绘制在Java中成长尺寸的图像 [英] Draw an image of growing size in Java

问题描述

我有，我想提请随着时间的推移生长在宽度的图像的应用程序。具体而言，应用程序监听麦克风，并计算每6毫秒的频谱，而我想提请更新的频谱，当谈到。我一直在使用 java.awt.image.BufferedImage中的绘制谱图，但只为pre-录制的文件，所以我对图像的固定宽度。什么是一个流媒体的应用，在这里我不知道先验的图像的宽度做到这一点的最好方法是什么？

I have an application where I want to draw an image that grows in width over time. Specifically, the application listens to the microphone and computes a spectrogram every 6 milliseconds, and I want to draw the updated spectrogram when it comes in. I've been using java.awt.image.BufferedImage to draw the spectrograms, but only for pre-recorded files, so I have a fixed width for the image. What's the best way to do this for a streaming application, where I don't know a priori the width of the image?

一种可能性是刚刚创建右边一个额外的像素一个新的BufferedImage并复制数据，但似乎没有效率的做每秒数百次。或者，我可以开始具有相对大的宽度，并保持右侧空白直到填满了，当它，类似于一个ArrayList如何摊销的规模扩大一倍的宽度 - 我只需要数据每秒几次复制或每隔几秒钟一次，或左右。有没有更好的选择？

One possibility is to just create a new BufferedImage with one extra pixel on the right and copy the data over, but that seems inefficient to do hundreds of times per second. Or I could start with a relatively large width and keep the right side blank until it fills up, and double the width when it does, similar to how an ArrayList amortizes its size - I would only have to copy the data a few times per second, or once every few seconds, or so. Is there a better option?

推荐答案

我会用的你有什么建议的组合，只有油漆总图像的子图像，并返回相应的preferred规模压倒一切的组件。

I would use a combination of what you suggest and an overriding component that only paints a subimage of the total image and returns an appropriate preferred size.

下面是一个演示code这显示了我的意思是：

Here is a demo code which shows what I mean:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class TestRecording {

    public static class MyPanel extends JPanel {

        private BufferedImage buffer = new BufferedImage(3000, 100, BufferedImage.TYPE_INT_RGB);

        private int width = 0;

        private int lastY = 50;

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);

            if (width > 0) {
                BufferedImage sub = buffer.getSubimage(0, 0, width, buffer.getHeight());
                g.drawImage(sub, 0, Math.max(0, (getHeight() - buffer.getHeight()) / 2), this);
            }

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(width, 100);
        }

        protected void drawSomething() {
            // Here need to handle growing image
            Graphics g = buffer.getGraphics();
            g.setColor(Color.GREEN);
            int y = new Random().nextInt(buffer.getHeight());
            g.drawLine(width, lastY, width + 1, y);
            lastY = y;
            width += 1;
            Rectangle r = new Rectangle();
            r.x = getWidth();
                    // Lame hack to auto-scroll to the end
            scrollRectToVisible(r);
            revalidate();
            repaint();
        }
    }

    protected void initUI() {
        JFrame frame = new JFrame(TestRecording.class.getSimpleName());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final MyPanel p = new MyPanel();
        JScrollPane scrollpane = new JScrollPane(p);
        frame.add(scrollpane);
        frame.setSize(400, 200);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        Timer t = new Timer(20, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                p.drawSomething();
            }
        });
        t.start();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestRecording().initUI();
            }
        });
    }
}

这是结果：

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