Printer Device - Revision history

Costel Mincea: Text replacement - "" to ""

2025-01-26T19:19:47Z

Text replacement - "<syntaxhighlight>" to "<syntaxhighlight lang="C" line>"

← Older revision		Revision as of 19:19, 26 January 2025
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	When using the printer device as PRT:, you can open it just as though it were a normal AmigaDOS output file.		When using the printer device as PRT:, you can open it just as though it were a normal AmigaDOS output file.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	BPTR file;		BPTR file;

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	Once you’ve opened it, you can print by calling the AmigaDOS Write() standard I/O routine.		Once you’ve opened it, you can print by calling the AmigaDOS Write() standard I/O routine.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	actual_length = IDOS->Write(file, dataLocation, length);		actual_length = IDOS->Write(file, dataLocation, length);
	</syntaxhighlight>		</syntaxhighlight>
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	When the printer I/O is complete, you should close PRT:. Don’t keep the device open when you are not using it. The user may have changed the printer settings by using the Workbench Preferences tool. There’s also the possibility the printer has been turned off and on again causing the printer to switch to its own default settings. Every time the printer device is opened, it reads the current Preferences settings. Hence, by always opening the printer device just before printing and always closing it afterwards, you ensure that your application is using the current Preferences settings.		When the printer I/O is complete, you should close PRT:. Don’t keep the device open when you are not using it. The user may have changed the printer settings by using the Workbench Preferences tool. There’s also the possibility the printer has been turned off and on again causing the printer to switch to its own default settings. Every time the printer device is opened, it reads the current Preferences settings. Hence, by always opening the printer device just before printing and always closing it afterwards, you ensure that your application is using the current Preferences settings.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	IDOS->Close(file);		IDOS->Close(file);
	</syntaxhighlight>		</syntaxhighlight>
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	For convenience, it is strongly recommended that ''you define'' a single data structure called printerIO, that can be used to represent any of the three pre-defined printer communications request blocks.		For convenience, it is strongly recommended that ''you define'' a single data structure called printerIO, that can be used to represent any of the three pre-defined printer communications request blocks.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	union printerIO		union printerIO
	{		{
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	* Open the printer device. Call OpenDevice(), passing the I/O request.		* Open the printer device. Call OpenDevice(), passing the I/O request.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	union printerIO		union printerIO
	{		{
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	To write a NULL-terminated string, set the length to -1; the device will output from your buffer until it encounters a value of zero (0x00).		To write a NULL-terminated string, set the length to -1; the device will output from your buffer until it encounters a value of zero (0x00).

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	PrintIO->ios.io_Length = -1;		PrintIO->ios.io_Length = -1;
	PrintIO->ios.io_Data = (APTR)"I went to a fight and a hockey game broke out.";		PrintIO->ios.io_Data = (APTR)"I went to a fight and a hockey game broke out.";
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	You write unprocessed text to the printer device by passing an IOStdReq to the device with PRD_RAWWRITE set in io_Command, the number of bytes to be written set in io_Length and the address of the write buffer set in io_Data.		You write unprocessed text to the printer device by passing an IOStdReq to the device with PRD_RAWWRITE set in io_Command, the number of bytes to be written set in io_Length and the address of the write buffer set in io_Data.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	uint8 *outbuffer;		uint8 *outbuffer;

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	All I/O requests must be complete before CloseDevice(). If any requests are still pending, abort them with AbortIO().		All I/O requests must be complete before CloseDevice(). If any requests are still pending, abort them with AbortIO().

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	AbortIO(PrintIO); /* Ask device to abort request, if pending */		AbortIO(PrintIO); /* Ask device to abort request, if pending */
	WaitIO(PrintIO); /* Wait for abort, then clean up */		WaitIO(PrintIO); /* Wait for abort, then clean up */
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	You send printer commands to the device by passing an IOPrtCmdReq to the device with PRD_PRTCOMMAND set in io_Command, the printer command set in io_PrtCommand and up to four parameters set in Parm0 through Parm3.		You send printer commands to the device by passing an IOPrtCmdReq to the device with PRD_PRTCOMMAND set in io_Command, the printer command set in io_PrtCommand and up to four parameters set in Parm0 through Parm3.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	#include <devices/printer.h>		#include <devices/printer.h>

