java image bitmap_使用java.awt.image.BufferedImage创建BIFF8 BITMAP记...

所以我正在创建一个HSSFSheet,它使用apache poi和自己的低级代码设置背景位图. https://www.openoffice.org/sc/excelfileformat.pdf声明BITMAP,BIFF8：

Pixel data (array of height lines of the bitmap, from bottom line to top line, see below)

…

In each line all pixels are written from left to right. Each pixel is stored as 3-byte array: the red, green, and blue component of the colour of the pixel, in this order. The size of each line is aligned to multiples of 4 by inserting zero bytes after the last pixel.

有关完整声明,请参见PDF图片：

为了实现这一点,我的方法是使用类型为BufferedImage.TYPE_3BYTE_BGR的java.awt.image.BufferedImage.然后从BufferedImage的栅格中以正确的顺序(从底线到顶线)获取所有字节R G B,并将其填充到宽度为4的多个(x方向).

看代码：

import java.io.FileOutputStream;

import java.io.FileInputStream;

import org.apache.poi.hssf.usermodel.*;

import org.apache.poi.hssf.record.RecordBase;

import org.apache.poi.hssf.record.StandardRecord;

import org.apache.poi.hssf.model.InternalSheet;

import org.apache.poi.util.LittleEndianOutput;

import java.lang.reflect.Field;

import java.util.List;

import java.util.ArrayList;

import java.util.Arrays;

import java.awt.image.BufferedImage;

import java.awt.Graphics2D;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import javax.imageio.ImageIO;

public class CreateExcelHSSFSheetBackgroundBitmap {

static List getBackgroundBitmapData(String filePath) throws Exception {

//see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

List data = new ArrayList();

// get file byte data in type BufferedImage.TYPE_3BYTE_BGR

BufferedImage in = ImageIO.read(new FileInputStream(filePath));

BufferedImage image = new BufferedImage(in.getWidth(), in.getHeight(), BufferedImage.TYPE_3BYTE_BGR);

Graphics2D graphics = image.createGraphics();

graphics.drawImage(in, null, 0, 0);

graphics.dispose();

short width = (short)image.getWidth();

short height = (short)image.getHeight();

// each pixel has 3 bytes but the width bytes must be filled up to multiple of 4

int widthBytesMultOf4 = (int)((width * 3 + 3) / 4 * 4);

// --- this part takes much time but I have not found any better possibility

// put the bytes R G B into the data; lines of the bitmap must be from bottom line to top line

int bytes = 0;

for (short y = (short)(height - 1); y >= 0; y--) {

for (short x = 0; x < width; x++) {

int r = image.getData().getSample(x, y, 2);

data.add(Byte.valueOf((byte)r));

bytes++;

int g = image.getData().getSample(x, y, 1);

data.add(Byte.valueOf((byte)g));

bytes++;

int b = image.getData().getSample(x, y, 0);

data.add(Byte.valueOf((byte)b));

bytes++;

}

// fill up x with 0 bytes up to multiple of 4

for (int x = width * 3; x < widthBytesMultOf4; x++) {

data.add(Byte.valueOf((byte)0));

bytes++;

}

}

// ---

// size 12 bytes (additional headers, see below) + picture bytes

int size = 12 + bytes;

// get size int as LITTLE_ENDIAN bytes

ByteBuffer bSize = ByteBuffer.allocate(4);

bSize.order(ByteOrder.LITTLE_ENDIAN);

bSize.putInt(size);

// get width short as LITTLE_ENDIAN bytes

ByteBuffer bWidth = ByteBuffer.allocate(2);

bWidth.order(ByteOrder.LITTLE_ENDIAN);

bWidth.putShort(width);

// get height short as LITTLE_ENDIAN bytes

ByteBuffer bHeight = ByteBuffer.allocate(2);

bHeight.order(ByteOrder.LITTLE_ENDIAN);

bHeight.putShort(height);

// put the record headers into the data

Byte[] dataPart = new Byte[] { 0x09, 0x00, 0x01, 0x00,

bSize.array()[0], bSize.array()[1], bSize.array()[2], bSize.array()[3], // size

//now 12 bytes follow

0x0C, 0x00, 0x00, 0x00,

bWidth.array()[0], bWidth.array()[1], // width

bHeight.array()[0], bHeight.array()[1], // height

0x01, 0x00, 0x18, 0x00

};

data.addAll(0, Arrays.asList(dataPart));

return data;

}

public static void main(String[] args) throws Exception {

HSSFWorkbook workbook = new HSSFWorkbook();

HSSFSheet sheet = workbook.createSheet("Sheet1");

sheet = workbook.createSheet("Sheet2"); // this sheet gets the background image set

// we need the binary records of the sheet

// get InternalSheet

Field _sheet = HSSFSheet.class.getDeclaredField("_sheet");

_sheet.setAccessible(true);

InternalSheet internalsheet = (InternalSheet)_sheet.get(sheet);

// get List of RecordBase

Field _records = InternalSheet.class.getDeclaredField("_records");

_records.setAccessible(true);

@SuppressWarnings("unchecked")

List records = (List)_records.get(internalsheet);

// get bytes of the image file

List data = getBackgroundBitmapData("dummyText.png"); //PNG must not have transparency

// do creating BitmapRecord and ContinueRecords from the data in parts of 8220 bytes

BitmapRecord bitmapRecord = null;

List continueRecords = new ArrayList();

int bytes = 0;

if (data.size() > 8220) {

bitmapRecord = new BitmapRecord(data.subList(0, 8220));

bytes = 8220;

while (bytes < data.size()) {

if ((bytes + 8220) < data.size()) {

continueRecords.add(new ContinueRecord(data.subList(bytes, bytes + 8220)));

bytes += 8220;

} else {

continueRecords.add(new ContinueRecord(data.subList(bytes, data.size())));

break;

}

}

} else {

bitmapRecord = new BitmapRecord(data);

}

// add the records after PageSettingsBlock

int i = 0;

for (RecordBase r : records) {

if (r instanceof org.apache.poi.hssf.record.aggregates.PageSettingsBlock) {

break;

}

i++;

}

records.add(++i, bitmapRecord);

for (ContinueRecord continueRecord : continueRecords) {

records.add(++i, continueRecord);

}

// debug output

for (RecordBase r : internalsheet.getRecords()) {

System.out.println(r);

}

// write out workbook

workbook.write(new FileOutputStream("CreateExcelHSSFSheetBackgroundBitmap.xls"));

workbook.close();

}

static class BitmapRecord extends StandardRecord {

//see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP

List data = new ArrayList();

BitmapRecord(List data) {

this.data = data;

}

public int getDataSize() {

return data.size();

}

public short getSid() {

return (short)0x00E9;

}

public void serialize(LittleEndianOutput out) {

for (Byte b : data) {

out.writeByte(b);

}

}

}

static class ContinueRecord extends StandardRecord {

//see https://www.openoffice.org/sc/excelfileformat.pdf - CONTINUE

List data = new ArrayList();

ContinueRecord(List data) {

this.data = data;

}

public int getDataSize() {

return data.size();

}

public short getSid() {

return (short)0x003C;

}

public void serialize(LittleEndianOutput out) {

for (Byte b : data) {

out.writeByte(b);

}

}

}

}

代码可以工作但是之间的部分

// --- this part takes much time but I have not found any better possibility

和

// ---

需要花费很多时间,因为根据上述奇怪的格式,需要获得每个单个像素的3个字节R G B.

有谁知道更好的方法？也许以上奇怪的格式并不像我想的那样奇怪,而且已经有其他用法了吗？