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YYAsyncLayer

YYAsyncLayer

作者: Code_人生 | 来源:发表于2019-09-30 14:34 被阅读0次
        NSMutableAttributedString *text = [NSMutableAttributedString new];
    
    {
        //Core Graphics
        NSMutableAttributedString *one = [[NSMutableAttributedString alloc] initWithString:@"Shadow"];
        one.font = [UIFont boldSystemFontOfSize:30];
        one.color = [UIColor whiteColor];
        YYTextShadow *shadow = [YYTextShadow new];
        shadow.color = [UIColor colorWithWhite:0.000 alpha:0.490];
        shadow.offset = CGSizeMake(0, 1);
        shadow.radius = 5;
        one.textShadow = shadow;
        [text appendAttributedString:one];
        [text appendAttributedString:[self padding]];
    }

    YYLabel *label = [YYLabel new];
    label.attributedText = text;
    label.width = self.view.width;
    label.height = self.view.height - (kiOS7Later ? 64 : 44);
    label.top = (kiOS7Later ? 64 : 0);
    label.textAlignment = NSTextAlignmentCenter;
    label.textVerticalAlignment = YYTextVerticalAlignmentCenter;
    label.numberOfLines = 0;
    label.backgroundColor = [UIColor colorWithWhite:0.933 alpha:1.000];
    [self.view addSubview:label];

    1、点击textShadow

    - (void)setTextShadow:(YYTextShadow *)textShadow {
    [self setTextShadow:textShadow range:NSMakeRange(0, self.length)];
}

    - (void)setTextShadow:(YYTextShadow *)textShadow range:(NSRange)range {
    //key-value的形式
    [self setAttribute:YYTextShadowAttributeName value:textShadow range:range];
}

    - (void)setAttribute:(NSString *)name value:(id)value range:(NSRange)range {
    if (!name || [NSNull isEqual:name]) return;
    if (value && ![NSNull isEqual:value]) [self addAttribute:name value:value range:range];
    else [self removeAttribute:name range:range];
}

    2、搜索YYTextShadowAttributeName

    //阴影绘制， Core Text : Graver
static void YYTextDrawShadow(YYTextLayout *layout, CGContextRef context, CGSize size, CGPoint point, BOOL (^cancel)(void)) {
    //move out of context. (0xFFFF is just a random large number)
    CGFloat offsetAlterX = size.width + 0xFFFF;
    BOOL isVertical = layout.container.verticalForm;
    CGFloat verticalOffset = isVertical ? (size.width - layout.container.size.width) : 0;
    
    CGContextSaveGState(context);{
        CGContextTranslateCTM(context, point.x, point.y);
        CGContextTranslateCTM(context, 0, size.height);
        CGContextScaleCTM(context, 1, -1);
        NSArray *lines = layout.lines;
        for (NSUInteger l = 0, lMax = layout.lines.count; l < lMax; l++) {
            if (cancel && cancel()) break;
            YYTextLine *line = lines[l];
            if (layout.truncatedLine && layout.truncatedLine.index == line.index) line = layout.truncatedLine;
            NSArray *lineRunRanges = line.verticalRotateRange;
            CGFloat linePosX = line.position.x;
            CGFloat linePosY = size.height - line.position.y;
            CFArrayRef runs = CTLineGetGlyphRuns(line.CTLine);
            for (NSUInteger r = 0, rMax = CFArrayGetCount(runs); r < rMax; r++) {
                CTRunRef run = CFArrayGetValueAtIndex(runs, r);
//                CGContextSetTextMatrix(context, CGAffineTransformIdentity);
                CGContextSetTextPosition(context, linePosX, linePosY);
                NSDictionary *attrs = (id)CTRunGetAttributes(run);
                YYTextShadow *shadow = attrs[YYTextShadowAttributeName];
                YYTextShadow *nsShadow = [YYTextShadow shadowWithNSShadow:attrs[NSShadowAttributeName]]; // NSShadow compatible
                if (nsShadow) {
                    nsShadow.subShadow = shadow;
                    shadow = nsShadow;
                }
                while (shadow) {
                    if (!shadow.color) {
                        shadow = shadow.subShadow;
                        continue;
                    }
                    CGSize offset = shadow.offset;
                    offset.width -= offsetAlterX;
                    CGContextSaveGState(context); {
                        CGContextSetShadowWithColor(context, offset, shadow.radius, shadow.color.CGColor);
                        CGContextSetBlendMode(context, shadow.blendMode);
                        CGContextTranslateCTM(context, offsetAlterX, 0);
                        YYTextDrawRun(line, run, context, size, isVertical, lineRunRanges[r], verticalOffset);
                    } CGContextRestoreGState(context);
                    shadow = shadow.subShadow;
                }
            }
        }
    }CGContextRestoreGState(context);
}

