IOS开发（86）之旋转图形

1 前言
使用 cgaffinetransformmakerotation/cgcontextrotatectm函数来创建一个仿射旋转变换。

2 代码实例
zyviewcontrollerview.m

 

[plain] - (void)drawrect:(cgrect)rect{ 
    /* create the path first. just the path handle. */ 
    cgmutablepathref path = cgpathcreatemutable(); 
    /* here are our rectangle boundaries */ 
    cgrect rectangle = cgrectmake(10.0f,10.0f, 200.0f, 300.0f); 
    /* add the rectangle to the path */ 
    cgpathaddrect(path,null, rectangle); 
    /* get the handle to the current context */ 
    cgcontextref currentcontext = uigraphicsgetcurrentcontext(); 
    /* save the state of the context to revert back to how it was at this state, later */ 
    cgcontextsavegstate(currentcontext); 
    //顺时针旋转45度 
    cgcontextrotatectm(currentcontext,(45.0f * m_pi) / 180.0f); 
    /* add the path to the context */ 
    cgcontextaddpath(currentcontext, path); 
    /* set the fill color to cornflower blue */ 
    [[uicolor colorwithred:0.20f green:0.60f blue:0.80f alpha:1.0f] setfill]; 
    /* set the stroke color to brown */ 
    [[uicolor browncolor] setstroke]; 
    /* set the line width (for the stroke) to 5 */ 
    cgcontextsetlinewidth(currentcontext,5.0f); 
    /* stroke and fill the path on the context */ 
    cgcontextdrawpath(currentcontext, kcgpathfillstroke); 
    /* dispose of the path */ 
    cgpathrelease(path); 
    /* restore the state of the context */ 
    cgcontextrestoregstate(currentcontext); 
}