Java Image Height Get getHeight(Image pImage)

Description

Gets the height of an Image.

License

Open Source License

Parameter

Parameter	Description
pImage	an image.

Return

the height of the image, or -1 if the height could not be determined (i.e. an error occured while waiting for the image to load).

Declaration

public static int getHeight(Image pImage) 

Method Source Code

//package com.java2s;
import java.awt.*;

public class Main {
    /**//  ww  w. j  a v  a  2  s.c o  m
     * Component that can be used with the MediaTracker etc.
     */
    private static final Component NULL_COMPONENT = new Component() {
    };
    /** Our static image tracker */
    private static MediaTracker sTracker = new MediaTracker(NULL_COMPONENT);

    /**
     * Gets the height of an Image.
     * This method has the side-effect of completely loading the image.
     *
     * @param pImage an image.
     *
     * @return the height of the image, or -1 if the height could not be
     *         determined (i.e. an error occured while waiting for the
     *         image to load).
     */
    public static int getHeight(Image pImage) {
        int height = pImage.getHeight(NULL_COMPONENT);
        if (height < 0) {
            if (!waitForImage(pImage)) {
                return -1; // Error while waiting
            }
            height = pImage.getHeight(NULL_COMPONENT);
        }

        return height;
    }

    /**
     * Waits for an image to load completely.
     * Will wait forever.
     *
     * @param pImage an Image object to wait for.
     *
     * @return true if the image was loaded successfully, false if an error
     *         occured, or the wait was interrupted.
     *
     * @see #waitForImage(Image,long)
     */
    public static boolean waitForImage(Image pImage) {
        return waitForImages(new Image[] { pImage }, -1L);
    }

    /**
     * Waits for an image to load completely.
     * Will wait the specified time.
     *
     * @param pImage an Image object to wait for.
     * @param pTimeOut the time to wait, in milliseconds.
     *
     * @return true if the image was loaded successfully, false if an error
     *         occurred, or the wait was interrupted.
     *
     * @see #waitForImages(Image[],long)
     */
    public static boolean waitForImage(Image pImage, long pTimeOut) {
        return waitForImages(new Image[] { pImage }, pTimeOut);
    }

    /**
     * Waits for a number of images to load completely.
     * Will wait forever.
     *
     * @param pImages an array of Image objects to wait for.
     *
     * @return true if the images was loaded successfully, false if an error
     *         occurred, or the wait was interrupted.
     *
     * @see #waitForImages(Image[],long)
     */
    public static boolean waitForImages(Image[] pImages) {
        return waitForImages(pImages, -1L);
    }

    /**
     * Waits for a number of images to load completely.
     * Will wait the specified time.
     *
     * @param pImages an array of Image objects to wait for
     * @param pTimeOut the time to wait, in milliseconds
     *
     * @return true if the images was loaded successfully, false if an error
     *         occurred, or the wait was interrupted.
     */
    public static boolean waitForImages(Image[] pImages, long pTimeOut) {
        // TODO: Need to make sure that we don't wait for the same image many times
        // Use hashcode as id? Don't remove images from tracker? Hmmm...
        boolean success = true;

        // Create a local id for use with the mediatracker
        int imageId;

        // NOTE: This is very experimental...
        imageId = pImages.length == 1 ? System.identityHashCode(pImages[0]) : System.identityHashCode(pImages);

        // Add images to tracker
        for (Image image : pImages) {
            sTracker.addImage(image, imageId);

            // Start loading immediately
            if (sTracker.checkID(imageId, false)) {
                // Image is done, so remove again
                sTracker.removeImage(image, imageId);
            }
        }

        try {
            if (pTimeOut < 0L) {
                // Just wait
                sTracker.waitForID(imageId);
            } else {
                // Wait until timeout
                // NOTE: waitForID(int, long) return value is undocumented.
                // I assume that it returns true, if the image(s) loaded
                // successfully before the timeout, however, I always check
                // isErrorID later on, just in case...
                success = sTracker.waitForID(imageId, pTimeOut);
            }
        } catch (InterruptedException ie) {
            // Interrupted while waiting, image not loaded
            success = false;
        } finally {
            // Remove images from mediatracker
            for (Image pImage : pImages) {
                sTracker.removeImage(pImage, imageId);
            }
        }

        // If the wait was successfull, and no errors were reported for the
        // images, return true
        return success && !sTracker.isErrorID(imageId);
    }
}

Related

1. getHeight(final File image)
2. getHeight(final Image image)
3. getHeight(java.awt.Image image)