请问在image如何编写取消上几步画的图案呢？

Question

请问在image如何编写取消上几步画的图案呢？

Answer 1

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls, Buttons, AppEvnts, jpeg, Menus, ActnList,
  ComCtrls, ToolWin, ImgList,TypeDefineU;
type
  TForm1 = class(TForm)
    imgPaint: TImage;
    ToolBar1: TToolBar;
    tbtBack: TToolButton;
    tbtForward: TToolButton;
    ActionList1: TActionList;
    actBack: TAction;
    actForward: TAction;
    ToolButton6: TToolButton;
    cmbShape: TComboBox;
    cmbWidth: TComboBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure imgPaintMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure imgPaintMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure imgPaintMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure actBackExecute(Sender: TObject);
    procedure actForwardExecute(Sender: TObject);
  private
    FDownPoint,FUpPoint:TPoint;
    FGShape:array[0..MaxCount-1] of TGShape;
    Fbitmap:TBitmap;
    FCount,FMaxCount:Integer;//the count of FGShape;
    procedure BackBitmap;
  public  end;var
  Form1: TForm1;
implementation
uses math, DateUtils;
{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);
begin
  FCount:=0;
  Fbitmap:=TBitmap.Create;
  with Fbitmap do
  begin
    //Canvas.Pen.Width:=cmbWidth.ItemIndex+1;
    Canvas.Pen.Style:=psSolid;
    Canvas.Pen.Mode:=pmMask;
    Canvas.Brush.Color:=clWhite;
    Width:=ClientWidth;
    Height:=ClientHeight;
  end;
  BackBitmap;
  //imgPaint.Canvas.CopyRect(imgPaint.Canvas.ClipRect,Fbitmap.Canvas,imgPaint.Canvas.ClipRect);end;procedure TForm1.BackBitmap;
var
  j:integer;
begin
  With Fbitmap.Canvas do
  begin
    Brush.Color:=clWhite;
    Pen.Color:=clWhite;
    FillRect(ClipRect);
    for  j:=0  to FCount-1 do
    begin
      Pen.Width:=FGShape[j].PenWidth;;
      Pen.Color:=FGShape[j].PenColor;
      Brush.Color:=FGShape[j].BrushColor;      case  FGShape[j].Shape of
      ssLine:
        begin
          MoveTo(FGShape[j].DownPoint.X,FGShape[j].DownPoint.Y,);
          LineTo(FGShape[j].UPPoint.X,FGShape[j].UPPoint.Y);
        end;
      ssRectangle:
        Rectangle(FGShape[j].DownPoint.X , FGShape[j].DownPoint.Y,
                 FGShape[j].UPPoint.X , FGShape[j].UPPoint.Y);
      ssEllipse:
        Ellipse(FGShape[j].DownPoint.X , FGShape[j].DownPoint.Y,
                FGShape[j].UPPoint.X , FGShape[j].UPPoint.Y);
      end;
    end;
  end;
end;procedure TForm1.FormDestroy(Sender: TObject);
begin
  Fbitmap.Free;
end;procedure TForm1.imgPaintMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  FDownPoint.X:=X;
  FDownPoint.Y:=Y;
end;procedure TForm1.imgPaintMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  FUpPoint.X:=X;
  FUpPoint.Y:=Y;
  if FCount<MaxCount-1 then
  begin
    Randomize;
    FGShape[FCount].DownPoint:=FDownPoint;
    FGShape[FCount].UpPoint:=FUpPoint;
    FGShape[FCount].PenWidth:=cmbWidth.ItemIndex+1;
    FGShape[FCount].PenColor:=RandomRange(255,255*255*1); //边线色
