为什么不根据paintComponent方法中的矩形绘制BufferedImage(它的高度计算错误)?

问题描述

我编写了一个具有用户剪切图像能力的应用程序.当前，下面的代码将图像剪切到绘制矩形上方一点(其目的是为了显示用户实际上要剪切图像的坐标).

I write an application with the ability for the user to cut images.Currently, the code below cut the image a little bit above the drawn rectangle(whose purpose is to show with which coordinates the user wants to cut the image, actually.)

public class ScreenCaptureRectangle extends JFrame implements MouseListener, MouseMotionListener {

int drag_status = 0, c1, c2, c3, c4;

public void cut() {
    ImagePanel im = new ImagePanel(PicChanges.getNewImage());
    JScrollPane scrollPane = new JScrollPane(im);
    add(scrollPane);
    setSize(500, 400);
    setVisible(true);
    im.addMouseListener(this);
    im.addMouseMotionListener(this);
}

public void draggedScreen() throws Exception {
    int w = c1 - c3;
    int h = c2 - c4;
    w = w * -1;
    h = h * -1;
    Robot robot = new Robot();
    BufferedImage img = robot.createScreenCapture(new Rectangle(c1, c2, w, h));
    File save_path = new File("screen1.jpg");
    ImageIO.write(img, "JPG", save_path);
    System.out.println("Cropped image saved successfully.");
}

@Override
public void mouseClicked(MouseEvent arg0) {
}

@Override
public void mouseEntered(MouseEvent arg0) {
}

@Override
public void mouseExited(MouseEvent arg0) {
}

@Override
public void mousePressed(MouseEvent arg0) {
    repaint();
    c1 = arg0.getX();
    c2 = arg0.getY();
}

@Override
public void mouseReleased(MouseEvent arg0) {
    repaint();
    if (drag_status == 1) {
        c3 = arg0.getX();
        c4 = arg0.getY();
        try {
            repaint();
            draggedScreen();
        } catch (Exception e) {
            e.printStackTrace();
        }
    } else {
        System.out.println("Issue is under construction");
    }
}

@Override
public void mouseDragged(MouseEvent arg0) {
    repaint();
    drag_status = 1;
    c3 = arg0.getX();
    c4 = arg0.getY();
}

@Override
public void mouseMoved(MouseEvent arg0) {
}

public void paint(Graphics g) {
    super.paint(g);
    int w = c1 - c3;
    int h = c2 - c4;
    w = w * -1;
    h = h * -1;
    if (w < 0)
        w = w * -1;
    g.setColor(Color.RED);
    g.drawRect(c1, c2, w, h);
}

public class ImagePanel extends JPanel {

private BufferedImage imageToCut;


public ImagePanel(BufferedImage img) {
    this.imageToCut = img;
    Dimension size = new Dimension(imageToCut.getWidth(null), imageToCut.getHeight(null));
    setPreferredSize(size);
    setMaximumSize(size);
    setMinimumSize(size);
    setSize(size);
}

@Override
protected void paintComponent(Graphics g) {
    g.drawImage(imageToCut, 0, 0, null);
}
}

到目前为止，当用户以这种方式裁剪图像时:

他得到了:

我的目标是获得以下结果:

我使用鼠标侦听器来获取绘制的矩形的坐标，然后使用这些坐标来剪切图像.现在，图像被剪切为不正确的高度(如我所见).如果有人可以告诉我代码中有什么错误，我将不胜感激.谢谢！

I use mouse listeners so to get the coordinates of the drawn rectangle and then using these coordinates cut the image. Now the image is cut with incorrect height(as I see it). I would appreciate it if anyone could tell me what can be wrong in the code?Thanks!

推荐答案

感谢我收到的建议，现在我没有为用户单击剪切"按钮后要剪切的照片打开单独的框架，我只是添加了JFrame的MouseListeners，更加方便和用户友好.根据MouseListeners的坐标，照片被正确裁剪了:

Thanks to the recommendations I received, now I don't open a separate frame for a photo to cut after a user clicks on the Cut button, I just add MouseListeners to JFrame, which is more convenient and user-friendly. The photo is cut correctly, according to the coordinates from the MouseListeners:

public class ImageScreenShot extends JFrame implements MouseListener, MouseMotionListener {

int drag_status = 0, c1, c2, c3, c4;

public int getC1() {
    return c1;
}

public int getC2() {
    return c2;
}

public int getC3() {
    return c3;
}

public int getC4() {
    return c4;
}

public void cut() {
    GraphicalUserInterface.getFrame().addMouseMotionListener(this);
    GraphicalUserInterface.getFrame().addMouseListener(this);
}

public void draggedScreen() throws Exception {
    int w = c1 - c3;
    int h = c2 - c4;
    w = w * -1;
    h = h * -1;
    Robot robot = new Robot();
    BufferedImage img = robot.createScreenCapture(new Rectangle(c1, c2, w, h));
    File save_path = new File("screen1.jpg");
    ImageIO.write(img, "JPG", save_path);
    GraphicalUserInterface.getLabelIcon().setIcon(new ImageIcon(new ImageIcon(img).getImage().getScaledInstance(img.getWidth(), img.getHeight(), Image.SCALE_SMOOTH)));
    JOptionPane.showConfirmDialog(null, "Would you like to save your cropped Pic?");
    if (JOptionPane.YES_OPTION == 0) {
    /**Need to implement some code*/
    } else {
    /**Need to implement some code*/

    }
    System.out.println("Cropped image saved successfully.");
}

@Override
public void mouseClicked(MouseEvent arg0) {
}

@Override
public void mouseEntered(MouseEvent arg0) {
}

@Override
public void mouseExited(MouseEvent arg0) {
}

@Override
public void mousePressed(MouseEvent arg0) {
    c1 = arg0.getXOnScreen();
    c2 = arg0.getYOnScreen();
}

@Override
public void mouseReleased(MouseEvent arg0) {
    if (drag_status == 1) {
        c3 = arg0.getXOnScreen();
        c4 = arg0.getYOnScreen();
        try {
            draggedScreen();
        } catch (Exception e) {
            e.printStackTrace();
        }
    } else {
        System.out.println("Issue is under construction");
    }
}

@Override
public void mouseDragged(MouseEvent arg0) {
    drag_status = 1;
    c3 = arg0.getXOnScreen();
    c4 = arg0.getYOnScreen();
}

@Override
public void mouseMoved(MouseEvent arg0) {
}

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