Java - 在图像的中心绘制文本

Question

I need to write text in the center of an image. The text to write is not always the same.

The code I'm using is here:

// Here I first draw the image
g.drawImage(img, 22, 15, 280, 225, null);
// I get the text 
String text = photoText.getText();
// Set the text color to black
g.setColor(Color.black);
// I draw the string 
g.drawString(text, 79.5F, 220.0F);

The problem is that the text isn't at the center of the image, what can I do?

I only need to draw the text at the horizontal center.

Answer 1

使用JLabel的工作量较少，但此处显示的FontMetrics将允许您直接管理几何体。

Answer 2

One possible solution: draw the image in a JPanel, being sure to set the panel's preferredsize as the size of the image, have the JPanel use a GridBagLayout, and place the text in a JLabel that is added to the JPanel, without GridBagConstraints. This is one way to center the JLabel in the JPanel.

Answer 3

The easy way is to use a JLabel with an Icon and Text. Then set the horizontal/vertical text position to CENTER and the text is painted in the center of the image.

From your code it looks like you are trying to paint the text near the bottom of the image. In this case you can use the JLabel with an Icon as a container. Then you can set the layout to something like a BoxLayout and add another label with the text.

No custom painting is required for either approach.

import java.awt.*;
import javax.swing.*;

public class LabelImageText extends JPanel
{
    public LabelImageText()
    {
        JLabel label1 = new JLabel( new ColorIcon(Color.ORANGE, 100, 100) );
        label1.setText( "Easy Way" );
        label1.setHorizontalTextPosition(JLabel.CENTER);
        label1.setVerticalTextPosition(JLabel.CENTER);
        add( label1 );

        JLabel label2 = new JLabel( new ColorIcon(Color.YELLOW, 200, 150) );
        label2.setLayout( new BoxLayout(label2, BoxLayout.Y_AXIS) );
        add( label2 );

        JLabel text = new JLabel( "More Control" );
        text.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        label2.add( Box.createVerticalGlue() );
        label2.add( text );
        label2.add( Box.createVerticalStrut(10) );
    }


    public static class ColorIcon implements Icon
    {
        private Color color;
        private int width;
        private int height;

        public ColorIcon(Color color, int width, int height)
        {
            this.color = color;
            this.width = width;
            this.height = height;
        }

        public int getIconWidth()
        {
            return width;
        }

        public int getIconHeight()
        {
            return height;
        }

        public void paintIcon(Component c, Graphics g, int x, int y)
        {
            g.setColor(color);
            g.fillRect(x, y, width, height);
        }
    }

    private static void createAndShowUI()
    {
        JFrame frame = new JFrame("LabelImageText");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add( new LabelImageText() );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible( true );
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

I mean I have to write a text in the center of the image and then save the image

You can use Screen Image to create an image of any component. This assumes you are displaying the image and text on a GUI.

Or, if you are talking about just reading in an image adding text to the image and then saving the image, then you will need to create a BufferedImage and draw the image on it and then draw the text on it. You will need to use the FontMetrics class as mentioned by Trashgod. My suggestion won't help.

Answer 4

I used TextLayout to get the text properly centered:

Here's how to create and save the image to file:

int imgWidth = 250;
int imgHeight = 250;
BufferedImage img = new BufferedImage(imgWidth, imgHeight,
        BufferedImage.TYPE_INT_RGB);

Graphics2D g = img.createGraphics();

Color backgroundColor = new Color(0, 150, 100);
g.setPaint(backgroundColor);
g.fillRect(0, 0, imgWidth, imgHeight);

Font font = new Font("Arial", Font.PLAIN, 80);
g.setFont(font);
g.setPaint(Color.WHITE);

String text = "0";

TextLayout textLayout = new TextLayout(text, g.getFont(),
        g.getFontRenderContext());
double textHeight = textLayout.getBounds().getHeight();
double textWidth = textLayout.getBounds().getWidth();

g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
        RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

// Draw the text in the center of the image
g.drawString(text, imgWidth / 2 - (int) textWidth / 2,
                   imgHeight / 2 + (int) textHeight / 2);

String imgFormat = "png";
ImageIO.write(img, imgFormat, new File("/home/me/new_image." + imgFormat));