java double buffer 作法

來源
http://www.realapplets.com/tutorial/DoubleBuffering.html

讚

/* Drawing in applets is almost always done with double-buffering.
This means that drawing is first done to an offscreen image, and when all
is done, the offscreen image is drawn on the screen.
This reduces the nasty flickering applets otherwise have.
Above you see:
No Double-buffering : It flickers because everything is draw straight to the screen.
Bad double-buffering: Same as this below but without the update() method
Double Buffering: Example of this source.
*/

import java.applet.*;
import java.awt.event.*;
import java.awt.*;

public class DoubleBuffering extends Applet implements MouseMotionListener
{
// The object we will use to write with instead of the standard screen graphics
Graphics bufferGraphics;
// The image that will contain everything that has been drawn on
// bufferGraphics.
Image offscreen;
// To get the width and height of the applet.
Dimension dim;
int curX, curY;

public void init()
{
// We'll ask the width and height by this
dim = getSize();
// We'll redraw the applet eacht time the mouse has moved.
addMouseMotionListener(this);
setBackground(Color.black);
// Create an offscreen image to draw on
// Make it the size of the applet, this is just perfect larger
// size could slow it down unnecessary.
offscreen = createImage(dim.width,dim.height);
// by doing this everything that is drawn by bufferGraphics
// will be written on the offscreen image.
bufferGraphics = offscreen.getGraphics();
}

public void paint(Graphics g)
{
// Wipe off everything that has been drawn before
// Otherwise previous drawings would also be displayed.
bufferGraphics.clearRect(0,0,dim.width,dim.width);
bufferGraphics.setColor(Color.red);
bufferGraphics.drawString("Bad Double-buffered",10,10);
// draw the rect at the current mouse position
// to the offscreen image
bufferGraphics.fillRect(curX,curY,20,20);
// draw the offscreen image to the screen like a normal image.
// Since offscreen is the screen width we start at 0,0.
g.drawImage(offscreen,0,0,this);
}

// Always required for good double-buffering.
// This will cause the applet not to first wipe off
// previous drawings but to immediately repaint.
// the wiping off also causes flickering.
// Update is called automatically when repaint() is called.

public void update(Graphics g)
{
paint(g);
}


// Save the current mouse position to paint a rectangle there.
// and request a repaint()
public void mouseMoved(MouseEvent evt)
{
curX = evt.getX();
curY = evt.getY();
repaint();
}


// The necessary methods.
public void mouseDragged(MouseEvent evt)
{
}

}

/*
This is all about double-buffering. It's easy to use and recommended to use always.
There is one dangerous pitfall here, when you create an offscreen image that's very large
the applet might run slow because it takes a lot of resources and effort.
I would not recommend offscreen images larger than 500*500 when redrawn at 30FPS.
(see Threads)
*/

java 載入圖檔方式

import java.awt.*;
import java.awt.event.*;
import java.awt.image.renderable.ParameterBlock;
import java.io.File;
import javax.media.jai.JAI;
import javax.media.jai.PlanarImage;
import javax.media.jai.RenderedOp;
import javax.media.jai.widget.ScrollingImagePanel;

public class FileTest extends WindowContainer {
 // Specify a default image in case the user fails to specify
 // one at run time.
 public static final String DEFAULT_FILE = "./images/glasses.jpg";
 public static void main(String args[]) {
  String fileName = null;
  // Check for a filename in the argument.
  if(args.length == 0) {
   fileName = DEFAULT_FILE;
  } else if(args.length == 1) {
   fileName = args[0];
  } else {
   System.out.println("\nUsage: java " + (new FileTest()).getClass().getName() + " [file]\n");
   System.exit(0);
  }
  new FileTest(fileName);
 }
 public FileTest() {}
 public FileTest(String fileName) {
  // Read the image from the designated path.
  System.out.println("Creating operation to load image from '" + fileName + "'");
  RenderedOp img = JAI.create("fileload", fileName);
  // Set display name and layout.
  setTitle(getClass().getName()+": "+fileName);
 
  // Display the image.
  System.out.println("Displaying image");
  add(new ScrollingImagePanel(img, img.getWidth(),  img.getHeight()));
  pack();
  show();
 }
}

 

class WindowContainer extends Frame implements WindowListener {

   public WindowContainer () {
     this.addWindowListener(this);
   }

   public void windowClosing(WindowEvent e) {
  System.exit(0);
   }
   public void windowOpened(WindowEvent e) {}
   public void windowClosed(WindowEvent e) {}
   public void windowIconified(WindowEvent e) {}
   public void windowDeiconified(WindowEvent e) {}
   public void windowActivated(WindowEvent e) {}
   public void windowDeactivated(WindowEvent e) {}

