Java 如何调整JLabel ImageIcon的大小？

我正在制作一个具有以下布局（）的Java Swing应用程序：

当用户添加或删除图标时，其他图标应缩小或增大

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我的问题非常简单：我有一个

JLabel

，其中包含一个

ImageIcon

；如何调整此图标的大小？

调整图标的大小并不简单。您需要使用Java的二维图形来缩放图像。第一个参数是一个图像类，您可以从

ImageIcon

class轻松获取该类。您可以使用

ImageIcon

类加载图像文件，然后只需调用getter方法即可获得图像

private Image getScaledImage(Image srcImg, int w, int h){
    BufferedImage resizedImg = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2 = resizedImg.createGraphics();

    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2.drawImage(srcImg, 0, 0, w, h, null);
    g2.dispose();

    return resizedImg;
}

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调整图像大小的一种方法是使用HTML并在图像元素中指定新的大小。这甚至适用于具有透明度的动画图像。

我同意这一代码的工作原理，即从文件中调整图像图标的大小以供显示，同时保持我在下面使用的纵横比

/*
 * source File of image, maxHeight pixels of height available, maxWidth pixels of width available
 * @return an ImageIcon for adding to a label
 */


public ImageIcon rescaleImage(File source,int maxHeight, int maxWidth)
{
    int newHeight = 0, newWidth = 0;        // Variables for the new height and width
    int priorHeight = 0, priorWidth = 0;
    BufferedImage image = null;
    ImageIcon sizeImage;

    try {
            image = ImageIO.read(source);        // get the image
    } catch (Exception e) {

            e.printStackTrace();
            System.out.println("Picture upload attempted & failed");
    }

    sizeImage = new ImageIcon(image);

    if(sizeImage != null)
    {
        priorHeight = sizeImage.getIconHeight(); 
        priorWidth = sizeImage.getIconWidth();
    }

    // Calculate the correct new height and width
    if((float)priorHeight/(float)priorWidth > (float)maxHeight/(float)maxWidth)
    {
        newHeight = maxHeight;
        newWidth = (int)(((float)priorWidth/(float)priorHeight)*(float)newHeight);
    }
    else 
    {
        newWidth = maxWidth;
        newHeight = (int)(((float)priorHeight/(float)priorWidth)*(float)newWidth);
    }


    // Resize the image

    // 1. Create a new Buffered Image and Graphic2D object
    BufferedImage resizedImg = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
    Graphics2D g2 = resizedImg.createGraphics();

    // 2. Use the Graphic object to draw a new image to the image in the buffer
    g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
    g2.drawImage(image, 0, 0, newWidth, newHeight, null);
    g2.dispose();

    // 3. Convert the buffered image into an ImageIcon for return
    return (new ImageIcon(resizedImg));
}

试试这个：

ImageIcon imageIcon = new ImageIcon("./img/imageName.png"); // load the image to a imageIcon
Image image = imageIcon.getImage(); // transform it 
Image newimg = image.getScaledInstance(120, 120,  java.awt.Image.SCALE_SMOOTH); // scale it the smooth way  
imageIcon = new ImageIcon(newimg);  // transform it back

（找到了）

那它呢

ImageIcon imageIcon = new ImageIcon(new ImageIcon("icon.png").getImage().getScaledInstance(20, 20, Image.SCALE_DEFAULT));
label.setIcon(imageIcon);

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From:

这将保持正确的纵横比

    public ImageIcon scaleImage(ImageIcon icon, int w, int h)
    {
        int nw = icon.getIconWidth();
        int nh = icon.getIconHeight();

        if(icon.getIconWidth() > w)
        {
          nw = w;
          nh = (nw * icon.getIconHeight()) / icon.getIconWidth();
        }

        if(nh > h)
        {
          nh = h;
          nw = (icon.getIconWidth() * nh) / icon.getIconHeight();
        }

        return new ImageIcon(icon.getImage().getScaledInstance(nw, nh, Image.SCALE_DEFAULT));
    }

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。。。。以下布局。

是否为FlowLayout？？？（defalut布局没有定义任何内容），你知道吗

    public ImageIcon scaleImage(ImageIcon icon, int w, int h)
    {
        int nw = icon.getIconWidth();
        int nh = icon.getIconHeight();

        if(icon.getIconWidth() > w)
        {
          nw = w;
          nh = (nw * icon.getIconHeight()) / icon.getIconWidth();
        }

        if(nh > h)
        {
          nh = h;
          nw = (icon.getIconWidth() * nh) / icon.getIconHeight();
        }

        return new ImageIcon(icon.getImage().getScaledInstance(nw, nh, Image.SCALE_DEFAULT));
    }