.Free;
  end;
end;

// Set up the coordinates for the region (hole) in the form
procedure TForm1.FormCreate(Sender: TObject);
begin
  R := Rect(10, 40, 175, 175);
  // Size the image we'll use later to fit the rectangle. We set
  // the position below.
  Image1.Width := R.Right - R.Left;
  Image1.Height := R.Bottom - R.Top;

  Self.Height := 375;
  Self.Width := 350;
  Button1.Left := 238;
  Button1.Top := 16;
  Button2.Left := 238;
  Button2.Top := 48;
  Image1.Left := 160;
  Image1.Top := 190;
  // Disable the second button until the first has been clicked
  Button2.Enabled := False;
end;

end.

如何创建特定区域的屏幕截图？

How create a screenshot of a particular area?

delphi

screenshot

rectangles