问题
We have an old Print driver which takes a document and sends PCL to the spooler. The client then processes this PCL and displays everything as TIFF. Our users have been complaining that the TIFF is fuzzy and the image is not sharp. I am given this stupid task of solving the mystery
Is the PCL itself bad. I don't have enough knowledge about a PCL and if it has resolution. How do I trap the output of a driver that's being sent to the spooler? Or is it the client that is somehow not rendering the PCL with a good resolution. Do I need to go through the pain of learning how to debug this driver. I will but is it going to help me fix a resolution issue. I have never done driver development so its going to be a curve for me. But if I need to do then thats ok. Where should I start? Is the PCL thats bad or the client that converts PCL to bitmap bad?
This is the C++ code
BOOL APIENTRY
CreatePCLRasterGraphicPage(
SURFOBJ *pso,
BOOL firstPage,
char *pageText
)
/*++
Routine Description:
Creates standard PCL end-of-document lines.
Arguments:
SURFOBJ - Surface Object
BOOL - First Page ?
char * Page Text
Return Value:
BOOL - True if successful
--*/
{
PDEVOBJ pDevObj = (PDEVOBJ)pso->dhpdev;
POEMPDEV pOemPDEV = (POEMPDEV)pDevObj->pdevOEM;
DWORD dwOffset = 0;
DWORD dwWritten = 0;
DWORD dwPageBufferSize = 0;
int i = 0;
ULONG n = 0;
BYTE bitmapRow[1050];
BYTE compRow[2100];
DWORD dwRowSize = 0;
DWORD dwCompPCLBitmapSize = 0;
//wchar_t traceBuff[256];
pOemPDEV->dwCompBitmapBufSize = 0;
// TRACE OUT ----------------------------------------------------
//ZeroMemory(traceBuff, 256);
//StringCchPrintf(traceBuff, 256, L"Top of CreatePCLRasterGraphicPage");
//WriteTraceLine(traceBuff);
// -----------------------------------------------------------------
// Invert color
for (n = 0; n < pso->cjBits; n++)
*(((PBYTE &)pso->pvBits) + n) ^= 0xFF;
// compress each row and store in a buffer with PCL line headings
for (i = 0; i < pso->sizlBitmap.cy; i++) {
// Zero Memory hack for bottom of form black line
if (*(((PBYTE &)pso->pvScan0) + (i * pso->lDelta) + 319) == 0xFF)
ZeroMemory(((PBYTE &)pso->pvScan0) + (i * pso->lDelta), 320);
// Copy the bitmap scan line into bitmapRow and send them off to be compressed
ZeroMemory(bitmapRow, 1050);
ZeroMemory(compRow, 2100);
MoveMemory(bitmapRow, ((PBYTE &)pso->pvScan0) + (i * pso->lDelta), pso->lDelta);
dwRowSize = CompressBitmapRow(compRow, bitmapRow, pso->lDelta);
// Create PCL Row Heading
char bufPCLLineHead[9];
StringCchPrintfA(bufPCLLineHead, 9, "%c%s%d%s", 27, "*b", dwRowSize, "W");
if ((dwCompPCLBitmapSize + dwRowSize + strlen(bufPCLLineHead))
> pOemPDEV->dwCompBitmapBufSize) {
if (!GrowCompBitmapBuf(pOemPDEV)) {
//ZeroMemory(traceBuff, 256);
//StringCchPrintf(traceBuff, 256,
// L"Compressed bitmap buffer could not allocate more memory.");
//WriteTraceLine(traceBuff);
}
}
if (pOemPDEV->pCompBitmapBufStart) {
// write the PCL line heading to the buffer
MoveMemory(pOemPDEV->pCompBitmapBufStart + dwCompPCLBitmapSize,
bufPCLLineHead, strlen(bufPCLLineHead));
dwCompPCLBitmapSize += strlen(bufPCLLineHead);
// write the compressed row to the buffer
MoveMemory(pOemPDEV->pCompBitmapBufStart + dwCompPCLBitmapSize,
compRow, dwRowSize);
dwCompPCLBitmapSize += dwRowSize;
}
}
// Calculate size and create buffer
dwPageBufferSize = 21;
if (!firstPage)
dwPageBufferSize++;
bGrowBuffer(pOemPDEV, dwPageBufferSize);
// Add all Raster Header Lines
if (!firstPage)
{
// Add a Form Feed
char bufFormFeed[2];
StringCchPrintfA(bufFormFeed, 2, "%c", 12); // 1 char
MoveMemory(pOemPDEV->pBufStart + dwOffset, bufFormFeed, 2);
dwOffset += 1;
}
// Position cursor at X0, Y0
char bufXY[8];
