java 绘制图形直方图
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Drawing a graphical histogram
提问by Ignacious
I am working on a project and I would like to display a single line histogram that looks like a bar graph except each line in the bar graph represents a pixel and its greyscale value.
我正在处理一个项目，我想显示一个看起来像条形图的单线直方图，但条形图中的每条线代表一个像素及其灰度值。
I have a array full of greyscale values, I just need to put them into this histogram and have it display the lines which will represent the values.. sort of like this
我有一个充满灰度值的数组，我只需要将它们放入这个直方图中并让它显示代表这些值的线......有点像这样
IMAGE [minimize][maximize][close]
picture histogram
I
(Loaded Picture) I I
I I I
I I I I
[open][save]
And below is the code loading the array... I just need to get some code that will use those greyscale values and represent them as bars like above.
下面是加载数组的代码......我只需要得到一些代码，这些代码将使用这些灰度值并将它们表示为像上面那样的条形。
public void showImage(File fileName) {
Scanner scan;
try {
scan = new Scanner(fileName);
typefile = scan.next();
iname = scan.next();
width = scan.nextInt();
height = scan.nextInt();
maxshade = scan.nextInt();
array = new int[width][height];
for(int r = 0; r < array.length; r++){
for(int c = 0; c < array[r].length; c++){
array[r][c] = scan.nextInt();
imageArray = array;
repaint();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
I know I have to do something like...
我知道我必须做一些像......
int hist[] = new int[256];
for (int r = 0; r < array.length; r++)
for (int c = 0; c < array[r].length; c++)
hist[array[r][c]]++;
But I don't know where to go from there or how to draw my graph.
但我不知道从那里去哪里或如何绘制我的图表。
回答by MadProgrammer
Something like
就像是
Perhaps??
也许？？
Personally, I'd still use something like JFreeChart, but this was a fun little exercise...
就个人而言，我仍然会使用JFreeChart 之类的东西，但这是一个有趣的小练习......
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import java.util.Map;
import java.util.TreeMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class TestHisogram {
//http://stackoverflow.com/a/12520104/714968
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new TestHisogram();
}
});
}
public TestHisogram() {
// For this example, I just randomised some data, you would
// Need to load it yourself...
int width = 256;
int height = 256;
int[][] data = new int[width][height];
for (int c = 0; c < height; c++) {
for (int r = 0; r < width; r++) {
data[c][r] = (int) (256 * Math.random());
}
}
Map<Integer, Integer> mapHistory = new TreeMap<Integer, Integer>();
for (int c = 0; c < data.length; c++) {
for (int r = 0; r < data[c].length; r++) {
int value = data[c][r];
int amount = 0;
if (mapHistory.containsKey(value)) {
amount = mapHistory.get(value);
amount++;
} else {
amount = 1;
}
mapHistory.put(value, amount);
}
}
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new JScrollPane(new Graph(mapHistory)));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
protected class Graph extends JPanel {
protected static final int MIN_BAR_WIDTH = 4;
private Map<Integer, Integer> mapHistory;
public Graph(Map<Integer, Integer> mapHistory) {
this.mapHistory = mapHistory;
int width = (mapHistory.size() * MIN_BAR_WIDTH) + 11;
Dimension minSize = new Dimension(width, 128);
Dimension prefSize = new Dimension(width, 256);
setMinimumSize(minSize);
setPreferredSize(prefSize);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (mapHistory != null) {
int xOffset = 5;
int yOffset = 5;
int width = getWidth() - 1 - (xOffset * 2);
int height = getHeight() - 1 - (yOffset * 2);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.DARK_GRAY);
g2d.drawRect(xOffset, yOffset, width, height);
int barWidth = Math.max(MIN_BAR_WIDTH,
(int) Math.floor((float) width
/ (float) mapHistory.size()));
System.out.println("width = " + width + "; size = "
+ mapHistory.size() + "; barWidth = " + barWidth);
int maxValue = 0;
for (Integer key : mapHistory.keySet()) {
int value = mapHistory.get(key);
maxValue = Math.max(maxValue, value);
}
int xPos = xOffset;
for (Integer key : mapHistory.keySet()) {
int value = mapHistory.get(key);
int barHeight = Math.round(((float) value
/ (float) maxValue) * height);
g2d.setColor(new Color(key, key, key));
int yPos = height + yOffset - barHeight;
//Rectangle bar = new Rectangle(xPos, yPos, barWidth, barHeight);
Rectangle2D bar = new Rectangle2D.Float(
xPos, yPos, barWidth, barHeight);
g2d.fill(bar);
g2d.setColor(Color.DARK_GRAY);
g2d.draw(bar);
xPos += barWidth;
}
g2d.dispose();
}
}
}
}
