zoom in/out graph using AWT on Applet
https://stackoverflow.com/questions/11777086
-
24-06-2021 - |
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I am newbie to the java....working on a piece of applet code...............as I am still going through the OOPs concepts and java understanding and need to develop below mentioned functionality. The piece of code I have works like this : First it reads all parameters from HTML tags and stores in global variables. Then it sends query to CGI to read graph data. Then it converts data for plotting and draws graph. There is a option for user to select 1-24 hours. Based on the selection graph will be plotted by plotting only selected data. Every 30 sec it sends query to CGI for collecting data.
The code uses following library and uses java 1.5 environment and i cannot change it due to embeded requirements :
I need to enchance it by implementing zoom in zoom out feature with x-y axis granuality changing with zoom in . My worry is how to do that?I know its Frustrating question ...but i am here to get suggestion from the java experts so that I can quickly learn and implement this stuff.
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import java.applet.*;
import java.net.*;
import java.io.*;
import java.util.*;
import java.text.*;
/******************************************************************************
*
* Class - Graph
*
* This is the entry point.
* This class extends Applet class and implements Runnable.
*
*****************************************************************************/
public class GraphPerf extends Applet implements Runnable,ItemListener,MouseMotionListener
{
//Global variables
int MAX_DATA_X ;
int SIZE_X= 480;
int SIZE_Y= 250;
int SIZE_Y1= 240;
int MIN_ERROR = -1;
int MAX_LOG10_ERROR_COUNT = 1001;
int MAX_ERROR_COUNT = 101;
int SIZE_Y_EXTENDED_BOTTOM = 20;
int MAX_DISP_PARMS = 16;
int MAX_NUM_INTERVELL_PER_DAY = 96;
int MAX_DISP_PARMS_STD = 7;
int refreshTime;
String serverAddress,hostAddr;
Color plotColor1,plotColor8;
float graphData[][];
float graph_data_rf_east,graph_data_rf_west;
int xOffset = 50;
int yOffset = 40;
int Y1_MAX_VALUE = 100;
int Y2_MAX_VALUE = 3;
float RANGE2;
Thread graphThread;
Image Buffer;
Graphics plot;
Choice timeChoice, modeChoice, seloptChoice;
int duration=1, viewMode=1, line_type = 0,viewOpt = 1;
Label valueLabel1, valueLabel2,valueLabel3,valueLabel4,valueLabel5;
boolean GraphBottomExtendFlag=true;
/******************************************************************************
*
* method - init
*
* This is the method called first after applet loaded in to browser.
* This function reads configurable parameters from HTML tag and updates
* global variables.
*****************************************************************************/
public void init()
{
MAX_DATA_X = 672;//Integer.parseInt(getParameter("max_data_x"));
//refreshTime = 30;//Integer.parseInt(getParameter("refresh_sec"));
/*URL url = getDocumentBase();
String host = url.getHost();
try
{
InetAddress addr = InetAddress.getByName(host);
hostAddr=addr.getHostAddress();
}catch (UnknownHostException ex) {
ex.printStackTrace();
}
*/
//serverAddress = new String ( getParameter("access_str")+ hostAddr + getParameter("data_server"));
graphData = new float[MAX_DISP_PARMS][MAX_DATA_X+1];
/*initialize the array with -1 not with 0(0 also valid for graph data) */
int i =0,j = 0;
for( j=0; j<MAX_DISP_PARMS; j++)
{
for( i=0; i<MAX_DATA_X+1; i++)
{
graphData[j][i] = -1;
}
}
graph_data_rf_east = -1;
graph_data_rf_west = -1;
plotColor1 = Color.orange;
plotColor2 = Color.black;
plotColor8 = Color.red;
plotColor9 = Color.green;
setBackground(Color.white);
setLayout(null);
timeChoice = new Choice();
timeChoice.add("1");
timeChoice.add("2");
timeChoice.add("3");
timeChoice.add("4");
timeChoice.add("5");
timeChoice.add("6");
timeChoice.add("7");
add(timeChoice);
timeChoice.setBounds(190,340,40,23);
timeChoice.addItemListener(this);
Label timeLabel1 = new Label("View graph for last");
Label timeLabel2 = new Label("day(s)");
add(timeLabel1);
timeLabel1.setBounds(xOffset+30,340,160,23);
add(timeLabel2);
timeLabel2.setBounds(240,340,50,23);
valueLabel1 = new Label();
add(valueLabel1);
valueLabel1.setBounds(300,340,50,23);
valueLabel2 = new Label();
add(valueLabel2);
valueLabel2.setBounds(370,340,70,23);
valueLabel3 = new Label();
add(valueLabel3);
valueLabel3.setBounds(440,340,70,23);
valueLabel4 = new Label();
add(valueLabel4);
valueLabel4.setBounds(500,340,70,23);
valueLabel5 = new Label();
add(valueLabel5);
valueLabel5.setBounds(370,370,80,25);
modeChoice = new Choice();
modeChoice.add("East");
modeChoice.add("West");
/* Display this only for Protected and East-West Mode */
if(2/*Integer.parseInt(getParameter("mode"))*/ == 2)
{
add(modeChoice);
}
else
{
viewOpt = 1;
}
modeChoice.setBounds(xOffset+SIZE_X-55, 0, 60, 25);
modeChoice.addItemListener(this);
addMouseMotionListener(this);
}
public void start()
{
graphThread = new Thread(this);
graphThread.start();
}
public void stop()
{
graphThread = null;
}
/******************************************************************************
*
* This method will be called after starting the thread. This is a
* infinite loop which will call query method for every 30 sec to read data
* from CGI. Then it plots graph by calling plotGraph method
* the thread.
