IOS開發（80）之畫線

1 前言
得到圖形環境,然後用 CGContextMoveToPoint 和 CGContextAddLineToPoint 函數來畫線。

2 代碼執行個體
ZYViewControllerView.m

 

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- (void)drawRect:(CGRect)rect{ 
    [self drawRooftopAtTopPointof:CGPointMake(160.0f, 40.0f) textToDisplay:@"Miter" 
                         lineJoin:kCGLineJoinMiter]; 
    [self drawRooftopAtTopPointof:CGPointMake(160.0f, 180.0f) textToDisplay:@"Bevel" 
                         lineJoin:kCGLineJoinBevel]; 
    [self drawRooftopAtTopPointof:CGPointMake(160.0f, 320.0f) textToDisplay:@"Round" 
                        lineJoin:kCGLineJoinRound]; 
} 
/* 
 paramTopPoint:一個點,頂部在這一點 
 textToDisplay:內顯示的文字 
 lineJoin:要使用的接合類型 
        kCGLineJoinMiter 
        接合點為尖角。這是預設的接合類型。 
        kCGLineJoinBevel 
        接合點為斜角 
        kCGLineJoinRound 
        接合點為圓角 
 */ 
- (void) drawRooftopAtTopPointof:(CGPoint)paramTopPoint textToDisplay:(NSString *)paramText 
                        lineJoin:(CGLineJoin)paramLineJoin{ 
    /*設定線條顏色*/ 
    [[UIColor brownColor] set]; 
    //獲得當前圖形上下文 
    CGContextRef currentContext = UIGraphicsGetCurrentContext(); 
    //設定連線類型 
    CGContextSetLineJoin(currentContext, paramLineJoin); 
    //設定線條寬度 
    CGContextSetLineWidth(currentContext,20.0f); 
    //設定開始點位置 
    CGContextMoveToPoint(currentContext,paramTopPoint.x - 140, paramTopPoint.y + 100); 
    //設定終點 
    CGContextAddLineToPoint(currentContext,paramTopPoint.x, paramTopPoint.y); 
    //設定另一個終點 
    CGContextAddLineToPoint(currentContext,paramTopPoint.x + 140, paramTopPoint.y + 100); 
    //畫線 
    CGContextStrokePath(currentContext); 
    [[UIColor blackColor] set]; 
    /* 寫文字 */ 
    CGPoint drawingPoint = CGPointMake(paramTopPoint.x - 40.0f, 
                                   paramTopPoint.y + 60.0f); 
    [paramText drawAtPoint:drawingPoint withFont:[UIFont boldSystemFontOfSize:30.0f]]; 
}