KEYPRESS
When a windowed control receives a key-press message (WM_CHAR) from Windows, its message handler calls the DoKeyPress method.
说明：响应WM_CHAR消息，不包括一些功能键，如：F1，SHIFT键等
KEYDOWN
When a windowed control receives a key-down message (WM_KEYDOWN) from Windows, its message handler calls the DoKeyDown method.
响应WM_KEYDOWN消息
一个是按下去，一个是按下放上来时
procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char);
begin
//只能触发单键事件
end;
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
//在keyDown事件里可以触发shift+A等组合键事件
end;
Drate回答正确,其它人都没搞清楚,那是OnKeyUp!其实响应WM_CHAR就是按下字符键时激发,而按下其他功能键无效!
procedure WMChar(var Message: TWMChar); message WM_CHAR;
procedure TWinControl.WMChar(var Message: TWMChar);
begin
if not DoKeyPress(Message) then inherited;
end;
procedure WMKeyDown(var Message: TWMKeyDown); message WM_KEYDOWN;
procedure TWinControl.WMKeyDown(var Message: TWMKeyDown);
begin
if not DoKeyDown(Message) then inherited;
end;
原文地址：https://www.cnblogs.com/jijm123/p/10351562.html