Graphics are painting a straight line, arc, as well as garden and cut a straight...

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现图形学中画直线，园和圆弧以及直线裁剪，区域填充等功能 1． 对于画直线，只需知道起点和终点即可。在工作区间中按下鼠标（即选择起点），拖动至另一处松开（终点），即得到直线。 2． 画圆需要圆心坐标、半径、及起始角和终止角，至于实验要求的画1/4圆弧，可设起始角=0，终止角=45，若要画整个圆弧起始角和终止角分别为0和360即可。-Graphics are painting a straight line, arc, as well as garden and cut a straight line, filled with features such as region 1. For painting a straight line, just know that you can start and finish. Interval in the work of the mouse click (that is, to choose the starting point), drag to another release (the end), that is to be a straight line. 2. Drawcircle need to center coordinates, radius, and the termination of the initial angle and angle, as required by experimental painting 1/4 arc, the starting angle can be set = 0, terminate the angle = 45, in order to draw the whole arc start angle and termination angle is 0 and 360, respectively, can be.