虽然我使用了Swing Timer，但在JPanel上从动画中绘制Wave时，GUI会冻结

Question

请看看我的代码片段，它是错的，当它在jpnael上重复绘制的Swing计时器统计数据时它会破坏GUI吗？

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();
            }
        }

    }

我从其父类调用WaveFormPanel的setAnimation。当动画启动时，它不会绘制任何东西而是冻结。拜托，给我解决方案。

谢谢 Mihir Parekh

Answer 1

java.swingx.Timer调用ActionPerformed中的EDT。那么问题是，什么花时间来渲染。它可能是对captureThread.getTempBuffer的调用，它可能是构建帮助，但我怀疑它只是你想要绘制的数据的份额。

最近玩这个，处理波形需要相当多的时间。

一个建议可能是减少您绘制的样本数量。而不是绘制每一个，可以根据组件的宽度每隔一个或每个第二个或第四个采样点进行绘制。你应该仍然得到同样的笑话，但没有所有的工作......

<强>已更新

所有样本，2.18秒

每第4个样本，0.711秒

每8个样本，0.450秒

而不是绘制以响应计时器，可能需要绘制以响应批量数据。

由于您的加载程序线程有一个“数据块”，因此可能会对其进行绘制。

正如HoverCraftFullOfEels建议的那样，你可以先将它画成BufferedImage然后再将它画到屏幕上......

SwingWorker或许可以为您实现这一目标

<强>已更新

这是我用来绘制上述样本的代码。

// 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++;

    }

}

我使用AudioStream流来加载Wav文件并生成2D样本。

Answer 2

我猜你在paintComponent(...)方法中调用的wave绘图代码花费的时间比你想象的要长，并且正在将Swing绘画和EDT联系起来。

如果这是我的代码，我会考虑将波形绘制到BufferedImages 一次，从这些图像中制作ImageIcons，然后只需在Swing Timer中交换图标。