Rotate NSImage in an NSImageView

Tags: Cocoa, NSImage, Objective C, Snippet

Drag and Drop Reordering of NSTableView’s Rows

09-12-09 01:47 Filed in: Cocoa | Objective C | Programming - 编程

I just had to re-implement drag-and-drop-reordering of Slider cells. I was lucky enough to find my post on the Cocoa-dev list – I just had to copy-paste the code.

#define MyPrivateTableViewDataType @"NSMutableDictionary"
 
- (void)awakeFromNib {
[table registerForDraggedTypes:[NSArray arrayWithObject:MyPrivateTableViewDataType]];
}
 
- (BOOL)tableView:(NSTableView *)tv writeRowsWithIndexes:(NSIndexSet *)rowIndexestoPasteboard:(NSPasteboard*)pboard{
 // Copy the row numbers to the pasteboard.
 NSData *data = [NSKeyedArchiver archivedDataWithRootObject:rowIndexes];
 
[pboard declareTypes:[NSArray arrayWithObject:MyPrivateTableViewDataType] owner:controller];
 
 [pboard setData:data forType:MyPrivateTableViewDataType];
 return YES;
}
 
- (NSDragOperation)tableView:(NSTableView*)tv validateDrop:(id <NSDraggingInfo>)info proposedRow:(int)row proposedDropOperation:(NSTableViewDropOperation)op{
 // Add code here to validate the drop
 NSLog(@"validate Drop");
 return NSDragOperationEvery;
}
 
- (BOOL)tableView:(NSTableView *)aTableView acceptDrop:(id <NSDraggingInfo>)info row:(int)to dropOperation:(NSTableViewDropOperation)operation{
 
//this is the code that handles dnd ordering - my table doesn't need to accept drops from outside! Hooray!
 NSPasteboard* pboard = [info draggingPasteboard];
 NSData* rowData = [pboard dataForType:MyPrivateTableViewDataType];
 
NSIndexSet* rowIndexes = [NSKeyedUnarchiver unarchiveObjectWithData:rowData];
 
 int from = [rowIndexes firstIndex];
 
NSMutableDictionary *traveller = [[controller arrangedObjects] objectAtIndex:from];
 
 [traveller retain];
   int length = [[controller arrangedObjects] count];
   NSMutableArray *replacement = [NSMutableArray new];
 
   int i;
 for (i = 0; i <= length; i++){
       if(i == to){
         if(from > to){
         [controller insertObject:traveller atArrangedObjectIndex:to];
         [controller removeObjectAtArrangedObjectIndex:from+1];
         }
         else{
             [controller insertObject:traveller atArrangedObjectIndex:to];
             [controller removeObjectAtArrangedObjectIndex:from];
         }
     }
   }
}

Posting replies to the lists helps more than just the receiver – keep in mind that source code can be lost. Time is saved when tedious sections can be copy-pasted in during rewriting!

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Tags: Cocoa, NSTableView, Objctive C

How to Prevent Noisy NSBitmapImageReps

09-11-10 13:00 Filed in: Cocoa | Objective C | Programming - 编程

Before

Images generated for Slider’s background and tabs contained a lot of noise – random ugly pixels throughout the images.

I was unsure why this was happening, so I asked the Cocoa-Dev mailing list.

Rob Keniger kindly replied with the following solution:

“An NSBitmapImageRep is not guaranteed to be empty when you create it and in general it’s just full of random bits. You need to clear it explicitly if you are drawing non-opaque content”

He included the following snippet that solved my problem nicely:

- (void) clearBitmapImageRep:(NSBitmapImageRep *)bitmap {
   unsigned char* bitmapData = [bitmap bitmapData];
   if (bitmapData != NULL)
   {
       bzero(bitmapData, [bitmap bytesPerRow] * [bitmap pixelsHigh]);
   }
}

I call it as soon as I’ve created a new NSBitmapImageRep, like so:

NSBitmapImageRep  *theImage = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL pixelsWide:imageSize.width pixelsHigh:imageSize.height
                            bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:NO
                            colorSpaceName:NSDeviceRGBColorSpace bytesPerRow:0 bitsPerPixel:0];
 
[self clearBitmapImageRep:theImage];

This results in noise-free images.

