在 java 中动态调整缓冲图像的大小

Question

我尝试使用 AffineTransform 和 Scalr.resize

调整缓冲图像的大小

这是我的代码。

使用 Scalr.resize:

    BufferedImage buff = robot.createScreenCapture(new Rectangle(bufx,bufy,bufwidth,bufheight)); // x-coord, y-coord, width, height

    BufferedImage scrCapt = Scalr.resize(buff, Method.BALANCED, scrwidth, scrheight);

使用仿射变换：

BufferedImage buff = robot.createScreenCapture(new Rectangle(bufx,bufy,bufwidth,bufheight)); // x-coord, y-coord, width, height

BufferedImage scrCapt = new BufferedImage(bufwidth,bufheight,BufferedImage.TYPE_INT_ARGB);
AffineTransform atscr = new AffineTransform();


atscr.scale(aspectRatioWidth,aspectRatioHeight);
AffineTransformOp scaleOp = new AffineTransformOp(atscr, AffineTransformOp.TYPE_BILINEAR);
scrCapt = scaleOp.filter(buff, scrCapt);

变量已经在class:

开头声明

static int bufx = 0;
static int bufy = 0;
static int bufwidth = 1;
static int bufheight = 1;
static int scrwidth = 0;
static int scrheight = 0;
static float aspectRatioWidth = 0;
static float aspectRatioHeight = 0;

我在不同的方法中动态获取所有变量的值：

aspectRatioWidth = bufwidth/scrwidth;
aspectRatioHeight = bufheight/scrheight;

然而，当我运行这段代码时，我在函数 AffineTransform 和 Scalr.resize:

中都遇到了错误

Scalr.resize:

Exception in thread "Thread-2" java.lang.IllegalArgumentException: Width (0) and height (0) cannot be <= 0
at java.awt.image.DirectColorModel.createCompatibleWritableRaster(DirectColorModel.java:1016)
at java.awt.image.BufferedImage.<init>(BufferedImage.java:331)
at org.imgscalr.Scalr.createOptimalImage(Scalr.java:2006)
at org.imgscalr.Scalr.scaleImage(Scalr.java:2133)
at org.imgscalr.Scalr.resize(Scalr.java:1667)
at org.imgscalr.Scalr.resize(Scalr.java:1415)

仿射变换：

Exception in thread "Thread-2" java.awt.image.ImagingOpException: Unable to invert transform AffineTransform[[0.0, 0.0, 0.0], [0.0, 1.0, 0.0]]
at java.awt.image.AffineTransformOp.validateTransform(AffineTransformOp.java:558)
at java.awt.image.AffineTransformOp.<init>(AffineTransformOp.java:151)

我该怎么做？我知道发生这种情况是因为我正在以不同的方法更改变量并以另一种方法访问它们。但是这两种方法不能结合使用。有什么办法可以使这项工作吗？

编辑：

我改变了调整大小的方法这是我现在所做的

public static BufferedImage resizeImage(BufferedImage image, double scalewidth, double scaleheight){

    BufferedImage img = new BufferedImage(image.getWidth(), image.getHeight(),BufferedImage.SCALE_FAST);
    Graphics2D g = img.createGraphics();
    g.scale(scalewidth, scaleheight);
    g.drawImage(image, null, 0, 0);
    g.dispose();
    return image;
}

编辑(2):

为了更清楚地了解到底发生了什么：

这是一个 returns scrwidth 和 scrheight

的方法

public static void showOnScreen( int screen, JFrame framenew )
   {
    GraphicsEnvironment ge = GraphicsEnvironment
      .getLocalGraphicsEnvironment();
    GraphicsDevice[] gs = ge.getScreenDevices();

  for (int i = 0; i < gs.length; i++) {
      screenwidth.add(gs[i].getDisplayMode().getWidth());
      screenheight.add(gs[i].getDisplayMode().getHeight());
}

scrwidth = screenwidth.get(screenwidth.size()-1);
scrheight = screenheight.get(screenheight.size()-1);




  System.out.print(ge);
  System.out.print(gs);
  if( screen > -1 && screen < gs.length )
  {gs[screen].setFullScreenWindow( framenew );}
  else if( gs.length > 0 )
  {gs[0].setFullScreenWindow( framenew );}
  else
  {throw new RuntimeException( "No Screens Found" );}}

这是 returns bufwidth 和 bufheight 的 actionlistener:

  btnNewButton.addActionListener(new ActionListener() {      
  public void actionPerformed(ActionEvent e)
  {
      //Execute when button is pressed
      System.out.println("You clicked the button");

      int ind = c.getSelectedIndex();
        bufx = capx.get(ind);
        bufy = capy.get(ind);
        bufwidth = capwidth.get(ind);
        bufheight = capheight.get(ind);
        frame.setVisible(false);
        framenew.setVisible(true);
        showOnScreen(1,framenew);

        aspectRatioWidth = (double) bufwidth/scrwidth;
        aspectRatioHeight = (double) bufheight/scrheight;   

