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/*
 * Copyright yz 2016-01-14  Email:[email protected].
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.javaweb.utils;

import java.io.*;

/**
 * 图片信息读取类
 * http://blog.jaimon.co.uk/simpleimageinfo/SimpleImageInfo.java.html
 */
public class ImageInfo {

	private int height;

	private int width;

	private String mimeType;

	private ImageInfo() {

	}

	public ImageInfo(File file) throws IOException {
		InputStream is = new FileInputStream(file);

		try {
			processStream(is);
		} finally {
			is.close();
		}
	}

	public ImageInfo(InputStream is) throws IOException {
		processStream(is);
	}

	public ImageInfo(byte[] bytes) throws IOException {
		InputStream is = new ByteArrayInputStream(bytes);

		try {
			processStream(is);
		} finally {
			is.close();
		}
	}

	private void processStream(InputStream is) throws IOException {
		int c1 = is.read();
		int c2 = is.read();
		int c3 = is.read();

		mimeType = null;
		width = height = -1;

		if (c1 == 'G' && c2 == 'I' && c3 == 'F') { // GIF
			is.skip(3);
			width = readInt(is, 2, false);
			height = readInt(is, 2, false);
			mimeType = "image/gif";
		} else if (c1 == 0xFF && c2 == 0xD8) { // JPG
			while (c3 == 255) {
				int marker = is.read();
				int len    = readInt(is, 2, true);

				if (marker == 192 || marker == 193 || marker == 194) {
					is.skip(1);
					height = readInt(is, 2, true);
					width = readInt(is, 2, true);
					mimeType = "image/jpeg";
					break;
				}

				is.skip(len - 2);
				c3 = is.read();
			}
		} else if (c1 == 137 && c2 == 80 && c3 == 78) { // PNG
			is.skip(15);
			width = readInt(is, 2, true);
			is.skip(2);
			height = readInt(is, 2, true);
			mimeType = "image/png";
		} else if (c1 == 66 && c2 == 77) { // BMP
			is.skip(15);
			width = readInt(is, 2, false);
			is.skip(2);
			height = readInt(is, 2, false);
			mimeType = "image/bmp";
		} else {
			int c4 = is.read();

			if ((c1 == 'M' && c2 == 'M' && c3 == 0 && c4 == 42) || (c1 == 'I' && c2 == 'I' && c3 == 42 && c4 == 0)) { //TIFF
				boolean bigEndian = c1 == 'M';
				int     ifd       = 0;
				int     entries;
				ifd = readInt(is, 4, bigEndian);
				is.skip(ifd - 8);
				entries = readInt(is, 2, bigEndian);

				for (int i = 1; i <= entries; i++) {
					int tag       = readInt(is, 2, bigEndian);
					int fieldType = readInt(is, 2, bigEndian);
					int valOffset;

					if (fieldType == 3 || fieldType == 8) {
						valOffset = readInt(is, 2, bigEndian);
						is.skip(2);
					} else {
						valOffset = readInt(is, 4, bigEndian);
					}

					if (tag == 256) {
						width = valOffset;
					} else if (tag == 257) {
						height = valOffset;
					}
					if (width != -1 && height != -1) {
						mimeType = "image/tiff";
						break;
					}
				}
			}
		}

		if (mimeType == null) {
			throw new IOException("不支持的图片类型");
		}
	}

	private int readInt(InputStream is, int noOfBytes, boolean bigEndian) throws IOException {
		int ret = 0;
		int sv  = bigEndian ? ((noOfBytes - 1) * 8) : 0;
		int cnt = bigEndian ? -8 : 8;

		for (int i = 0; i < noOfBytes; i++) {
			ret |= is.read() << sv;
			sv += cnt;
		}

		return ret;
	}

	public int getHeight() {
		return height;
	}

	public void setHeight(int height) {
		this.height = height;
	}

	public int getWidth() {
		return width;
	}

	public void setWidth(int width) {
		this.width = width;
	}

	public String getMimeType() {
		return mimeType;
	}

	public void setMimeType(String mimeType) {
		this.mimeType = mimeType;
	}

	@Override
	public String toString() {
		return "MIME Type : " + mimeType + "\t Width : " + width + "\t Height : " + height;
	}

}