Question

我坚持这个问题。我需要在前一个终点到下一个起点之间划一条线。我在2点之间画一条线的代码是

- (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) ;
}

我如何提供多个点，以便我可以像图表一样显示。提前致谢

Answer 1

另外，Apple更倾向于使用更高级的UIKit方法而不是Core Graphics调用来处理绘制线条和曲线之类的简单内容，因此您可以像这样重写方法：

[[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];

Answer 2

只需添加更多CGContextAddLineToPoint来电

- (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 3

对你的代码稍微纠正一下：

-(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是您正在使用的imageview的插座。

正如您所看到的 - 您只需向此方法发送您的起点和结束点！轻松1-2-3。

编辑1

如何使用它？声明全局CGPoint“startPoint”;

然后说：

//___________________________________________________
- (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;
}

编辑2

这是绘制积分的另一种方式：

- (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];
    }
}

在前一个终点到下一个起点之间画一条线

3 个答案: