Correcting error of write Image to file
bH
Hi All,
I want to correct an error of ImageIO.write(...
1 error found:
File: C:\Documents and
Settings\bH\Desktop\OpaqueToTransparent.java [line: 39]
Error: C:\Documents and Settings\bH\Desktop\OpaqueToTransparent.
java:39: cannot find symbol
symbol : method write(java.awt.Image,java.lang.String,java.
io.File)
location: class javax.imageio.ImageIO
TIA
bH
//from http://www.rgagnon.com/javadetails/java-0265.html
//from http://www.exampledepot.com/egs/javax.imageio/
import java.awt.Image;
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.io.IOException;
import java.io.File;
import javax.imageio.ImageIO;
public class OpaqueToTransparent extends JFrame {
Image GifOrigWithBlueBackgrnd;
Image GifModifWithTransparentBackgrnd;
OpaqueToTransparent() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
init();
setVisible(true);
}
public void init() {
try {
// Read from a file
File file = new File("images/cosmob.gif");
GifOrigWithBlueBackgrnd = ImageIO.read(file);
GifModifWithTransparentBackgrnd =
Transparency.makeColorTransparent
(GifOrigWithBlueBackgrnd, new Color(0).blue);
} catch (IOException e) {}
//try {
File file = new File("images/cosmobX.gif");
//error on the next line
ImageIO.write(GifModifWithTransparentBackgrnd,
"gif", file);
}
catch (IOException e) {}
// Use a label to display the image
JFrame frame = new JFrame();
JLabel label1 = new JLabel(new
ImageIcon(GifOrigWithBlueBackgrnd));
JLabel label2 = new JLabel(new
ImageIcon(GifModifWithTransparentBackgrnd));
frame.getContentPane().add(label1, BorderLayout.CENTER);
frame.getContentPane().add(label2, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new OpaqueToTransparent();
}
});
}
}
import java.awt.*;
import java.awt.image.*;
public class Transparency {
public static Image makeColorTransparent
(Image im, final Color color) {
ImageFilter filter = new RGBImageFilter() {
// the color we are looking for...
// Alpha bits are set to opaque
public int markerRGB = color.getRGB() | 0xFF000000;
public final int filterRGB(int x, int y, int rgb) {
if ( ( rgb | 0xFF000000 ) == markerRGB ) {
// Mark the alpha bits as zero - transparent
return 0x00FFFFFF & rgb;
}
else {
// nothing to do
return rgb;
}
}
};
ImageProducer ip = new FilteredImageSource(im.getSource(),
filter);
return Toolkit.getDefaultToolkit().createImage(ip);
}
}
Joshua Cranmer
> Correcting error of write Image to file
>
> Hi All,
> I want to correct an error of ImageIO.write(...
>
> 1 error found:
> File: C:\Documents and
> Settings\bH\Desktop\OpaqueToTransparent.java [line: 39]
> Error: C:\Documents and Settings\bH\Desktop\OpaqueToTransparent.
> java:39: cannot find symbol
> symbol : method write(java.awt.Image,java.lang.String,java.
> io.File)
> location: class javax.imageio.ImageIO
Perhaps you want to write a BufferedImage, not an Image?
--
Beware of bugs in the above code; I have only proved it correct, not
tried it. -- Donald E. Knuth
bH
Hi Joshua,
Thanks for your hint, but a problem error
is shown below.
I made an attempt to replace what I have originally with
your suggestion but it produces the error found below.
I was following the tutorial from:
http://java.sun.com/docs/books/tutorial/2d/images/saveimage.html
bH
import java.awt.image.BufferedImage;
.......
BufferedImage bi = null;
.......
try {
BufferedImage bi = GifModifWithTransparentBackgrnd;
// retrieve image
File outputfile = new File("images/cosmobX.gif");
ImageIO.write(bi, "gif", outputfile);
} catch (IOException e) {}
1 error found:
File: C:\Documents and Settings\bH\Desktop\
OpaqueToTransparent.java [line: 40]
Error: C:\Documents and Settings\bH\OpaqueToTransparent.java:40:
incompatible types
found : java.awt.Image
required: java.awt.image.BufferedImage
Lew
>> I want to correct an error of ImageIO.write(...
>>
>> 1 error found:
>> File: C:\Documents and
>> Settings\bH\Desktop\OpaqueToTransparent.java [line: 39]
>> Error: C:\Documents and Settings\bH\Desktop\OpaqueToTransparent.
>> java:39: cannot find symbol
>> symbol : method write(java.awt.Image,java.lang.String,java.
>> io.File)
>> location: class javax.imageio.ImageIO
Joshua Cranmer wrote:
> Perhaps you want to write a BufferedImage, not an Image?
Indeed, quick perusal of the ImageIO Javadocs, an undertaking whose need is
clearly indicated by the cited error message,
<http://java.sun.com/javase/6/docs/api/javax/imageio/ImageIO.html>
reveals that there is no such method in that class, rather, the 'write()'
methods take a 'RenderedImage' parameter,
<http://java.sun.com/javase/6/docs/api/javax/imageio/ImageIO.html#write(java.awt.image.RenderedImage,
java.lang.String, java.io.File)>
Any time you see a compiler error that it cannot find a symbol, and that
symbol is a method call, suspect that you've got the argument types wrong.
