用用户定义的量水平滚动图像

Question

我正在努力学习如何水平滚动图像。假设用户输入了一个整数量，返回的图像将是一个新的图像，该值将向左移动，而左边的大多数像素将出现在图像的右侧。我一直想弄清楚这一点，但是我遇到了一些错误。

有什么想法吗？我对图像处理和处理非常陌生。

到目前为止我写的都是这样的。

public void scrollHorizontal(int numpixels){
    horizontalscroll = new Picture(image6.getWidth(), image6.getHeight());

    for (int i = 0; i<image6.getWidth(); i++){
        for (int j=0; j<image6.getHeight(); j++){
            pix2 = image6.getPixel(i, j);
            horizontalscroll.setPixel(i-numpixels, j, pix2);
            System.out.println(i);
        }
    }
    for (int i = 0; i< image6.getWidth(); i++){
        for (int j = 0; j<image6.getHeight(); j++){
            pix2 = horizontalscroll.getPixel(i, j);
            horizontalscroll.setPixel(image6.getWidth()-numpixels-i ,j, pix2);
            //System.out.println(i);
        }

    }
    horizontalscroll.store("scrollhorizontal.gif");
}

Picture类只是基于(x，y)创建一个图片对象。getPixel()是Picture类的一个方法。'pix2‘是一个像素对象。

Answer 1

经过多次反复试验，我终于明白了这一点。谢谢。我只是想和你分享！

public void scrollHorizontal(int numpixels){ //allows the user to define numpixels to scroll horizontally by.
    int height = image6.getHeight();        //creates a new image that is scrolled horizontally by the entered numpixels amount.
    int width = image6.getWidth();
    horizontalscroll = new Picture(image6.getWidth(), image6.getHeight());
    for (int i = numpixels; i < width; i++){
        for (int j = 0; j < height; j++){
            pix2 = image6.getPixel(i, j);
            horizontalscroll.setPixel(i-numpixels, j, pix2);
        }
    }
    for (int i = 0; i < numpixels; i++){
        for (int j = 0; j < height; j++){
            pix2 = image6.getPixel(i, j);
            horizontalscroll.setPixel((width-numpixels) + i, j, pix2);
        }
    }
    horizontalscroll.store("scrollhorizontal.gif"); //stores new picture object to a new file.
}

Answer 2

您的bug位于类似于此的行中：

horizontalscroll.setPixel(i-numpixels, j, pix2);

当我小于numPixels时，您将尝试在负坐标下设置值。

正确的解决办法是：

public void scrollHorizontal(int numpixels){
  int wid = image6.getWidth();
  int hei = image6.getHeight();
  if (wid < Math.abs(numPixels)) {
    numPixels = numPixels % wid;
  }
  horizontalscroll = new Picture();
  if (numpixels >= 0) {
    for (int i = 0; i< hei; i++){
      for (int j = 0, h = wid - numPixels - 1; j < numPixels; ++j, ++h) {
        pix2 = image6.getPixel(i, h);
        horizontalscroll.setPixel(i, j, pix2);
      }
      for (int j = numPixels, h = 0; j< wid; ++j, ++h){
        pix2 = image6.getPixel(i, h);
        horizontalscroll.setPixel(i, j, pix2);
      }
    }
  } else {
    for (int i = 0; i< hei; i++){
      for (int j = 0, h = numPixels; j< wid - numPixels - 1; ++j, ++h) {
        pix2 = image6.getPixel(i, h);
        horizontalscroll.setPixel(i, j, pix2);
      }
      for (int j = wid - numPixels, h = 0; j < wid; ++j, ++h) {
        pix2 = image6.getPixel(i, h);
        horizontalscroll.setPixel(i, j, pix2);
      }
    }
  }

}