How to Correctly Overlay Text on a BufferedImage Using Graphics2D?

Overlaying Text on a BufferedImage Using Graphics2D

When attempting to overlay text onto a BufferedImage using Graphics2D, it is important to understand the correct usage of the 'drawString()' method. The x and y coordinates provided for this method represent the baseline for the leftmost character of the text, rather than the top-left corner of the text.

Problem:

If the text contains no descending characters (such as 'p' or 'g'), and is rendered at a position of (0,0), it will appear rendered outside of the image. This is because there is no room for the characters to be displayed within the given space.

Solution:

To ensure that the text is rendered within the image, it is recommended to render the image and modify it directly instead.

Code Example:

Consider the following code example, which renders an image with the text "Hello, world!" overlaid on it:

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;

public class TextOverlay {

    public static void main(String[] args) throws IOException {
        // Read the image from a URL
        BufferedImage image = ImageIO.read(new URL("image-url"));

        // Create a new image to draw on
        BufferedImage newImage = new BufferedImage(
                image.getWidth(), image.getHeight(), BufferedImage.TYPE_INT_ARGB);

        // Get the graphics context for the new image
        Graphics2D g = newImage.createGraphics();

        // Draw the original image onto the new image
        g.drawImage(image, 0, 0, null);

        // Set the font and color for the text
        g.setFont(new Font("Serif", Font.BOLD, 20));
        g.setColor(Color.red);

        // Calculate the position of the text
        int x = image.getWidth() - g.getFontMetrics().stringWidth("Hello, world!") - 5;
        int y = g.getFontMetrics().getHeight();

        // Draw the text onto the new image
        g.drawString("Hello, world!", x, y);

        // Dispose of the graphics context
        g.dispose();

        // Save or display the new image
    }
}

By modifying the image after it has been rendered, it is possible to ensure that the text is overlayed correctly within the image itself.

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