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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