Hive Color

package main;

import java.awt.Color;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.imageio.ImageIO;

import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.usermodel.XSSFCellStyle;
import org.apache.poi.xssf.usermodel.XSSFColor;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class App {

	public BufferedImage readImage(String fileName){
		BufferedImage image = null;
		try {
			image = ImageIO.read(new File(fileName));
		} catch (IOException e) {
			e.printStackTrace();
		}
		return image;
	}

	public void drawImageToWorkbook(Workbook wb, BufferedImage image, Map<Integer, CellStyle> colorToCellStyle){
		int width = image.getWidth();
		int height = image.getHeight();
		Sheet sheet = wb.getSheet(wb.getSheetName(0));

		int processCount = 0;

		for(int y = 0; y < height; y++){
			Row row = sheet.createRow(y);
			row.setHeightInPoints(CELL_HEIGHT_IN_POINTS);

			for(int x = 0; x < width; x++){
				int rgb = toGrayScale(image.getRGB(x, y));
				row.createCell(x).setCellStyle(getCellStyle(rgb, wb, colorToCellStyle));

				if(processCount != 0 && processCount % 100 == 0)
					System.out.println("processCount: " + processCount);

				processCount++;
			}

			row = null;

			// 画像のサイズが大きすぎる時は強制的に打ち切り
			if(processCount > 300000)
				break;
		}
	}

	/**
	 * フルカラーからグレースケールカラーに変換する。<br>
	 * フルカラーだと処理が遅すぎるため現実的にはグレースケールで描画する必要がある。
	 * @return
	 */
	public int toGrayScale(int rgb){
		int b = rgb & 0x000000FF;
		int g = rgb >> 8 & 0x000000FF;
		int r = rgb >> 16 & 0x000000FF;
		int avgRGB = (r + g + b) / 3;

		return (avgRGB << 16 | avgRGB << 8 | avgRGB);
	}

	public CellStyle getCellStyle(int rgb, Workbook wb, Map<Integer, CellStyle> colorToCellStyle){
		CellStyle style = null;

		if(colorToCellStyle.containsKey(rgb))
			style = colorToCellStyle.get(rgb);
		else{
			XSSFCellStyle xssStyle = (XSSFCellStyle) wb.createCellStyle();
			xssStyle.setFillPattern(CellStyle.SOLID_FOREGROUND);
			xssStyle.setFillForegroundColor(new XSSFColor(new Color(rgb)));
			colorToCellStyle.put(rgb, xssStyle);
			style = xssStyle;
		}

		return style;
	}

	public void writeWorkbook(String fileName, Workbook wb){
		FileOutputStream out = null;
		try {
			out = new FileOutputStream(fileName);
			wb.write(out);
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				out.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	public BufferedImage resize(BufferedImage image){
		if(image.getWidth() < MAX_IMAGE_LENGTH && image.getHeight() < MAX_IMAGE_LENGTH)
			return image;

		double width = image.getWidth();
		double height = image.getHeight();
		double scale = 1.0;

		double maxLength = Math.max(width, height);
		if(maxLength > MAX_IMAGE_LENGTH){
			scale = (double) MAX_IMAGE_LENGTH / maxLength;
		}

		int w = (int) (width * scale);
		int h = (int) (height * scale);

		BufferedImage shrinkedImage = new BufferedImage(w, h, image.getType());
		shrinkedImage.getGraphics().drawImage(
				image.getScaledInstance(w, h, Image.SCALE_AREA_AVERAGING), 0, 0, w, h, null);

		return shrinkedImage;
	}

	/** 画像の長い方の辺がこの数値を超えていたら小さくリサイズする */
	public static final int MAX_IMAGE_LENGTH = 500;

	/** in units of 1/256th of a character width<br>つまり、256を指定すると1文字分の横幅 */
	public static final int CELL_WIDTH = 256;
	/** row height measured in point size<br>仕様上、ポイント単位でしか指定できない */
	public static final int CELL_HEIGHT_IN_POINTS = 6;

	/** The numerator for the zoom magnification.<br>要は、numerator÷denominatorが最終的な倍率になる */
	public static final int SHEET_ZOOM_NUMERATOR = 1;
	/** The denominator for the zoom magnification.<br>要は、numerator÷denominatorが最終的な倍率になる */
	public static final int SHEET_ZOOM_DENOMINATOR = 5;

	public static final String IMAGE_NAME = "sunset_l.jpg";
	public static final String WORKBOOK_NAME = IMAGE_NAME + ".xlsx";

	public App() {
		Map<Integer, CellStyle> colorToCellStyle = new HashMap<Integer, CellStyle>();

		BufferedImage image = resize(readImage(IMAGE_NAME));
		System.out.println("画像の読み込み完了: " + IMAGE_NAME + ", width: " + image.getWidth() + ", height: " + image.getHeight());

		Workbook workbook = new XSSFWorkbook();
		Sheet sheet = workbook.createSheet(IMAGE_NAME);
		sheet.setZoom(SHEET_ZOOM_NUMERATOR, SHEET_ZOOM_DENOMINATOR);
		System.out.println("ワークブックの作成完了: ");

		for(int i = 0; i < image.getWidth(); i++)
			sheet.setColumnWidth(i, CELL_WIDTH);
		System.out.println("セルの横幅の設定完了: ");


		drawImageToWorkbook(workbook, image, colorToCellStyle);
		System.out.println("エクセルへの画像描画完了: ");

		writeWorkbook(WORKBOOK_NAME, workbook);
		System.out.println("エクセルファイルへの書き出し完了: " + WORKBOOK_NAME);
	}

	public static void main(String[] args) {
		new App();
	}
}