在上一個終點到下一個起點之間劃一條線

Question

我被困在這個問題上。我需要在上一個終點到下一個起點之間畫一條線。我在2點之間繪製一條線的代碼是

- (void)drawRect:(CGRect)rect 
{ 
    CGContextRef c=UIGraphicsGetCurrentContext(); 
    CGContextSetLineWidth(c, 4.0); 
    CGFloat red[4]={0.0f, 0.0f, 0.0f, 1.0f}; 
    CGContextSetStrokeColor(c, red); 
    CGContextBeginPath(c); 
    CGContextMoveToPoint(c, 50.0f, 50.0f); 
    CGContextAddLineToPoint(c, 100.0f, 100.0f); 
    CGContextStrokePath(c) ; 
} 

我該如何給出多個點，以便我可以將它顯示爲一個圖形。 在此先感謝

Answer 1

只需添加更多CGContextAddLineToPoint電話

- (void)drawRect:(CGRect)rect 
{ 
    CGContextRef c=UIGraphicsGetCurrentContext(); 
    CGContextSetLineWidth(c, 4.0); 
    CGFloat red[4]={0.0f, 0.0f, 0.0f, 1.0f}; 
    CGContextSetStrokeColor(c, red); 
    CGContextBeginPath(c); 
    CGContextMoveToPoint(c, 50.0f, 50.0f); 
    CGContextAddLineToPoint(c, 100.0f, 100.0f); 
    CGContextAddLineToPoint(c, 120.0f, 80.0f); 
    CGContextAddLineToPoint(c, 140.0f, 120.0f); 
    CGContextAddLineToPoint(c, 160.0f, 80.0f); 
    ... 

    CGContextStrokePath(c) ; 
} 

Answer 2

只求一點點修正代碼：

-(void)drawLineFromPoint:(CGPoint)startPoint toPoint:(CGPoint)endPoint{ 
    UIGraphicsBeginImageContext(YOUR_IMAGEVIEW.image.size); 
    [YOUR_IMAGEVIEW.image drawInRect:CGRectMake(0, 0, YOUR_IMAGEVIEW.image.size.width, YOUR_IMAGEVIEW.image.size.height)]; 
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); 
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); 
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0); 
    CGContextBeginPath(UIGraphicsGetCurrentContext()); 
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), startPoint.x, startPoint.y); 
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), endPoint.x, endPoint.y); 
    CGContextStrokePath(UIGraphicsGetCurrentContext()); 
    [YOUR_IMAGEVIEW setImage:UIGraphicsGetImageFromCurrentImageContext()]; 
    UIGraphicsEndImageContext(); 
} 

YOUR_IMAGEVIEW是出口到您的ImageView你借鑑。

正如你所看到的 - 你只需要發送到這個方法你的起點和最後一個！易1-2-3。

編輯1

如何使用它？聲明全局CGPoint「startPoint」;

然後說：

//___________________________________________________ 
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    startPoint = [touch locationInView:YOUR_IMAGEVIEW]; 
} 
//___________________________________________________ 
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ 
    UITouch *touch = [touches anyObject]; 
    CGPoint nextPoint = [touch locationInView:YOUR_IMAGEVIEW]; 
    [self drawLineFromPoint:startPoint toPoint:nextPoint]; 
    startPoint = nextPoint; 
} 

EDIT 2

這裏是另一種方式來提醒你幾點：

- (void)drawGraphMethod{ 
    NSMutableArray *pointsArr = [[[NSMutableArray alloc]init]autorelease]; 
    //now you should add the needed points to your array 
    //I have no idea what graph do you have, so I just 
    //put there some random points that will look like a graph 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(30.0, 10.0)]]; 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(40.0, 26.0)]]; 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(70.0, 55.0)]]; 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(80.0, 88.0)]]; 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(90.0, 33.0)]]; 
    [pointsArr addObject:[NSValue valueWithCGPoint:CGPointMake(130.0, 100.0)]]; 
    //well, you can store only objects, that's why I used NSValue. 
    //it's not hard to cenvert it back 

    //now parse the array 
    for (int i = 0; i < pointsArr.count-1; i++) { 
     CGPoint startPoint = [[pointsArr objectAtIndex:i] CGPointValue]; 
     CGPoint nextPoint = [[pointsArr objectAtIndex:i+1] CGPointValue]; 
     [self drawLineFromPoint:startPoint toPoint:nextPoint]; 
    } 
} 

Answer 3

在一個附帶說明，蘋果更喜歡使用更高的UIKit方法代替核芯顯卡要求像畫線和曲線簡單的東西，所以你可以重寫你這樣的方法：

[[UIColor redColor] setStroke]; 

UIBezierPath *linePath = [UIBezierPath bezierPath]; 

[linePath moveToPoint:CGPointMake(50.0, 50.0)]; 
[linePath addLineToPoint:CGPointMake(100.0, 100.0)]; 
[linePath setLineWidth:4.0]; 
[linePath stroke];