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	You query the printer device by passing an IOStdReq to the device with PRD_QUERY set in io_Command and a pointer to a structure to hold the status set in io_Data.		You query the printer device by passing an IOStdReq to the device with PRD_QUERY set in io_Command and a pointer to a structure to hold the status set in io_Data.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	struct PStat		struct PStat
	{		{
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	The printer device returns error codes whenever an operation is attempted. There are two types of error codes that can be returned. Printer device error codes have positive values; Exec I/O error codes have negative values. Therefore, an application should check for a ''non-zero'' return code as evidence of an error, not simply a value greater than zero.		The printer device returns error codes whenever an operation is attempted. There are two types of error codes that can be returned. Printer device error codes have positive values; Exec I/O error codes have negative values. Therefore, an application should check for a ''non-zero'' return code as evidence of an error, not simply a value greater than zero.

	<syntaxhighlight>		<syntaxhighlight lang="C" line>
	PrintIO->ios.io_Length = strlen(outbuffer);		PrintIO->ios.io_Length = strlen(outbuffer);
	PrintIO->ios.io_Data = (APTR)outbuffer;		PrintIO->ios.io_Data = (APTR)outbuffer;

Steven Solie: /* Testing the Printer Driver */

2013-03-28T20:30:39Z

Testing the Printer Driver

← Older revision		Revision as of 20:30, 28 March 2013
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	* Make sure that the printer doesn’t force graphic dumps to be done within the text margins. This can easily be tested by setting the text margins to 30 and 50, the pitch to 10 cpi and then doing a graphic dump wider than 2 inches. The dump should be left justified and as wide as you instructed. If the dump starts at character position 30 and is cut off at position 50, the driver will have to be changed. These changes involve clearing the margins before the dump (Case 0) and restoring the margins after the dump (Case 4). An example of this is present in render.c source example listed at the end of this chapter.		* Make sure that the printer doesn’t force graphic dumps to be done within the text margins. This can easily be tested by setting the text margins to 30 and 50, the pitch to 10 cpi and then doing a graphic dump wider than 2 inches. The dump should be left justified and as wide as you instructed. If the dump starts at character position 30 and is cut off at position 50, the driver will have to be changed. These changes involve clearing the margins before the dump (Case 0) and restoring the margins after the dump (Case 4). An example of this is present in render.c source example listed at the end of this chapter.

		⚫	{{Note\|title=The Invisible Setup\|text=Before the graphic dump, some text must be sent to the printer to have the printer device initialize the printer. The “text” sent does not have to contain any printable characters (i.e., you can send a carriage return or other control characters).}}
	{\| class="wikitable"
⚫	\| ''The Invisible Setup~~.''~~ Before the graphic dump, some text must be sent to the printer to have the printer device initialize the printer. The “text” sent does not have to contain any printable characters (i.e., you can send a carriage return or other control characters).
	\|}

	* As a final test, construct an image with a white background that has objects in it surrounded by white space. Dump this as black and white, grey scale and color. This will test the white-space stripping or RLE, and the ability of the driver to handle null lines. The white data areas should be separated by at least as many lines of white space as the NumRows value in the printertag.asm file.		* As a final test, construct an image with a white background that has objects in it surrounded by white space. Dump this as black and white, grey scale and color. This will test the white-space stripping or RLE, and the ability of the driver to handle null lines. The white data areas should be separated by at least as many lines of white space as the NumRows value in the printertag.asm file.

Steven Solie: /* Render() */

2013-03-28T20:29:43Z

Render()

← Older revision		Revision as of 20:29, 28 March 2013
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	: height (in pixels) of printed picture		: height (in pixels) of printed picture

		⚫	{{Note\|title=Everything is A-OK\|text=At this point the printer device has already checked that the values are within range for the printer. This is done by checking values listed in printertag.asm.}}
	{\| class="wikitable"
⚫	\| ''Everything is A-OK~~.''~~ At this point the printer device has already checked that the values are within range for the printer. This is done by checking values listed in printertag.asm.
	\|}

	The x and y value should be used to allocate enough memory for a command and data buffer for the printer. If the allocation fails, PDERR_BUFFERMEMORY should be returned. In general, the buffer needs to be large enough for the commands and data required for one pass of the print head. These typically take the following form:		The x and y value should be used to allocate enough memory for a command and data buffer for the printer. If the allocation fails, PDERR_BUFFERMEMORY should be returned. In general, the buffer needs to be large enough for the commands and data required for one pass of the print head. These typically take the following form:
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	: Enter the graphics mode, set density, etc.		: Enter the graphics mode, set density, etc.

