关于 Drawrect方法的使用

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// Initialization code
static UIImage *defaultImage = nil;

static dispatch_once_t onceToken;意思是只允许创建一次
dispatch_once(&onceToken, ^{
UIGraphicsBeginImageContextWithOptions(frame.size, NO, 0.0f);
[[UIColor blackColor] setFill];
[[UIBezierPath bezierPathWithRect:CGRectMake(0, 0, frame.size.width-2, 40)] fill];
[[UIBezierPath bezierPathWithRect:CGRectMake(0, 41 ,frame.size.width-2, 40)] fill];
[[UIBezierPath bezierPathWithRect:CGRectMake(0, 82, frame.size.width-2, 40)] fill];
defaultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.backgroundColor = [UIColor colorWithPatternImage:defaultImage];
});
}
1.必须在UIView的类里面实现 - (void)drawRect:(CGRect)rect 方法
#import "MyView.h"
@interface ViewController : UIViewController
{
MyView *drawView;
}
@end
@interface MyView : UIView

@end
#import "MyView.h"

@implementation MyView

- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
self.backgroundColor=[UIColor whiteColor];
self.frame=CGRectMake(10, 20, 300, 400);
}
return self;
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
}
*/

-(void)drawRect:(CGRect )rect
{
CGContextRef context=UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 0.5, 0.5, 0.5, 0.5);
CGContextMoveToPoint(context, 20, 20);
CGContextAddLineToPoint(context, 200, 20);
CGContextStrokePath(context);
｝
1. 1. // Only override drawRect: if you perform custom drawing.
2. // An empty implementation adversely affects performance during animation.
3. - (void)drawRect:(CGRect)rect {
4. // Drawing code.
5. //获得处理的上下文
6. CGContextRef context = UIGraphicsGetCurrentContext();
7. //设置线条样式
8. CGContextSetLineCap(context, kCGLineCapSquare);
9. //设置线条粗细宽度
10. CGContextSetLineWidth(context, 1.0);
12. //设置颜色
13. CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
14. //开始一个起始路径
15. CGContextBeginPath(context);
16. //起始点设置为(0,0):注意这是上下文对应区域中的相对坐标，
17. CGContextMoveToPoint(context, 0, 0);
18. //设置下一个坐标点
19. CGContextAddLineToPoint(context, 100, 100);
20. //设置下一个坐标点
21. CGContextAddLineToPoint(context, 0, 150);
22. //设置下一个坐标点
23. CGContextAddLineToPoint(context, 50, 180);
24. //连接上面定义的坐标点
25. CGContextStrokePath(context);
27. }
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();

/*NO.1画一条线

   CGContextSetRGBStrokeColor(context, 0.5, 0.5, 0.5, 0.5);//线条颜色
   CGContextMoveToPoint(context, 20, 20);
   CGContextAddLineToPoint(context, 200,20);
   CGContextStrokePath(context);
*/

/*NO.2写文字

CGContextSetLineWidth(context, 1.0);
CGContextSetRGBFillColor (context, 0.5, 0.5, 0.5, 0.5);
UIFont *font = [UIFont boldSystemFontOfSize:18.0];
[@"公司：北京中软科技股份有限公司\n部门：ERP事业部\n姓名：McLiang" drawInRect:CGRectMake(20, 40, 280, 300) withFont:font];
*/

/*NO.3画一个正方形图形没有边框

CGContextSetRGBFillColor(context, 0, 0.25, 0, 0.5);
CGContextFillRect(context, CGRectMake(2, 2, 270, 270));
CGContextStrokePath(context);
*/


/*NO.4画正方形边框

CGContextSetRGBStrokeColor(context, 0.5, 0.5, 0.5, 0.5);//线条颜色
CGContextSetLineWidth(context, 2.0);
CGContextAddRect(context, CGRectMake(2, 2, 270, 270));
CGContextStrokePath(context);
*/

/*NO.5画方形背景颜色

CGContextTranslateCTM(context, 0.0f, self.bounds.size.height);
CGContextScaleCTM(context, 1.0f, -1.0f);
UIGraphicsPushContext(context);
CGContextSetLineWidth(context,320);
CGContextSetRGBStrokeColor(context, 250.0/255, 250.0/255, 210.0/255, 1.0);
CGContextStrokeRect(context, CGRectMake(0, 0, 320, 460));
UIGraphicsPopContext();
*/

