android paint cap join 理解 图示

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网上查了很多资料，对paint的里面的枚举类cap join讲的不是很透彻。在这里自己做一个比较深入的研究。

首先说Cap，比较形象的解释就是 用来控制我们的画笔在离开画板时候留下的最后一点图形，比如矩形，圆形等。不懂？那接着往下看。

先看看源码：

    /**
     * The Cap specifies the treatment for the beginning and ending of
     * stroked lines and paths. The default is BUTT.
     */
    public enum Cap {
        /**
         * The stroke ends with the path, and does not project beyond it.
         */
        BUTT    (0),
        /**
         * The stroke projects out as a semicircle, with the center at the
         * end of the path.
         */
        ROUND   (1),
        /**
         * The stroke projects out as a square, with the center at the end
         * of the path.
         */
        SQUARE  (2);
        
        private Cap(int nativeInt) {
            this.nativeInt = nativeInt;
        }
        final int nativeInt;
    }

下面看几张图片，我想足以理解Cap的用途。

BUTT
ROUND
SQUARE

上表就是三种样式的区别，竖线处即为画笔结束处，图中区别明显，在此不再赘述。

接着我们看Join，Join的理解也很容易，他是用来控制画的图形接触时候的样式的。

看源码：

    /**
     * The Join specifies the treatment where lines and curve segments
     * join on a stroked path. The default is MITER.
     */
    public enum Join {
        /**
         * The outer edges of a join meet at a sharp angle
         */
        MITER   (0),
        /**
         * The outer edges of a join meet in a circular arc.
         */
        ROUND   (1),
        /**
         * The outer edges of a join meet with a straight line
         */
        BEVEL   (2);
        
        private Join(int nativeInt) {
            this.nativeInt = nativeInt;
        }
        final int nativeInt;
    }

MITER
ROUND
BEVEL

上表就是三种样式的区别，区别明显，在此不再赘述。