Zoom the selected area in an image!!

Question

hi all,
i heve created a an application in which user can select an area and on an image and then zoom that particular portion but when i zoom it the image keeps on going to the right bottom corner of the screen.I want my zoom to keep the selected area in the center of the screen.can anybody help me in thet.
thanks
sangeeta

Answer 1

hi,
can u solve ome more problem for me as u seem to be very comfortable in 2d.my problem is that once i'm able to zoom my image ,if i want to zoom it further either on mouse click or selecting a rectangle again on mousedrag,it throws an exception coz i'm not able to get either size or bofferedimage from the once zoomed image.
do u have any suggestions:
i'm sending my latest code
private Graphics2D createGraphics2D(int w, int h) {
Graphics2D g2 = null;
if (bimg == null || bimg.getWidth() != w || bimg.getHeight() != h) {
bimg = (java.awt.image.BufferedImage) createImage(w, h);
g2 = bimg.createGraphics();
g2.setBackground(getBackground());
g2.clearRect(0, 0, w, h);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
return g2;
public void update(Graphics g) {
paint(g);
public void paint(Graphics g) {
super.paint(g);
try{
t=new AffineTransform();
//////added 09aug
Dimension d = getSize();
System.out.println(d);
if(!first_paint){
setScale(d.width,d.height - DRG_YPOS);
first_paint = true;
if(!image1)
Graphics2D g2 = createGraphics2D(d.width, d.height -DRG_YPOS);
g2.translate(((d.width/2) - ((zoomx*maxx + zoomx*minx)/2))
+ zoomx*scrollx,
(((d.height-DRG_YPOS)/2))+scrolly);
g2.scale(zoomx,zoomy);
draw(d.width, (int)(maxy - (maxy- miny)/2) , g2);
g.drawImage(bimg, 0, DRG_YPOS, this);
System.out.println("image drawn for the "+counter+"time");
counter++;
System.out.println("counter is"+counter);
System.out.println("image1 is"+image1);
file://t= g2.getTransform();
if(fzoom1)
g.setColor(Color.red);
g.drawRect(beginX,beginY,end1X-beginX,end1Y-beginY);
System.out.println("drawing rect");
if(fzoom){
wx=beginX;
wy=beginY;
ww=end1X-beginX;
wh=end1Y-beginY;
bi = bimg.getSubimage(wx,wy,ww,wh);
System.out.println("hello 2d");
System.out.println(wx+","+wy+","+ww+","+wh);
Dimension d1=getSize();
Graphics2D g2d = bi.createGraphics();
// g2d.setBackground(getBackground());
int w=500;
int h=500;
System.out.println(w+","+h);
System.out.println("g2d"+g2d);
System.out.println("settransform callrd");
// zoomFactor *=1;
g2d.translate(100.0f, 100.0f);
g2d.scale(zoomFactor, zoomFactor);
System.out.println("scale called"+zoomFactor);
file://zoomFactor++;
g.drawImage(bi,50,50,w,h,this);
System.out.println("w,h,bi"+w+","+h+","+bi);
file://repaint();
image1=true;
file://zoomFactor++;
file://fzoom=false;
g2.dispose();
}catch(Exception e)
System.out.println("exception"+e);
class IMS2DFrameMouseAdapter extends MouseAdapter implements MouseMotionListener{
int mx;
int my;
int endx,endy;
int X;
int Y;
Point point;
public void mouseClicked( MouseEvent event ) {
if(select)
Dimension d = getSize();
AffineTransform at = new AffineTransform();
at.setToIdentity();
at.translate(((d.width/2) - ((zoomx*maxx + zoomx*minx)/2))
+ zoomx*scrollx,
(((d.height-DRG_YPOS)/2))+scrolly);
at.scale(zoomx,zoomy);
Point src = new Point(event.getX(),event.getY() - DRG_YPOS);
Point pt = new Point();
try{
at.inverseTransform( src, pt);
catch( NoninvertibleTransformException e)
e.printStackTrace();
pt.setLocation(pt.getX(), (maxy - (maxy- miny)/2 - pt.getY()));
hitObject(pt);
/*if(fence_zoom){
fzoom2=true;
}else
fzoom2=false;
public void mousePressed( MouseEvent event ) {
if(fence_zoom)
System.out.println("mouse Pressed");
beginX = event.getX();
beginY = event.getY();
repaint();
public void mouseReleased( MouseEvent event ) {
end1X = event.getX();
end1Y = event.getY();
System.out.println("ENDX---"+endx);
System.out.println("endy-----"+endy);
if(translation)
translatedrawing(endx - startx,endy - starty);
if(fence_zoom){
System.out.println("mouse released");
file://end1X = event.getX();
// end1Y = event.getY();
fzoom=true;
repaint(); file://updateSize(event);
else{
fzoom=false;
public void mouseDragged(MouseEvent event) {
if(fence_zoom){
end1X = event.getX();
end1Y = event.getY();
fzoom1=true;
System.out.println("mouse dragged");
repaint();
else {
fzoom1=false;
public void mouseMoved(MouseEvent event)
thanks
sangeeta
"Gustavo Henrique Soares de Oliveira Lyrio" wrote:
I think you are using the wrong drawimage method. If you have the selection retangle coordinates, you will need a method that draw this selection in a new retangle selection (your canvas or panel)
Where goes my paintMethod:
protected void paintComponent(Graphics g)
g.drawImage(image, START_WINDOW_X, START_WINDOW_Y, WINDOW_X, WINDOW_Y, px1, py1, px2, py2, this);
Take a look in the drawimage methods in the java web page. I think it will help.
[]`s
Gustavo
----- Original Message -----
From: sangeetagarg
To: Gustavo Henrique Soares de Oliveira Lyrio
Sent: Thursday, August 16, 2001 9:14 AM
Subject: Re: Re: re:zoom in 2d
i'm sending u the paint method.but still i'm not able to select the desired area .it zooms the while image.tell me if there is any error in the code.
file://if(fence_zoom)
if(fzoom1 )
if (currentRect != null) {
System.out.println("hello");
g.setColor(Color.white);
g.drawRect(rectToDraw.x, rectToDraw.y,
rectToDraw.width - 1, rectToDraw.height - 1);
System.out.println("drawing rectangle");
fzoom1=false;
if(fzoom)
bi = bimg.getSubimage(rectToDraw.x, rectToDraw.y, rectToDraw.width, rectToDraw.height);
System.out.println(rectToDraw.x+","+ rectToDraw.y+","+rectToDraw.width+","+ rectToDraw.height);
Graphics2D g2d = bi.createGraphics();
g2d.setBackground(getBackground());
g2d.clearRect(0, 0,0,0 );
file://ZoomIn();
file://t= g2d.getTransform();
file://g2d.setTransform(t);
System.out.println("settransform callrd");
// zoomFactor *=1;
g2d.translate(100.0f, 0.0f);
g2d.scale(zoomx, zoomy);
System.out.println("scale called"+zoomFactor);
zoomx += ZOOMSTEP;
zoomy += ZOOMSTEP;
file://zoomFactor+=zoomFactorupdate;
g.drawImage(bi, 0, 0, this);
// g.drawImage(bi,10,10,this);
repaint();
fzoom=false;
thanks
sangeeta