StringCchPrintfA(bufXY, 8, "%c%s", 27, "*p0x0Y"); // 7 chars
MoveMemory(pOemPDEV->pBufStart + dwOffset, bufXY, 8);
dwOffset += 7;
// Start Raster Graphics
char bufStartRas[6];
StringCchPrintfA(bufStartRas, 6, "%c%s", 27, "*r1A"); // 5 chars
MoveMemory(pOemPDEV->pBufStart + dwOffset, bufStartRas, 6);
dwOffset += 5;
// Raster Encoding - Run-Length Encoding
char bufRasEncoding[6];
StringCchPrintfA(bufRasEncoding, 6, "%c%s", 27, "*b1M"); // 5 chars
MoveMemory(pOemPDEV->pBufStart + dwOffset, bufRasEncoding, 6);
dwOffset += 5;
// Write out bitmap header PCL
dwWritten = pDevObj->pDrvProcs->DrvWriteSpoolBuf(pDevObj, pOemPDEV->pBufStart, dwPageBufferSize);
// Write out PCL plus compressed bitmap bytes
dwWritten = pDevObj->pDrvProcs->DrvWriteSpoolBuf(pDevObj, pOemPDEV->pCompBitmapBufStart, dwCompPCLBitmapSize);
// End Raster Graphics
char bufEndRas[5];
StringCchPrintfA(bufEndRas, 5, "%c%s", 27, "*rB"); // 4 chars
MoveMemory(pOemPDEV->pBufStart + dwOffset, bufEndRas, 5);
// Write out PCL end bitmap
dwWritten = pDevObj->pDrvProcs->DrvWriteSpoolBuf(pDevObj, bufEndRas, 4);
// Free Compressed Bitmap Memory
if (pOemPDEV->pCompBitmapBufStart) {
MemFree(pOemPDEV->pCompBitmapBufStart);
pOemPDEV->pCompBitmapBufStart = NULL;
pOemPDEV->dwCompBitmapBufSize = 0;
dwPageBufferSize = 0;
}
// Free Memory
vFreeBuffer(pOemPDEV);
// Write Page Text to the spooler
size_t charCount = 0;
StringCchLengthA(pageText, 32767, &charCount);
char bufWriteText[15];
ZeroMemory(bufWriteText, 15);
StringCchPrintfA(bufWriteText, 15, "%c%s%d%s", 27, "(r", charCount, "W");
dwWritten = pDevObj->pDrvProcs->DrvWriteSpoolBuf(pDevObj, bufWriteText, strlen(bufWriteText));
dwWritten = pDevObj->pDrvProcs->DrvWriteSpoolBuf(pDevObj, pageText, charCount);
return TRUE;
}
BOOL
GrowCompBitmapBuf(
POEMPDEV pOemPDEV
)
/*++
Routine Description:
Grows memory by 1000 bytes (per call) to hold compressed
bitmap and PCL data.
Arguments:
POEMPDEV - Pointer to the private PDEV structure
Return Value:
BOOL - True is successful
--*/
{
DWORD dwOldBufferSize = 0;
PBYTE pNewBuffer = NULL;
dwOldBufferSize = pOemPDEV->pCompBitmapBufStart ? pOemPDEV->dwCompBitmapBufSize : 0;
pOemPDEV->dwCompBitmapBufSize = dwOldBufferSize + 4096;
pNewBuffer = (PBYTE)MemAlloc(pOemPDEV->dwCompBitmapBufSize);
if (pNewBuffer == NULL) {
MemFree(pOemPDEV->pCompBitmapBufStart);
pOemPDEV->pCompBitmapBufStart = NULL;
pOemPDEV->dwCompBitmapBufSize = 0;
return FALSE;
}
if (pOemPDEV->pCompBitmapBufStart) {
CopyMemory(pNewBuffer, pOemPDEV->pCompBitmapBufStart, dwOldBufferSize);
MemFree(pOemPDEV->pCompBitmapBufStart);
pOemPDEV->pCompBitmapBufStart = pNewBuffer;
}
else {
pOemPDEV->pCompBitmapBufStart = pNewBuffer;
}
return TRUE;
}
RLE encoding (I have not had a chance to add this yet). I was looking at different forums as how the code should like and this is what I came up with. I will add, test the document and update the post
public virtual sbyte[] decompressRL(sbyte[] data, int startOffset, int width, int count)
{
/*type 1 compression*/
int dataCount = count;
List<sbyte> decompressed = new List<sbyte>();
int numberOfDecompressedBytes = 0;
int dataStartOffset = startOffset;
while (dataCount-- > 0)
{
int cntrlByte = (int) data[dataStartOffset++];
// Repeated pattern
int val = data[dataStartOffset++];
dataCount--;
while (cntrlByte >= 0)
{
decompressed.Insert(numberOfDecompressedBytes++, new sbyte?((sbyte) val));
cntrlByte--;
}
}
mMaxUncompressedByteCount = numberOfDecompressedBytes;
return getBytes(decompressed);
}
This is how fuzzy the users claim that the image looks. This is when printed from a word document to the driver. The original is very clear.
来源：https://stackoverflow.com/questions/61125988/legacy-print-driver-is-fuzzy