/*NO.6椭圆

   CGRect aRect= CGRectMake(80, 80, 160, 100);
   CGContextSetRGBStrokeColor(context, 0.6, 0.9, 0, 1.0);
   CGContextSetLineWidth(context, 3.0);
   CGContextAddEllipseInRect(context, aRect); //椭圆
   CGContextDrawPath(context, kCGPathStroke);
*/

/*NO.7
CGContextBeginPath(context);
CGContextSetRGBStrokeColor(context, 0, 0, 1, 1);
CGContextMoveToPoint(context, 100, 100);
CGContextAddArcToPoint(context, 50, 100, 50, 150, 50);
CGContextStrokePath(context);
*/

/*NO.8渐变
CGContextClip(context);
CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
CGFloat colors[] =
{
204.0 / 255.0, 224.0 / 255.0, 244.0 / 255.0, 1.00,
29.0 / 255.0, 156.0 / 255.0, 215.0 / 255.0, 1.00,
0.0 / 255.0, 50.0 / 255.0, 126.0 / 255.0, 1.00,
};
CGGradientRef gradient = CGGradientCreateWithColorComponents
(rgb, colors, NULL, sizeof(colors)/(sizeof(colors[0])*4));
CGColorSpaceRelease(rgb);
CGContextDrawLinearGradient(context, gradient,CGPointMake
(0.0,0.0) ,CGPointMake(0.0,self.frame.size.height),
kCGGradientDrawsBeforeStartLocation);
   */


/* NO.9四条线画一个正方形
//画线
UIColor *aColor = [UIColor colorWithRed:0 green:1.0 blue:0 alpha:0];
CGContextSetRGBStrokeColor(context, 1.0, 0, 0, 1.0);
   CGContextSetFillColorWithColor(context, aColor.CGColor);
CGContextSetLineWidth(context, 4.0);
CGPoint aPoints[5];
aPoints[0] =CGPointMake(60, 60);
aPoints[1] =CGPointMake(260, 60);
aPoints[2] =CGPointMake(260, 300);
aPoints[3] =CGPointMake(60, 300);
aPoints[4] =CGPointMake(60, 60);
CGContextAddLines(context, aPoints, 5);
CGContextDrawPath(context, kCGPathStroke); //开始画线
   */

/* NO.10
UIColor *aColor = [UIColor colorWithRed:0 green:1.0 blue:0 alpha:0];
CGContextSetRGBStrokeColor(context, 1.0, 0, 0, 1.0);
CGContextSetFillColorWithColor(context, aColor.CGColor);
//椭圆
CGRect aRect= CGRectMake(80, 80, 160, 100);
CGContextSetRGBStrokeColor(context, 0.6, 0.9, 0, 1.0);
CGContextSetLineWidth(context, 3.0);
CGContextSetFillColorWithColor(context, aColor.CGColor);
   CGContextAddRect(context, rect); //矩形
CGContextAddEllipseInRect(context, aRect); //椭圆
CGContextDrawPath(context, kCGPathStroke);
   */

/* NO.11
   画一个实心的圆

   CGContextFillEllipseInRect(context, CGRectMake(95, 95, 100.0, 100));
*/

/*NO.12
   画一个菱形
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextMoveToPoint(context, 100, 100);
CGContextAddLineToPoint(context, 150, 150);
CGContextAddLineToPoint(context, 100, 200);
CGContextAddLineToPoint(context, 50, 150);
CGContextAddLineToPoint(context, 100, 100);
CGContextStrokePath(context);
   */

/*NO.13 画矩形
CGContextSetLineWidth(context, 2.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGRect rectangle = CGRectMake(60,170,200,80);

CGContextAddRect(context, rectangle);

CGContextStrokePath(context);
   */


/*椭圆
CGContextSetLineWidth(context, 2.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGRect rectangle = CGRectMake(60,170,200,80);

CGContextAddEllipseInRect(context, rectangle);

