使用Graphics2D覆盖BufferedImage上的文本并返回BufferedImage

问题描述

我已经检查过类似命名的问题，但他们没有回答这个用例。

基本上，我是要覆盖一些文字（文本）给定坐标（x，y）我在包中有以下函数;

  protected BufferedImage Process2（BufferedImage）图片）{
 Graphics2D gO = image.createGraphics（）; 
 gO.setColor（Color.red）; 
 gO.setFont（new Font（SansSerif，Font.BOLD，12））; 
 gO.drawString（this.text，this.x，this.y）; 
 System.err.println（this.text + this.x + this.y）; 
返回图片; 
} 
  

我觉得我错过了一些显而易见的东西;我可以找到的每个对Graphics2D的引用都是处理游戏或直接写入文件，但我只想要返回BufferedImage。覆盖'渲染'

在当前代码中，图像显示为未更改。

谢谢！

解决方案

方法

  import java.awt.Color; 
 import java.awt.Dimension; 
 import java.awt.EventQueue; 
 import java.awt.Font; 
 import java.awt.FontMetrics; 
 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; 
 import javax.swing.JFrame; 
 import javax.swing.JPanel; 
 
 / ** 
 * @see https://stackoverflow.com/questions/2658663 
 * / 
公共类TextOverlay扩展JPanel {
 
 private BufferedImage图像; 
 
 public TextOverlay（）{
 try {
 image = ImageIO.read（new URL（
http://cdn.sstatic.net/stackexchange/img /logos/so/so-logo.png））; 
} catch（IOException e）{
 e.printStackTrace（）; 
} 
 image = process（image）; 
} 
 
 @Override 
 public Dimension getPreferredSize（）{
 return new Dimension（image.getWidth（），image.getHeight（））; 
} 
 
私有BufferedImage进程（BufferedImage old）{
 int w = old.getWidth（）/ 3; 
 int h = old.getHeight（）/ 3; 
 BufferedImage img = new BufferedImage（
 w，h，BufferedImage.TYPE_INT_ARGB）; 
 Graphics2D g2d = img.createGraphics（）; 
 g2d.drawImage（old，0,0，w，h，this）; 
 g2d.setPaint（Color.red）; 
 g2d.setFont（new Font（Serif，Font.BOLD，20））; 
 String s =Hello，world！; 
 FontMetrics fm = g2d.getFontMetrics（）; 
 int x = img.getWidth（） -  fm.stringWidth（s） -  5; 
 int y = fm.getHeight（）; 
 g2d.drawString（s，x，y）; 
 g2d.dispose（）; 
 return img; 
} 
 
 @Override 
 protected void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 g.drawImage（image，0,0，null）; 
} 
 
 private static void create（）{
 JFrame f = new JFrame（）; 
 f.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 f.add（new TextOverlay（））; 
 f.pack（）; 
 f.setVisible（true）; 
} 
 
 public static void main（String [] args）{
 EventQueue.invokeLater（new Runnable（）{
 
 @Override 
 public void run（）{
 create（）; 
} 
}）; 
} 
} 
  

I have checked similarly named questions, but they don't answer this use case.

Basically, I was to overlay some text (text) at a given coordinate (x,y) I have the below function in a package;

protected BufferedImage Process2(BufferedImage image){
    Graphics2D gO = image.createGraphics();
    gO.setColor(Color.red);
    gO.setFont(new Font( "SansSerif", Font.BOLD, 12 ));
    gO.drawString(this.text, this.x, this.y);
    System.err.println(this.text+this.x+this.y);
    return image;
}

I feel like im missing something patently obvious; every reference to Graphics2D I can find is dealing with either games or writing directly to a file but I just want a BufferedImage returned. with the overlay 'rendered'

In the current code, the image appears out the end unchanged.

Thanks!

解决方案

The method drawString() uses x and y for the leftmost character's baseline. Numbers typically have no descenders; if the same is true of text, a string drawn at position (0,0) will be rendered entirely outside the image. See this example.

Addendum: You may be having trouble with an incompatible color model in your image. One simple expedient is to render the image and then modify it in situ.

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
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;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * @see https://stackoverflow.com/questions/2658663
 */
public class TextOverlay extends JPanel {

    private BufferedImage image;

    public TextOverlay() {
        try {
            image = ImageIO.read(new URL(
                "http://cdn.sstatic.net/stackexchange/img/logos/so/so-logo.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        image = process(image);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(image.getWidth(), image.getHeight());
    }

    private BufferedImage process(BufferedImage old) {
        int w = old.getWidth() / 3;
        int h = old.getHeight() / 3;
        BufferedImage img = new BufferedImage(
            w, h, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = img.createGraphics();
        g2d.drawImage(old, 0, 0, w, h, this);
        g2d.setPaint(Color.red);
        g2d.setFont(new Font("Serif", Font.BOLD, 20));
        String s = "Hello, world!";
        FontMetrics fm = g2d.getFontMetrics();
        int x = img.getWidth() - fm.stringWidth(s) - 5;
        int y = fm.getHeight();
        g2d.drawString(s, x, y);
        g2d.dispose();
        return img;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 0, 0, null);
    }

    private static void create() {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new TextOverlay());
        f.pack();
        f.setVisible(true);
    }

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

            @Override
            public void run() {
                create();
            }
        });
    }
}

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