libs-gui/Source/GSGhostscriptImageRep.m

/** <title>GSGhostscriptImageRep</title>

   <abstract>Ghostscript image representation.</abstract>

   Copyright (C) 2011 Free Software Foundation, Inc.
   
   Author:  Eric Wasylishen <ewasylishen@gmail.com>
   Date: June 2011
   
   This file is part of the GNUstep Application Kit Library.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; see the file COPYING.LIB.
   If not, see <http://www.gnu.org/licenses/> or write to the 
   Free Software Foundation, 51 Franklin Street, Fifth Floor, 
   Boston, MA 02110-1301, USA.
*/ 

#import <Foundation/NSArray.h>
#import <Foundation/NSAffineTransform.h>
#import <Foundation/NSCharacterSet.h>
#import <Foundation/NSCoder.h>
#import <Foundation/NSData.h>
#import <Foundation/NSException.h>
#import <Foundation/NSFileManager.h>
#import <Foundation/NSProcessInfo.h>
#import <Foundation/NSString.h>
#import <Foundation/NSTask.h>
#import <Foundation/NSUserDefaults.h>
#import "AppKit/NSImageRep.h"
#import "AppKit/NSPasteboard.h"
#import "AppKit/NSGraphicsContext.h"
#import "GNUstepGUI/GSGhostscriptImageRep.h"

@implementation GSGhostscriptImageRep 

+ (BOOL) canInitWithData: (NSData *)data
{
  char buf[4];

  if ([data length] < 4)
    {
      return NO;
    }

  [data getBytes: buf length: 4];

  // Simple check for PostScript or EPS, Windows EPS, PDF  

  if ((buf[0] == '%' && buf[1] == '!' && buf[2] == 'P' && buf[3] == 'S') ||
      (buf[0] == '\xc5' && buf[1] == '\xd0' && buf[2] == '\xd3' && buf[3] == '\xc6') ||
      (buf[0] == '%' && buf[1] == 'P' && buf[2] == 'D' && buf[3] == 'F'))
    {
      return YES;
    }
  else
    {
      return NO;
    }
}

+ (NSArray *) imageUnfilteredFileTypes
{
  static NSArray *types = nil;

  if (types == nil)
    {
      types = [[NSArray alloc] initWithObjects: @"ps", @"eps", @"pdf", nil];
    }

  return types;
}

+ (NSArray *) imageUnfilteredPasteboardTypes
{
  static NSArray *types = nil;

  if (types == nil)
    {
      types = [[NSArray alloc] initWithObjects: NSPostScriptPboardType,
			       NSPDFPboardType,
			       nil];
    }
  
  return types;
}

// Locating Ghostscript

- (NSString *) _PATHSeparator
{
  NSProcessInfo *pinfo = [NSProcessInfo processInfo];
  const NSInteger os = [pinfo operatingSystem];
  
  if (os == NSWindowsNTOperatingSystem ||
      os == NSWindows95OperatingSystem)
    {
      return @";";
    }
  else
    {
      return @":";
    }
}

- (NSArray *) _PATHDirectories
{
  NSProcessInfo *pinfo = [NSProcessInfo processInfo];
  NSString *PATH = [[pinfo environment] objectForKey: @"PATH"];  
  NSString *separator = [self _PATHSeparator];

  if (PATH != nil)
    {
      return [PATH componentsSeparatedByString: separator];
    }
  else
    {
      return [NSArray array];
    }
}

- (NSString *) _pathForExecutable: (NSString *)executable
{
  NSFileManager *fm = [NSFileManager defaultManager];
  NSArray *PATHDirectories = [self _PATHDirectories];
  NSEnumerator *enumerator = [PATHDirectories objectEnumerator];
  id object;

  while ((object = [enumerator nextObject]) != nil)
    {
      NSString *path = [object stringByAppendingPathComponent: executable];
      if ([fm isExecutableFileAtPath: path])
	{
	  return path;
	}
    }
  return nil;
}

- (NSString *) _ghostscriptExecutablePath
{
  NSString *result = [[NSUserDefaults standardUserDefaults] stringForKey: @"GSGhostscriptExecutablePath"];

  if (result == nil)
    {
      static BOOL searched = NO;
      static NSString *resultOfSearch = nil;
      
      // Only search PATH once.
      if (!searched)
	{
	  searched = YES;

