java图像裁剪 [英] java image crop

问题描述

我知道 BufferedImage.getSubimage 然而，它无法处理小于抛出异常的裁剪尺寸的裁剪图像：

I am aware of BufferedImage.getSubimage However, it cant deal with cropping images that are smaller than the cropping size throwing the exception:

java.awt.image.RasterFormatException: (y + height) is outside raster

我希望能够将PNG / JPG / GIF裁剪为特定尺寸，但是如果图像小于裁剪区域中心本身在白色背景上。是否有电话要这样做？或者我是否需要手动创建图像以使图像居中，如果是这样，我将如何处理？

I want to be able to crop either a PNG/JPG/GIF to a certain size however if the image is smaller than the cropping area centre itself on a white background. Is there a call to do this? Or do I need to create an image manually to centre the image on if so, how would I go about this?

谢谢

推荐答案

您无法裁剪更大的图像，只能缩小图像。所以，你从目标维度开始，比方说100x100。你的 BufferedImage （ bi ），比方说150x50。

You cannot crop an image larger, only smaller. So, you start with the goal dimension,let's say 100x100. And your BufferedImage (bi), let's say 150x50.

创建一个目标矩形：

Rectangle goal = new Rectangle(100, 100);

然后将其与图片的尺寸相交：

Then intersect it with the dimensions of your image:

Rectangle clip = goal.intersection(new Rectangle(bi.getWidth(), bi.getHeight());

现在，clip对应于 bi 中符合你目标的部分。在这种情况下为100 x50。

Now, clip corresponds to the portion of bi that will fit within your goal. In this case 100 x50.

现在使用剪辑的值获取 subImage 。

BufferedImage clippedImg = bi.subImage(clip,1, clip.y, clip.width, clip.height);

创建一个新的 BufferedImage （ bi2 ），目标的大小：

BufferedImage bi2 = new BufferedImage(goal.width, goal.height);

填写它用白色（或你选择的任何bg颜色）：

Fill it with white (or whatever bg color you choose):

Graphics2D big2 = bi2.getGraphics();
big2.setColor(Color.white);
big2.fillRect(0, 0, goal.width, goal.height);

并将剪裁的图像绘制到其上。

and draw the clipped image onto it.

int x = goal.width - (clip.width / 2);
int y = goal.height - (clip.height / 2);
big2.drawImage(x, y, clippedImg, null);

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