Ol�, Michael!
Eu peguei esse artigo em um site na net, se n�o me engano em um artigo
t�cnico na pr�pria sun!
No corpo dele tem um fonte que gera "Thumbnails", ou aquelas imagens menores
de uma maior!
Qq coisa estamos a�!!!
[]�s
Andr� Barbosa
----- Original Message -----
From: "Michael L Pereira" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, November 15, 2002 4:40 AM
Subject: [java-list] miniaturas de imagens
> Ola,
>
> gostaria de saber se alguem conhece algum programa ou API em java
> que faz a miniaturizacao de imagens?
> tenho que fazer um sistema no qual o cliente envia uma imagem
> e tem que aparecer sua miniatura na Web. ser� que isso � possivel?
>
> Grato desde j�.
>
>
> Michael
>
> www.technoweb.com.br
>
>
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CREATING IMAGE THUMBNAILS
This tip demonstrates how you can create a small thumbnail version of a larger image.
This is especially important for web applications that need to display a number of
images on a page and do it in a reasonable amount of time.
The tip applies to the JavaTM 2 Platform, JDKTM v1.2 and uses the
com.sun.image.codec.jpeg package. Although this package is currently included in JDK
v1.2, it's not yet part of the Java 2 Platform APIs and so it might change or be
deleted in the future.
The example program below illustrates how to create an image thumbnail. The program
takes any GIF or JPEG file and creates a smaller JPEG file. The program shrinks the
original image so that it fits into a square whose size you specify. In other words,
the program maintains the aspect ratio, that is, the width-to-height ratio, of the
original image. It also ensures that the width and height of the thumbnail are less
than the size you specify.
Here's the code for the example program.
import java.awt.Image;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FileOutputStream;
import javax.swing.ImageIcon;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
class Thumbnail {
public static void main(String[] args) {
createThumbnail(args[0], args[
1], Integer.parseInt(args[2]));
}
/**
* Reads an image in a file and creates
* a thumbnail in another file.
* @param orig The name of image file.
* @param thumb The name of thumbnail file.
* Will be created if necessary.
* @param maxDim The width and height of
* the thumbnail must
* be maxDim pixels or less.
*/
public static void createThumbnail(
String orig, String thumb, int maxDim) {
try {
// Get the image from a file.
Image inImage = new ImageIcon(
orig).getImage();
// Determine the scale.
double scale = (double)maxDim/(
double)inImage.getHeight(null);
if (inImage.getWidth(
null) > inImage.getHeight(null)) {
scale = (double)maxDim/(
double)inImage.getWidth(null);
}
// Determine size of new image.
//One of them
// should equal maxDim.
int scaledW = (int)(
scale*inImage.getWidth(null));
int scaledH = (int)(
scale*inImage.getHeight(null));
// Create an image buffer in
//which to paint on.
BufferedImage outImage =
new BufferedImage(scaledW, scaledH,
BufferedImage.TYPE_INT_RGB);
// Set the scale.
AffineTransform tx =
new AffineTransform();
// If the image is smaller than
//the desired image size,
// don't bother scaling.
if (scale < 1.0d) {
tx.scale(scale, scale);
}
// Paint image.
Graphics2D g2d =
outImage.createGraphics();
g2d.drawImage(inImage, tx, null);
g2d.dispose();
// JPEG-encode the image
//and write to file.
OutputStream os =
new FileOutputStream(thumb);
JPEGImageEncoder encoder =
JPEGCodec.createJPEGEncoder(os);
encoder.encode(outImage);
os.close();
} catch (IOException e) {
e.printStackTrace();
}
System.exit(0);
}
}
You run the program like this:
java Thumbnail <original.{gif,jpg}>
<thumbnail.jpg> <maxDim>
Notice that the program takes three parameters. The first parameter is the name of the
file for the source image. The second parameter is the name of the file for the
resulting image thumbnail. The third parameter specifies the maximum number of pixels
for the width and height of the thumbnail. The width and height of the thumbnail will
be no larger than the value of maxDim. The width or height of the thumbnail can be
smaller than maxDim if the width or height of the original image is smaller.
The program first loads the image file using the ImageIcon class. This class differs
from Toolkit.getImage() in that ImageIcon doesn't return until the image is fully
loaded. The image needs to be fully loaded in order to immediately access its width
and height.
With the width and height, the program can determine the scaling factor. This means
how much the image needs to be reduced so that it can fit into a square of maxDim
pixels. Both the width and height of the image are scaled down by the same amount to
maintain the aspect ratio.
The program scales the image. It creates a transform (AffineTransform) object to do
the scaling and an image buffer to hold the new scaled image. Using the scale factor,
the program can determine the exact size of the thumbnail image and the size of an
image buffer just large enough to hold it. The transform is set with the scaling
factor. However, no scaling takes place if the original image is smaller than the
thumbnail.
After scaling, the program paints the original image onto the new image buffer. It
does this by creating a graphic context on the image buffer and then painting the
original image using the graphics context. Now the thumbnail is in image buffer.
The final step is to convert the image buffer into a JPEG stream to be written to a
file. This is done using the JPEGImageEncoder.encode() method.
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d�vidas mais comuns: http://www.soujava.org.br/faq.htm
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