}

jpeg 轉 bmp方法

procedure Bmp2Jpeg(const BmpFileName, JpgFileName: string);
var
Bmp: TBitmap;
Jpg: TJPEGImage;
begin
Bmp := TBitmap.Create;
Jpg := TJPEGImage.Create;
try
Bmp.LoadFromFile(BmpFileName);
Jpg.Assign(Bmp);
Jpg.SaveToFile(JpgFileName);
finally
Jpg.Free;
Bmp.Free;
end;
end;

procedure Jpeg2Bmp(const BmpFileName, JpgFileName: string);
var
Bmp: TBitmap;
Jpg: TJPEGImage;
begin
Bmp := TBitmap.Create;
Jpg := TJPEGImage.Create;
try
Jpg.LoadFromFile(JpgFileName);
Bmp.Assign(Jpg);
Bmp.SaveToFile(BmpFileName);
finally
Jpg.Free;
Bmp.Free;
end;
end;

vista 中delphi 開發的程式發送封包權限不足的處理

http://delphi.ktop.com.tw/board.php?cid=168&fid=920&tid=99333

有關function節省編譯後空間? 真的有效嗎?沒試過

http://delphi.ktop.com.tw/board.php?cid=30&fid=70&tid=99044

1.type TDataProvider=class
2.private:
3. procedure _AppendData(SKey : String; SName : String; SValue1 : integer; SValue2 : String);
4.public:
5. procedure AppendData(SKey :String; SName : String);
6. procedure AppendData(SKey : String; SName : String; SValue2 : String);
7.end;
8.
9.//implementation;
10.
11.procedure TDataProvider._AppendData(SKey : String; SName : String; SValue1 : integer; SValue2 : String);
12.begin
13.//優先處理會被省略的參數
14.//原先的函式本體
15.end;
16.
17.procedure TDataProvider.AppendData(SKey : String; SName : String);
18.begin
19.self._AppendData(SKey, SName, nil, -1, nil);
20.end;
21.
22.procedure TDataProvider.AppendData(SKey : String; SName : String; SValue2 : String);
23.
24.begin
25.self._AppendData(SKey, SName, nil, -1, SValue2);
26.end;

ShellListView 選擇的檔案

procedure TForm1.ShellListView1MouseUp(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var i:integer;
begin
  for i := 0 to ShellListView1.Items.Count-1 do
  begin
    if ShellListView1.Items[i].Selected then
      ShowMessage(ShellListView1.Folders[i].PathName); // 這就是檔案全路徑
  end;
end;

測試pas檔轉html 的功能

unit uMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,StrUtils;

const VK_RTN = chr(13)+ chr(10);

type
  TMain = class(TForm)
    Button1: TButton;
    OpenDialog1: TOpenDialog;
    Memo1: TMemo;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    ColorDialog1: TColorDialog;
    procedure Button1Click(Sender: TObject);
    procedure Label1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
  TmpStyle=(mpReservedWord, mpSymbol , mpString , mpComment ,mpSpace );

  TDataSec=record
    DataString:String;
    Style:TmpStyle;
  end;

  TPasFile=Class
    Data,FFileName:String;
  protected
    ReservedWordList:TStringList;
  public
    function EncodeToHtml:String;
    constructor Create(FileName:string);
    destructor Destroy;override;
  End;

var
  Main: TMain;

implementation

{$R *.dfm}

procedure TMain.Button1Click(Sender: TObject);
var o:TPasFile;
  s:String;
begin
  s := '中文實驗<>'' '' ';
  if OpenDialog1.Execute then
  begin
    o := TPasFile.Create(OpenDialog1.FileName);
    Memo1.Lines.Clear;
    Memo1.Lines.Add(o.EncodeToHtml);
    Memo1.Lines.SaveToFile('C:\a.html');
    Application.ProcessMessages;
    winexec('explorer.exe C:\a.html',SW_SHOW );
    o.Free;
  end;
end;

{ TPasFile }

constructor TPasFile.Create(FileName:string);
var sl:TStringList;
begin
  sl :=TStringList.Create;
  FFileName :=FileName;
  sl.LoadFromFile(FileName);
  Data := sl.Text;
  sl.Free;

  ReservedWordList := TStringList.Create;
  ReservedWordList.Add('constructor');
  ReservedWordList.Add('destructor');
  ReservedWordList.Add('begin');
  ReservedWordList.Add('inherited');
  ReservedWordList.Add('end');
  ReservedWordList.Add('var');
  ReservedWordList.Add('Integer');
  ReservedWordList.Add('string');
  ReservedWordList.Add('procedure');
  ReservedWordList.Add('function');
  ReservedWordList.Add('protected');
  ReservedWordList.Add('public');
  ReservedWordList.Add('if');
  ReservedWordList.Add('then');
  ReservedWordList.Add('While');
  ReservedWordList.Add('do');
  ReservedWordList.Add('for');
  ReservedWordList.Add('to');
  ReservedWordList.Add('in');
  ReservedWordList.Add('else');
  ReservedWordList.Add('override');
  ReservedWordList.Add('type');
  ReservedWordList.Add('record');
  ReservedWordList.Add('class');
  ReservedWordList.Add('implementation');
  ReservedWordList.Add('private');
  ReservedWordList.Add('case');
  ReservedWordList.Add('of');
  ReservedWordList.Add('array');
  ReservedWordList.Add('unit');
  ReservedWordList.Add('interface');


