WinAPI: OffsetWindowOrgEx - 移动窗口坐标原点

相关函数: OffsetViewportOrgEx

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本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, ComCtrls, ExtCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    procedure FormCreate(Sender: TObject);

    procedure FormDestroy(Sender: TObject);

    procedure FormPaint(Sender: TObject);

    procedure FormMouseDown(Sender: TObject; Button: TMouseButton;

      Shift: TShiftState; X, Y: Integer);

    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);

    procedure FormMouseUp(Sender: TObject; Button: TMouseButton;

      Shift: TShiftState; X, Y: Integer);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



var

  cvs: TCanvas;

  bit: TBitmap;

  f: Boolean;

  x1,y1: Integer;



procedure TForm1.FormCreate(Sender: TObject);

begin

  bit := TBitmap.Create;

  bit.LoadFromFile('c:\temp\test.bmp');

  cvs := TCanvas.Create;

  cvs.Handle := GetDC(Handle);

end;



procedure TForm1.FormPaint(Sender: TObject);

const

  str = 'Delphi';

var

  x,y: Integer;

begin

  {在图片中绘制文本}

  bit.Canvas.Font.Size := 24;

  bit.Canvas.Font.Style := [fsBold];

  bit.Canvas.Font.Color := 0;

  bit.Canvas.Brush.Style := bsClear;

  x := (bit.Width - bit.Canvas.TextWidth(str)) div 2;

  y := (bit.Height - bit.Canvas.TextHeight(str)) div 2 + 32;

  bit.Canvas.TextOut(x, y, str);



  {在窗体上绘制图片}

  x := (ClientWidth - bit.Width) div 2;

  y := (ClientHeight - bit.Height) div 2;

  cvs.Draw(x, y, bit);

end;



procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;

  Shift: TShiftState; X, Y: Integer);

begin

  f := True;

  x1 := X;

  y1 := Y;

end;



procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,

  Y: Integer);

begin

  if f then

  begin

    OffsetWindowOrgEx(cvs.Handle, -(X-x1), -(Y-y1), nil);

    x1 := X;

    y1 := Y;

    Repaint;

  end;

end;



procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton;

  Shift: TShiftState; X, Y: Integer);

begin

  f := False;

end;



procedure TForm1.FormDestroy(Sender: TObject);

begin

  bit.Free;

  cvs.Free;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 212

  Top = 116

  Caption = 'Form1'

  ClientHeight = 204

  ClientWidth = 262

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  Position = poDesigned

  OnCreate = FormCreate

  OnDestroy = FormDestroy

  OnMouseDown = FormMouseDown

  OnMouseMove = FormMouseMove

  OnMouseUp = FormMouseUp

  OnPaint = FormPaint

  PixelsPerInch = 96

  TextHeight = 13

  object Button1: TButton

    Left = 96

    Top = 171

    Width = 75

    Height = 25

    Caption = 'Button1'

    TabOrder = 0

  end

end