Use of the Clipboard in Delphi [1]: Astext, Settextbuf, Gettextbuf

The shear plate class Tclipboard is defined in the CLIPBRD unit, before using the uses CLIPBRD;

uses　Clipbrd;

procedure　TForm1.Button1Click(Sender:　TObject);
var
　clip:　TClipboard;
begin
　clip　:=　TClipboard.Create;　{建立}
　clip.AsText　:=　Self.Text;　{把窗体标题放入剪切板}
　ShowMessage(clip.AsText);　{从剪切板读取,　返回结果是:　Form1}
　{因为剪切板是全局的,　此时可以在其他地方粘贴一试}
　clip.Free;　　　　　　　　　{释放}
end;

According to Delphi to provide us with the convenience, the above example can be simplified to:

uses　Clipbrd;

procedure　TForm1.Button1Click(Sender:　TObject);
begin
　Clipboard.AsText　:=　Text;
　ShowMessage(Clipboard.AsText);　{Form1}
end;

What is this Clipboard? Is it a type variable like screen?

The answer is NO! Clipboard is just a function, is a parameterless function, is defined in the CLIPBRD unit of a global function, it returns a tclipboard type of variable, when I see the source code of this function, really feel and learn a trick, very sophisticated ideas.

In addition to using the Tclipboard.astext property, we can also use Settextbuf to put text into the Clipboard and use Gettextbuf to read out the text in the Clipboard.

uses　Clipbrd;

{使用　SetTextBuf}
procedure　TForm1.Button1Click(Sender:　TObject);
begin
　Clipboard.SetTextBuf(PChar(Text));　{按参数类型要求,　需要转换一下}
　ShowMessage(Clipboard.AsText);　　　{Form1}
end;

{使用　GetTextBuf　就和使用　API　差不多,　需要给个缓冲区}
procedure　TForm1.Button2Click(Sender:　TObject);
var
　arr:　array[0..255]　of　Char;
begin
　Clipboard.AsText　:=　Text;
　Clipboard.GetTextBuf(arr,　Length(arr));
　ShowMessage(arr);　　　　　　　　　　　　{Form1}
end;

{如果不给缓冲区,　那你自己得申请并释放内存}
procedure　TForm1.Button3Click(Sender:　TObject);
var
　pc:　PChar;
begin
　Clipboard.AsText　:=　Text;
　GetMem(pc,　256);　　　　　　　　{申请内存}
　Clipboard.GetTextBuf(pc,　256);
　ShowMessage(pc);　　　　　　　　{Form1}
　FreeMem(pc);　　　　　　　　　　{释放内存}
end;