*****************************************************************************/
public void run()
{
/*while (false)
{
try
{//getData(serverAddress);
int sizeY = SIZE_Y;
if(GraphBottomExtendFlag)
{
sizeY += SIZE_Y_EXTENDED_BOTTOM;
}
repaint(xOffset+1,yOffset+1,SIZE_X-1,sizeY-1);
//graphThread.sleep(refreshTime*1000);
}catch (Exception e) { System.out.println(e); }
}*/
}
/******************************************************************************
*
* method - paint
*
* This method displays the graph plotted by plotGraph method
* in the screen. Then it draws axis for the graph
*
*****************************************************************************/
public void paint(Graphics g1)
{
int sizeY = SIZE_Y;
/*If Graph Bottom is to be Etended
*soo that zero is displayed properly
*/
if(GraphBottomExtendFlag)
{
sizeY += SIZE_Y_EXTENDED_BOTTOM;
}
if( duration <= 5 )
{
Buffer = createImage(SIZE_X, sizeY);
plot = Buffer.getGraphics();
plotGraph(plot);
g1.drawImage (Buffer,xOffset,yOffset,this);
}
else
{
Buffer = createImage(MAX_DATA_X*duration/7,sizeY);
plot = Buffer.getGraphics();
plotGraph(plot);
g1.drawImage (Buffer,xOffset,yOffset,SIZE_X,sizeY,this);
}
g1.setColor(Color.black);
g1.drawRect(70,150,270,80);
/*Dram Graph boarder */
g1.drawRect(xOffset,yOffset,SIZE_X,sizeY);
g1.drawRect(xOffset-1,yOffset-1,SIZE_X+2,sizeY+2);
/*Plot X axis*/
int max_x_marks = 8;
int temp = 1,cnt_graph = 0;
int float_temp,float_temp2;
/*max 8 plots on x axis*/
for(int x=max_x_marks; x>0; x--)
{
float_temp = (int)((MAX_NUM_INTERVELL_PER_DAY*duration)/max_x_marks)*((max_x_marks+1)-x);
float_temp2 = SIZE_X-(60*cnt_graph);
g1.drawString(String.valueOf(float_temp),(float_temp2-20) ,SIZE_Y+yOffset+35);
cnt_graph++;
}
/*Plot Y1 AXIS*/
temp = Y1_MAX_VALUE;
for(int x = 0; x <= SIZE_Y; x+= 25)
{
g1.drawString(String.valueOf(temp), 25, x + yOffset+10);
temp -= (Y1_MAX_VALUE - 0)/10;
}
temp = 1000;
/*Plot Y2 AXIS*/
int index_log = 1;
for(int x = 0; x <= SIZE_Y1; x+= 80)
{
if(x== 240)
index_log--;
if(temp>=1)
{
g1.drawString(String.valueOf(temp), 550, x+yOffset+8-index_log);
g1.drawLine(530,x+yOffset+5-index_log, 540, x+yOffset+5-index_log);
}
temp = temp/10;
}
Font thisFont = new Font("Times New Roman", Font.BOLD, 14);
g1.setFont(thisFont);
g1.drawString("Y2", 550, 160);
g1.drawString("Y1",5, 160);
}
/******************************************************************************
*
* method - plotGraph
*
* Depending on the mode, "East", "West" or "Combined", it plots
* single or two graphs in the same applet.
