在石英2D中擦除操作

Question

關於如何在Quartz 2D中執行擦除操作的任何建議？

Answer 1

CGContextClearRect(UIGraphicsGetCurrentContext(), rect); 

Answer 2

if (clear) { 

     CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal); 
     CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [UIColor    colorWithPatternImage:[UIImage imageNamed:@"rainbow-colors-orange-320x480.jpg"]].CGColor); 
     // your background image. make sure it is same size 

    } else { 
     CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal); 
     NSUInteger red, green, blue; 
     sscanf([stringColor UTF8String], "#%02X%02X%02X", &red, &green, &blue); 
     UIColor *colors = [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:1]; 
     CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [colors CGColor]); 

    }