| public Write ( byte buffer, int offset, int count ) : void | ||
| buffer | byte | /// The byte array /// |
| offset | int | /// The offset into the byte array where to start. /// |
| count | int | /// The number of bytes to write. /// |
| return | void | |
/**
* Write the image data into the pngBytes array.
* This will write one or more PNG "IDAT" chunks. In order
* to conserve memory, this method grabs as many rows as will
* fit into 32K bytes, or the whole image; whichever is less.
*
*
* @return true if no errors; false if error grabbing pixels
*/
protected bool WriteImageData()
{
int rowsLeft = height; // number of rows remaining to write
int startRow = 0; // starting row to process this time through
int nRows; // how many rows to grab at a time
byte[] scanLines; // the scan lines to be compressed
int scanPos; // where we are in the scan lines
int startPos; // where this line's actual pixels start (used for filtering)
byte[] compressedLines; // the resultant compressed lines
int nCompressed; // how big is the compressed area?
//int depth; // color depth ( handle only 8 or 32 )
bytesPerPixel = (encodeAlpha) ? 4 : 3;
Deflater scrunch = new Deflater(compressionLevel);
MemoryStream outBytes = new MemoryStream(1024);
DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
try {
while (rowsLeft > 0) {
nRows = Math.Min(32767 / (width * (bytesPerPixel + 1)), rowsLeft);
nRows = Math.Max(nRows, 1);
int[] pixels = new int[width * nRows];
Array.Copy(this.pixelData, width * startRow, pixels, 0, width * nRows);
/*
* Create a data chunk. scanLines adds "nRows" for
* the filter bytes.
*/
scanLines = new byte[width * nRows * bytesPerPixel + nRows];
if (filter == FILTER_SUB) {
leftBytes = new byte[16];
}
if (filter == FILTER_UP) {
priorRow = new byte[width * bytesPerPixel];
}
scanPos = 0;
startPos = 1;
for (int i = 0; i < width * nRows; i++) {
if (i % width == 0) {
scanLines[scanPos++] = (byte) filter;
startPos = scanPos;
}
scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff);
scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff);
if (encodeAlpha) {
scanLines[scanPos++] = (byte) ((pixels[i] >> 24) & 0xff);
}
if ((i % width == width - 1) && (filter != FILTER_NONE)) {
if (filter == FILTER_SUB) {
FilterSub(scanLines, startPos, width);
}
if (filter == FILTER_UP) {
FilterUp(scanLines, startPos, width);
}
}
}
/*
* Write these lines to the output area
*/
compBytes.Write(scanLines, 0, scanPos);
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.Close();
/*
* Write the compressed bytes
*/
compressedLines = outBytes.ToArray();
nCompressed = compressedLines.Length;
crc.Reset();
bytePos = WriteInt4(nCompressed, bytePos);
bytePos = WriteBytes(IDAT, bytePos);
crc.Update(IDAT);
bytePos = WriteBytes(compressedLines, nCompressed, bytePos);
crc.Update(compressedLines, 0, nCompressed);
crcValue = crc.Value;
bytePos = WriteInt4((int) crcValue, bytePos);
scrunch.Finish();
return true;
} catch {
return false;
}
}
/**
* Write the image data into the pngBytes array.
* This will write one or more PNG "IDAT" chunks. In order
* to conserve memory, this method grabs as many rows as will
* fit into 32K bytes, or the whole image; whichever is less.
*
*
* @return true if no errors; false if error grabbing pixels
*/
protected bool WriteImageData()
{
int rowsLeft = height; // number of rows remaining to write
int startRow = 0; // starting row to process this time through
int nRows; // how many rows to grab at a time
byte[] scanLines; // the scan lines to be compressed
int scanPos; // where we are in the scan lines
int startPos; // where this line's actual pixels start (used for filtering)
byte[] compressedLines; // the resultant compressed lines
int nCompressed; // how big is the compressed area?
//int depth; // color depth ( handle only 8 or 32 )
bytesPerPixel = (encodeAlpha) ? 4 : 3;
Deflater scrunch = new Deflater(compressionLevel);
MemoryStream outBytes = new MemoryStream(1024);
DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes, scrunch);
try {
while (rowsLeft > 0)
{
nRows = Math.Min(32767 / (width * (bytesPerPixel + 1)), rowsLeft);
nRows = Math.Max(nRows, 1);
int[] pixels = new int[width * nRows];
Array.Copy(this.pixelData, width * startRow, pixels, 0, width * nRows);
/*
* Create a data chunk. scanLines adds "nRows" for
* the filter bytes.
*/
scanLines = new byte[width * nRows * bytesPerPixel + nRows];
if (filter == FILTER_SUB)
{
leftBytes = new byte[16];
}
if (filter == FILTER_UP)
{
priorRow = new byte[width * bytesPerPixel];
}
scanPos = 0;
startPos = 1;
for (int i = 0; i < width * nRows; i++)
{
if (i % width == 0)
{
scanLines[scanPos++] = (byte)filter;
startPos = scanPos;
}
scanLines[scanPos++] = (byte)((pixels[i] >> 16) & 0xff);
scanLines[scanPos++] = (byte)((pixels[i] >> 8) & 0xff);
scanLines[scanPos++] = (byte)((pixels[i]) & 0xff);
if (encodeAlpha)
{
scanLines[scanPos++] = (byte)((pixels[i] >> 24) & 0xff);
}
if ((i % width == width - 1) && (filter != FILTER_NONE))
{
if (filter == FILTER_SUB)
{
FilterSub(scanLines, startPos, width);
}
if (filter == FILTER_UP)
{
FilterUp(scanLines, startPos, width);
}
}
}
/*
* Write these lines to the output area
*/
compBytes.Write(scanLines, 0, scanPos);
startRow += nRows;
rowsLeft -= nRows;
}
compBytes.Close();
/*
* Write the compressed bytes
*/
compressedLines = outBytes.ToArray();
nCompressed = compressedLines.Length;
crc.Reset();
bytePos = WriteInt4(nCompressed, bytePos);
bytePos = WriteBytes(IDAT, bytePos);
crc.Update(IDAT);
bytePos = WriteBytes(compressedLines, nCompressed, bytePos);
crc.Update(compressedLines, 0, nCompressed);
crcValue = crc.Value;
bytePos = WriteInt4((int)crcValue, bytePos);
scrunch.Finish();
return(true);
} catch {
return(false);
}
}