Question

我正在尝试开发一个绘画应用程序，它允许用户通过选择不同颜色的画笔来绘制/绘制图像。我试图通过继承uiimageview来实现它并覆盖以下方法：

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

    UITouch *touch = [touches anyObject];


    lastPoint = [touch locationInView:self];
    //  lastPoint.y -=20;// only if signature goes bottom of the screen
}


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

    UITouch *touch = [touches anyObject];   
    CGPoint currentPoint = [touch locationInView:self];
    //  currentPoint.y -=20; // only if signature goes bottom of the screen


    UIGraphicsBeginImageContext(self.frame.size);

    CGContextRef currentContext = UIGraphicsGetCurrentContext();
    [self.image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
    CGContextSetLineCap(currentContext, kCGLineCapRound);
    CGContextSetLineWidth(currentContext, 15.0);
    CGContextSetRGBStrokeColor(currentContext, 1.0, 0.0, 0.0, 1.0);
    CGContextBeginPath(currentContext);
    CGContextMoveToPoint(currentContext, lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(currentContext, currentPoint.x, currentPoint.y);
    CGContextStrokePath(currentContext);
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    lastPoint = currentPoint;
}

但问题在于，如果用户绘制图像的边界线，则颜色会隐藏边界线。即使用户也在边界线上绘制，我也需要使边界线可见。是否可以这样做或者我是否需要继续使用任何openGL技术。请分享您的意见..

提前致谢..

Answer 1

您可以创建仅包含边框的UIView子类，并将其添加到当前视图之上。您只需在pointInside: withEvent:方法中返回否，即可将触摸转移到其下方的视图中。

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event{
    return NO;
}

iphone绘画应用程序

1 个答案: