在delphi中怎样象拖动滚动条一样拖动图像？？

Question

我试过下面的代码可以拖动，但是怎样让用户在图像的大小范围之内拖动，如果不控制用户可以托动的范围超过图像的大小，就看到底色，怎么处理？？能不能大用户拖动时改变scrollbox的scrollbox1.VertScrollBar.Position，scrollbox1.HorzScrollBar.Position或激活滚动条的事件，各位高手有没有这样的代码？unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls;type
  TForm1 = class(TForm)
    Image1: TImage;
    procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Image1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  XPos,YPos:integer;   //记录鼠标按下时位置
  CanMove:boolean; //判断是否可以移动
implementation{$R *.dfm}procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
    if  CanMove then
        begin
                Image1.Left:=Image1.Left+X-XPos;
                Image1.Top:=Image1.Top+Y-YPos;
        end;
end;procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
    if (Button=mbLeft) then
        begin
                CanMove:=true;
                XPos:=X;
                YPos:=Y;
        end;
end;procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
    if (Button=mbLeft) then
        CanMove:=false;
end;end.

Answer 1

if Canmove then
  begin
    if (Image1.Left+X-OldX>Width-Image1.Width) and (Image1.Left+X-OldX<0) then
    begin
      Image1.Left:=Image1.Left+X-OldX;
    end;
    if (Image1.Top+Y-OldY>Height-Image1.Height) and (Image1.Top+Y-OldY<0) then
    begin
      Image1.Top:=Image1.Top+Y-OldY;
    end;
  end;

Answer 2

OldX,OldY分别对应你的XPos,YPos
最好在FormCreate事件中写入这样一行
DoubleBuffered:=True;

Answer 3

能不能让用户拖动时改变scrollbox的scrollbox1.VertScrollBar.Position，scrollbox1.HorzScrollBar.Position或激活滚动条的事件，各位高手有没有这样的代码？

Answer 4

//Unit Source
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, jpeg, ExtCtrls, StdCtrls;type
  TForm1 = class(TForm)
    ScrollBox1: TScrollBox;
    Image1: TImage;
    ScrollBar1: TScrollBar;
    ScrollBar2: TScrollBar;
    procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Image1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormCreate(Sender: TObject);
    procedure ScrollBar2Change(Sender: TObject);
    procedure ScrollBar1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}var CanMove:boolean;
    OldX,OldY:Integer;procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if Canmove then
  begin
    if (Image1.Left+X-OldX>ScrollBox1.Width-Image1.Width) and (Image1.Left+X-OldX<0) then
    begin
      Image1.Left:=Image1.Left+X-OldX;
      ScrollBar1.Position:=-Image1.Left;
    end;
    if (Image1.Top+Y-OldY>ScrollBox1.Height-Image1.Height) and (Image1.Top+Y-OldY<0) then
    begin
      Image1.Top:=Image1.Top+Y-OldY;
      ScrollBar2.Position:=-Image1.Top;
    end;
  end;
end;procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  CanMove:=true;
  OldX:=X;
  OldY:=Y;
end;procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  CanMove:=False;
end;procedure TForm1.FormCreate(Sender: TObject);
begin
  ScrollBox1.DoubleBuffered:=True;
  ScrollBar1.Max:=Image1.Width-ScrollBox1.Width;
  ScrollBar2.Max:=Image1.Height-ScrollBox1.Height;
end;procedure TForm1.ScrollBar2Change(Sender: TObject);
begin
  Image1.Top:=-ScrollBar2.Position;
end;procedure TForm1.ScrollBar1Change(Sender: TObject);
begin
  Image1.Left:=-ScrollBar1.Position;
end;end.//Form Source
object Form1: TForm1
  Left = 210
  Top = 114
  AutoScroll = False
  Caption = 'Form1'
  ClientHeight = 446
  ClientWidth = 688
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'MS Sans Serif'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object ScrollBox1: TScrollBox
    Left = 8
    Top = 8
    Width = 649
    Height = 377
    AutoScroll = False
    TabOrder = 0
    object Image1: TImage
      Left = 0
      Top = 0
      Width = 1024
      Height = 768
      Picture.Data = {
           //省去图形信息
      }
      Stretch = True
      OnMouseDown = Image1MouseDown
      OnMouseMove = Image1MouseMove
      OnMouseUp = Image1MouseUp
    end
  end
  object ScrollBar1: TScrollBar
    Left = 9
    Top = 384
    Width = 647
    Height = 17
    LargeChange = 10
    PageSize = 0
    TabOrder = 1
    OnChange = ScrollBar1Change
  end
  object ScrollBar2: TScrollBar
    Left = 655
    Top = 9
    Width = 17
    Height = 373
    Kind = sbVertical
    LargeChange = 10
    PageSize = 0
    TabOrder = 2
    OnChange = ScrollBar2Change
  end
end

Answer 5

http://expert.csdn.net/Expert/topic/1306/1306342.xml?temp=.5650904参考一下