Question

如何将NSString旋转到一定程度？当我和图像一起画一个字符串时。

我提到了这个问题Drawing rotated text with NSString drawInRect，但我的椭圆已经消失了。

//Add text to UIImage
-(UIImage *)addMoodFound:(int)moodFoundCount andMoodColor:(CGColorRef)mColour
{
    float scaleFactor = [[UIScreen mainScreen] scale];
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(36, 36), NO,scaleFactor);

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);

    //CGContextSetRGBFillColor(context, kCGAggressiveColor);
    CGContextSetFillColorWithColor(context,mColour);
    CGContextFillEllipseInRect(context, CGRectMake(0, 0, 36, 36));
    CGContextSetRGBFillColor(context, 250, 250, 250, 1);

//nsstring missing after adding this 3 line
 CGAffineTransform transform1 = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(65));
    CGContextConcatCTM(context, transform1);
    CGContextTranslateCTM(context, 36, 0);

/////////////////////////////////////////////// /

    [[NSString stringWithFormat:@"%d",moodFoundCount ] drawInRect : CGRectMake(0, 7, 36, 18)
             withFont : [UIFont fontWithName:monR size:17]
        lineBreakMode : NSLineBreakByTruncatingTail
            alignment : NSTextAlignmentCenter ];

    CGContextRestoreGState(context);

    UIImage *theImage=UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return theImage;
}

Answer 1

CGAffineTransformMakeRotation将围绕上下文的原点旋转（在这种情况下x = 0，y = 0）。

要正确旋转文本，您需要首先使用包含字符串的框的中心翻译上下文的原点，旋转并将原点移回原位。

将您使用旋转的3行替换为：

CGContextConcatCTM(context, CGAffineTransformMakeTranslation(18, 18));
CGContextConcatCTM(context, CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(65)));
CGContextConcatCTM(context, CGAffineTransformMakeTranslation(-18, -18));

如何在CGContext中旋转NSString drawinrect

1 个答案: