Java - 多分辨率图像API

多分辨率图像 API 在 Java 9 中引入。此 API 支持具有不同分辨率变体的多个图像。此 API 允许将一组具有不同分辨率的图像用作单个多分辨率图像。

考虑以下图像。

这些是三个不同大小的徽标图像。

现在，为了使用这三个图像，从 Java 9 开始，可以使用多分辨率图像 API 作为单个 API 来获取所有变体或要显示的特定变体。

// read all images into one multiresolution image
MultiResolutionImage multiResolutionImage = 
   new BaseMultiResolutionImage(images.toArray(new Image[0]));

这里 MultiResolutionImage 和 BaseMultiResolutionImage 类是 java.awt.image 包的一部分。

以下是多分辨率图像的主要操作。

• Image getResolutionVariant(double destImageWidth, double destImageHeight) − 获取最适合在指示大小下表示此逻辑图像的特定图像。

• List<Image> getResolutionVariants() − 获取所有分辨率变体的可读列表。

示例 - 获取所有变体

在此示例中，我们加载了三个图像并将它们存储在 MultiResolutionImage 中。然后使用 getResolutionVariants() 方法，我们检查此多分辨率图像中所有可用的图像变体并打印它。

package com.tutorialspoint;

import java.awt.Image;
import java.awt.image.BaseMultiResolutionImage;
import java.awt.image.MultiResolutionImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.imageio.ImageIO;

public class Tester {
   public static void main(String[] args) throws IOException, MalformedURLException {

	  // prepare a list of urls of all images
      List<String> imgUrls = List.of("https://tutorialspoint.com/java9/images/logo.png",
         "https://tutorialspoint.com/java9/images/mini_logo.png",
         "https://tutorialspoint.com/java9/images/large_logo.png");

      // create a list of Image object
      List<Image> images = new ArrayList<Image>();

      // Create image objects using image urls
      for (String url : imgUrls) {
         images.add(ImageIO.read(new URL(url)));
      }

      // read all images into one multiresolution image
      MultiResolutionImage multiResolutionImage = 
         new BaseMultiResolutionImage(images.toArray(new Image[0]));

      // get all variants of images
      List<Image> variants = multiResolutionImage.getResolutionVariants();

     
      System.out.println("Total number of images: " + variants.size());
     
      // print all the images
      for (Image img : variants) {
         System.out.println(img);
      }     
   }  
}

输出

让我们编译并运行上述程序，这将产生以下结果：

Total number of images: 3
BufferedImage@7ce6a65d: type = 6 ColorModel: #pixelBits = 32 numComponents = 4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3 
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =311 
height = 89 #numDataElements 4 dataOff[0] = 3

BufferedImage@4c762604: type = 6 ColorModel: #pixelBits = 32 numComponents = 4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3 
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =156 
height = 45 #numDataElements 4 dataOff[0] = 3

BufferedImage@2641e737: type = 6 ColorModel: #pixelBits = 32 numComponents = 4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3 
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =622 
height = 178 #numDataElements 4 dataOff[0] = 3

示例 - 获取特定变体

在此示例中，我们加载了三个图像并将它们存储在 MultiResolutionImage 中。然后使用 getResolutionVariant() 方法，我们根据此多分辨率图像中提供的分辨率获取特定图像变体并打印它。如果分辨率不完全匹配，此方法将返回最接近的分辨率图像。

package com.tutorialspoint;

import java.awt.Image;
import java.awt.image.BaseMultiResolutionImage;
import java.awt.image.MultiResolutionImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.imageio.ImageIO;

public class Tester {
   public static void main(String[] args) throws IOException, MalformedURLException {

	  // prepare a list of urls of all images
      List<String> imgUrls = List.of("https://tutorialspoint.com/java9/images/logo.png",
         "https://tutorialspoint.com/java9/images/mini_logo.png",
         "https://tutorialspoint.com/java9/images/large_logo.png");

      // create a list of Image object
      List<Image> images = new ArrayList<Image>();

      // Create image objects using image urls
      for (String url : imgUrls) {
         images.add(ImageIO.read(new URL(url)));
      }

      // read all images into one multiresolution image
      MultiResolutionImage multiResolutionImage = 
         new BaseMultiResolutionImage(images.toArray(new Image[0]));

      // get all variants of images
      List<Image> variants = multiResolutionImage.getResolutionVariants();

     
      System.out.println("Total number of images: " + variants.size());
     
      // get a resolution-specific image variant for each indicated size
      Image variant1 = multiResolutionImage.getResolutionVariant(156, 45);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 
         156, 45, variant1.getWidth(null), variant1.getHeight(null));

      Image variant2 = multiResolutionImage.getResolutionVariant(311, 89);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 311, 89, 
         variant2.getWidth(null), variant2.getHeight(null));

      Image variant3 = multiResolutionImage.getResolutionVariant(622, 178);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 622, 178, 
         variant3.getWidth(null), variant3.getHeight(null));

      Image variant4 = multiResolutionImage.getResolutionVariant(300, 300);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 300, 300, 
         variant4.getWidth(null), variant4.getHeight(null));
   }  
} 

输出

让我们编译并运行上述程序，这将产生以下结果：

Total number of images: 3
Image for destination[156,45]: [311,89]
Image for destination[311,89]: [311,89]
Image for destination[622,178]: [622,178]
Image for destination[300,300]: [622,178]