    //FGShape[FCount].BrushColor:=clWhite;    //填充色
    FGShape[FCount].BrushColor:=RandomRange(255*255*8,255*255*16);
    FGShape[FCount].Shape:=tshapestyle(cmbShape.ItemIndex);
    // if mouse ,Down and Up are not a same point,it will be add into FCount
    if (FUpPoint.X<>FDownPoint.X) and ((FUpPoint.Y<>FDownPoint.Y)) then
    inc(FCount);
    FMaxCount:=FCount;
  end;
  BackBitmap;  tbtBack.Enabled:=(FCount>0)
end;procedure TForm1.imgPaintMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  imgPaint.Canvas.CopyRect(imgPaint.Canvas.ClipRect,Fbitmap.Canvas,imgPaint.Canvas.ClipRect);
  FUpPoint.X:=X;
  FUpPoint.Y:=Y;
  if FCount<MaxCount-1 then
  begin
    FGShape[FCount].DownPoint:=FDownPoint;
    FGShape[FCount].UpPoint:=FUpPoint;
    FGShape[FCount].PenWidth:=cmbWidth.ItemIndex+1;
    //FGShape[FCount].PenColor:=RandomRange(255,255*255*1); //边线色
    //FGShape[FCount].BrushColo
    FGShape[FCount].PenColor:=RGB(123,125,123);//RGB(0,255,0);//clred;
    FGShape[FCount].Shape:=tshapestyle(cmbShape.ItemIndex);;
  end;
  if ssleft in Shift then
  begin
    with imgPaint.Canvas do
    begin
      Pen.Color:=FGShape[FCount].PenColor;
      Brush.Color:=FGShape[FCount].BrushColor;
      Pen.Width:=FGShape[FCount].PenWidth;
      // Pen.Style:=psDashDot ;
      Brush.Style:=bsClear ;
      case FGShape[FCount].Shape of
      ssLine:
      begin
        MoveTo(FGShape[FCount].DownPoint.X, FGShape[FCount].DownPoint.Y);
        LineTo(FGShape[FCount].UPPoint.X, FGShape[FCount].UPPoint.Y);
      end;
      ssRectangle:
        Rectangle(FGShape[FCount].DownPoint.X, FGShape[FCount].DownPoint.Y,
                  FGShape[FCount].UPPoint.X, FGShape[FCount].UPPoint.Y);
      ssEllipse:
        Ellipse(FGShape[FCount].DownPoint.X, FGShape[FCount].DownPoint.Y,
                FGShape[FCount].UPPoint.X, FGShape[FCount].UPPoint.Y); 
      end;    end;
  end;
end;procedure TForm1.actBackExecute(Sender: TObject);
begin
  if FCount>0 then
  begin
    Dec(FCount);
    BackBitmap;
    imgPaint.Canvas.CopyRect(imgPaint.Canvas.ClipRect,Fbitmap.Canvas,imgPaint.Canvas.ClipRect);
    Caption:=inttostr(FCount);
  end;
  tbtBack.Enabled:=(FCount>0);
  tbtForward.Enabled:=(FCount<FMaxCount)
end;procedure TForm1.actForwardExecute(Sender: TObject);
begin
  if FCount<FMaxCount then
  begin
    Inc(FCount);
    BackBitmap;
    imgPaint.Canvas.CopyRect(imgPaint.Canvas.ClipRect,Fbitmap.Canvas,imgPaint.Canvas.ClipRect);
    Caption:=inttostr(FCount);
  end;
  tbtForward.Enabled:=(FCount<FMaxCount);
  tbtBack.Enabled:=(FCount>0)
end;end.

Answer 2

用面向对象的思维去回答这个问题，很简单。每次将image对象复制到一个备份的Image对象。如果你想保留撤销几步，就创建几个备份的image对象。代码也很简单，就只需要一个Assign语句。

Answer 3

你可不可以用tbitmap数组来保存已显示的图片呀

Answer 4

lianshaohua(连少华) 兄
你的提议好象不错，实现也很简单，但是图片占用的内存太大了，所以这种方法不可取
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song317(山东老实人) 兄
记录各动作（动作可当作一个对象，可以是个记录，用个数组来统一管理）  就是我采用的方法（我暂时是当作记录），但是我取消的时候不是执行反动作，而是重新画的时候，将有删除标记的不画出来而已

Answer 5

cll007(gazo)兄：
   说得非常有道理，嘿嘿。收藏了。