WinAPI: 输入光标相关的函数[4]

本例效果图:

---

代码文件:

---

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TForm1 = class(TForm)
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormKeyPress(Sender: TObject; var Key: Char);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  str: string;
  x1,y1: Integer;

procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char);
var
  x2: Integer;
begin
  HideCaret(Handle);
  Repaint;

  if Key = #8 then
  begin
    if Length(str) > 0 then
    SetLength(str, Length(str) - 1);
  end else str := str + Key;

  Text := str;

  Canvas.TextOut(x1, y1, str);
  x2 := x1 + Canvas.TextWidth(str);
  SetCaretPos(x2, y1);
  ShowCaret(Handle);
end;

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  str := '';
  DestroyCaret;
  CreateCaret(Handle, 0, 0, Canvas.TextHeight('A'));
  SetCaretPos(X,Y);
  ShowCaret(Handle);

  x1 := X;
  y1 := Y;
end;

end.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 339
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnKeyPress = FormKeyPress
  OnMouseDown = FormMouseDown
  PixelsPerInch = 96
  TextHeight = 13
end