如何缩放图像

Question

我正在尝试创建一个使用滑块的程序，该程序也放大了图像。 我已经使用矩形和圆形了，但是当我尝试添加图像时，它们会显示，但是当我滑动滑块时，它们不会放大，只会在屏幕上平移或对角移动它，根本不调整其大小。 有人可以帮我解决这个问题吗？ 这是我的代码：

import javax.swing.*;


public class Parker
{
    public static void main(String[] args)
    {

        TheWindow w = new TheWindow();
        w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //X wont close the window with out this line
        w.setSize(375,375);
        w.setVisible(true);
    }

}



import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;


public class TheWindow extends JFrame
{
    private JSlider slider; //declare slider
    private drawRect myPanel; //declare/ create panel


    public TheWindow()
    {
        super("Slider Example"); //make title
        myPanel = new drawRect();
        myPanel.setBackground(Color.cyan); //change background color

        slider = new JSlider(SwingConstants.VERTICAL, 0, 315, 10);// restrains the slider from scaling square to 0-300 pixels
        slider.setMajorTickSpacing(20); //will set tick marks every 10 pixels
        slider.setPaintTicks(true); //this actually paints the ticks on the screen

        slider.addChangeListener
        (
            new ChangeListener()
            {
                public void stateChanged(ChangeEvent e)
                {
                    myPanel.setD(slider.getValue()); //Wherever you set the slider, it will pass that value and that will paint on the screen
                }
            }

        );

        add(slider, BorderLayout.WEST); //similar to init method, adds slider and panel to GUI
        add(myPanel, BorderLayout.CENTER);


    }






}




import java.awt.*;
import javax.swing.*;

public class drawRect extends JPanel
{

    private int d = 20; //this determines the beginning size of the rect. 

    public void paintComponent(Graphics g)//paints obj on the screen
    {
        super.paintComponent(g); //prepares graphic object for drawing

        ImageIcon i = new ImageIcon("A:\\Capture.png"); //location of Image
        i.paintIcon(this, g, d, d); //paints icon on screen

        int originX = getWidth() / 2; //this is subtracting half of 'd' from the center point to scale it form the center
        int originY = getHeight() / 2;

        int x = originX - (d / 2);
        int y = originY - (d / 2);
        System.out.println(x + "x" + y);

       // g.fillRect(x, y, d, d); //paints rectangle on screen
        //x , y, width, height      
    }           

    public void setD(int newD)
    {
        d = (newD >= 0 ? newD : 10); //if number is less than zero it will use 10 for diameter(compressed if statement)
        repaint();

    }

    public Dimension getPrefferedSize()
    {

        return new Dimension(200, 200);     
    }

    public Dimension getMinimumSize()
    {
        return getPrefferedSize();
    }

}

Answer 1

这是调整图像大小的方法。 适合您的代码。

public BufferedImage resizeImage(Image originalImage, int newD) throws IOException {
    BufferedImage resizedImage = new BufferedImage(newD, newD,
            BufferedImage.TYPE_INT_ARGB);
    Graphics2D g = resizedImage.createGraphics();
    g.drawImage(originalImage, 0, 0, newD, newD, null);
    g.dispose();
    return resizedImage;
}

---

- 编辑 -

赞成继承而非继承 。

除非并且要覆盖现有逻辑，否则不要扩展任何类。

完整的示例代码：

class drawRect {

    private Image image;
    private JLabel label;

    public JLabel getLabel() {
        return label;
    }

    public drawRect() {
        try {
            label = new JLabel();
            image = ImageIO.read(new File("resources/1.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        setD(10);
    }

    public void setD(int newD) {
        int d = (newD >= 0 ? newD : 10);

        try {
            label.setIcon(new ImageIcon(resizeImage(image, d)));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private BufferedImage resizeImage(Image originalImage, int newD) throws IOException {
        BufferedImage resizedImage = new BufferedImage(newD, newD, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g = resizedImage.createGraphics();
        g.drawImage(originalImage, 0, 0, newD, newD, label);
        g.dispose();
        return resizedImage;
    }

}