After

Thanks Rob!

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Tags: Cocoa, NSBitmapImageRep, Objective C

The Mutations of Slider’s Tab Option Pane

09-11-09 20:46 Filed in: Cocoa | Objective C | Programming - 编程 | Rapidweaver | Slider

During the past week, I’ve been working on Slider’s new Tab option pane.

I took screen shots before making changes to the layout.

Here they are:

I hope I’m not tempted to change things around again… I really need to get the backend going now!

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Tags: Cocoa, Objective C, Slider

Accessing Primitives From NSDictionarys in Cocoa…

09-11-07 22:23 Filed in: Cocoa | Objective C

This “gotcha” had me scratching my head for a little while.

Edit: this “gotcha” stemmed more from my inexperience with Cocoa than anything else. NSDictionaries store only objects, one shouldn’t try to insert int/float/bool etc into one. Instead use NSNumber for these values. Duh.

When storing various NSObjects in an NSMutableDictionary, I assumed one would access (in this case the object being stored is an NSColor) them like:

1	[[dictionary objectForKey:idle_TabBorderAllColourKey] color]

I also assumed that one would access “int”, “float” and other primitives like:

1	[dictionary objectForKey:idle_TabBorderAllWidthKey]

After writing, compiling and attempting run my code, however, I discovered that I was wrong.

It should be done like so:

1	[dictionary objectForKey:idle_TabBorderAllColourKey]

For NSObjects, and:

1	[[dictionary objectForKey:idle_TabBorderAllWidthKey] intValue]

for primitives.

Cocoa noob learns more about Cocoa with each passing minute!

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Tags: Cocoa, NSDictionary, Objective C

Fill a Path With A Scaled Image, Ignoring Image Proportions

09-10-27 19:19 Filed in: Cocoa | Objective C | Programming - 编程 | Tutorial - 教程

While continuing to rebuild Slider’s background image features, I was forced to rewrite the code that scales an image up/down to Slider’s portal size, ignoring the image’s original proportions. The image also had to be painted within a path, as Slider may have differently shaped corners compared to the image to be scaled.

The below code accomplishes the scaling and painting of the image.

//theImage = the resulting image, that will have a scaled (proportions ignored) version of "bgImage" painted onto it
NSBitmapImageRep *theImage = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:NULL pixelsWide:imageSize.width pixelsHigh:imageSize.height
 bitsPerSample:8 samplesPerPixel:4 hasAlpha:YES isPlanar:NO
 colorSpaceName:NSDeviceRGBColorSpace bytesPerRow:0 bitsPerPixel:0];
 
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithBitmapImageRep:theImage]];
 
NSImage bg = [[NSImage alloc] initWithSize: imageSize];
 
//bgImage can be any NSImage
NSSize originalSize = [bgImage size];
[bg lockFocus];
[bgImage drawInRect: NSMakeRect(0, 0, imageSize.width, imageSize.height) 
fromRect: NSMakeRect(0, 0, originalSize.width, originalSize.height) 
operation: NSCompositeSourceOver fraction: 1.0];
 
[bg unlockFocus];
 
NSColor *c = [NSColor colorWithPatternImage:bg];
[c set];
[path appendBezierPathWithRoundedRect:NSMakeRect(0, 0, imageSize.width, imageSize.height) xRadius:10.0 yRadius:10.0];
[aPath fill];
 
[NSGraphicsContext restoreGraphicsState];

“path” could be any NSBezierPath.

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Tags: Cocoa, NSBezierPath, NSImage, Objective C, Slider, Snippet - 小片, Tutorial - 教程

Feel Like A Cup of Cocoa?

08-06-30 19:02 Filed in: Cocoa | Programming - 编程 | Rapidweaver