Java程式旋轉影像-java教程-PHP中文網

一個影像檔案可以順時針或逆時針旋轉。要旋轉圖像，需要下載一個隨機的圖像檔案並將其保存在系統的任何資料夾中。此外，需要一個.pdf文件，在打開下載的圖像文件後，可以在該特定的.pdf文件中旋轉一些角度。對於90度的旋轉，新影像的錨點可以幫助我們使用Java中的平移變換執行旋轉操作。錨點是任何特定圖像的中心。

Algorithm to Rotate an Image by Using Java

The "AffineTransformOp" class is the simplest way to rotate an image file by using Java. A user can load the image data as Buffered Image and apply the rotate operation using anchorpoint to produce the exuffered is always recommended that to use JPEG files for these operation with JDeli(Filetype with wide range).

透過使用Java程式旋轉影像，程式設計師可以使用一些內建的方法，如BufferedImage類別和Color c。

使用這個過程，我們需要將一張圖像作為BufferedImage載入到Java中，然後使用相同的函數旋轉圖像，並將資料保存到新檔案中。

步驟 1
Step 2
Step 3
#第四步
Step 5

Syntax

Code declaration: public static Image rotate(Image image, double angle)

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#Image
角度

#返回

Step 1

BufferedImage image = ImageIO.read(new File("C:\path\to\image name.jpg"));

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Step 2

#To rotate an image file by 90 degree follow the below code −

final double rads = Math.toRadians(90);
final Rotate rotate = new Rotate(90);
BufferedImage rotatedImage = rotate.apply(image);

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Step 3 −

Save the image file

Use Java ImageIO 
ImageIO.write(rotatedImage,"JPG",newFile("C:\path\to\rotatedImagename.jpg"));

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Example

import java.awt.*;
import java.awt.image.BufferedImage;
public class Main {
   public static Image rotate(Image image, double angle) {
      BufferedImage bufImg = toBufferedImage(image);
      double sin = Math.abs(Math.sin(angle)), cos = Math.abs(Math.cos(angle));
      int w = bufImg.getWidth(), h = bufImg.getHeight();
      int neww = (int) Math.floor(w * cos + h * sin), newh = (int) Math.floor(h * cos + w * sin);
      BufferedImage result = new BufferedImage(neww, newh, Transparency.TRANSLUCENT);
      Graphics2D g = result.createGraphics();
      g.translate((neww - w) / 2, (newh - h) / 2);
      g.rotate(angle, w / 2, h / 2);
      g.drawRenderedImage(bufImg, null);
      g.dispose();
      return result;
   } 
   public static BufferedImage toBufferedImage(Image image) {
      if (image instanceof BufferedImage) {
         return (BufferedImage) image;
      }
      BufferedImage buff = new BufferedImage(image.getWidth(null), image.getHeight(null),
      BufferedImage.TYPE_INT_ARGB);
      Graphics2D g = buff.createGraphics();
      g.drawImage(image, 0, 0, null);
      g.dispose();
      return buff;
   }
}

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Rotation of an Image Using BufferedImage Function

#By using a try-catch blocking method, we can handle the exceptions as they may disturb the flow of the code.
- 文檔類別主要用於展示PDF文檔。在這個特定的Java程式中，我們需要使用ie.documentobj函數來建立一個文檔類別。這個函數用於開啟和關閉PDF檔案。
− The function supports the PDF, XML,RTF file generations to code the image file rotation. The directory function we use here is fileOutputStream() to handle a file for a java code.
− output.pdf 是一個函數類，表示使用Java程式碼執行操作後的輸出。此函數可協助取得提供的輸入的輸出。

- The function helps us to set up a size in the input file preset.
- the coder can use this to rotate the image in certain angle. It can be used as a parameter in the method we used.
>
documentobj.open()
- 此函數可協助使用者在操作時開啟檔案。

- 使用此函數關閉一個.pdf檔。

Example

package JavaApplication29;
import java.io.FileOutputStream;
import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.pdf.PdfWriter;

public class JavaApplication29 {
   public static void main(String[] args) {
      try {
         Document documentobj = new Document(PageSize.A4, 20, 20, 20, 20);
         PdfWriter.getInstance(documentobj, new FileOutputStream("output.pdf"));
         documentobj.open();
         Image imageobj = Image.getInstance("C:\Users\lenovo\Desktop\RDD\Logo Org.jpg");
         imageobj.scaleToFit(200f, 200f);
         imageobj.setRotationDegrees(90);
         documentobj.add(imageobj);
         documentobj.close();
         System.out.println("Task completed");
      } catch (Exception e) {
         System.out.println("Exception occurred");
      }
   }
}

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Output Java程式旋轉影像