*
* Inputs :
* g - Graphics object
*****************************************************************************/
public void plotGraph(Graphics g)
{
g.setColor(new Color(255,255,220));
/*If Error-Sec-Count Graph
*Then extend the lower portion
*soo that zero is displayed properly
*/
if(GraphBottomExtendFlag)
{
g.fillRect(0,0,MAX_DATA_X,SIZE_Y + SIZE_Y_EXTENDED_BOTTOM);
}
else
{
g.fillRect(0,0,MAX_DATA_X,SIZE_Y);
}
switch(viewMode)
{
case 1 :
plot1(g);
plot_timeelapsed_east(g);
break;
case 2 :
plot8(g);
plot_timeelapsed_west(g);
break;
}
}
/******************************************************************************
*
* method - plot1
*
* This method uses graphData[0][] global variable and plots series of lines
* in the applet
*
* Inputs :
* g - Graphics object
*****************************************************************************/
void plot1(Graphics g)
{
int end = MAX_DATA_X;
int localPlotBuffer[];
localPlotBuffer = new int[2];
g.setColor(plotColor1);
if(duration > 5)
{
for(int x=(duration*MAX_NUM_INTERVELL_PER_DAY); x > 0 ; x--)
{
/*if data is valid data then plot else ignore*/
if((graphData[0][end]>MIN_ERROR)&&(graphData[0][end-1]<MAX_LOG10_ERROR_COUNT)&&(graphData[0][end-1]>MIN_ERROR)&&(graphData[0][end]<MAX_LOG10_ERROR_COUNT))
{
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[0][end] == 0)
{
localPlotBuffer[0] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[0][end]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[0][end])/(float)Y2_MAX_VALUE));
}
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[0][end-1] == 0)
{
localPlotBuffer[1] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[0][end-1]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[1] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[0][end-1])/(float)Y2_MAX_VALUE));
}
g.drawLine(x-1,(localPlotBuffer[0]+5), x-2,(localPlotBuffer[1]+5));
g.drawLine(x,(localPlotBuffer[0]+5), x-1,(localPlotBuffer[1]+5));
}
end--;
}
}
else
{
float temp = SIZE_X;
for(int x=(duration*MAX_NUM_INTERVELL_PER_DAY) ; x > 0 ; x--)
{
float LocalTemp1 = temp;
float LocalTemp2 = (int)(temp-(double)5/(double)duration);
/*Normalise the pixcel positions */
/*Normalise the pixcel positions */
if(duration == 1)
{
if(LocalTemp1>(SIZE_X-3))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-3))
LocalTemp2 = SIZE_X;
}
/*Normalise the pixcel positions */
else if(duration == 2)
{
if(LocalTemp1>(SIZE_X-2))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-2))
LocalTemp2 = SIZE_X;
}
/*Normalise the pixcel positions */
else if(duration == 3)
{
if(LocalTemp1>(SIZE_X-1))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-1))
LocalTemp2 = SIZE_X;
}
/*if data is valid data then plot else ignore*/
if((graphData[0][end]>MIN_ERROR)&&(graphData[0][end-1]<MAX_LOG10_ERROR_COUNT)&&(graphData[0][end-1]>MIN_ERROR)&&(graphData[0][end]<MAX_LOG10_ERROR_COUNT))
{
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[0][end] == 0)
{
localPlotBuffer[0] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[0][end]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[0][end])/(float)Y2_MAX_VALUE));
}
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[0][end-1] == 0)
{
localPlotBuffer[1] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[0][end-1]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[1] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[0][end-1])/(float)Y2_MAX_VALUE));
}
g.drawLine((int)LocalTemp1,(localPlotBuffer[0]+5), (int)LocalTemp2,(localPlotBuffer[1]+5));
}
temp-=(double)5/(double)duration;
end--;
}
}
}
/******************************************************************************
*
* method - plot8
*
* This method uses graphData[7][] global variable and plots series of lines
* in the applet
*
* Inputs :
* g - Graphics object
*****************************************************************************/
void plot8(Graphics g)
{
int end = MAX_DATA_X;
int localPlotBuffer[];
localPlotBuffer = new int[2];
g.setColor(plotColor1);
if(duration > 5)
{
for(int x=(duration*MAX_NUM_INTERVELL_PER_DAY); x > 0 ;x-- )
{
/*if data is valid data then plot else ignore*/
if((graphData[8][end]>MIN_ERROR)&&(graphData[8][end-1]<MAX_LOG10_ERROR_COUNT)&&(graphData[8][end-1]>MIN_ERROR)&&(graphData[8][end]<MAX_LOG10_ERROR_COUNT))
{
