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NSWorkspace+PreviewFile.m
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NSWorkspace+PreviewFile.m
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//
// NSWorkspace+PreviewFile.m
// Filie
//
// Created by Uli Kusterer on 5.12.2004
// Copyright 2004 by Uli Kusterer.
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would be
// appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
// -----------------------------------------------------------------------------
// Headers:
// -----------------------------------------------------------------------------
#import "NSWorkspace+PreviewFile.h"
#import "NSImage+Epeg.h"
#import "NSString+CarbonUtilities.h"
// -----------------------------------------------------------------------------
// Data Structures:
// -----------------------------------------------------------------------------
// 'pnot' resource's data structure used by QuickTime for its previews:
#pragma options align=mac68k
typedef struct PnotResItem {
unsigned long modDate;/* last modification date of item */
OSType useType; /* what type of data */
OSType resType;/* resource type containing item */
short resID; /* resource ID containing this item */
short rgnCode;/* region code */
long reserved;/* set to 0 */
} PnotResItem;
typedef struct PnotResource {
unsigned long modDate; /* modification date */
short version;/* version number of preview resource */
OSType resType;/* type of resource used as preview cache */
short resID; /* resource identification number of resource used as preview cache */
signed short numResItems;/* number of additional file descriptions */
PnotResItem resItem[0]; /* array of file descriptions */
} PnotResource;
typedef PnotResource **PnotResHandle;
#pragma options align=reset
@implementation NSWorkspace (UKPreviewFile)
// -----------------------------------------------------------------------------
// previewImageForFile:size:
// Generates a preview image for an image file and gives it the specified
// dimensions.
// Uses libepeg for JPEG files, otherwise attempts to load a QuickTime
// preview if there is one. Returns NIL if both of these fail.
//
// REVISIONS:
// 2004-12-05 UK Created.
// -----------------------------------------------------------------------------
-(NSImage*) previewImageForFile: (NSString*)fpath size: (NSSize)neededSize
{
FSRef fileRef;
NSImage* img = nil;
NSString* suf = [[fpath pathExtension] lowercaseString];
// Amazingly, this is faster than loading QuickTime's preview:
if( [suf isEqualToString: @"jpg"] || [suf isEqualToString: @"jpeg"] )
img = [NSImage previewImageWithContentsOfFile: fpath boundingBox: neededSize];
// If it's not a JPEG, we can't quick-preview, so try the QuickTime Preview:
if( !img && [fpath getFSRef: &fileRef] )
{
short refNum = FSOpenResFile( &fileRef, fsRdPerm );
if( refNum > 0 && ResError() == noErr )
{
OSType resType = 0;
short resID = 0;
UseResFile( refNum ); // In case it was already open.
PnotResHandle theRes = (PnotResHandle) Get1Resource( 'pnot', 0 );
if( theRes != NULL && ResError() == noErr && MemError() == noErr )
{
int x;
resType = (**theRes).resType;
resID = (**theRes).resID;
if( (**theRes).numResItems < 16384 ) // 16384 == -1.
{
for( x = 0; x < (**theRes).numResItems; x++ )
{
if( (**theRes).resItem[x].useType == 'Prev' )
{
resType = (**theRes).resItem[x].resType;
resID = (**theRes).resItem[x].resID;
}
}
}
}
// Now, if we've found a preview we know how to handle, generate an image from it:
if( resType == 'PICT' )
{
Handle thePic = Get1Resource( 'PICT', resID );
NSData* data = [NSData dataWithBytes: *thePic length: GetHandleSize(thePic)];
img = [[[NSImage alloc] initWithData: data] autorelease];
}
CloseResFile( refNum );
}
}
return img;
}
@end