如何在UIImageView上绘制喷枪？

Question

我是一名初学者，在iphone上进行绘画应用。

为我的iPhone应用程序称为喷枪......

将喷上的UIImageView添加新工具。任何人都可以帮助我解决如何使用它。

Answer 1

我想你可能在寻找CGContextBeginPath及其相关功能。我不太确定如何定义一个新的笔划，但我想它可以用类似[UIColor colorFromImage:myImage]的东西来处理。你应该看看Quartz 2D，试着看看here。

/托马斯

Answer 2

Logic for air brush......... 

- (UIBezierPath *)pathFromPoint:(CGPoint)start toPoint:(CGPoint)end { 

    CGFloat lineWidth=10; 
    redrawRect = CGRectMake(end.x-lineWidth,end.y-lineWidth,lineWidth*2,lineWidth*2); 
    UIBezierPath *bezierPath = [UIBezierPath bezierPath]; 
    UIBezierPath *circle = [UIBezierPath bezierPathWithOvalInRect:redrawRect]; 
    NSInteger i, x, y; 

    NSInteger modNumber =4*(int)lineWidth; 
    for (i = 0; i < (lineWidth*lineWidth)/2; i++) { 
     do { 
      x = (random() % modNumber)+end.x - 2*lineWidth; 
      y = (random() % modNumber)+end.y - 2*lineWidth; 
     } while (![circle containsPoint:CGPointMake(x,y)]); 

     [bezierPath appendPath:[UIBezierPath bezierPathWithRect:CGRectMake(x,y,0.5,0.5)]]; 
    } 
    return bezierPath; 
} 

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [touches anyObject]; 
    currentPoint = [touch locationInView:self.view]; 
    currentPoint.y -=20; 
    [self drawCircle]; 
} 
-(void)drawCircle{ 
    UIGraphicsBeginImageContext(self.drawImage.frame.size); 
    [drawImage.image drawInRect:CGRectMake(0,0, drawImage.frame.size.width, drawImage.frame.size.height)]; //originally self.frame.size.width, self.frame.size.height)]; 
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(),10); 
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 0.0, 0.0, 1.0); 
    UIBezierPath *path=[self pathFromPoint:currentPoint 
            toPoint:currentPoint]; 
    [path stroke]; 
    lastPoint = currentPoint; 
    CGContextStrokePath(UIGraphicsGetCurrentContext()); 
    CGContextFlush(UIGraphicsGetCurrentContext()); 
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
}