            System.out.print("aspectRatioWidth:  ");
            System.out.println(aspectRatioWidth);

            System.out.print("aspectRatioHeight:  ");
            System.out.println(aspectRatioHeight);          
  }
  });

并且里面使用了aspectRatios 运行:

public void run() {
System.out.print("aspectRatioWidth:  ");
System.out.println(aspectRatioWidth);

System.out.print("aspectRatioHeight:  ");
System.out.println(aspectRatioHeight);

while(true){
    BufferedImage buff = robot.createScreenCapture(new Rectangle(bufx,bufy,bufwidth,bufheight)); // x-coord, y-coord, width, height

    BufferedImage resizedbuff = resizeImage(buff, aspectRatioWidth, aspectRatioHeight);}

Answer 1

你正在做整数除法，它总是 returns 一个整数，这里是 0，因为你的屏幕尺寸可能会大于你的图像尺寸：

aspectRatioWidth = bufwidth/scrwidth;
aspectRatioHeight = bufheight/scrheight;

解决方案：将数字转换为双精度，然后进行双除法。

aspectRatioWidth = (double) bufwidth/scrwidth;
aspectRatioHeight = (double) bufheight/scrheight;

编辑

不确定您最终要做什么 -- post GUI 中的计算机屏幕图像？如果是这样，也许像...

import java.awt.AWTException;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.util.List;

import javax.swing.*;

public class ChangeVars extends JPanel {
   private static final int PREF_W = 400;
   private static final int PREF_H = PREF_W;
   private static final int DELAY = 20;
   public BufferedImage displayImage;
   private MyWorker myWorker;

   public ChangeVars() {
      try {
         myWorker = new MyWorker(DELAY);
         myWorker.execute();
      } catch (AWTException e) {
         e.printStackTrace();
      }
   }

   @Override
   // to initialize the panel to something
   public Dimension getPreferredSize() {
      if (isPreferredSizeSet()) {
         return super.getPreferredSize();
      }
      return new Dimension(PREF_W, PREF_H);
   }

   @Override
   protected void paintComponent(Graphics g) {
      super.paintComponent(g);
      if (displayImage != null) {
         g.drawImage(displayImage, 0, 0, null);
      }
   }

   public void stopWorker() {
      if (myWorker != null && !myWorker.isDone()) {
         myWorker.setRunning(false);
         myWorker.cancel(true);
      }
   }

   private class MyWorker extends SwingWorker<Void, BufferedImage> {

      private volatile boolean running = true;
      private Robot robot;
      private int delay;

      public MyWorker(int delay) throws AWTException {
         this.delay = delay;
         robot = new Robot();
      }

      @Override
      protected Void doInBackground() throws Exception {
         while (running) {
            Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
            Rectangle screenRect = new Rectangle(0, 0, d.width, d.height);
            BufferedImage img = robot.createScreenCapture(screenRect);
            publish(img);
            Thread.sleep(delay);
         }
         return null;
      }

      @Override
      protected void process(List<BufferedImage> chunks) {
         for (BufferedImage image : chunks) {
            Dimension sz = getSize();
            double scaleX = (double) sz.width / image.getWidth();
            double scaleY = (double) sz.height / image.getHeight();
            AffineTransform transform = AffineTransform.getScaleInstance(
                  scaleX, scaleY);
            AffineTransformOp transformOp = new AffineTransformOp(transform,
                  AffineTransformOp.TYPE_BILINEAR);
            displayImage = new BufferedImage(sz.width, sz.height,
                  BufferedImage.TYPE_INT_ARGB);
            displayImage = transformOp.filter(image, displayImage);
            repaint();
         }
      }

      public void setRunning(boolean running) {
         this.running = running;
      }

      public boolean getRunning() {
         return running;
      }

   }

   private static void createAndShowGui() {
      final ChangeVars changeVars = new ChangeVars();

      JFrame frame = new JFrame("ChangeVars");
      frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
      frame.addWindowListener(new WindowAdapter() {

         @Override
         public void windowClosing(WindowEvent e) {
            if (changeVars != null) {
               changeVars.stopWorker();
            }
            System.exit(0);
         }

      });
      frame.getContentPane().add(changeVars);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

虽然更简单的方法是让 paintComponent 进行缩放：

@Override
protected void paintComponent(Graphics g) {
  super.paintComponent(g);
  if (displayImage != null) {
     int width = getWidth();
     int height = getHeight();
     g.drawImage(displayImage, 0, 0, width, height, null);
  }
}

// ....

  @Override
  protected void process(List<BufferedImage> chunks) {
     for (BufferedImage image : chunks) {
        displayImage = image;
        repaint();
     }
  }

在 java 中动态调整缓冲图像的大小

Dynamically resize a bufferedimage in java

java

bufferedimage

affinetransform

image-resizing

imgscalr