如何实现图片等比例放大或者缩小？？？ ( 积分: 50 )

如何实现图片等比例放大或者缩小？？

如何实现图片等比例放大或者缩小？？

不知道等比例是什么意思，最简单的办法就是通过Canvas.StretchDraw的方式

我用的是7.0，那个控件是 IMAGE
等比例就是 像看图软件中的点击放大 然后 长高 同时按比例放大

简单：
如长80，高60，比例为4：3
放大后如图为120，那宽*(3/4)

把Image的Stretch属性选“true”，然后找个触发条件，例如用按钮控制，当要放大的时候，将Image的Height和Width属性值分别*2就可以了

设置你个放大的比例，
button1.onclick
begin
image1.width:=round(image1.width*(1+比例))；

image1.height:=round(image1.height*(1+比例))；
end;

朋友的代码，可以点击鼠标滚轮放大缩小

unit Unit1;

interface

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

type
TForm1 = class(TForm)
ApplicationEvents1: TApplicationEvents;
Image1: TImage;
procedure ApplicationEvents1Message(var Msg: tagMSG;
var Handled: Boolean);
procedure Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
procedure Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

var
dx,dy : integer;
md : boolean;


procedure TForm1.ApplicationEvents1Message(var Msg: tagMSG;
var Handled: Boolean);
begin
if(Msg.message=WM_MOUSEWHEEL) then //捕获鼠标轮事件
begin
if(Msg.wParam>0) then //上滚
begin
image1.width:=image1.width+1;
image1.height:=image1.height+1;
end
else //下滚
begin
image1.height:=image1.height-1;
image1.width:=image1.width-1;
end;
end;
end;


procedure TForm1.Image1MouseDown(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
dx:=x;
dy:=y;
md:=true;
end;

procedure TForm1.Image1MouseUp(Sender: TObject; Button: TMouseButton;
Shift: TShiftState; X, Y: Integer);
begin
md := false;
end;

procedure TForm1.Image1MouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
var
mx,my : integer;
begin
if md then
begin
mx:=x-dx;
my:=y-dy;
image1.Left:=image1.Left+mx;
image1.Top:=image1.Top+my;
end;
end;

end.


窗体文件
object Form1: TForm1
Left = 207
Top = 108
Width = 696
Height = 480
Caption = 'Form1'
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'MS Sans Serif'
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object Image1: TImage
Left = 224
Top = 64
Width = 81
Height = 81
Picture.Data = {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}
Stretch = True
OnMouseDown = Image1MouseDown
OnMouseMove = Image1MouseMove
OnMouseUp = Image1MouseUp
end
object ApplicationEvents1: TApplicationEvents
OnMessage = ApplicationEvents1Message
Left = 104
Top = 40
end
end

谢谢