Objective-c核心图形绘制旋转图像不起作用

Question

我正在尝试使用以下代码绘制旋转图像

CGLayerRef layer=CGLayerCreateWithContext(context,CGSizeMake(brush.size.width*2,brush.size.height*2), NULL);
CGContextRef tmp=CGLayerGetContext(layer);
CGContextDrawImage(tmp,CGRectMake(brush.size.width/2, brush.size.height/2, brush.size.width, brush.size.height), brush.CGImage);

CGContextSetFillColorWithColor(tmp, [UIColor clearColor].CGColor);
CGContextSetBlendMode(tmp, kCGBlendModeClear);
CGContextFillRect(tmp, CGRectMake(0, 0, 2*brush.size.width, 2*brush.size.height));
CGContextSetBlendMode(tmp, kCGBlendModeNormal);
CGContextTranslateCTM(tmp, -brush.size.width/2, -brush.size.height/2);
CGContextRotateCTM(tmp, angle);
CGContextTranslateCTM(tmp, brush.size.width/2, brush.size.height/2);
CGContextDrawImage(tmp,CGRectMake(brush.size.width/2, brush.size.height/2, brush.size.width, brush.size.height), brush.CGImage);

我想将图像放在图层的中心（图像是正方形）

Answer 1

尝试旋转然后翻译