Java 使用 Graphics2D 在 BufferedImage 上叠加文本并返回 BufferedImage
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Using Graphics2D to overlay text on a BufferedImage and return a BufferedImage
提问by Bolster
I have checked similarly named questions, but they don't answer this use case.
我检查了类似命名的问题，但他们没有回答这个用例。
Basically, I was to overlay some text (text) at a given coordinate (x,y) I have the below function in a package;
基本上，我是在给定的坐标 (x,y) 上覆盖一些文本 (text) 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);
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'
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”
In the current code, the image appears out the end unchanged.
在当前代码中，图像出现在末尾不变。
Thanks!
谢谢！
采纳答案by trashgod
The method drawString()uses xand yfor 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.
该方法drawString()使用x和y作为最左边字符的基线。数字通常没有降序；如果 也是如此text，则在位置 (0,0) 绘制的字符串将完全呈现在图像之外。请参阅此示例。
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.
附录：您的图像中的颜色模型可能不兼容。一种简单的权宜之计是渲染图像，然后原位修改。
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();
}
});
}
}
