Java 简明教程
Java - Multiresolution Image API
多分辨率图像 API 在 Java 9 中引入。该 API 支持具有不同分辨率变体的多个图像。该 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。
这些是具有不同大小的三张徽标图像。
现在为了操作这三个图像，可以使用 Java 9 开始的多分辨率图像 API 作为单个 API，以获取所有变体或待显示的特定变体。
// 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) − 获取特定图像，该图像作为指示大小的逻辑图像的最佳变体。
-
List<Image> getResolutionVariants() − 获取所有分辨率变体的可读列表。
Example - Get All variants
在该示例中，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，正在检查这个多分辨率图像中的所有可用图像变体并打印它。
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("http://www.tutorialspoint.com/java9/images/logo.png",
"http://www.tutorialspoint.com/java9/images/mini_logo.png",
"http://www.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);
}
}
}Output
让我们编译并运行上述程序，这将生成以下结果 −
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] = 3Example - Get Specific variant
在这个示例中，我们加载了三张图像，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将其打印出来。如果分辨率不完全匹配，此方法将返回最近 t 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("http://www.tutorialspoint.com/java9/images/logo.png",
"http://www.tutorialspoint.com/java9/images/mini_logo.png",
"http://www.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));
}
}