2014/10/15 下午 10:05:31

iphone Programming Glossary: context's

Retrieving a pixel alpha value for a UIImage

http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage

the blend mode to replace before drawing the image since you want the image's alpha value not the one which was in the context's buffer before CGContextSetBlendMode context kCGBlendModeCopy Edit after thinking You could do the lookup much more efficient..

Customizing the colors of a UISegmentedControl

http://stackoverflow.com/questions/1196679/customizing-the-colors-of-a-uisegmentedcontrol

create a CGContext do whatever drawing you need to in that context including strings and then get a UIImage out of the context's CGImage CGContextRef drawContext CGBitmapContextCreate many parameters do drawing here CGImageRef finalImage CGBitmapContextCreateImage..

Drop Shadow on UITextField text

http://stackoverflow.com/questions/1274168/drop-shadow-on-uitextfield-text

functions and call super drawRect rect . Hopefully that works in case the original UITextField code clears the drawing context's shadow parameters that idea is hosed and you'll have to write the whole drawing code yourself which I anti recommend because..

iPhone CoreData: How can I track/observe all changes within a subgraph?

http://stackoverflow.com/questions/2463950/iphone-coredata-how-can-i-track-observe-all-changes-within-a-subgraph

to any of its properties associations or the properties associations of any of the objects it contains. Using the context's 'hasChanges' doesn't give me enough granularity. The objects 'isUpdated' method only applies to the given object and not..

UIImage with transparent rounded corners

http://stackoverflow.com/questions/4885713/uiimage-with-transparent-rounded-corners

rounded rectangle we have an ordinary one. if ovalWidth 0 ovalHeight 0 CGContextAddRect context rect return Save the context's state so that the translate and scale can be undone with a call to CGContextRestoreGState. CGContextSaveGState context Translate.. CGRectGetWidth rect ovalWidth fh CGRectGetHeight rect ovalHeight CGContextAddArcToPoint adds an arc of a circle to the context's path creating the rounded corners . It also adds a line from the path's last point to the begining of the arc making the.. context fw 0 fw fh 2 1 Back to lower right Close the path CGContextClosePath context Restore the context's state. This removes the translation and scaling but leaves the path since the path is not part of the graphics state. CGContextRestoreGState..

iOS5 NSManagedObjectContext Concurrency types and how are they used?

http://stackoverflow.com/questions/9657760/ios5-nsmanagedobjectcontext-concurrency-types-and-how-are-they-used

a NSFetchedResultsController up to it or any other ui related tasks that need to be interwoven with processing that context's objects. The real fun comes when you combine them. Imagine having a parent context that does all io on a background thread..