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[8][end] == 0)
{
localPlotBuffer[0] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[8][end]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[8][end])/(float)Y2_MAX_VALUE));
}
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[8][end-1]== 0)
{
localPlotBuffer[1] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[8][end-1]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[1] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[8][end-1])/(float)Y2_MAX_VALUE));
}
g.drawLine(x-1,(localPlotBuffer[0]+5), x-2,(localPlotBuffer[1]+5));
g.drawLine(x,(localPlotBuffer[0]+5), x-1,(localPlotBuffer[1]+5));
}
end--;
}
}
else
{
float temp = SIZE_X;
for(int x=(duration*MAX_NUM_INTERVELL_PER_DAY) ; x > 0 ; x--)
{
float LocalTemp1 = temp;
float LocalTemp2 = (int)(temp-(double)5/(double)duration);
/*Normalise the pixcel positions */
if(duration == 1)
{
if(LocalTemp1>(SIZE_X-3))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-3))
LocalTemp2 = SIZE_X;
}
/*Normalise the pixcel positions */
else if(duration == 2)
{
if(LocalTemp1>(SIZE_X-2))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-2))
LocalTemp2 = SIZE_X;
}
/*Normalise the pixcel positions */
else if(duration == 3)
{
if(LocalTemp1>(SIZE_X-1))
LocalTemp1 = SIZE_X;
if(LocalTemp2>(SIZE_X-1))
LocalTemp2 = SIZE_X;
}
/*if data is valid data then plot else ignore*/
if((graphData[8][end]>MIN_ERROR)&&(graphData[8][end-1]<MAX_LOG10_ERROR_COUNT)&&(graphData[8][end-1]>MIN_ERROR)&&(graphData[8][end]<MAX_LOG10_ERROR_COUNT))
{
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[8][end] == 0)
{
localPlotBuffer[0] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[8][end]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[8][end])/(float)Y2_MAX_VALUE));
}
/*if data present is 0, log10(0) is not define so then plot this graph in normal scale */
if(graphData[8][end-1]== 0)
{
localPlotBuffer[1] = (int)((float)(SIZE_Y )*(float)(1 - (float)graphData[8][end-1]/(float)Y1_MAX_VALUE)) ;
}
else
{
localPlotBuffer[1] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graphData[8][end-1])/(float)Y2_MAX_VALUE));
}
g.drawLine((int)LocalTemp1,(localPlotBuffer[0]+5), (int)LocalTemp2,(localPlotBuffer[1]+5));
}
temp-=(double)5/(double)duration;
end--;
}
}
}
/******************************************************************************
*
* method - plot_timeelapsed_east
*
* This method uses graph_data_rf_east global variable and plots series of lines
* in the applet
*****************************************************************************/
void plot_timeelapsed_east(Graphics g)
{
int end = MAX_DATA_X;
int localPlotBuffer[];
int x= 0;
localPlotBuffer = new int[2];
x= (duration*MAX_NUM_INTERVELL_PER_DAY);
g.setColor(plotColor9);
/*if data is valid data then plot else ignore*/
if((graph_data_rf_east>0)&&(graph_data_rf_east<MAX_LOG10_ERROR_COUNT))
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graph_data_rf_east)/(float)Y2_MAX_VALUE));
if(duration>5)
g.drawLine(x-1,SIZE_Y+5, x-2,(localPlotBuffer[0]+5));
else
g.drawLine(SIZE_X,SIZE_Y+5, 474+duration,(localPlotBuffer[0]+5));
}
}/*End for plot_timeelapsed_east() */
/******************************************************************************
*
* method - plot_timeelapsed_west
*
* This method uses graph_data_rf_east global variable and plots series of lines
* in the applet
*****************************************************************************/
void plot_timeelapsed_west(Graphics g)
{
int end = MAX_DATA_X;
int localPlotBuffer[];
int x= 0;
localPlotBuffer = new int[2];
x= (duration*MAX_NUM_INTERVELL_PER_DAY);
g.setColor(plotColor9);
/*if data is valid data then plot else ignore*/
if((graph_data_rf_east>MIN_ERROR)&&(graph_data_rf_east<MAX_LOG10_ERROR_COUNT))
{
localPlotBuffer[0] = (int)((float)(SIZE_Y1 )*(float)(1 - (float)Math.log10(graph_data_rf_west)/(float)Y2_MAX_VALUE));
if(duration>5)
g.drawLine(x-1,SIZE_Y+5, x-2,(localPlotBuffer[0]+5));
else
g.drawLine(SIZE_X,SIZE_Y+5, 474+duration,(localPlotBuffer[0]+5));
}
}
/******************************************************************************
*
* method - getData
*
* This method sends query to CGI to collect data. Then it converts the
* data for applet area then updates global variable.
