Java2D&形象创作
我想从 Java 动态创建一些图像并将其保存到文件中。 正如我在各种教程中阅读的那样，我需要使用 BufferedImage。
但是，BufferedImage 构造函数需要高度和宽度作为参数。但我不知道图像的最终尺寸。我应该如何创建预先未知尺寸的图像？
有两种明显的策略：
- 首先创建一个非常大的图像，例如 10000x10000。
- 逐渐创建更大的图像，并将原始图像复制到其中。缺点是每次我想添加一些东西之前我都需要检查边界。
你如何处理这个问题？
I want to dynamically create some image from Java and save it to a file.
As I read in various tutorials, I need to use BufferedImage.
But, the BufferedImage constructor requires that the height and width as parameters. But I don't know the final size of my image. How should I create an image with size unknown in advance?
There are two obvious strategies:
- Create a very large image initially, say 10000x10000.
- Gradually creating larger image, and copying the original to it. The drawback is that I need to check the bounds before each time I want to add something.
How do you deal with this problem?
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你刚刚遇到了空间与时间的问题。我会采用第一种策略，创建一个非常大的图像 10000x10000，原因很简单，你所说的第二种方法涉及大量的矩阵副本，你会不惜一切代价避免这种情况。
此外，在充分了解图像尺寸的情况下，您可以进一步将 10000 x 10000 的值优化为最初的 1000x1000 之类的值。如果图像似乎超过了这个值，请将其加倍，例如 2000 x 2000，然后将旧图像复制到新图像，并在图像扩展时继续执行此操作。这更像是著名的
java 中使用的一种经过验证的策略.util.ArrayList通过这种方式，您可以间接地弥合时间与空间的权衡。是的，你每次都必须计算边界，但这对我来说并不是一个大任务，它可以在 O(1) 时间内完成。
You've just run into space vs time issue here. I would be going for the first strategy of creating a very large image 10000x10000, the simple reason being the second approach you say involves mountains of matrix copies which you would want to avoid at any cost.
Moreover, with a good knowledge of the image size, you can further optimize that value of 10000 x 10000 to something like 1000x1000 initially. If the image seems to exceed this, double it like 2000 x 2000 and copy the old one to the new one and keep doing this as your image expands.. This is more of a proven strategy that is used in the famous
java.util.ArrayListBy this way, you are indirectly bridging the time vs space trade-off. And yes, you will have to calculate the bounds everytime but that does not look a big task to me, it can be done in O(1) time.
当然，我们不知道您问题的具体情况，但一个简单的方法可能是这样的：您构建某种图像模型：哪个形状去哪里以及它有多大。由此您应该能够计算出整个图像的尺寸。
Of course we don't know the specifics of your problem but a simple approach could be like this: You build some kind of model of your image: Which shape goes where and how large is it. From that you should be able to calculate the dimensions of the total image.