java - GUI freezes when drawing Wave from animation on JPanel though i used Swing Timer

Question

plese look at my code snippets , wha is wrong with it , it frrezes GUI when the Swing timer stats which is repeteadly paints on the jpnael ??

class WaveformPanel extends JPanel {

        Timer graphTimer = null;
        AudioInfo helper = null;

        WaveformPanel() {
            setPreferredSize(new Dimension(200, 80));
            setBorder(BorderFactory.createLineBorder(Color.BLACK));
            graphTimer = new Timer(15, new TimerDrawing());
        }

        /**
         * 
         */
        private static final long serialVersionUID = 969991141812736791L;
        protected final Color BACKGROUND_COLOR = Color.white;
        protected final Color REFERENCE_LINE_COLOR = Color.black;
        protected final Color WAVEFORM_COLOR = Color.red;

        protected void paintComponent(Graphics g) {

            super.paintComponent(g);

            int lineHeight = getHeight() / 2;
            g.setColor(REFERENCE_LINE_COLOR);
            g.drawLine(0, lineHeight, (int) getWidth(), lineHeight);

            if (helper == null) {
                return;
            }

            drawWaveform(g, helper.getAudio(0));

        }

        protected void drawWaveform(Graphics g, int[] samples) {

            if (samples == null) {
                return;
            }

            int oldX = 0;
            int oldY = (int) (getHeight() / 2);
            int xIndex = 0;

            int increment = helper.getIncrement(helper
                    .getXScaleFactor(getWidth()));
            g.setColor(WAVEFORM_COLOR);

            int t = 0;

            for (t = 0; t < increment; t += increment) {
                g.drawLine(oldX, oldY, xIndex, oldY);
                xIndex++;
                oldX = xIndex;
            }

            for (; t < samples.length; t += increment) {
                double scaleFactor = helper.getYScaleFactor(getHeight());
                double scaledSample = samples[t] * scaleFactor;
                int y = (int) ((getHeight() / 2) - (scaledSample));
                g.drawLine(oldX, oldY, xIndex, y);

                xIndex++;
                oldX = xIndex;
                oldY = y;
            }
        }

        public void setAnimation(boolean turnon) {
            if (turnon) {
                graphTimer.start();
            } else {
                graphTimer.stop();
            }
        }

        class TimerDrawing implements ActionListener {

            @Override
            public void actionPerformed(ActionEvent e) {

                byte[] bytes = captureThread.getTempBuffer();

                if (helper != null) {
                    helper.setBytes(bytes);
                } else {
                    helper = new AudioInfo(bytes);
                }
                repaint();
            }
        }

    }

I am calling setAnimation of WaveFormPanel from its parent class.when animation starts it does not draw anything but freezes. please , give me solution.

Thank You Mihir Parekh

Answer 1

The java.swingx.Timer calls the ActionPerformed within the EDT. The question then is, what's taking the time to render. It could be the call to captureThread.getTempBuffer it could be the construction of the help, but I suspect it's just the share amount of data you are trying to paint.

Having playing with this recently, it takes quite a bit of time to process the waveform.

One suggestion might be to reduce the number of samples that you paint. Rather then painting each one, maybe paint every second or forth sample point depending on the width of the component. You should still get the same jest but without all the work...

UPDATED

All samples, 2.18 seconds

Every 4th sample, 0.711 seconds

Every 8th sample, 0.450 seconds

Rather then paint in response to the timer, maybe you need to paint in response to batches of data.

As your loader thread has a "chunk" of data, may be paint it then.

As HoverCraftFullOfEels suggested, you could paint this to a BufferedImage first and then paint that to the screen...

SwingWorker might be able to achieve this for you

UPDATED

This is the code I use to paint the above samples.

// Samples is a 2D int array (int[][]), where the first index is the channel, the second is the sample for that channel
if (samples != null) {

    Graphics2D g2d = (Graphics2D) g;

    int length = samples[0].length;

    int width = getWidth() - 1;
    int height = getHeight() - 1;

    int oldX = 0;
    int oldY = height / 2;
    int frame = 0;

    // min, max is the min/max range of the samples, ie the highest and lowest samples
    int range = max + (min * -2);
    float scale = (float) height / (float) range;

    int minY = Math.round(((height / 2) + (min * scale)));
    int maxY = Math.round(((height / 2) + (max * scale)));

    LinearGradientPaint lgp = new LinearGradientPaint(
            new Point2D.Float(0, minY),
            new Point2D.Float(0, maxY),
            new float[]{0f, 0.5f, 1f},
            new Color[]{Color.BLUE, Color.RED, Color.BLUE});
    g2d.setPaint(lgp);
    for (int sample : samples[0]) {

        if (sample % 64 == 0) {

            int x = Math.round(((float) frame / (float) length) * width);
            int y = Math.round((height / 2) + (sample * scale));

            g2d.drawLine(oldX, oldY, x, y);

            oldX = x;
            oldY = y;

        }

        frame++;

    }

}

I use an AudioStream stream to load a Wav file an produce the 2D samples.