核心图形文本比核心文本更快 - 我觉得我错过了一些东西

Question

这是我用来在核心图形中显示一些文本的代码:

int y = MESSAGE_FRAME.origin.y + 8;

if (month) y = y + 27;
int height = [JHomeViewCellContentView heightOfMessage:self.entry.message];

CGRect rect = CGRectMake(MESSAGE_FRAME.origin.x + 8, y, MESSAGE_FRAME.size.width - 16, height);

UIFont *font = [UIFont fontWithName:@"Crimson" size:15.0f];

[[UIColor colorWithWhite:0.2 alpha:1.0] setFill];

[self.entry.message drawInRect:rect withFont:font lineBreakMode:UILineBreakModeWordWrap alignment:UITextAlignmentLeft];

如果我想在核心文本中显示相同的文本,这是代码:

CGRect rect2 = CGRectMake(MESSAGE_FRAME.origin.x + 8, self.bounds.size.height - y - height + 2, MESSAGE_FRAME.size.width - 16, height);


    UIFont *font = [UIFont fontWithName:@"Crimson" size:15.0f];
    CGFloat lineHeight = [font lineHeight];

    CTFontRef fontRef = CTFontCreateWithName((CFStringRef)@"Crimson", 15.0f, NULL);

    CGFloat lineSpacing = 0;

    CTParagraphStyleSetting settings[] = {
        { kCTParagraphStyleSpecifierMinimumLineHeight, sizeof(lineHeight), &lineHeight },
        { kCTParagraphStyleSpecifierMaximumLineSpacing, sizeof(lineSpacing), &lineSpacing },

    };

    CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settings, sizeof(settings) / sizeof(settings[0]));

    NSMutableDictionary *attDictionary = [NSMutableDictionary dictionaryWithObjectsAndKeys:
                                   (__bridge_transfer id)fontRef, (NSString *)kCTFontAttributeName,
                                          (id)[[UIColor colorWithWhite:0.2 alpha:1.0] CGColor], (NSString *)kCTForegroundColorAttributeName,
                                          paragraphStyle, kCTParagraphStyleAttributeName,
                                          nil];

     NSAttributedString *attString = [[NSAttributedString alloc] initWithString:self.entry.message attributes:attDictionary];

    //Flip the coordinate system
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);



    CGMutablePathRef path = CGPathCreateMutable();
    CGPathAddRect(path, NULL, rect2);


    self.framesetter = CTFramesetterCreateWithAttributedString((__bridge_retained CFAttributedStringRef)attString);
    CTFrameRef theFrame = CTFramesetterCreateFrame(self.framesetter, CFRangeMake(0, [attString length]), path, NULL);

    CFRelease(path);

    CTFrameDraw(theFrame, context);
    CFRelease(theFrame);

显然,尽管更加长篇大论,核心文本意味着比核心图形更快,这也是我学会如何做到这一点的原因.但是通过仪器运行此代码,核心图形实现了5ms,而核心文本则在14ms内完成.我觉得我在这里错过了一些东西.drawInRect几乎快了3倍,我听说它应该慢一些.我已经根据我的知识对底部的代码进行了改进,但我不是专家,我很感激任何帮助.

为了澄清,我正在将一段文本绘制到视图上.这就是我想做的一切.并且所有文本都具有相同的外观.

Answer 1

我不使用 CT 的东西，但在我看来，你在每次绘制时都设置了不变的字体和其他属性。尝试分解注释“翻转坐标系，并缓存 attString”之前的所有内容。

这应该会提高速度，以便更好地进行面对面测试。