In Cocoa: How to open image, resize it and save it with a new name - cocoa

Question

I am trying to open an image with open dialog, resize it and save it with a new name, I found some code in other posts and putting 2 or 3 things togheter I finished having this code, but it doesn't work... here is my code:
-(IBAction)apriFileImmagine:(id)sender
{
[pannelloHome makeKeyAndOrderFront:self];
int i; // Loop counter.
// Create the File Open Dialog class.
NSOpenPanel* openDlg = [NSOpenPanel openPanel];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory2 = [paths objectAtIndex:0];
NSURL *myUrl = [NSURL fileURLWithPath:documentsDirectory2];
[openDlg setDirectoryURL:myUrl];
// Enable the selection of files in the dialog.
[openDlg setCanChooseFiles:YES];
// Enable the selection of directories in the dialog.
[openDlg setCanChooseDirectories:YES];
// Display the dialog. If the OK button was pressed,
// process the files.
if ( [openDlg runModal] == NSOKButton )
{
// Get an array containing the full filenames of all
// files and directories selected.
NSArray* files = [openDlg URLs];
// Loop through all the files and process them.
for( i = 0; i < [files count]; i++ )
{
NSURL* fileName = [files objectAtIndex:i];
[self scaleIcons:documentsDirectory2 :fileName];
}
}
}
- (void)scaleIcons:(NSString *)outputPath :(NSURL *)nomeImmagine
{
NSImage *image = [NSImage imageNamed:[NSString stringWithFormat:#"%#",nomeImmagine]];
NSSize outputSize = NSMakeSize(512.0f,512.0f);
NSImage *anImage = [self scaleImage:image toSize:outputSize];
NSString *finalPath = [outputPath stringByAppendingString:#"/icon_512x512.png"];
NSData *imageData = [anImage TIFFRepresentation];
NSBitmapImageRep *rep = [NSBitmapImageRep imageRepWithData:imageData];
NSData *dataToWrite = [rep representationUsingType:NSPNGFileType properties:nil];
[dataToWrite writeToFile:finalPath atomically:NO];
}
- (NSImage *)scaleImage:(NSImage *)image toSize:(NSSize)targetSize
{
if ([image isValid])
{
NSSize imageSize = [image size];
float width = imageSize.width;
float height = imageSize.height;
float targetWidth = targetSize.width;
float targetHeight = targetSize.height;
float scaleFactor = 0.0;
float scaledWidth = targetWidth;
float scaledHeight = targetHeight;
NSPoint thumbnailPoint = NSZeroPoint;
if (!NSEqualSizes(imageSize, targetSize))
{
float widthFactor = targetWidth / width;
float heightFactor = targetHeight / height;
if (widthFactor < heightFactor)
{
scaleFactor = widthFactor;
}
else
{
scaleFactor = heightFactor;
}
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
if (widthFactor < heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else if (widthFactor > heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
newImage = [[NSImage alloc] initWithSize:targetSize];
[newImage lockFocus];
NSRect thumbnailRect;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[image drawInRect:thumbnailRect
fromRect:NSZeroRect
operation:NSCompositeSourceOver
fraction:1.0];
[newImage unlockFocus];
}
}
return newImage;
}
as you can see I'm trying to save in the same directory where the image has been taken... but all I'm getting is an error:
: ImageIO: CGImageSourceCreateWithData data parameter is nil
Anyone knows what I am doing wrong? Any help will be very much appreciated... thanks Massy

Answer 1

The problem with your image only, image is nil, So I have modified this method:
- (void)scaleIcons:(NSString *)outputPath :(NSURL *)nomeImmagine
{
//NSImage *image = [NSImage imageNamed:[NSString stringWithFormat:#"%#",nomeImmagine]]; commented this part
//start modification
NSImage *image = [[NSImage alloc] initWithContentsOfFile:[[nomeImmagine path] autorelease]];
if (!image)
image = [[NSWorkspace sharedWorkspace] iconForFile:[nomeImmagine path]];
//end modification
NSSize outputSize = NSMakeSize(512.0f,512.0f);
NSImage *anImage = [self scaleImage:image toSize:outputSize];
NSString *finalPath = [outputPath stringByAppendingString:#"/icon_512x512.png"];
NSData *imageData = [anImage TIFFRepresentation];
NSBitmapImageRep *rep = [NSBitmapImageRep imageRepWithData:imageData];
NSData *dataToWrite = [rep representationUsingType:NSPNGFileType properties:nil];
[dataToWrite writeToFile:finalPath atomically:NO];
}
Try This , it worked for me..

Answer 2

Yes that's wrong. Try:
NSImage *image = [[NSImage alloc] initWithContentsOfFile:nomeImage];
NSAssert(image, #"Image is NOT valid");
This should then return a valid NSImage.... ? Depending on if you're using ARC you may want to release/auto release as you have 'alloc'd.