图像攻略_ide

1、绘制简单的形状


#import <UIKit/UIKit.h>  @interface MyView : UIView  @property (strong, nonatomic)UIImage *image;  @end


1 #import "MyView.h"  2   3 @implementation MyView  4   5 - (id)initWithFrame:(CGRect)frame  6 {  7     self = [super initWithFrame:frame];  8     if (self) {  9         // Initialization code 10     } 11     return self; 12 } 13  14 // Only override drawRect: if you perform custom drawing. 15 // An empty implementation adversely affects performance during animation. 16 - (void)drawRect:(CGRect)rect 17 { 18     CGContextRef context = UIGraphicsGetCurrentContext(); 19     // Draw rectangle 20     CGRect drawingRect = CGRectMake(0.0, 20.0f, 100.0f, 180.0f); 21     const CGFloat *rectColorComponents = CGColorGetComponents([[UIColor greenColor] CGColor]); 22     CGContextSetFillColor(context, rectColorComponents); 23     CGContextFillRect(context, drawingRect); 24     // Draw ellipse 25     CGRect ellipseRect = CGRectMake(140.0f, 200.0f, 75.0f, 50.0f); 26     const CGFloat *ellipseColorComponenets = CGColorGetComponents([[UIColor blueColor] CGColor]); 27     CGContextSetFillColor(context, ellipseColorComponenets); 28     CGContextFillEllipseInRect(context, ellipseRect); 29     // Draw parallelogram 30     CGContextBeginPath(context); 31     CGContextMoveToPoint(context, 0.0f, 0.0f); 32     CGContextAddLineToPoint(context, 100.0f, 0.0f); 33     CGContextAddLineToPoint(context, 140.0f, 100.0f); 34     CGContextAddLineToPoint(context, 40.0f, 100.0f); 35     CGContextClosePath(context); 36     CGContextSetGrayFillColor(context, 0.4f, 0.85f); 37     CGContextSetGrayStrokeColor(context, 0.0, 0.0); 38     CGContextFillPath(context); 39      40     if (self.image) 41     { 42         CGFloat imageWidth = self.frame.size.width / 2; 43         CGFloat imageHeight = self.frame.size.height / 2; 44         CGRect imageRect = CGRectMake(imageWidth, imageHeight, imageWidth, imageHeight); 45         [self.image drawInRect:imageRect]; 46     } 47 } 48  49 @end


2、屏幕截图编程


#import <UIKit/UIKit.h> #import <QuartzCore/QuartzCore.h> #import "MyView.h"  @interface ViewController : UIViewController  @property (weak, nonatomic) IBOutlet MyView *myView;  @end


1 #import "ViewController.h"  2   3 @interface ViewController ()  4   5 @end  6   7 @implementation ViewController  8   9 - (void)viewDidLoad 10 { 11     [super viewDidLoad]; 12     // Do any additional setup after loading the view, typically from a nib. 13 } 14  15 - (void)didReceiveMemoryWarning 16 { 17     [super didReceiveMemoryWarning]; 18     // Dispose of any resources that can be recreated. 19 } 20  21 - (BOOL) canBecomeFirstResponder 22 { 23     return YES; 24 } 25  26 - (void) viewWillAppear: (BOOL)animated 27 { 28     [self.view becomeFirstResponder]; 29     [super viewWillAppear:animated]; 30 } 31  32 - (void) viewWillDisappear: (BOOL)animated 33 { 34     [self.view resignFirstResponder]; 35     [super viewWillDisappear:animated]; 36 } 37  38 - (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event 39 { 40     if (event.subtype == UIEventSubtypeMotionShake) 41     { 42         // Device was shaken 43          44         // Acquire image of current layer 45         UIGraphicsBeginImageContext(self.view.bounds.size); 46         CGContextRef context = UIGraphicsGetCurrentContext(); 47         [self.view.layer renderInContext:context]; 48         //截图方法 49         UIImage * image = UIGraphicsGetImageFromCurrentImageContext(); 50         UIGraphicsEndImageContext(); 51          52         self.myView.image =  image; 53         //UIView重新调用drawRect方法，从而包含最新的变化。 54         [self.myView setNeedsDisplay]; 55  56     } 57 } 58  59 @end