調整 Java BufferedImage 的大小，保持縱橫比並填充背景

Question

我正在使用 Java 來存儲和修改 .jpg 圖像（不是 Android 或 Swing）。 如果新尺寸與原始圖像不成比例，我想轉換具有新尺寸的圖像以保持縱橫比並用白色填充背景。

 BufferedImage image = /*Here i read from disk and load the image */;
 image = resizeImage(image,  newWidth, newHeight);
 ImageIO.write(image, extension, new File(filename + "_" + page + "." + extension));

我試圖實現的功能是 resizeImage：在示例中調整圖像大小，但它不保持縱橫比。

  private static BufferedImage resizeImage(BufferedImage originalImage, int width, int height) {
        BufferedImage resizedImage = new BufferedImage(width, height, originalImage.getType());
        Graphics2D g = resizedImage.createGraphics();
        g.drawImage(originalImage, 0, 0, width, height, null);
        g.dispose();
        return resizedImage;
    }

我認為一張圖片將更能說明我的要求：

如果原始圖像是 200x200 並且被要求將大小調整為 400x300，則結果應該是帶有白邊的圖片，並且原始圖片的大小在內部進行了調整。 在此示例中應為 300x300。

問題不在於如何調整大小，而在於如何用白色填充剩余的圖像，並將原始調整大小的圖像放在它的中心。

Answer 1

這段代碼對我有用：

private static BufferedImage resizeImage(BufferedImage originalImage, int newWidth, int newHeight) {
    BufferedImage resizedImage = new BufferedImage(newWidth, newHeight, originalImage.getType());
    Graphics2D graphics = resizedImage.createGraphics();
    graphics.setColor(Color.WHITE);
    // fill the entire picture with white
    graphics.fillRect(0, 0, newWidth, newHeight);
    int maxWidth = 0;
    int maxHeight = 0;
    // go along the width and height in increments of 1 until one value is equal to the specified resize value
    while (maxWidth <= newWidth && maxHeight <= newHeight)
    {
        ++maxWidth;
        ++maxHeight;
    }
    // calculate the x value with which the original image is centred
    int centerX = (resizedImage.getWidth() - maxWidth) / 2;
    // calculate the y value with which the original image is centred
    int centerY = (resizedImage.getHeight() - maxHeight) / 2;
    // draw the original image
    graphics.drawImage(originalImage, centerX, centerY, maxWidth, maxHeight, null);
    graphics.dispose();
    return resizedImage;
}

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