Java：最快的文字绘制方法？ [英] Java: Fastest way to draw text?

问题描述

我正在尝试编写一个仅用文本创建图像的程序（例如，在白色正方形上写 hello并存储图像），这听起来很简单，但是必须尽快完成。我尝试了Java2D库，但是绘制到BufferedImage上只需要2秒钟即可绘制图像，甚至不保存或显示图像。我也尝试过基于Java的CAPTCHA生成器，但是它们花费的时间太长（5秒）。

这看起来很简单，只能绘制文本，但是我很沮丧

是否可以通过某些命令行选项（例如分配更多的内存或优先）？是我应该使用一个特定的Java库，还是我应该知道的一些怪异的Java2D库，以使处理速度更快？

这是我的整个程序。我在Eclipse中运行它：

  import java.awt。*; 
 import java.awt.image.BufferedImage; 
 
公共类SimpleGraphics {
 public static void main（String [] args）{
 long time = System.currentTimeMillis（）; 
 
字符串消息= Hello world; 
 int width = 100; 
 int高度= 100; 
 BufferedImage img =新的BufferedImage（宽度，高度，BufferedImage.TYPE_BYTE_GRAY）; 
 
 Graphics2D graphics = img.createGraphics（）; 
 graphics.setColor（Color.black）; 
 graphics.setFont（new Font（ TimesRoman，Font.BOLD，12））; 
 
 FontMetrics fontMetrics = graphics.getFontMetrics（）; 
 int stringWidth = fontMetrics.stringWidth（message）; 
 int stringHeight = fontMetrics.getAscent（）; 
 
 graphics.drawString（message，（width-stringWidth）/ 2，height / 2 + stringHeight / 4）; 
 System.out.println（System.currentTimeMillis（）-时间）; //一致地〜2秒
} 
} 
  

解决方案

我从命令行运行我的代码（在Windows 7上使用JDK8），我大约用了300毫秒。

我将代码修改为以下内容：

  import java.awt。*; 
 import java.awt.image.BufferedImage; 
 
公共类SimpleGraphics {
 public static void main（String [] args）{
 long time = System.currentTimeMillis（）; 
 
 for（int i = 0; i< 100; i ++）
 createImage（）; 
 
 System.out.println（System.currentTimeMillis（）-时间）; //一致地〜2秒
} 
 
 public static void createImage（）
 {
 String message = Hello world; 
 int width = 100; 
 int高度= 100; 
 BufferedImage img =新的BufferedImage（宽度，高度，BufferedImage.TYPE_BYTE_GRAY）; 
 
 Graphics2D graphics = img.createGraphics（）; 
 graphics.setColor（Color.black）; 
 graphics.setFont（new Font（ TimesRoman，Font.BOLD，12））; 
 
 FontMetrics fontMetrics = graphics.getFontMetrics（）; 
 int stringWidth = fontMetrics.stringWidth（message）; 
 int stringHeight = fontMetrics.getAscent（）; 
 
 graphics.drawString（message，（width-stringWidth）/ 2，height / 2 + stringHeight / 4）; 
} 
} 
  

我仍然可以保持300ms左右。

所以问题不在于绘画代码。

我不知道为什么会得到2秒，但显然加载类需要一些开销。因此，我只能建议分批创建图像，以减少时间。

I'm trying to write a program that just creates an image out of text (e.g. write "hello" on a white square and store the image), which sounds simple but it must be done quickly. I tried the Java2D library but drawing onto a BufferedImage takes ~2 seconds to just draw the image, not even save or display it. I also tried Java-based CAPTCHA generators but they take much too long (5 seconds).

This seems like simple enough task to just draw text, but I'm frustrated that I can't do this faster than 2 seconds.

Is there a way I can do this faster on my machine by some command line options (e.g. allocating more memory or priority)? Is there a particular Java library I ought to use, or some weird quirk to Java2D I should be aware of to make things faster?

This is my entire program. I run this in Eclipse:

import java.awt.*;
import java.awt.image.BufferedImage;

public class SimpleGraphics {
    public static void main(String[] args) {
        long time = System.currentTimeMillis();

        String message = "Hello world";
        int width = 100;
        int height = 100;
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);

        Graphics2D graphics = img.createGraphics();
        graphics.setColor(Color.black);
        graphics.setFont(new Font("TimesRoman", Font.BOLD, 12));

        FontMetrics fontMetrics = graphics.getFontMetrics();
        int stringWidth = fontMetrics.stringWidth(message);
        int stringHeight = fontMetrics.getAscent();

        graphics.drawString(message, (width - stringWidth) / 2, height / 2 + stringHeight / 4);
        System.out.println(System.currentTimeMillis() - time); //consistently ~2 seconds
    }
}

解决方案

I run my code from the command line (using JDK8 on Windows 7) and I get around 300ms.

I modified your code to the following:

import java.awt.*;
import java.awt.image.BufferedImage;

public class SimpleGraphics {
    public static void main(String[] args) {
        long time = System.currentTimeMillis();

        for (int i = 0; i < 100; i++)
            createImage();

        System.out.println(System.currentTimeMillis() - time); //consistently ~2 seconds
    }

    public static void createImage()
    {
        String message = "Hello world";
        int width = 100;
        int height = 100;
        BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);

        Graphics2D graphics = img.createGraphics();
        graphics.setColor(Color.black);
        graphics.setFont(new Font("TimesRoman", Font.BOLD, 12));

        FontMetrics fontMetrics = graphics.getFontMetrics();
        int stringWidth = fontMetrics.stringWidth(message);
        int stringHeight = fontMetrics.getAscent();

        graphics.drawString(message, (width - stringWidth) / 2, height / 2 + stringHeight / 4);
    }
}

I still get around 300ms.

So the problem is not with the painting code.

I don't know why you get 2 seconds, but there is obviously some overhead to loading the class. So all I can suggest is to do your image creation in batches to minimize the time.

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