Turns out, in fact, you are calling 'write()' with an argument
'GifModifWithTransparentBackgrnd', which appears in the declarations:
>> public class OpaqueToTransparent extends JFrame {
>> Image GifOrigWithBlueBackgrnd;
>> Image GifModifWithTransparentBackgrnd;
While you're fixing that, change the variable names to conform with the Java
naming conventions, to whit, to start with a lower-case letter.
Also, don't eat exceptions. I expect you just didn't worry about them for
this simple example, but didn't plan to be so casual in the real world.
--
Lew
Lew
Well, yeah.
There are two problems with that. First, and the one that caused the compiler
to choke, is that you completely disregarded the type incompatibility. Java is
not a language where you just toss things into the program and magically they
figure out what you mean. You have to follow the rules.
One of the most fundamental, basic rules in Java is that you cannot cast
references between incompatible types. One type must be a supertype of the
other. If you are casting to a supertype, you are automatically fine, because
every instance of a subtype /is-an/ instance of its supertype already. But
NOT every instance of a supertype belongs to a particular subtype.
To cast "down" from supertype to subtype, you have to explicitly cast the
change with a "(<type>)" cast operator. This "downcast" always risks a
'ClassCastException', so you must either prevent it or catch it.
You left out the cast operator, and completely neglected to handle a possible
'ClassCastException'.
The other problem is that your (misnamed) 'GifModifWithTransparentBackgrnd'
might never be set to the correct image. It's hard to say with the
fragmentary snippet you share.
--
Lew
John B. Matthews
<d44e84ed-f362-42b1...@i37g2000yqn.googlegroups.com>,
bH <bher...@hotmail.com> wrote:
> Correcting error of write Image to file
>
> Hi All,
> I want to correct an error of ImageIO.write(...
>
> 1 error found:
> File: C:\Documents and
> Settings\bH\Desktop\OpaqueToTransparent.java [line: 39]
> Error: C:\Documents and Settings\bH\Desktop\OpaqueToTransparent.
> java:39: cannot find symbol
> symbol : method write(java.awt.Image,java.lang.String,java.
> io.File)
> location: class javax.imageio.ImageIO
>
> //from http://www.rgagnon.com/javadetails/java-0265.html
> //from http://www.exampledepot.com/egs/javax.imageio/
[...]
> public class OpaqueToTransparent extends JFrame {
> ...
> // Use a label to display the image
> JFrame frame = new JFrame();
If you extend JFrame, you don't need to create another one.
> try {
> File file = new File("images/cosmobX.gif");
> //error on the next line
> ImageIO.write(GifModifWithTransparentBackgrnd,
> "gif", file);
> }
You can render your transformed image in order to write it:
private void saveImage(Image image, String name) throws IOException {
BufferedImage bi = new BufferedImage(
image.getWidth(null), image.getHeight(null),
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = bi.createGraphics();
g2d.drawImage(image, 0, 0, null);
ImageIO.write(bi, "gif", new File(name));
g2d.dispose();
}
I don't know enough about GIF format to say if that produces the result
you want. See this thread "Regarding transparent gif creation":
http://forums.sun.com/thread.jspa?threadID=5337139
> catch (IOException e) {}
Don't swallow exceptions; at least write
ex.printStackTrace();
[...]
--
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>
bH
> In article
> <d44e84ed-f362-42b1-b743-bf9af2103...@i37g2000yqn.googlegroups.com>,
>
>
>
>
>
> bH <bherbs...@hotmail.com> wrote:
> > Correcting error of write Image to file
>
> > Hi All,
> > I want to correct an error of ImageIO.write(...
>
> > 1 error found:
> > File: C:\Documents and
> > Settings\bH\Desktop\OpaqueToTransparent.java [line: 39]
> > Error: C:\Documents and Settings\bH\Desktop\OpaqueToTransparent.
> > java:39: cannot find symbol
> > symbol : method write(java.awt.Image,java.lang.String,java.
> > io.File)
> > location: class javax.imageio.ImageIO
>
> > //fromhttp://www.rgagnon.com/javadetails/java-0265.html
>
> - Show quoted text -
Hi John,
Thanks so much for your "saveImage" help.
I have also corrected the "catch" errors you mentioned.
Within the program the gif transparency is
correct. However, the gif images do not display
with the correct oolors when saved.
The items listed in your link were observed.
I have written a similar program to use a
gif from a URL and filter out a green color in
a downloaded gif.
Thanks again.
bH
John B. Matthews
<748fc0af-f43f-429b...@r18g2000yqd.googlegroups.com>,
bH <bher...@hotmail.com> wrote:
> On Apr 12, 12:49 am, "John B. Matthews" <nos...@nospam.invalid> wrote:
> > In article
> > I don't know enough about GIF format to say if that produces the
> > result you want. See this thread "Regarding transparent gif
> > creation":
> >
> > http://forums.sun.com/thread.jspa?threadID=5337139
> >
> > [...]
> Hi John,
> Thanks so much for your "saveImage" help.
> I have also corrected the "catch" errors you mentioned.
> Within the program the gif transparency is
> correct. However, the gif images do not display
> with the correct oolors when saved.
> The items listed in your link were observed.
>
> I have written a similar program to use a
> gif from a URL and filter out a green color in
> a downloaded gif.
It's a problem. For reference, the ImageJ menu command Image > Color >
Show LUT is a convenient way to examine the lookup tables before and
after: