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我正在创建一个绘画应用程序，但是如果描边一条线一种颜色，如果描边另一条线穿过前一个描边，则第一个描边将颜色更改为第二种颜色在此处输入图像描述

这是我用来绘画的代码：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];

    previousPoint1 = [touch previousLocationInView:self];
    previousPoint2 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];

    [self touchesMoved:touches withEvent:event];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];

    CGPoint point = [touch locationInView:self];

    /* check if the point is farther than min dist from previous */
    CGFloat dx = point.x - currentPoint.x;
    CGFloat dy = point.y - currentPoint.y;

    if ((dx * dx + dy * dy) < kPointMinDistanceSquared) {
        return;
    }

    previousPoint2 = previousPoint1;
    previousPoint1 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];

    CGPoint mid1 = midPoint(previousPoint1, previousPoint2);
    CGPoint mid2 = midPoint(currentPoint, previousPoint1);
    CGMutablePathRef subpath = CGPathCreateMutable();
    CGPathMoveToPoint(subpath, NULL, mid1.x, mid1.y);
    CGPathAddQuadCurveToPoint(subpath, NULL, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y);
    CGRect bounds = CGPathGetBoundingBox(subpath);

    CGPathAddPath(path, NULL, subpath);
    CGPathRelease(subpath);

    CGRect drawBox = bounds;
    drawBox.origin.x -= self.lineWidth * 2.0;
    drawBox.origin.y -= self.lineWidth * 2.0;
    drawBox.size.width += self.lineWidth * 4.0;
    drawBox.size.height += self.lineWidth * 4.0;

    [self setNeedsDisplayInRect:drawBox];
}

- (void)drawRect:(CGRect)rect {

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextAddPath(context, path);
    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, self.lineWidth);
    CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);

    CGContextStrokePath(context);


    self.empty = NO;
}

你们中的任何人都知道我做错了什么，或者我怎样才能让每个笔画彼此独立？

我会非常感谢你的帮助。

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1 回答 1

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我认为您需要做的是在更改颜色时开始新的路径。不要只是不断地将具有新颜色的新子路径添加到具有旧颜色的同一路径中。

您将需要为每个路径存储它应该呈现的颜色，然后在 drawRect 方法中循环遍历您的路径。

于 2012-10-22T01:18:25.680 回答