*
* Inputs :
* serverAddress - server CGI path
*****************************************************************************/
public void getData(String serverAddress)
{
URL addr;
BufferedReader in;
String inputLine;
int count = 0;
int i=0,j = 0;
try
{
addr = new URL(serverAddress);
URLConnection connection = addr.openConnection();
in = new BufferedReader(new InputStreamReader(addr.openStream()));
/*Read data for first link */
for( j=0; j<MAX_DISP_PARMS_STD; j++)
{
for( i=0; i<MAX_DATA_X+1; i++)
{
inputLine = in.readLine();
graphData[j][i] = Integer.parseInt(inputLine);
}
}
for( i=0; i<MAX_DATA_X; i++)
{
inputLine = in.readLine();
graphData[7][i] = Integer.parseInt(inputLine);
if(graphData[7][i] == 1)
graphData[7][i] = 10;
}
inputLine = in.readLine();
graph_data_rf_east = Integer.parseInt(inputLine);
/*Reading data for second link */
if(Integer.parseInt(getParameter("mode")) == 2)
{
for( j=8; j<15; j++)
{
for( i=0; i<MAX_DATA_X+1; i++)
{
inputLine = in.readLine();
graphData[j][i] = Integer.parseInt(inputLine);
}
}
for( i=0; i<MAX_DATA_X; i++)
{
inputLine = in.readLine();
graphData[15][i] = Integer.parseInt(inputLine);
if(graphData[15][i] == 1)
graphData[15][i] = 10;
}
inputLine = in.readLine();
graph_data_rf_west = Integer.parseInt(inputLine);
}
in.close();
}catch (Exception e) { System.out.println("Server Data Read Error:"+e); }
}
/******************************************************************************
*
* method - itemStateChanged
*
* This method will be called whenever event occured on this choice.
* it read the current status and changes scale accordingly.
* *****************************************************************************/
public void itemStateChanged(ItemEvent evt)
{
if( evt.getSource() == timeChoice )
duration = Integer.parseInt(timeChoice.getSelectedItem());
else
viewMode = modeChoice.getSelectedIndex()+1;
repaint();
}
/******************************************************************************
*
* method - mouseMoved
*
* This method will be called whenever mouse cursor is moved over the
* applet. Depending on the cursor position, it will display Actual
* X and Y values of the graph.
*****************************************************************************/
public void mouseMoved(MouseEvent evt)
{
int x = evt.getX()-xOffset;
int y = evt.getY()-yOffset-5;
int a = evt.getX();
int b = evt.getY();
int duration = Integer.parseInt(timeChoice.getSelectedItem());
if( (x>=0) && (x<=SIZE_X) && (y>=0) && (y<=SIZE_Y) )
{
valueLabel1.setText("X ");
valueLabel2.setText("Y1 ");
valueLabel3.setText("Y2 ");
try
{
int x_max_value = ((SIZE_X*duration)/5);
int x1 = (int)((float)((float)((float)(SIZE_X*duration))/5) * ((float)((float)(SIZE_X - x))/((float)SIZE_X)));
/*For Durations less than 16 scale starts with 1*/
int y1 = (int)((float)Y1_MAX_VALUE * (((float)SIZE_Y - (float)y)/((float)SIZE_Y)));
int y2 = (int) Math.pow(10,((float)(3 * ((float)(1 - (float)y/((float)SIZE_Y1))))));
valueLabel1.setText("X="+x1);
valueLabel2.setText("X pix="+a);
valueLabel3.setText("Y="+y1);
valueLabel4.setText("Y pix="+b);
valueLabel5.setText("Y2="+y2);
}
catch(Exception e) {System.out.println("Mouse Moved Error" + e);}
}
else
{
valueLabel1.setText(" ");
valueLabel2.setText(" ");
valueLabel3.setText(" ");
}
}
public void mouseDragged(MouseEvent evt) { }
}
Solução 2
I used JCC kit for my target platform and it's less than 100kb library. You need to understand the library and after that you can play without worrying about size. :)
Good library to use in embedded systems whether size is always the issue. it has inbuilt function o transform coordinates into screen coordinates and vice-verse.
Outras dicas
There are many ways to do this. Here are two:
You can simply scale the values: Multiply every coordinate with the zoom factor.
Use Java2D and
AffineTransform:AffineTransform transformer = new AffineTransform(); transformer.scale(zoom, zoom); Graphics2D g2d = (Graphics2D)g; g2d.setTransform(transformer); // draw to g2d.
[EDIT] If you want to do everything yourself, see this page for a refresh of basic linear algebra: 2D Transformations
Don't mind the 3D example at the top; the rest of the page is about 2D.
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