How to scale Image/ Graphics2d after drawing only if necessary

Question

I am creating a very simple chart using awt.Graphics2D:

    int width = countRange, height = 200;
    BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
    Graphics2D ig2 = bi.createGraphics();
    //drawing some stuff

Now i want to scale in width if width exceeds maximum (i need to scale after drawing, and the drawing relies on full width=countRange):

    if (countRange > MAX_IMAGE_WIDTH) {
        float yScale = (float) MAX_IMAGE_WIDTH / countRange;
        ig2.scale(1,yScale);
    }

Image is put out as byte[]:

    ByteArrayOutputStream os = new ByteArrayOutputStream();
    try {
        ImageIO.write(bi, "PNG", os);
    } catch (IOException e) {
        throw new IllegalStateException("Problem");
    }
    return os.toByteArray();

The problem is: the output is not scaled. It returns the image in original size. So how to scale the image after drawing and put it out?

score 1 · Answer 1 · answered Dec 08 '15 at 16:16

1

The Graphics2D.scale(double, double) only sets the scaling for the following drawing operations.

You need BufferedImage.getScaledInstance(width, height, hints)

answered Dec 08 '15 at 16:16

Thomas Kläger

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thanks, but getScaledInstance only returns "Image" and this is not usable with ImageIO.write – dermoritz Dec 08 '15 at 16:28
I see the problem. Another solution would be this one: (http://stackoverflow.com/questions/4216123/how-to-scale-a-bufferedimage) – Thomas Kläger Dec 08 '15 at 18:16

How to scale Image/ Graphics2d after drawing only if necessary

1 Answers1