Axel Richter:
Então, eu estou criando um HSSFSheettendo um conjunto de fundo bitmap usando apache poieo código próprio baixo nível. O https://www.openoffice.org/sc/excelfileformat.pdf declara para a Record BITMAP, BIFF8:
dados de pixel (gama de linhas de altura do mapa de bits, a partir de linha de fundo a linha superior, ver abaixo)
...
Em cada linha de todos os pixels são escritos da esquerda para a direita. Cada pixel é armazenada como uma matriz de 3 bytes: o componente vermelho, verde e azul da cor do pixel, por esta ordem. O tamanho de cada linha está alinhada com múltiplos de 4 através da inserção de zero bytes, após o último pixel.
Veja a imagem do PDF para a declaração completa: 
Para cumprir essa a minha abordagem está usando java.awt.image.BufferedImageter tipo BufferedImage.TYPE_3BYTE_BGR. Em seguida, ficando todos os bytes de RGB que raster de BufferedImage na ordem correcta (linha de fundo a partir de linha de topo) e encheu-se até múltiplo de 4 em largura (direcção X).
Ver código:
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<Byte> getBackgroundBitmapData(String filePath) throws Exception {
//see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP
List<Byte> data = new ArrayList<Byte>();
// 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<RecordBase> records = (List<RecordBase>)_records.get(internalsheet);
// get bytes of the image file
List<Byte> 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<ContinueRecord> continueRecords = new ArrayList<ContinueRecord>();
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<Byte> data = new ArrayList<Byte>();
BitmapRecord(List<Byte> 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<Byte> data = new ArrayList<Byte>();
ContinueRecord(List<Byte> 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);
}
}
}
}
O código funciona, mas a parte entre
// --- this part takes much time but I have not found any better possibility
e
// ---
leva muito tempo desde 3 bytes RGB para cada pixel precisa ser obtido para começá-los de acordo com o formato estranho acima.
Alguém sabe de uma melhor abordagem? Talvez o formato estranho acima não é tão estranho quanto eu acho que é e já existem outros usos do mesmo?
haraldK:
Aqui está uma versão modificada do seu código que funciona para mim, e é bastante rápido.
- Eu estou usando
byte[](eByteArrayOutputStream) em todo, não maisList<Byte>. - As we already have a
BufferedImageofTYPE_3BYTE_BGR, we can use that almost directly as the BMP output. We just need to a) prepend a valid BMP header and b) write bottom-up, c) pad each scanline (row) to a 32 bit boundary and d) switch BGR -> RGB order. - I'm using the
Rasterto copy (padded) rows of data into the output, as copying larger chunks is faster than copying single bytes.
As already noted in the comments, the structure is a standard BMP with BITMAPCOREHEADER (and no file header). Unfortunately, the ImageIO BMPImageWriter always write the file header and uses the BITMAPINFOHEADER which is 40 bytes. You could probably get around these things, and use the standard writer, by massaging the data a little (hint: the file header contains an offset to the pixel data at offset 10), but as the core BMP format is trivial to implement, it might be just as easy to do as below.
While the documentation certainly implies that using other formats like PNG and JPEG directly, I haven't managed to do this properly.
There's probably still room for improvement if you like, to avoid some byte array copying (ie. use offset/length and pass the entire data array to the Bitmap/ContinueRecords instead of Arrays.copyOfRange()).
Code:
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.imageio.ImageIO;
import org.apache.poi.hssf.model.InternalSheet;
import org.apache.poi.hssf.record.RecordBase;
import org.apache.poi.hssf.record.StandardRecord;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.util.LittleEndianOutput;
public class CreateExcelHSSFSheetBackgroundBitmap {
static byte[] getBackgroundBitmapData(String filePath) throws Exception {
//see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP
// 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();
// calculate row size (c)
int rowSize = ((24 * image.getWidth() + 31) / 32) * 4;
ByteArrayOutputStream output = new ByteArrayOutputStream(image.getHeight() * rowSize * 3 + 1024);
// put the record headers into the data
ByteBuffer header = ByteBuffer.allocate(8 + 12);
header.order(ByteOrder.LITTLE_ENDIAN);
// Undocumented XLS stuff
header.putShort((short) 0x09);
header.putShort((short) 0x01);
header.putInt(image.getHeight() * rowSize + 12); // Size of image stream
// BITMAPCOREHEADER (a)
header.putInt(12);
header.putShort((short) image.getWidth());
header.putShort((short) image.getHeight()); // Use -height if writing top-down
header.putShort((short) 1); // planes, always 1
header.putShort((short) 24); // bitcount
output.write(header.array());
// Output rows bottom-up (b)
Raster raster = image.getRaster()
.createChild(0, 0, image.getWidth(), image.getHeight(), 0, 0, new int[]{2, 1, 0}); // Reverse BGR -> RGB (d)
byte[] row = new byte[rowSize]; // padded (c)
for (int i = image.getHeight() - 1; i >= 0; i--) {
row = (byte[]) raster.getDataElements(0, i, image.getWidth(), 1, row);
output.write(row);
}
return output.toByteArray();
}
public static void main(String[] args) throws Exception {
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet 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<RecordBase> records = (List<RecordBase>)_records.get(internalsheet);
// get bytes of the image file
byte[] data = getBackgroundBitmapData("dummy.png"); //PNG must not have transparency
// do creating BitmapRecord and ContinueRecords from the data in parts of 8220 bytes
BitmapRecord bitmapRecord;
List<ContinueRecord> continueRecords = new ArrayList<>();
int bytes;
if (data.length > 8220) {
bitmapRecord = new BitmapRecord(Arrays.copyOfRange(data, 0, 8220));
bytes = 8220;
while (bytes < data.length) {
if ((bytes + 8220) < data.length) {
continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, bytes + 8220)));
bytes += 8220;
} else {
continueRecords.add(new ContinueRecord(Arrays.copyOfRange(data, bytes, data.length)));
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("backgroundImage.xls"));
workbook.close();
}
static class BitmapRecord extends StandardRecord {
//see https://www.openoffice.org/sc/excelfileformat.pdf - BITMAP
byte[] data;
BitmapRecord(byte[] data) {
this.data = data;
}
public int getDataSize() {
return data.length;
}
public short getSid() {
return (short)0x00E9;
}
public void serialize(LittleEndianOutput out) {
out.write(data);
}
}
static class ContinueRecord extends StandardRecord {
//see https://www.openoffice.org/sc/excelfileformat.pdf - CONTINUE
byte[] data;
ContinueRecord(byte[] data) {
this.data = data;
}
public int getDataSize() {
return data.length;
}
public short getSid() {
return (short)0x003C;
}
public void serialize(LittleEndianOutput out) {
out.write(data);
}
}
}