2014/10/15 下午 10:13:13

iphone Programming Glossary: redrawing

http://stackoverflow.com/questions/10133109/fastest-way-to-do-shadows-on-ios

draws a shadow during animations the following code allows you to cache the shadow as a bitmap and reuse it instead of redrawing it self.view.layer.shouldRasterize YES Don't forget the rasterization scale I spent days trying to figure out why retina..

When do I need to call setNeedsDisplay in iOS?

http://stackoverflow.com/questions/10818319/when-do-i-need-to-call-setneedsdisplay-in-ios

app I'm confused as to when exactly I need to call setNeedsDisplay I know that it has something to do with updating redrawing the UI however do I need to call this every time I change any of my views For example do I need to call it After programatically..

Create a custom animatable property

http://stackoverflow.com/questions/14192816/create-a-custom-animatable-property

of the path. I can also animate the change within the UIView subclass by animating the percentage of the CGPath and redrawing the path. Can I set some property i.e. percentage on the UIView so that I can stick the change into a UIView animateWithDuration..

to drawRect or not to drawRect (when should one use drawRect/Core Graphics vs subviews/images and why?)

http://stackoverflow.com/questions/14659563/to-drawrect-or-not-to-drawrect-when-should-one-use-drawrect-core-graphics-vs-su

hierarchy so any perceived extra effort using CG isn't worth the gain You want to update pieces of the view without redrawing the whole thing The layout of your subviews needs to update when the parent view size changes So bestow your knowledge...

Drawing incrementally in a UIView (iPhone)

http://stackoverflow.com/questions/1798414/drawing-incrementally-in-a-uiview-iphone

drawAtPoint CGPointZero draw the cached image EDIT After all I combined one of the methods mention below with redrawing only in the new rect. The result is FAST METHOD void addDotAt CGPoint point if myPoints count kMaxPoints Drop drop Drop.. Rather than redraw all the content of the UIView every single time you can mark only the areas of the view that need redrawing using UIView setNeedsDisplayInRect instead of UIView setNeedsDisplay . You also need to make sure that the graphics content..

Animating a custom property of CALayer subclass

http://stackoverflow.com/questions/2395382/animating-a-custom-property-of-calayer-subclass

dynamic so that CA implements the accessors for you @dynamic myInt Tell the layer that changes of the property require redrawing BOOL needsDisplayForKey NSString key if key isEqualToString @ myInt return YES else return super needsDisplayForKey key..

How much more complex is it to draw simple curves, lines and circles in OpenGL ES rather than in Quartz 2D?

http://stackoverflow.com/questions/2720804/how-much-more-complex-is-it-to-draw-simple-curves-lines-and-circles-in-opengl-e

to OpenGL is to accelerate the animation of your drawn elements. In that question you were attempting to animate by redrawing your UIView's contents with Quartz every frame. That will be incredibly slow because of the way that the iPhone's drawing.. D elements to be as hard or harder than with Quartz. Instead my recommendation is to not try animating your content by redrawing it each frame in Quartz but by layering your drawing and using Core Animation to move these layers around. Even on the original..

Must drawInRect: for a separate context be executed on the main thread?

http://stackoverflow.com/questions/3207536/must-drawinrect-for-a-separate-context-be-executed-on-the-main-thread

size and storing the thumbnails for previewing. Note that I'm doing this in a separate image context this is not about redrawing a UIView that is on the screen. This code is rather intensive so I'm running it in a separate thread. The actual scaling..

Redrawing UIScrollView contents after every zoom

http://stackoverflow.com/questions/3313947/redrawing-uiscrollview-contents-after-every-zoom

redraw after every zoom not just at certain zoom thresholds like it tries to do. Does anyone know how to do the proper redrawing of the UIView on a zoom iphone uiscrollview ios share improve this question Tom Your question is a bit old but I came..

My custom UI elements are not being updated while UIScrollView is scrolled

http://stackoverflow.com/questions/4109898/my-custom-ui-elements-are-not-being-updated-while-uiscrollview-is-scrolled

keep coming even while scrolling. But my problem is that my spinning circle is still stopping on scrolling I suspect redrawing is halted until the next iteration of the main thread's run loop . So even if its angle is changed all the time it might..

Setting the background colour/highlight colour for a given string range using Core Text

http://stackoverflow.com/questions/4498918/setting-the-background-colour-highlight-colour-for-a-given-string-range-using-co

What's the best approach to draw lines between views?

http://stackoverflow.com/questions/5847876/whats-the-best-approach-to-draw-lines-between-views

There's an easy way to do this completely avoiding the described overhead Use a CALayer for your line but instead of redrawing the contents on the CPU just fill it completely with the line's color setting its backgroundColor property to the line's..

When Do You Need To Reset the view.frame Property After a Transformation iOS

http://stackoverflow.com/questions/7772016/when-do-you-need-to-reset-the-view-frame-property-after-a-transformation-ios

improve this question ahh ok after reading it again I understand what you're asking ^^ Setting the frame results in redrawing the view. This needs to be done because otherwise the old graphics may interfere and it looks ugly. The redraw should sharpen..

Dispelling the UIImage imageNamed: FUD

http://stackoverflow.com/questions/924740/dispelling-the-uiimage-imagenamed-fud

that you need to redraw often then there are alternatives although the one I would recommend primarily is to avoid redrawing that large image . With respect to the general behavior of the cache it does cache based on filename so two instances of..