	  ASSIGN(resultOfSearch, [self _pathForExecutable: @"gs"]);
	  
	  if (resultOfSearch == nil)
	    {
	      ASSIGN(resultOfSearch, [self _pathForExecutable: @"gswin32c.exe"]);
	    }

	  if (resultOfSearch == nil)
	    {
	      NSLog(@"GNUstep was unable to locate the Ghostscript executable in your PATH. If you would like to use Ghostscript to render PDF, PS, or PS images, please set the GSGhostscriptExecutablePath user default to the full path to the gs executable or ensure Ghostscript is installed and located in your PATH.");
	    }
	}

      result = resultOfSearch;
    }

  return result;
}

// Launching Ghostscript

- (NSData *) _pngWithGhostscriptData: (NSData *)psData atResolution: (CGFloat)res
{
  NSTask *task = [[[NSTask alloc] init] autorelease];
  NSPipe *inputPipe = [NSPipe pipe];
  NSPipe *outputPipe = [NSPipe pipe];
  NSFileHandle *inputHandle = [inputPipe fileHandleForWriting];
  NSFileHandle *outputHandle = [outputPipe fileHandleForReading];
  NSData *result = nil;
  NSString *launchPath = [self _ghostscriptExecutablePath];

  NS_DURING
    {
      [task setLaunchPath: launchPath];
      [task setArguments: [NSArray arrayWithObjects: @"-dSAFER",
				   @"-q",
				   @"-o",
				   @"-", // Write output image to stdout
				   @"-sDEVICE=pngalpha",
				   [NSString stringWithFormat: @"-r%d", (int)res],
				   @"-dTextAlphaBits=4",
				   @"-dGraphicsAlphaBits=4",
				   @"-dDOINTERPOLATE",
				   @"-dFirstPage=1",
				   @"-dLastPage=1", // pngalpha device can only print 1 page
				   @"-", // Read input from stdin
				   nil]];
      [task setStandardInput: inputPipe];
      [task setStandardOutput: outputPipe];
      [task launch];
      
      [inputHandle writeData: psData];
      [inputHandle closeFile];
      
      result = [outputHandle readDataToEndOfFile];
      [outputHandle closeFile];

      if (![task isRunning] && [task terminationStatus] != 0)
	{
	  NSLog(@"Ghostscript returned exit status %d", [task terminationStatus]);
	}
    }
  NS_HANDLER
    {
      static BOOL warned = NO;
      if (!warned)
	{
	  warned = YES;
	  NSLog(@"An error occurred while attempting to invoke Ghostscript at the following path: %@", launchPath);
	}
    }
  NS_ENDHANDLER

  return result;
}



// Initializing a New Instance 
+ (id) imageRepWithData: (NSData *)psData
{
  return AUTORELEASE([[self alloc] initWithData: psData]);
}

- (id) initWithData: (NSData *)psData
{
  NSData *pngData;
  
  ASSIGN(_psData, psData);

  pngData = [self _pngWithGhostscriptData: _psData atResolution: 72.0];

  if (pngData == nil)
    {
      [self release];
      return nil;
    }

  ASSIGN(_bitmap, [NSBitmapImageRep imageRepWithData: pngData]);
 
  [self setSize: [_bitmap size]];
  [self setAlpha: [_bitmap hasAlpha]];
  [self setBitsPerSample: NSImageRepMatchesDevice];
  [self setPixelsWide: NSImageRepMatchesDevice];
  [self setPixelsHigh: NSImageRepMatchesDevice];
  // FIXME: Other properties?

  return self;
}

// Drawing the Image 
- (BOOL) draw
{
  if (_bitmap != nil)
    {
      // FIXME: Re-cache at a higher resolution if needed

      return [_bitmap draw];
    }
  return NO;
}

// NSCopying protocol
- (id) copyWithZone: (NSZone *)zone
{
  GSGhostscriptImageRep *copy = [super copyWithZone: zone];

  copy->_psData = [_psData copyWithZone: zone];
  copy->_bitmap = [_bitmap copyWithZone: zone];

  return copy;
}

// NSCoding protocol
- (void) encodeWithCoder: (NSCoder*)aCoder
{
  // FIXME:
  [super encodeWithCoder: aCoder];
  [_psData encodeWithCoder: aCoder];
}

- (id) initWithCoder: (NSCoder*)aDecoder
{
  // FIXME:
  NSData	*data;

  self = [super initWithCoder: aDecoder];
  data = [aDecoder decodeObject];
  return [self initWithData: data];
}

@end