		⚫	{{Note\|title=Multi-Pass? Don’t Forget the Memory\|text=In addition to the memory for commands and data, a multi-pass color printer must allocate enough buffer space for each of the different color passes.}}
	{\| class="wikitable"
⚫	\| ''Multi-Pass? Don’t Forget the Memory~~.''~~ In addition to the memory for commands and data, a multi-pass color printer must allocate enough buffer space for each of the different color passes.
	\|}

	The printer should never be reset during the master initialization case This will cause problems during multiple dumps. Also, the pointer to the IODRPReq structure in ct should not be used except for those rare printers which require it to do the dump themselves. Return the PDERR_TOOKCONTROL error in that case so that the printer device can exit gracefully.		The printer should never be reset during the master initialization case This will cause problems during multiple dumps. Also, the pointer to the IODRPReq structure in ct should not be used except for those rare printers which require it to do the dump themselves. Return the PDERR_TOOKCONTROL error in that case so that the printer device can exit gracefully.

		⚫	{{Note\|title=PDERR_TOOKCONTROL, An Error in Name Only\|text=The printer device error code, PDERR_TOOKCONTROL, is not an error at all, but an internal indicator that the printer driver is doing the graphic dump entirely on its own. The printer device can assume the dump has been done. The calling application will not be informed of this, but will receive PDERR_NOERR instead.}}
	{\| class="wikitable"
⚫	\| ''PDERR_TOOKCONTROL, An Error in Name Only~~.''~~ The printer device error code, PDERR_TOOKCONTROL, is not an error at all, but an internal indicator that the printer driver is doing the graphic dump entirely on its own. The printer device can assume the dump has been done. The calling application will not be informed of this, but will receive PDERR_NOERR instead.
	\|}

	The example render.c functions listed at the end of this chapter use double buffering to reduce the dump time which is why the AllocMem() calls are for , where BUFSIZE represents the amount of memory for one entire print cycle. However, contrary to the example source code, allocating the two buffers independently of each other is recommended. A request for one large block of contiguous memory might be refused. Two smaller requests are more likely to be granted.		The example render.c functions listed at the end of this chapter use double buffering to reduce the dump time which is why the AllocMem() calls are for , where BUFSIZE represents the amount of memory for one entire print cycle. However, contrary to the example source code, allocating the two buffers independently of each other is recommended. A request for one large block of contiguous memory might be refused. Two smaller requests are more likely to be granted.

Steven Solie: /* Render() */

2013-03-28T20:27:25Z

Render()

← Older revision		Revision as of 20:27, 28 March 2013
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	* Switching to the next color(Case 6) (special case for multi-color printers)		* Switching to the next color(Case 6) (special case for multi-color printers)

		⚫	{{Note\|title=State Your Case\|text=The numbering of the cases reflects the value of each step as a case in a C-language switch statement. It does not denote the order that the functions are executed; the order in which they are listed above denotes that.}}
	{\| class="wikitable"
⚫	\| ''State Your Case~~.''~~ The numbering of the cases reflects the value of each step as a case in a C-language switch statement. It does not denote the order that the functions are executed; the order in which they are listed above denotes that.
	\|}

	For each case, Render() receives four long variables as parameters: ct, x, y and status. These parameters are described below for each of the seven cases that Render() must handle.		For each case, Render() receives four long variables as parameters: ct, x, y and status. These parameters are described below for each of the seven cases that Render() must handle.

Steven Solie: /* DoSpecial() */

2013-03-28T20:13:27Z

DoSpecial()

← Older revision		Revision as of 20:13, 28 March 2013
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	Certain functions are implemented both in the CommandTable and in the DoSpecial() routine. These are functions such as superscript, subscript, PLU (partial line up), and PLD (partial line down), which can often be handled by a simple conversion. However, some of these functions must also adjust the printer device’s line-position variable.		Certain functions are implemented both in the CommandTable and in the DoSpecial() routine. These are functions such as superscript, subscript, PLU (partial line up), and PLD (partial line down), which can often be handled by a simple conversion. However, some of these functions must also adjust the printer device’s line-position variable.

