iOS 플랫폼에서 선을 그리는 방법

Question

대나무 책과 종이 같은 앱을 사용하고 있습니다. iPad에서는 경험이 정말 좋은데, 어떻게 작동합니까? 어떤 기술이 선이나 곡선을 화면에 그릴 때 사용됩니까?

Answer 1

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 

    mouseSwiped = NO; 
    UITouch *touch = [touches anyObject]; 

    if ([touch tapCount] == 2) { 
     //self.imageView.image = nil; 
     return; 
    } 

    lastPoint = [touch locationInView:self.view]; 
    lastPoint.y -= 20; 

} 

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
    mouseSwiped = YES; 

    UITouch *touch = [touches anyObject]; 
    CGPoint currentPoint = [touch locationInView:self.view]; 
    currentPoint.y -= 20; 

    CGFloat components[3]; 
    [self getRGBComponents:components forColor:self.colorView.backgroundColor]; 
    NSLog(@"%f %f %f", components[0], components[1], components[2]); 

    UIGraphicsBeginImageContext(self.view.frame.size); 
    [self.imageView.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; 
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); 
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 10.0); 
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), components[0], components[1], components[2],5.0); 
    CGContextBeginPath(UIGraphicsGetCurrentContext()); 
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); 
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y); 


     CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeNormal); 


    CGContextStrokePath(UIGraphicsGetCurrentContext()); 
    self.imageView.image = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    lastPoint = currentPoint; 

    mouseMoved++; 

    if (mouseMoved == 10) { 
     mouseMoved = 0; 
    } 

} 

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { 

    UITouch *touch = [touches anyObject]; 

    if ([touch tapCount] == 2) { 
     //self.imageView.image = nil; 
     return; 
    } 


    if(!mouseSwiped) { 

     CGFloat components[3]; 
     [self getRGBComponents:components forColor:self.colorView.backgroundColor]; 
     NSLog(@"%f %f %f", components[0], components[1], components[2]); 

     UIGraphicsBeginImageContext(self.view.frame.size); 
     [self.imageView.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)]; 
     CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); 
     CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); 
     CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), components[0], components[1], components[2], 5.0); 
     CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); 
     CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); 
     CGContextStrokePath(UIGraphicsGetCurrentContext()); 
     CGContextFlush(UIGraphicsGetCurrentContext()); 
     self.imageView.image = UIGraphicsGetImageFromCurrentImageContext(); 
     UIGraphicsEndImageContext(); 
    } 
} 

또한 링크를 확인 정확하게 프로그래밍 질문,하지만 아이폰 OS에서이 높습니다 아니에요

http://www.techotopia.com/index.php/An_iOS_4_iPhone_Graphics_Drawing_Tutorial_using_Quartz_2D

https://stackoverflow.com/questions/6449661/drawing-2d-images-on-iphone-tutorials

http://mobile.tutsplus.com/tutorials/iphone/ios-sdk_freehand-drawing/

http://www.raywenderlich.com/18840/how-to-make-a-simple-drawing-app-with-uikit