  ReservedWordList.Text := UpperCase( ReservedWordList.Text);
end;

destructor TPasFile.Destroy;
begin
  ReservedWordList.Free;
  inherited;
end;

function TPasFile.EncodeToHtml: String;
var
  I,oldPos: Integer;
  htmlStr,sHead,sFoot:string;
  oDs:TDataSec;

  function GotoStr(sa:array of string):integer;
    var ii,j:integer;
  begin
    Result := Length(Data);
    for j := (i+1) to Length(Data) do
       for ii := Low(sa) to High(sa) do
         if data[j]=sa[ii] then
         begin
           Result := j ;
           exit;
         end;
  end;

  function GotoNextComm:integer;
    var j:integer;
  begin
    Result := Length(Data);
    for j := (i+1) to Length(Data) do
      if (data[j]='''')and(data[j+1]<>'''') then
      begin
        Result := j ;
        exit;
      end;
  end;

  procedure SetDataSec(S:String;style:TmpStyle);
  begin
    //處理關鍵字
    if ReservedWordList.IndexOf( UpperCase(s)) <> -1  then
      style := mpReservedWord;

    //處理 html 不能使用的字
    s:= StringReplace(s,'<','<',[rfReplaceAll] );
    s:= StringReplace(s,'>','>',[rfReplaceAll] );

    oDs.DataString := s;
    oDs.Style := style;
  end;

  function HtmlColorStr(Color:TColor):String;
  begin
    Result := format('#%.2x%.2x%.2x',[GetRValue(Color)
        ,GetGValue(Color),GetBValue(Color) ]);
  end;


begin
  i := 1;

  while i < Length(Data) do
  begin
    oldPos := i;
    case Data[i] of
     ' ' : SetDataSec(' ',mpSpace) ;
     '{' :
        begin
          i := GotoStr(['}']);
          SetDataSec(Copy(Data,oldPos,i - oldPos +1),mpComment );
        end;

     '/' :
        begin
          if Data[i+1]='/' then
          begin
            i := GotoStr( [ chr(10)]);
            SetDataSec(Copy(Data,oldPos,i - oldPos +1 ),mpComment );
          end
          else
            SetDataSec(string( data[i]),mpSymbol );
        end;

     ':','=',';','.','[',']','(',')',',',chr(13),chr(10):
        begin
          SetDataSec(string( data[i]),mpSymbol );
        end;

     '''':
        begin
          i := GotoNextComm;
          SetDataSec(Copy(Data,oldPos,i - oldPos +1),mpString );
        end;
    else
        begin
          i := GotoStr([' ','{','/',chr(13),chr(10),':','=',';','.','[',']','(',')',',' ]);
          SetDataSec(Copy(Data,oldPos,i - oldPos ),mpString );
          dec(i);
        end;
    end;
//    <font color=#ff0000><b></b></font> 紅
//    <font color=#009900></font>  綠
//    <font color=#7d0000> 咖啡色

    if (ods.Style = mpReservedWord) and(Main.Label1.Font.Color<>clBlack)then
      htmlStr := htmlStr +'<font color='+HtmlColorStr(Main.Label1.Font.Color)+'><b>' + ods.DataString +'</b></font>'
    else if (ods.Style = mpComment) and(Main.Label2.Font.Color<>clBlack) then
      htmlStr := htmlStr +'<font color='+HtmlColorStr(Main.Label2.Font.Color)+'>' + ods.DataString +'</font>'
    else if (ods.Style = mpSymbol)and(Main.Label3.Font.Color<>clBlack) then
      htmlStr := htmlStr +'<font color='+HtmlColorStr(Main.Label3.Font.Color)+'>' + ods.DataString +'</font>'
    else if (Main.Label4.Font.Color<>clBlack) then
      htmlStr := htmlStr +'<font color='+HtmlColorStr(Main.Label4.Font.Color)+'>' + ods.DataString +'</font>'
    else
      htmlStr := htmlStr + ods.DataString;

    inc(i);
  end;

sHead :=
'<html>' + VK_RTN +
'<head>' + VK_RTN +
'<meta http-equiv="Content-Type" content="text/html; charset=big5">' + VK_RTN +
'<title>'+FFileName+'</title>' + VK_RTN +
'</head>' + VK_RTN +
//'<body text="#000000" bgcolor="#FFFFFF" >'+ VK_RTN +
'<pre><code>' + VK_RTN ;


sFoot :=  VK_RTN +
'</code></pre>' + VK_RTN +
//'</body>' + VK_RTN +
'</html>' ;


  Result := sHead + htmlStr + sFoot;
end;



procedure TMain.Label1Click(Sender: TObject);
begin
  if ColorDialog1.Execute then
    (Sender as TLabel).Font.Color := ColorDialog1.Color;

  //Memo1.Text := ColorToString( ColorDialog1.Color );
 // Memo1.Text := format('#%.2x%.2x%.2x',[GetRValue(ColorDialog1.Color)
 // ,GetGValue(ColorDialog1.Color),GetBValue(ColorDialog1.Color) ]);
end;

end.