旋转位图像素 [英] Rotate Bitmap pixels

问题描述

我想在那里旋转像素存储在阵列 INT像素[] A位图。我得到了下面的方法：

I'm trying to rotate a Bitmap where the pixels are stored in an Array int pixels[]. I got the following method:

public void rotate(double angle) {
    double radians = Math.toRadians(angle);
    double cos, sin;
    cos = Math.cos(radians);
    sin = Math.sin(radians);
    int[] pixels2 = pixels;
    for (int x = 0; x < width; x++)
        for (int y = 0; y < height; y++) {
            int centerx = this.width / 2, centery = this.height / 2;
            int m = x - centerx;
            int n = y - centery;
            int j = (int) (m * cos + n * sin);
            int k = (int) (n * cos - m * sin);
            j += centerx;
            k += centery;
            if (!((j < 0) || (j > this.width - 1) || (k < 0) || (k > this.height - 1)))

                try {
                    pixels2[(x * this.width + y)] = pixels[(k * this.width + j)];
                } catch (Exception e) {
                    e.printStackTrace();
                }
        }
    pixels = pixels2;

}

但它只是给我疯狂的结果。有谁知道哪里出错？

But it just gives me crazy results. Does anyone know where the error is?

推荐答案

行

int[] pixels2 = pixels;

应该是数组复制，但你只是复制引用。使用 pixels.clone（）。其实，你只需要一个新的空数组，所以新INT [pixels.lenght] 就足够了。最后，你需要 System.arraycopy 来新的内容复制到旧数组。

is supposed to copy the array, but you are just copying the reference to it. Use pixels.clone(). In fact, you just need a new, empty array, so new int[pixels.lenght] is enough. In the end you need System.arraycopy to copy the new content into the old array.

有在code其他问题 - 你是混合行和列。仿佛该图像是由行通过柱存储行，其他如同柱一些前pressions写入。如果行由行（我的假设），那么这是没有意义的： X *宽+ Y 。它应该阅读 Y *宽+ X - 你跳过是行下来，然后移动 X 到右侧列。所有的一切，我有这个code，它的工作原理确定：

There are other problems in your code -- you are mixing up rows and columns. Some expressions are written as though the image is stored row by row, others as if column by column. If row-by-row (my assumption), then this doesn't make sense: x*width + y. It should read y*width + x -- you are skipping y rows down and then moving x columns to the right. All in all, I have this code that works OK:

import static java.lang.System.arraycopy;

public class Test
{
  private final int width = 5, height = 5;
  private int[] pixels = {0,0,1,0,0,
                          0,0,1,0,0,
                          0,0,1,0,0,
                          0,0,1,0,0,
                          0,0,1,0,0};

  public Test rotate(double angle) {
    final double radians = Math.toRadians(angle),
    cos = Math.cos(radians), sin = Math.sin(radians);
    final int[] pixels2 = new int[pixels.length];
    for (int x = 0; x < width; x++)
      for (int y = 0; y < height; y++) {
        final int
          centerx = this.width / 2, centery = this.height / 2,
          m = x - centerx,
          n = y - centery,
          j = ((int) (m * cos + n * sin)) + centerx,
          k = ((int) (n * cos - m * sin)) + centery;
        if (j >= 0 && j < width && k >= 0 && k < this.height)
          pixels2[(y * width + x)] = pixels[(k * width + j)];
      }
    arraycopy(pixels2, 0, pixels, 0, pixels.length);
    return this;
  }
  public Test print() {
    for (int y = 0; y < height; y++) {
      for (int x = 0; x < width; x++)
        System.out.print(pixels[width*y + x]);
      System.out.println();
    }
    System.out.println();
    return this;
  }
  public static void main(String[] args) {
    new Test().print().rotate(-45).print();
  }
}

这篇关于旋转位图像素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！