    2.1、找到谁调用了YYTextDrawShadow方法

    - (void)drawInContext:(CGContextRef)context
                 size:(CGSize)size
                point:(CGPoint)point
                 view:(UIView *)view
                layer:(CALayer *)layer
                debug:(YYTextDebugOption *)debug
                cancel:(BOOL (^)(void))cancel{
    @autoreleasepool {
        if (self.needDrawBlockBorder && context) {
            if (cancel && cancel()) return;
            YYTextDrawBlockBorder(self, context, size, point, cancel);
        }
        if (self.needDrawBackgroundBorder && context) {
            if (cancel && cancel()) return;
            YYTextDrawBorder(self, context, size, point, YYTextBorderTypeBackgound, cancel);
        }
        if (self.needDrawShadow && context) {
            if (cancel && cancel()) return;
            YYTextDrawShadow(self, context, size, point, cancel);
        }
        if (self.needDrawUnderline && context) {
            if (cancel && cancel()) return;
            YYTextDrawDecoration(self, context, size, point, YYTextDecorationTypeUnderline, cancel);
        }
        if (self.needDrawText && context) {
            if (cancel && cancel()) return;
            YYTextDrawText(self, context, size, point, cancel);
        }
        if (self.needDrawAttachment && (context || view || layer)) {
            if (cancel && cancel()) return;
            YYTextDrawAttachment(self, context, size, point, view, layer, cancel);
        }
        if (self.needDrawInnerShadow && context) {
            if (cancel && cancel()) return;
            YYTextDrawInnerShadow(self, context, size, point, cancel);
        }
        if (self.needDrawStrikethrough && context) {
            if (cancel && cancel()) return;
            YYTextDrawDecoration(self, context, size, point, YYTextDecorationTypeStrikethrough, cancel);
        }
        if (self.needDrawBorder && context) {
            if (cancel && cancel()) return;
            YYTextDrawBorder(self, context, size, point, YYTextBorderTypeNormal, cancel);
        }
        if (debug.needDrawDebug && context) {
            if (cancel && cancel()) return;
            YYTextDrawDebug(self, context, size, point, debug);
        }
    }
}
    • callers [YYLabel newAsyncDisplayTask]
    - (YYAsyncLayerDisplayTask *)newAsyncDisplayTask {
    
    // capture current context
    BOOL contentsNeedFade = _state.contentsNeedFade;
    NSAttributedString *text = _innerText;
    YYTextContainer *container = _innerContainer;
    YYTextVerticalAlignment verticalAlignment = _textVerticalAlignment;
    YYTextDebugOption *debug = _debugOption;
    NSMutableArray *attachmentViews = _attachmentViews;
    NSMutableArray *attachmentLayers = _attachmentLayers;
    BOOL layoutNeedUpdate = _state.layoutNeedUpdate;
    BOOL fadeForAsync = _displaysAsynchronously && _fadeOnAsynchronouslyDisplay;
    __block YYTextLayout *layout = (_state.showingHighlight && _highlightLayout) ? self._highlightLayout : self._innerLayout;
    __block YYTextLayout *shrinkLayout = nil;
    __block BOOL layoutUpdated = NO;
    if (layoutNeedUpdate) {
        text = text.copy;
        container = container.copy;
    }
    
    // create display task
    YYAsyncLayerDisplayTask *task = [YYAsyncLayerDisplayTask new];
    
    task.willDisplay = ^(CALayer *layer) {
        [layer removeAnimationForKey:@"contents"];
        
        // If the attachment is not in new layout, or we don't know the new layout currently,
        // the attachment should be removed.
        for (UIView *view in attachmentViews) {
            if (layoutNeedUpdate || ![layout.attachmentContentsSet containsObject:view]) {
                if (view.superview == self) {
                    [view removeFromSuperview];
                }
            }
        }
        for (CALayer *layer in attachmentLayers) {
            if (layoutNeedUpdate || ![layout.attachmentContentsSet containsObject:layer]) {
                if (layer.superlayer == self.layer) {
                    [layer removeFromSuperlayer];
                }
            }
        }
        [attachmentViews removeAllObjects];
        [attachmentLayers removeAllObjects];
    };

    task.display = ^(CGContextRef context, CGSize size, BOOL (^isCancelled)(void)) {
        if (isCancelled()) return;
        if (text.length == 0) return;
        
