java 图片的放大与缩小--等距采样算法

叁歲伎倆 2022-08-20 04:21 201阅读 0赞

package test;
    
    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.io.IOException;
    
    import javax.imageio.ImageIO;
    
    /*
     * 通过像素的缩放技术，改变图片的大小
     * --等距采样法
     */
    public class ImageChange {
    	private  String filePath;//需要修改的图片途径
    	private BufferedImage oldBufferedImage;//修改图片的图片缓冲区
    	private String newFilePath;//新的图片路径
    	public ImageChange(String filePath,String newFilePath) throws IOException{
    		this.filePath=filePath;
    		this.newFilePath=newFilePath;
    		oldBufferedImage = ImageIO.read(new File(this.filePath));
    	}
    	/**
    	 * 
    	 * @param width 改变后图片的宽
    	 * @param heigth 改变后图片的高
    	 * @throws IOException 
    	 */
    	public void flex(float width,float height) throws IOException{
    		//1原来宽和高与新的宽高的比例K
    		/**
    		 -------------------------------------------
    		 ******************
    		 ******************
    		 ****************** 
    		 ****************** 
    		 ****************** 
    		 把原来的图形像素填充到更大的区域里面去,分到大的空间，每一份的比例
    		 ********************************
    		 ********************************
    		 ********************************
    		 ********************************
    		 ********************************
    		 ********************************
    		 ********************************
    		 ---------------------------------------------
    		 */
    		float kx = oldBufferedImage.getWidth()/width;//新的图片的宽占原来像素的大小
    		float ky = oldBufferedImage.getHeight()/height;//新的图片的高占原来像素的大小
    		
    		int startX=0,startY=0,offset=0;//初始定义值，具体含义见上一篇blog
    		int oldWidth = oldBufferedImage.getWidth();
    		int scansize= oldWidth;//扫描间距
    		int oldHeight = oldBufferedImage.getHeight();
    		int newWidth = (int) (oldWidth/kx);//新图片宽
    		int newHeight = (int) (oldHeight/ky);//新图片高
    		//获取旧的像素数组
    		 int[] pix = new int[offset+(int) (oldHeight-startY)*scansize+(oldWidth-startX)];
    		 oldBufferedImage.getRGB(startX, startY, oldWidth, oldHeight, pix, offset, scansize);
    		//新的像素数组定义
    		 
    		 int newStartX=0,newStartY=0,newOffset=0;
    		 int newScansize=newWidth;
    		 System.out.print(newScansize);
    		 int[] newPix = new int[newOffset+(int) (newHeight-newStartY)*newScansize+(newWidth-newStartX)]; 
    		 for(int x = 0;x<newWidth-startX;x++){//遍历每一个行
    			 for(int y=0; y<newHeight-startY;y++){//遍历每一个列
    				 newPix[newOffset+(y-newStartY)*newScansize+(x-newStartX)]  = pix[offset+((int)((y-startY)*ky))*scansize+(int)((x-startX)*kx)];
    			//这里取值的时候记得用变量乘以头先算出来的比例	
    			 }
    		 }
    		 BufferedImage imgOut = new BufferedImage(newWidth,newHeight,oldBufferedImage.getType());  
    		 imgOut.setRGB(newStartX, newStartY, newWidth, newHeight, newPix, newOffset, newScansize); 
    		 ImageIO.write(imgOut, "jpg", new File(newFilePath));
    	}
    	
    	
    }