使用 CGContextRef 进行简单内容绘制

摘要 : CGContextRef 功能强大，我们借助它可以画各种图形。这里所举例子只是简单内容绘制，冰山一角，对此感兴趣的朋友可以举一反三，实现各种酷炫效果。

 

效果如下：

KMDrawView.h

 

1 #import <UIKit/UIKit.h>

2 

3 @interface KMDrawView : UIView

4 

5 @end

KMDrawView.m

 1 #import "KMDrawView.h"

 2 

 3 @interface KMDrawView ()

 4 - (void)drawFont;

 5 - (void)drawLine;

 6 - (void)drawCircle;

 7 - (void)drawRectangle;

 8 

 9 @end

10 

11 @implementation KMDrawView

12 

13 - (instancetype)initWithFrame:(CGRect)frame{

14     if (self=[super initWithFrame:frame]) {

15         self.backgroundColor = [UIColor colorWithWhite:0.7 alpha:1.0];

16     }

17     return self;

18 }

19 

20 - (void)drawRect:(CGRect)rect {

21     [self drawFont];

22     [self drawLine];

23     [self drawCircle];

24     [self drawRectangle];

25     

26     [super drawRect:rect];

27 }

28 

29 #pragma mark - 绘制『文字』、『线条』、『圆形』、『矩形』

30 - (void)drawFont {

31     NSDictionary *dicAttribute = @{

32                                    NSForegroundColorAttributeName : [UIColor brownColor],

33                                    NSFontAttributeName : [UIFont systemFontOfSize:18.0]

34                                    };

35     

36     [@"我是文字" drawInRect:CGRectMake(20.0, 20.0, 100.0, 30.0) withAttributes:dicAttribute];

37 }

38 

39 - (void)drawLine {

40     CGContextRef contextRef = UIGraphicsGetCurrentContext(); //获取绘制上下文对象实例

41     CGContextSetRGBStrokeColor(contextRef, 0.5, 0.5, 0.5, 1.0); //设置笔画颜色

42     CGContextSetLineWidth(contextRef, 2.0); //设置线条粗细大小

43     

44     CGContextMoveToPoint(contextRef, 20.0, 100.0); //设置直线的首端

45     CGContextAddLineToPoint(contextRef, 320.0, 100.0); //设置直线的末端

46     CGContextStrokePath(contextRef); //沿着要求的路径，开始绘制

47 }

48 

49 - (void)drawCircle {

50     CGContextRef contextRef = UIGraphicsGetCurrentContext(); //获取绘制上下文对象实例

51     CGContextSetRGBStrokeColor(contextRef, 1.0, 1.0, 1.0, 1.0); //设置笔画颜色

52     CGContextSetLineWidth(contextRef, 2.0); //设置线条粗细大小

53     

54     //voidCGContextAddArc(CGContextRef c,CGFloat x,CGFloat y,CGFloat radius,CGFloat startAngle,CGFloat endAngle,int clockwise)

55     //1弧度＝180°/π（≈57.3°）度

56     //360°＝360 * π/180＝2π弧度

57     //x,y为圆点坐标，radius半径，startAngle为开始的弧度，endAngle为结束的弧度，clockwise0为顺时针，1为逆时针。

58     CGContextAddArc(contextRef, 70.0, 200.0, 50.0, 0, 2*M_PI, 0); //添加一个圆；M_PI为180度

59     CGContextDrawPath(contextRef, kCGPathStroke); //绘制路径

60 }

61 

62 - (void)drawRectangle {

63     CGContextRef contextRef = UIGraphicsGetCurrentContext(); //获取绘制上下文对象实例

64     CGContextSetRGBStrokeColor(contextRef, 0.0, 0.0, 0.0, 1.0); //设置笔画颜色

65     CGContextSetLineWidth(contextRef, 2.0); //设置线条粗细大小

66     

67     CGContextAddRect(contextRef, CGRectMake(20.0, 300.0, 200.0, 100.0)); //设置矩形位置和宽高

68     CGContextStrokePath(contextRef); //沿着要求的路径，开始绘制

69 }

70 

71 @end

ViewController.h

 

1 #import <UIKit/UIKit.h>

2 

3 @interface ViewController : UIViewController

4 

5 

6 @end

ViewController.m

 1 #import "ViewController.h"

 2 #import "KMDrawView.h"

 3 

 4 @interface ViewController ()

 5 - (void)layoutUI;

 6 @end

 7 

 8 @implementation ViewController

 9 

10 - (void)viewDidLoad {

11     [super viewDidLoad];

12     

13     [self layoutUI];

14 }

15 

16 - (void)didReceiveMemoryWarning {

17     [super didReceiveMemoryWarning];

18     // Dispose of any resources that can be recreated.

19 }

20 

21 - (void)layoutUI {

22     KMDrawView *drawView = [[KMDrawView alloc] initWithFrame:self.view.frame];

23     [self.view addSubview:drawView];

24 }

25 

26 @end