        YYTextLayout *drawLayout = layout;
        if (layoutNeedUpdate) {
            layout = [YYTextLayout layoutWithContainer:container text:text];
            shrinkLayout = [YYLabel _shrinkLayoutWithLayout:layout];
            if (isCancelled()) return;
            layoutUpdated = YES;
            drawLayout = shrinkLayout ? shrinkLayout : layout;
        }
        
        CGSize boundingSize = drawLayout.textBoundingSize;
        CGPoint point = CGPointZero;
        if (verticalAlignment == YYTextVerticalAlignmentCenter) {
            if (drawLayout.container.isVerticalForm) {
                point.x = -(size.width - boundingSize.width) * 0.5;
            } else {
                point.y = (size.height - boundingSize.height) * 0.5;
            }
        } else if (verticalAlignment == YYTextVerticalAlignmentBottom) {
            if (drawLayout.container.isVerticalForm) {
                point.x = -(size.width - boundingSize.width);
            } else {
                point.y = (size.height - boundingSize.height);
            }
        }
        point = CGPointPixelRound(point);
        [drawLayout drawInContext:context size:size point:point view:nil layer:nil debug:debug cancel:isCancelled];
    };

    task.didDisplay = ^(CALayer *layer, BOOL finished) {
        YYTextLayout *drawLayout = layout;
        if (layoutUpdated && shrinkLayout) {
            drawLayout = shrinkLayout;
        }
        if (!finished) {
            // If the display task is cancelled, we should clear the attachments.
            for (YYTextAttachment *a in drawLayout.attachments) {
                if ([a.content isKindOfClass:[UIView class]]) {
                    if (((UIView *)a.content).superview == layer.delegate) {
                        [((UIView *)a.content) removeFromSuperview];
                    }
                } else if ([a.content isKindOfClass:[CALayer class]]) {
                    if (((CALayer *)a.content).superlayer == layer) {
                        [((CALayer *)a.content) removeFromSuperlayer];
                    }
                }
            }
            return;
        }
        [layer removeAnimationForKey:@"contents"];
        
        __strong YYLabel *view = (YYLabel *)layer.delegate;
        if (!view) return;
        if (view->_state.layoutNeedUpdate && layoutUpdated) {
            view->_innerLayout = layout;
            view->_shrinkInnerLayout = shrinkLayout;
            view->_state.layoutNeedUpdate = NO;
        }
        
        CGSize size = layer.bounds.size;
        CGSize boundingSize = drawLayout.textBoundingSize;
        CGPoint point = CGPointZero;
        if (verticalAlignment == YYTextVerticalAlignmentCenter) {
            if (drawLayout.container.isVerticalForm) {
                point.x = -(size.width - boundingSize.width) * 0.5;
            } else {
                point.y = (size.height - boundingSize.height) * 0.5;
            }
        } else if (verticalAlignment == YYTextVerticalAlignmentBottom) {
            if (drawLayout.container.isVerticalForm) {
                point.x = -(size.width - boundingSize.width);
            } else {
                point.y = (size.height - boundingSize.height);
            }
        }
        point = CGPointPixelRound(point);
        [drawLayout drawInContext:nil size:size point:point view:view layer:layer debug:nil cancel:NULL];
        for (YYTextAttachment *a in drawLayout.attachments) {
            if ([a.content isKindOfClass:[UIView class]]) [attachmentViews addObject:a.content];
            else if ([a.content isKindOfClass:[CALayer class]]) [attachmentLayers addObject:a.content];
        }
        
        if (contentsNeedFade) {
            CATransition *transition = [CATransition animation];
            transition.duration = kHighlightFadeDuration;
            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
            transition.type = kCATransitionFade;
            [layer addAnimation:transition forKey:@"contents"];
        } else if (fadeForAsync) {
            CATransition *transition = [CATransition animation];
            transition.duration = kAsyncFadeDuration;
            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
            transition.type = kCATransitionFade;
            [layer addAnimation:transition forKey:@"contents"];
        }
    };
    
    return task;
}

    2.2、搜索newAsyncDisplayTask

    - (void)_displayAsync:(BOOL)async {
    __strong id<YYAsyncLayerDelegate> delegate = (id)self.delegate;
    //YYLabel
    YYAsyncLayerDisplayTask *task = [delegate newAsyncDisplayTask];
    //具体的绘制任务 task.display
    if (!task.display) {
        //即将显示
        if (task.willDisplay) task.willDisplay(self);
        self.contents = nil;
        //绘制结束！！
        if (task.didDisplay) task.didDisplay(self, YES);
        return;
    }
    
