在 JPanel 内旋转 BufferedImage

问题描述

我正在尝试旋转 BufferedImage 并将其显示在 JLabel(位于 JPanel 内)内.当前结果生成一个在黑色背景上旋转 10 度的白色方块，但图像不存在于方块内.我知道 myPicture 不是空白的，因为 myPicture 本身在不旋转时会在 JPanel 内正确显示.

I am trying to rotate a BufferedImage and display it inside a JLabel (which is inside a JPanel). The current result produces a white square rotated 10 degrees against a black background, but the image is not present inside the square. I know myPicture is not blank, since myPicture itself displays properly inside the JPanel when not rotated.

代码如下:

int w = myPicture.getWidth();

int h = myPicture.getHeight();

BufferedImage newImage = new BufferedImage(w, h, myPicture.getType());

Graphics2D graphic = newImage.createGraphics();

graphic.rotate(Math.toRadians(10), w/2, h/2);

graphic.drawImage(myPicture, null, 0, 0);

picLabel.setIcon(new ImageIcon(newImage));

推荐答案

我自己解决了问题.问题出在代码上:

I solved my own issue. The problem lay in the code:

myPicture.getType()

由于您可以放入程序的图像类型有很多可变性，当您开始绘制新的 BufferedImage 时，结果将是不可预测的.我通过显式设置类型解决了这个问题，在我的情况下需要

Since there is a lot of variability in the types of images you could put in to the program, the results are going to be unpredictable when you start drawing into the new BufferedImage. I solved the problem by setting the type explicitly, which in my case required

BufferedImage.TYPE_INT_ARGB

所以完整的声明如下:

BufferedImage newImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

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