CGContextStrokePath(context);
   */

/*用红色填充了一段路径:

CGContextMoveToPoint(context, 100, 100);
CGContextAddLineToPoint(context, 150, 150);
CGContextAddLineToPoint(context, 100, 200);
CGContextAddLineToPoint(context, 50, 150);
CGContextAddLineToPoint(context, 100, 100);
CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
CGContextFillPath(context);
*/

/*填充一个蓝色边的红色矩形
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGRect rectangle = CGRectMake(60,170,200,80);
CGContextAddRect(context, rectangle);
CGContextStrokePath(context);
CGContextSetFillColorWithColor(context, [UIColor redColor].CGColor);
CGContextFillRect(context, rectangle);
*/

/*画弧
   //弧线的是通过指定两个切点，还有角度，调用CGContextAddArcToPoint()绘制
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGContextMoveToPoint(context, 100, 100);
CGContextAddArcToPoint(context, 100,200, 300,200, 100);
CGContextStrokePath(context);
*/


/*
绘制贝兹曲线
//贝兹曲线是通过移动一个起始点，然后通过两个控制点,还有一个中止点，调用CGContextAddCurveToPoint()函数绘制
CGContextSetLineWidth(context, 2.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGContextMoveToPoint(context, 10, 10);

CGContextAddCurveToPoint(context, 0, 50, 300, 250, 300, 400);

CGContextStrokePath(context);
   */

/*绘制二次贝兹曲线

CGContextSetLineWidth(context, 2.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGContextMoveToPoint(context, 10, 200);

CGContextAddQuadCurveToPoint(context, 150, 10, 300, 200);

CGContextStrokePath(context);
   */

/*绘制虚线
CGContextSetLineWidth(context, 5.0);

CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);

CGFloat dashArray[] = {2,6,4,2};

CGContextSetLineDash(context, 3, dashArray, 4);//跳过3个再画虚线，所以刚开始有6-（3-2）=5个虚点

CGContextMoveToPoint(context, 10, 200);

CGContextAddQuadCurveToPoint(context, 150, 10, 300, 200);

CGContextStrokePath(context);
*/
/*绘制图片
NSString* imagePath = [[NSBundle mainBundle] pathForResource:@"dog" ofType:@"png"];
UIImage* myImageObj = [[UIImage alloc] initWithContentsOfFile:imagePath];
//[myImageObj drawAtPoint:CGPointMake(0, 0)];
[myImageObj drawInRect:CGRectMake(0, 0, 320, 480)];

NSString *s = @"我的小狗";

[s drawAtPoint:CGPointMake(100, 0) withFont:[UIFont systemFontOfSize:34.0]];
*/

/*
NSString *path = [[NSBundle mainBundle] pathForResource:@"dog" ofType:@"png"];
UIImage *img = [UIImage imageWithContentsOfFile:path];
CGImageRef image = img.CGImage;
CGContextSaveGState(context);
CGRect touchRect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, touchRect, image);
CGContextRestoreGState(context);
   */

/*NSString *path = [[NSBundle mainBundle] pathForResource:@"dog" ofType:@"png"];
UIImage *img = [UIImage imageWithContentsOfFile:path];
CGImageRef image = img.CGImage;
CGContextSaveGState(context);

CGContextRotateCTM(context, M_PI);
CGContextTranslateCTM(context, -img.size.width, -img.size.height);

CGRect touchRect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, touchRect, image);
CGContextRestoreGState(context);*/

/*
NSString *path = [[NSBundle mainBundle] pathForResource:@"dog" ofType:@"png"];
UIImage *img = [UIImage imageWithContentsOfFile:path];
CGImageRef image = img.CGImage;

CGContextSaveGState(context);

CGAffineTransform myAffine = CGAffineTransformMakeRotation(M_PI);
myAffine = CGAffineTransformTranslate(myAffine, -img.size.width, -img.size.height);
CGContextConcatCTM(context, myAffine);

CGContextRotateCTM(context, M_PI);
CGContextTranslateCTM(context, -img.size.width, -img.size.height);

CGRect touchRect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, touchRect, image);
CGContextRestoreGState(context);
*/
}