使用 Graphics2D 在 BufferedImage 上叠加文本并返回 BufferedImage [英] Using Graphics2D to overlay text on a BufferedImage and return a BufferedImage

问题描述

我检查了类似命名的问题，但它们没有回答这个用例.

基本上，我是在给定的坐标(x，y)上覆盖一些文本(文本)我在包中有以下功能；

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);返回图像；}

我觉得我错过了一些显而易见的东西；我能找到的每个对 Graphics2D 的引用都是处理游戏或直接写入文件，但我只想返回一个 BufferedImage .叠加渲染"

在当前代码中，图像出现在末尾不变.

谢谢！

解决方案

import java.awt.Color;导入 java.awt.Dimension;导入 java.awt.EventQueue;导入 java.awt.Font;导入 java.awt.FontMetrics;导入 java.awt.Graphics;导入 java.awt.Graphics2D;导入 java.awt.image.BufferedImage;导入 java.io.IOException;导入 java.net.URL;导入 javax.imageio.ImageIO;导入 javax.swing.JFrame;导入 javax.swing.JPanel;/*** @see https://stackoverflow.com/questions/2658663*/公共类 TextOverlay 扩展 JPanel {私有 BufferedImage 图像；公共文本覆盖(){尝试 {图像 = ImageIO.read(新网址("http://cdn.sstatic.net/stackexchange/img/logos/so/so-logo.png"));} catch (IOException e) {e.printStackTrace();}图像 = 过程(图像)；}@覆盖公共维度 getPreferredSize() {返回新维度(image.getWidth(), image.getHeight());}私有 BufferedImage 进程(BufferedImage 旧){int w = old.getWidth()/3;int h = old.getHeight()/3;BufferedImage img = 新的 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 = "你好，世界！";FontMetrics fm = g2d.getFontMetrics();int x = img.getWidth() - fm.stringWidth(s) - 5;int y = fm.getHeight();g2d.drawString(s, x, y);g2d.dispose();返回图像；}@覆盖受保护的无效paintComponent(图形g){super.paintComponent(g);g.drawImage(image, 0, 0, null);}私有静态无效创建(){JFrame f = new JFrame();f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);f.add(new TextOverlay());f.pack();f.setVisible(true);}公共静态无效主(字符串 [] args){EventQueue.invokeLater(new Runnable() {@覆盖公共无效运行(){创建();}});}}

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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