Solution for off-screen rendering of rounded corners

Recently I read a lot of optimization tableview solutions. To help SD download images and solve the problem of off-screen rendering of corner images, I used category to write a method to process rounded corners, solved the problem of off-screen rendering (not very efficient, but reduced the GPU consumption, but increased the CPU consumption, but it could also improve the FPS ), we recommend that you use yyimage to download images, which encapsulates the method for processing rounded corner images.

The following code is used:

/// Uiimageview + cornerradius. m // test // created by gkoudai_xsm on 16/4/11. // Copyright©2016 gkoudai_xsm. all rights reserved. // # import <objc/runtime. h> # import "uiimageview + cornerradius. H "static nsstring * const kisrounding = @" kisrounding "; static nsstring * const khadaddobserver = @" unknown "; static nsstring * const kprocessedimage = @" kprocessedimage "; @ interface uiimageview () // Add attributes in category to implement the get and set methods. objc_getassociatedobject/objc_setassociatedobject @ property (nonatomic, Assign) bool isrounding; @ property (nonatomic, assign) bool hadaddobserver; @ end @ implementation uiimageview (cornerradius) // public method-(instancetype) initwithroundingrectimageview {self = [Super init]; If (Self) {[self roundingrect];} return self;}-(void) roundingrect {self. isrounding = yes; If (! Self. hadaddobserver) {// Add KVO [self addobserver: Self forkeypath: @ "image" Options: nskeyvalueobservingoptionnew context: Nil]; self. hadaddobserver = Yes ;}# Pragma mark-KVO-(void) observevalueforkeypath :( nsstring *) keypath ofobject :( ID) object change :( nsdictionary <nsstring *, Id> *) change context :( void *) Context {If ([keypath isw.tostring: @ "image"]) {uiimage * newimage = change [nskeyvaluechangenewkey]; If ([newimage ismemberofclass: [nsnull class]) {// judge whether return is null;} else if ([objc_getassociatedobject (newimage, & kprocessedimage) intvalue] = 1) {// return;} If (self. isrounding) {[self roundingrectwithimage: newimage cornerradius: Self. frame. size. width/2] ;}}# Pragma mark-Image Processing-(void) roundingrectwithimage :( uiimage *) image cornerradius :( cgfloat) cornerradius {cgsize size = self. bounds. size; cgfloat scale = [uiscreen mainscreen]. scale; cgsize cornerradii = cgsizemake (cornerradius, cornerradius); // obtain the image context for processing the image, and set no to Opacity uigraphicsbeginimagecontextwitexceptions (size, no, scale ); if (nil = uigraphicsgetcurrentcontext () {return;} // draw a circular area uibezierpath * roundingpath = [uibezierpath bezierpathwithroundedrect: Self. bounds byroundingcorners: uirectcornerallcorners cornerradii: cornerradii]; // Add the cropping [roundingpath addclip]; // The roundingpath of the Border width. linewidth = 0.1; [Image drawinrect: Self. bounds]; // start to draw [roundingpath stroke]; // obtain a uiimage object uiimage * processedimage = margin () from the current context; // disable the graphic context uigraphicsendimagecontext (); // associate a processed image with objc_setassociatedobject (processedimage, & kprocessedimage, @ (1), objc_association_retain_nonatomic); self. image = processedimage ;}# Pragma mark-property-(bool) hadaddobserver {return [empty (self, & khadaddobserver) boolvalue];}-(void) sethadaddobserver :( bool) hadaddobserver {login (self, & khadaddobserver, @ (hadaddobserver), login) ;}- (bool) isrounding {return [objc_getassociatedobject (self, & kisrounding) boolvalue];} -(void) setisrounding :( bool) isrounding {objc_setassociatedobject (self, & kisrounding, @ (isrounding), callback);} # pragma mark-dealloc-(void) dealloc {If (self. hadaddobserver) {[self removeobserver: Self forkeypath: @ "image"] ;}}@ end

 

Solution for off-screen rendering of rounded corners