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  1. POWhy are my lines getting thicker and thicker?
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    <p>I try to draw some lines with different colors. </p> <p>This code tries to draw two rectangles with 1px thin lines. However, the second rectangle is drawn with 2px width lines, while the first one is drawn with 1px width.</p> <pre><code>- (void)addLineFrom:(CGPoint)p1 to:(CGPoint)p2 context:(CGContextRef)context { // set the current point CGContextMoveToPoint(context, p1.x, p1.y); // add a line from the current point to the wanted point CGContextAddLineToPoint(context, p2.x, p2.y); } - (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGPoint from, to; // ----- draw outer black frame (left, bottom, right) ----- CGContextBeginPath(context); // set the color CGFloat lineColor[4] = {26.0f * colorFactor, 26.0f * colorFactor, 26.0f * colorFactor, 1.0f}; CGContextSetStrokeColor(context, lineColor); // left from = CGPointZero; to = CGPointMake(0.0f, rect.size.height); [self addLineFrom:from to:to context:context]; // bottom from = to; to = CGPointMake(rect.size.width, rect.size.height); [self addLineFrom:from to:to context:context]; // right from = to; to = CGPointMake(rect.size.width, 0.0f); [self addLineFrom:from to:to context:context]; CGContextStrokePath(context); CGContextClosePath(context); // ----- draw the middle light gray frame (left, bottom, right) ----- CGContextSetLineWidth(context, 1.0f); CGContextBeginPath(context); // set the color CGFloat lineColor2[4] = {94.0f * colorFactor, 94.0f * colorFactor, 95.0f * colorFactor, 1.0f}; CGContextSetStrokeColor(context, lineColor2); // left from = CGPointMake(200.0f, 1.0f); to = CGPointMake(200.0f, rect.size.height - 2.0f); [self addLineFrom:from to:to context:context]; // bottom from = to; to = CGPointMake(rect.size.width - 2.0f, rect.size.height - 2.0f); [self addLineFrom:from to:to context:context]; // right from = to; to = CGPointMake(rect.size.width - 2.0f, 1.0f); [self addLineFrom:from to:to context:context]; // top from = to; to = CGPointMake(1.0f, 1.0f); [self addLineFrom:from to:to context:context]; CGContextStrokePath(context); } </code></pre>
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