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