		⚫	{{Note\|title=Save the Data\|text=Some printers lose data when sent their own reset command. For this reason, it is recommended that if the printer’s own reset command is going to be used, PD->pd_PWaitEnabled should be defined to be a character that the printer will not print. This character should be put in the reset string before and after the reset character(s) in the command table.}}
	{\| class="wikitable"
	\|-
⚫	\| ''Save the Data'' Some printers lose data when sent their own reset command. For this reason, it is recommended that if the printer’s own reset command is going to be used, PD->pd_PWaitEnabled should be defined to be a character that the printer will not print. This character should be put in the reset string before and after the reset character(s) in the command table.
	\|}

	In the EpsonX[CBM_MPS-1250] DoSpecial() function you’ll see		In the EpsonX[CBM_MPS-1250] DoSpecial() function you’ll see

Steven Solie: /* Command Table */

2013-03-28T20:12:35Z

Command Table

← Older revision		Revision as of 20:12, 28 March 2013
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	The CommandTable is used to convert all escape codes that can be handled by simple substitution. It has one entry per ANSI command supported by the printer driver. When you are creating a custom CommandTable, you must maintain the order of the commands in the same sequence as that shown in devices/printer.h. By placing the specific codes for your printer in the proper positions, the conversion takes place automatically.		The CommandTable is used to convert all escape codes that can be handled by simple substitution. It has one entry per ANSI command supported by the printer driver. When you are creating a custom CommandTable, you must maintain the order of the commands in the same sequence as that shown in devices/printer.h. By placing the specific codes for your printer in the proper positions, the conversion takes place automatically.

		⚫	{{Note\|title=Octal knows NULL\|text=If the code for your printer requires a decimal 0 (an ASCII NULL character), you enter this NULL into the CommandTable as octal 376 (decimal 254).}}
	{\| class="wikitable"
⚫	\| ''Octal knows NULL~~.''~~ If the code for your printer requires a decimal 0 (an ASCII NULL character), you enter this NULL into the CommandTable as octal 376 (decimal 254).
	\|}

	Placing an octal value of 377 (255 decimal) in a position in the command table indicates to the printer device that no simple conversion is available on this printer for this ANSI command. For example, if a daisy-wheel printer does not have a foreign character set, 377 octal (255 decimal) is placed in that position in the command table. However, 377 in a position can also mean that the ANSI command is to be handled by code located in the DoSpecial() function. For future compatibility ''all'' printer commands should be present in the command table, and those not supported by the printer filled with the dummy entry 377 octal.		Placing an octal value of 377 (255 decimal) in a position in the command table indicates to the printer device that no simple conversion is available on this printer for this ANSI command. For example, if a daisy-wheel printer does not have a foreign character set, 377 octal (255 decimal) is placed in that position in the command table. However, 377 in a position can also mean that the ANSI command is to be handled by code located in the DoSpecial() function. For future compatibility ''all'' printer commands should be present in the command table, and those not supported by the printer filled with the dummy entry 377 octal.

Steven Solie: /* Additional Notes About Graphic Dumps */

2013-03-28T20:11:38Z

Additional Notes About Graphic Dumps

← Older revision		Revision as of 20:11, 28 March 2013
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	# Densities which use more than one pass tend to produce muddy grey-scale or color printouts. It is recommended not to choose these densities when doing a grey-scale or color dump.		# Densities which use more than one pass tend to produce muddy grey-scale or color printouts. It is recommended not to choose these densities when doing a grey-scale or color dump.

