Java Swing：使用图像调整 JPanel 的大小

Question

我正在尝试调整已绘制到 ImagePanel（扩展 JPanel）上的图像大小，但它似乎不起作用。我从互联网上获得了一些覆盖组件 paint() 方法的示例代码，我认为这可能是问题所在，这是我的代码。

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    if (img != null) { // Scale it by width int scaledWidth = (int)((img.getWidth() * getHeight()/img.getHeight()));
        // If the image is not off the screen horizontally...
        if (scaledWidth < getWidth()) {
            // Center the left and right destination x coordinates.

            int leftOffset = getWidth() / 2 - scaledWidth / 2;
            int rightOffset = getWidth() / 2 + scaledWidth / 2;
            g.drawImage(img, leftOffset, 0, rightOffset, getHeight(), 0, 0, img.getWidth(), img.getHeight(), null);
        }
        // Otherwise, the image width is too much, even scaled
        // So we need to center it the other direction
        else {
            int scaledHeight = (img.getHeight() * getWidth()) / img.getWidth();

            int topOffset = getHeight() / 2 - scaledHeight / 2;
            int bottomOffset = getHeight() / 2 + scaledHeight / 2;

            g.drawImage(img, 0, topOffset, getWidth(), bottomOffset, 0, 0, img.getWidth(), img.getHeight(), null);
        }
    }
}

我从...调用它

public void resetImage(double width, double height) {
     BufferedImage scaledImage = new BufferedImage((int)width, (int)height,BufferedImage.TYPE_INT_ARGB);
     // Paint scaled version of image to new image
     Graphics2D graphics2D = scaledImage.createGraphics(); 
     graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR); 

     this.setSize((int)img.getWidth(), (int)img.getHeight());
     graphics2D.drawImage(this.img, 0, 0, (int)width, (int)height, null); graphics2D.dispose(); 
}

（此模糊中的宽度和高度是要应用的新宽度和高度。

谢谢。

Answer 1

你确定调用了paintComponent 方法吗？尝试在resetImage 末尾调用ImagePanel.repaint()