how to display whole image on fixed size of canvas?

Question

i am using Jtree for image list and displaying the selected image, but problem is that if the image size is larger than the canvas size(i.e. 300 X 300) it displays only top left of the image, how to display the whole image in fixed size canvas?

i am using following code:

private void displayImage(File file) {

    try 
    {
        BufferedImage image = ImageIO.read(file);
        ta.Picture = image;
    }
    catch (Exception e) 
    {}

    Graphics g = ta.imageCanvas.getGraphics();
    g.clearRect(0, 0, 300, 300);
    g.drawImage(ta.Picture, 00, 00, this);

} // displayImage

public void valueChanged(TreeSelectionEvent e) 
{
    // TODO Auto-generated method stub
    FileTreeNode node = (FileTreeNode) tree.getLastSelectedPathComponent();

    if (node.isLeaf()) 
    {

        currentFile = node.file;

        File ff = new File("F:/images_blue/" + currentFile.getName());
        displayImage(ff);

    } else
        currentFile = null;

}

Take a look at [this](http://stackoverflow.com/questions/11959758/java-maintaining-aspect-ratio-of-jpanel-background-image/11959928#11959928) and [this](http://stackoverflow.com/questions/14115950/quality-of-image-after-resize-very-low-java/14116752#14116752) and [this](http://stackoverflow.com/questions/12797933/jpanel-resize-on-repaint/12798480#12798480) and [this](http://stackoverflow.com/questions/14548808/scale-the-imageicon-automatically-to-label-size/14553003#14553003) — MadProgrammer, Jan 29 '13 at 07:19
BTW - Applet + `BufferedImage image = ImageIO.read(file);` is going to be a disaster at time of deployment. Resources for applets would typically be accessed by URL formed relative to the code or document base of the applet. — Andrew Thompson, Jan 29 '13 at 09:28

score 2 · Accepted Answer · edited May 23 '17 at 10:31

I'd just like to point out that...

Graphics g = ta.imageCanvas.getGraphics();
g.clearRect(0, 0, 300, 300);
g.drawImage(ta.Picture, 00, 00, this);

Is a really bad idea.

getGraphics may return null and is, at best, simply a snapshot of the last repaint cycle and could be invalidated or dereferenced on the next paint cycle.

You should be extending from something like JPanel and overriding the paintComponent method. This would allow you to supply a getter and setter as apart of the image management and allow you to produce the scaled image in a self contained and reusable manner

You check out Perfoming Custom Painting for me information

And, as per my comment, you might like to check out these previous questions for examples

+1 .. and I luurv the linked examples too :P. @mohit_pipariya See [this](http://stackoverflow.com/a/12475560/1133011) variation and [expanded example](http://stackoverflow.com/questions/12660122/image-resizing-and-displaying-in-a-jpanel-or-a-jlabel-without-loss-of-quality/12660146#12660146). — David Kroukamp, Jan 29 '13 at 16:36

score 1 · Answer 2 · edited May 23 '17 at 11:56

1

you can scale BufferedImage like this..

BufferedImage before = getBufferedImage(encoded);
int w = before.getWidth();
int h = before.getHeight();
BufferedImage after = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
AffineTransform at = new AffineTransform();
at.scale(2.0, 2.0);
AffineTransformOp scaleOp = 
   new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
after = scaleOp.filter(before, after);

I found the snippet here

edited May 23 '17 at 11:56

Community

1
1

answered Jan 29 '13 at 07:14

user1983527

304
1
7

Isn't that going to scale the image to twice its size? – MadProgrammer Jan 29 '13 at 07:15
@user1983527 i want to reduce the size ,will it work if i keep the scale=0.5 ? and what is encoded in above code? – mohit_pipariya Jan 29 '13 at 07:34
@MadProgrammer *"Yes, if you use a fraction value below zero it will down scale the image"* By 'value below zero' DYM 'value below one'? – Andrew Thompson Jan 29 '13 at 09:26
@mohit_pipariya Yes, if you use a fraction value below one it will down scale the image. What do you mean by "encoded"? – MadProgrammer Jan 29 '13 at 09:30

how to display whole image on fixed size of canvas?

2 Answers2