		⚫	{{Note\|title=Keep This in Mind\|text=It is possible that the printer has been instructed to receive a certain amount of data and is still in an “expecting” state if an I/O request has been aborted by the user. This means the printer would try to finish the job with the data the next I/O request might send. Currently the best way to overcome this problem is for the printer to be reset.}}
	{\| class="wikitable"
⚫	\| ''Keep This in Mind~~.''~~ It is possible that the printer has been instructed to receive a certain amount of data and is still in an “expecting” state if an I/O request has been aborted by the user. This means the printer would try to finish the job with the data the next I/O request might send. Currently the best way to overcome this problem is for the printer to be reset.
	\|}

	== Creating a Printer Driver ==		== Creating a Printer Driver ==

Steven Solie: /* Printing with Corrected Aspect Ratio */

2013-03-28T20:11:01Z

Printing with Corrected Aspect Ratio

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	# Using an integer multiple of one of the standard (NTSC) display resolutions and setting the io_Modes argument accordingly. For example if your RastPort dimensions were 1,280800 (an even multiple of 640400) you would set io_Modes to LACE \| HIRES. Setting the SPECIAL_ASPECT flag would enable the printer device to properly calculate the aspect ratio of the image.		# Using an integer multiple of one of the standard (NTSC) display resolutions and setting the io_Modes argument accordingly. For example if your RastPort dimensions were 1,280800 (an even multiple of 640400) you would set io_Modes to LACE \| HIRES. Setting the SPECIAL_ASPECT flag would enable the printer device to properly calculate the aspect ratio of the image.
	# When using an arbitrary sized RastPort, you can supply the ModeID of a display mode which has the aspect ratio you would like for your RastPort. The aspect ratio of the various display modes are defined as ticks-per-pixel in the Resolution field of the DisplayInfo structure. You can obtain this value from the graphics database. For example, the resolution of ''Productivity Mode'' is 22:22, in other words, 1:1, perfect for a RastPort sized to the limits of the output device. See [[Graphics_Library_and_Text\|Graphics Library]] for general information on the graphics system.		# When using an arbitrary sized RastPort, you can supply the ModeID of a display mode which has the aspect ratio you would like for your RastPort. The aspect ratio of the various display modes are defined as ticks-per-pixel in the Resolution field of the DisplayInfo structure. You can obtain this value from the graphics database. For example, the resolution of ''Productivity Mode'' is 22:22, in other words, 1:1, perfect for a RastPort sized to the limits of the output device. See [[Graphics_Library_and_Text\|Graphics Library]] for general information on the graphics system.

			==== Demo_Dump.c ====

	The following example will dump a RastPort to the printer and wait for either the printer to finish or the user to cancel the dump and act accordingly.		The following example will dump a RastPort to the printer and wait for either the printer to finish or the user to cancel the dump and act accordingly.

Steven Solie: /* Error Codes from the Printer Device */

2013-03-28T20:09:37Z

Error Codes from the Printer Device

← Older revision		Revision as of 20:09, 28 March 2013
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	The printer device returns error codes whenever an operation is attempted. There are two types of error codes that can be returned. Printer device error codes have positive values; Exec I/O error codes have negative values. Therefore, an application should check for a ''non-zero'' return code as evidence of an error, not simply a value greater than zero.		The printer device returns error codes whenever an operation is attempted. There are two types of error codes that can be returned. Printer device error codes have positive values; Exec I/O error codes have negative values. Therefore, an application should check for a ''non-zero'' return code as evidence of an error, not simply a value greater than zero.

			<syntaxhighlight>
	<pre>
	PrintIO-~~>~~ios.io_Length = strlen(outbuffer);		PrintIO->ios.io_Length = strlen(outbuffer);
	PrintIO-~~>~~ios.io_Data = (APTR)outbuffer;		PrintIO->ios.io_Data = (APTR)outbuffer;
	PrintIO-~~>~~ios.io_Command = PRD_RAWWRITE;		PrintIO->ios.io_Command = PRD_RAWWRITE;
	if (DoIO((struct IORequest *)PrintIO))		if (IExec->DoIO((struct IORequest *)PrintIO))
	~~printf~~(~~"~~RAW Write failed. Error: %~~d "~~,PrintIO-~~>~~ios.io_Error);		IDOS->Printf("RAW Write failed. Error: %ld", PrintIO->ios.io_Error);
			</syntaxhighlight>
	</pre>

	The error is found in io_Error.		The error is found in io_Error.

Steven Solie: /* Querying the Printer Device */

2013-03-28T20:08:11Z

Querying the Printer Device

Show changes