There are several basic plotting methods and several plotting Methods

There are several basic plotting methods and several plotting Methods

1. drawRect:

Rewrite the UIView subclass

2. drawLayer: inContext:

CALayer sets proxy (this is a proxy method)

3. drawInContext:

CALayer subclass Rewriting

4. Use the image context to generate an image:

ImageContext

Try to avoid mixing

------- Implementation of drawRect: Method ----------

1. Use UIKit

　　　　　　

/** 1. Implement drawRect in the UIView subclass: Method 2: Draw the drawRect in the current context provided by UIKit */-(void) drawRect :( CGRect) rect {// besser path depicts the elliptical UIBezierPath * path = [UIBezierPath bezierPathWithOvalInRect: CGRectMake (100,100,200,100)]; // color fill [[UIColor blueColor] setFill]; // fill in the current context [path fill];}

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2. Use Core Graphic

　　　　　

/** 1. Implement drawRect in the UIView subclass: method 2. Use Core Graphics to obtain the current context for plotting */-(void) drawRect :( CGRect) rect {// obtain the current context CGContextRef context = UIGraphicsGetCurrentContext (); // draw a graphic watermark (context, CGRectMake (100,100,200,100); // set the fill color CGContextSetFillColorWithColor (context, context, [UIColor redColor]. CGColor); // render CGContextFillPath (context );}

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------- Proxy implementation drawLayer: inContext: Method ----------

1. Use UIKit

　　　　　　

@ Implementation ViewController-(void) viewDidLoad {[super viewDidLoad]; // 1. create a custom layer CALayer * layer = [CALayer layer]; // 2. sets the layer attribute layer. backgroundColor = [UIColor brownColor]. CGColor; layer. bounds = CGRectMake (0, 0,200,150); layer. anchorPoint = CGPointZero; layer. position = CGPointMake (100,100); layer. cornerRadius = 20; layer. shadowColor = [UIColor redColor]. CGColor; layer. shadowOffset = CGSizeMake (10, 20); layer. shadowOpacity = 0.6; // sets the proxy layer. delegate = self; // trigger the proxy method to draw [layer setNeedsDisplay]; // 3. add layer [self. view. layer addSublayer: layer];}-(void) drawLayer :( CALayer *) layer inContext :( CGContextRef) ctx {// converts the referenced context to the current context. UIGraphicsPushContext (ctx); // draw the image UIBezierPath * p = [UIBezierPath layout: CGRectMake (,)]; [[UIColor blueColor] setFill]; [p fill]; UIGraphicsPopContext () ;}@ end

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2. Use Core Graphic

　　　　　　

@ Implementation ViewController-(void) viewDidLoad {[super viewDidLoad]; // 1. create a custom layer CALayer * layer = [CALayer layer]; // 2. sets the layer attribute layer. backgroundColor = [UIColor brownColor]. CGColor; layer. bounds = CGRectMake (0, 0,200,150); layer. anchorPoint = CGPointZero; layer. position = CGPointMake (100,100); layer. cornerRadius = 20; layer. shadowColor = [UIColor redColor]. CGColor; layer. shadowOffset = CGSizeMake (10, 20); layer. shadowOpacity = 0.6; // sets the proxy layer. delegate = self; [layer setNeedsDisplay]; // 3. add layer [self. view. layer addSublayer: layer];}-(void) drawLayer :( CALayer *) layer inContext :( CGContextRef) ctx {ctx (ctx, CGRectMake (50,50, 100,50); CGContextSetFillColorWithColor (ctx, [UIColor blueColor]. CGColor); CGContextFillPath (ctx) ;}@ end

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------- Customize CALayer to override drawInContext :----------

1. Use UIKit

Custom Layer class:

　　　　　　　　

# Import "DXLayer. h "# import <UIKit/UIKit. h> @ implementation DXLayer // rewrite this method and draw the image-(void) drawInContext :( CGContextRef) ctx {UIGraphicsPushContext (ctx); // 1. drawing a graphic UIBezierPath * p = [UIBezierPath labels: CGRectMake (50, 50,)]; [[UIColor blueColor] setFill]; [p fill]; UIGraphicsPopContext ();} @ end

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@ Implementation ViewController-(void) viewDidLoad {[super viewDidLoad]; // 1. create a custom layer DXLayer * layer = [DXLayer layer]; // 2. sets the layer attribute layer. backgroundColor = [UIColor brownColor]. CGColor; layer. bounds = CGRectMake (0, 0,200,150); layer. anchorPoint = CGPointZero; layer. position = CGPointMake (100,100); layer. cornerRadius = 20; layer. shadowColor = [UIColor yellowColor]. CGColor; layer. shadowOffset = CGSizeMake (5, 5); layer. shadowOpacity = 0.6; // 3. drawInContext for triggering a layer: Draw a Layer on a custom layer [layer setNeedsDisplay]; // 4. add layer [self. view. layer addSublayer: layer];} @ end

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2. Use Core Graphic

　　　　　　

# Import "DXLayer. h "@ implementation DXLayer // rewrite this method and draw the image-(void) drawInContext :( CGContextRef) ctx {// 1. draw a graph // draw a circle CGContextAddEllipseInRect (ctx, CGRectMake (50, 50,100,100); // set the attribute (color) // [[UIColor yellowColor] set]; CGContextSetRGBFillColor (ctx, 0, 0, 1, 1); // 2. rendering CGContextFillPath (ctx);} @ end

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------- Use Image Context ----------

1. Use ImageContext to generate a UIImage object

2. There is no limit on the code location. Both methods are restricted to drawRect: Or drawLayer: inContext: method.

 

1. Use UIKit

　　　　　　

@ Implementation ViewController-(void) viewDidLoad {[super viewDidLoad]; UIImageView * imgView = [[UIImageView alloc] initWithFrame: CGRectMake (100,100,200,100)]; imgView. image = [self createImageFromImageContext]; [self. view addSubview: imgView];}/** create an image object (draw a circle) */-(UIImage *) createImageFromImageContext {/** Create Image context 1: size of the image to be created 2: specify whether the background of the generated image is not transparent 3: Specify the scaling factor of the generated image, which corresponds to the scale attribute of the UIImage The meaning is consistent. Input 0 indicates that the scaling factor of the image is changed according to the screen resolution */uigraphicsbeginimagecontextwitexceptions (CGSizeMake (200,100), NO, 0 ); // drawing UIBezierPath * p = [UIBezierPath bezierPathWithOvalInRect: CGRectMake (200,100,)]; [[UIColor blueColor] setFill]; [p fill]; // obtain the image object UIImage * img = UIGraphicsGetImageFromCurrentImageContext () from the context; // disable the image context UIGraphicsEndImageContext (); return img;} @ end

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2. Use Core Graphic

　　　　　　

/** Create an image object by drawing (drawing a circle) */-(UIImage *) createImageFromImageContext {/** Create Image context 1: size of the image to be created 2: specify whether the background of the generated image is not transparent. 3: Specify the scaling factor of the generated image, which is consistent with the meaning indicated by the scale attribute of the UIImage. If 0 is input, the scaling factor of the image is changed according to the screen resolution */resize (CGSizeMake (200,100), NO, 0); CGContextRef con = UIGraphicsGetCurrentContext (); CGContextAddEllipseInRect (con, CGRectMake (0,0, 200,100); CGContextSetFillColorWithColor (con, [UIColor blueColor]. CGColor); CGContextFillPath (con); UIImage * img = UIGraphicsGetImageFromCurrentImageContext (); UIGraphicsEndImageContext (); return img ;}

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