    if (async) {
        if (task.willDisplay) task.willDisplay(self);
        //计数器 ： 标识当前的绘制任务！！！
        YYSentinel *sentinel = _sentinel;
        int32_t value = sentinel.value;
        //取消绘制的标识！
        BOOL (^isCancelled)(void) = ^BOOL() {
            return value != sentinel.value;
        };
        CGSize size = self.bounds.size;
        BOOL opaque = self.opaque;
        CGFloat scale = self.contentsScale;
        CGColorRef backgroundColor = (opaque && self.backgroundColor) ? CGColorRetain(self.backgroundColor) : NULL;
        if (size.width < 1 || size.height < 1) {
            CGImageRef image = (__bridge_retained CGImageRef)(self.contents);
            self.contents = nil;
            if (image) {
                dispatch_async(YYAsyncLayerGetReleaseQueue(), ^{
                    CFRelease(image);
                });
            }
            if (task.didDisplay) task.didDisplay(self, YES);
            CGColorRelease(backgroundColor);
            return;
        }
        
        //子线程
        dispatch_async(YYAsyncLayerGetDisplayQueue(), ^{
            if (isCancelled()) {
                CGColorRelease(backgroundColor);
                return;
            }
            //Core Graphics 合成一张图片
            UIGraphicsBeginImageContextWithOptions(size, opaque, scale);
            CGContextRef context = UIGraphicsGetCurrentContext();
            if (opaque && context) {
                CGContextSaveGState(context); {
                    if (!backgroundColor || CGColorGetAlpha(backgroundColor) < 1) {
                        CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
                        CGContextAddRect(context, CGRectMake(0, 0, size.width * scale, size.height * scale));
                        CGContextFillPath(context);
                    }
                    if (backgroundColor) {
                        CGContextSetFillColorWithColor(context, backgroundColor);
                        CGContextAddRect(context, CGRectMake(0, 0, size.width * scale, size.height * scale));
                        CGContextFillPath(context);
                    }
                } CGContextRestoreGState(context);
                CGColorRelease(backgroundColor);
            }
            task.display(context, size, isCancelled);
            if (isCancelled()) {
                UIGraphicsEndImageContext();
                dispatch_async(dispatch_get_main_queue(), ^{
                    if (task.didDisplay) task.didDisplay(self, NO);
                });
                return;
            }
            UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
            if (isCancelled()) {
                dispatch_async(dispatch_get_main_queue(), ^{
                    if (task.didDisplay) task.didDisplay(self, NO);
                });
                return;
            }
            dispatch_async(dispatch_get_main_queue(), ^{
                if (isCancelled()) {
                    if (task.didDisplay) task.didDisplay(self, NO);
                } else {
                    self.contents = (__bridge id)(image.CGImage);
                    if (task.didDisplay) task.didDisplay(self, YES);
                }
            });
        });
    } else {
        [_sentinel increase];
        if (task.willDisplay) task.willDisplay(self);
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.opaque, self.contentsScale);
        CGContextRef context = UIGraphicsGetCurrentContext();
        if (self.opaque && context) {
            CGSize size = self.bounds.size;
            size.width *= self.contentsScale;
            size.height *= self.contentsScale;
            CGContextSaveGState(context); {
                if (!self.backgroundColor || CGColorGetAlpha(self.backgroundColor) < 1) {
                    CGContextSetFillColorWithColor(context, [UIColor whiteColor].CGColor);
                    CGContextAddRect(context, CGRectMake(0, 0, size.width, size.height));
                    CGContextFillPath(context);
                }
                if (self.backgroundColor) {
                    CGContextSetFillColorWithColor(context, self.backgroundColor);
                    CGContextAddRect(context, CGRectMake(0, 0, size.width, size.height));
                    CGContextFillPath(context);
                }
            } CGContextRestoreGState(context);
        }
        task.display(context, self.bounds.size, ^{return NO;});
        UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        self.contents = (__bridge id)(image.CGImage);
        if (task.didDisplay) task.didDisplay(self, YES);
    }
}
    • callers _displayAsync
    //子类重载，自定义绘制任务！！！CALayer 的方法！！！！
- (void)display {
    super.contents = super.contents;
    //是否开启异步绘制！！！（线程！！）
    [self _displayAsync:_displaysAsynchronously];
}

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