iOS-CoreText的那些事【電子書的那些事】

這段時間在搞電子書，把這些天出現的問題歸總下，我還是希望電子書的格式包括返回的數據，可直觀的反應出客戶端想表達的內容；原生的體驗還是比較好的，希望對coretext再深入。 1.判斷點擊的位置是否在某個NSRange範圍內 2.通過CFRange與CTFrameRef獲取要操作（塗色，劃線）的CGR ...

這段時間在搞電子書，把這些天出現的問題歸總下，我還是希望電子書的格式包括返回的數據，可直觀的反應出客戶端想表達的內容；原生的體驗還是比較好的，希望對coretext再深入。

1.判斷點擊的位置是否在某個NSRange範圍內

#pragma mark 判斷點擊的位置是否在 range內
/**
 將點擊的位置轉換成字元串的偏移量，如果沒有找到，則返回-1
 view：view
 point：點擊位置
 frameRef：當前view的frameRef
 */
+ (CFIndex)wkj_touchContentOffsetInView:(UIView *)view
                            point:(CGPoint)point
                           frameRef:(CTFrameRef)frameRef{
    CTFrameRef textFrame = frameRef;
    CFArrayRef lines = CTFrameGetLines(textFrame);
    if (!lines) {
        return -1;
    }
    CFIndex count = CFArrayGetCount(lines);
    
    // 獲得每一行的origin坐標
    CGPoint origins[count];
    CTFrameGetLineOrigins(textFrame, CFRangeMake(0,0), origins);
    
    // 翻轉坐標系
    CGAffineTransform transform =  CGAffineTransformMakeTranslation(0, view.bounds.size.height);
    transform = CGAffineTransformScale(transform, 1.f, -1.f);
    
    CFIndex idx = -1;
    for (int i = 0; i < count; i++) {
        CGPoint linePoint = origins[i];
        CTLineRef line = CFArrayGetValueAtIndex(lines, i);
        // 獲得每一行的CGRect信息
        CGRect flippedRect = [self wkj_getLineBounds:line point:linePoint];
        CGRect rect = CGRectApplyAffineTransform(flippedRect, transform);
        
        if (CGRectContainsPoint(rect, point)) {
            // 將點擊的坐標轉換成相對於當前行的坐標cocoapods
            CGPoint relativePoint = CGPointMake(point.x-CGRectGetMinX(rect),
                                                point.y-CGRectGetMinY(rect));
            // 獲得當前點擊坐標對應的字元串偏移
            idx = CTLineGetStringIndexForPosition(line, relativePoint);
        }
    }
    return idx;
}

+ (CGRect)wkj_getLineBounds:(CTLineRef)line point:(CGPoint)point {
    CGFloat ascent = 0.0f;
    CGFloat descent = 0.0f;
    CGFloat leading = 0.0f;
    CGFloat width = (CGFloat)CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
    CGFloat height = ascent + descent;
    return CGRectMake(point.x, point.y - descent, width, height);
}

/**
 此處判斷
 根據上面返回的字元串的偏移量，對比range是否在點擊的位置
 */
+ (BOOL)wkj_judgeAtIndex:(CFIndex)index range:(NSRange)range {
    if (NSLocationInRange(index, range)) {
        ///點擊處在range內
        return YES;
    }
    return NO;
}

2.通過CFRange與CTFrameRef獲取要操作（塗色，劃線）的CGRect數組

#pragma mark 通過range獲取rect集合【用於劃線、塗色】
+ (NSArray*)wkj_frameGetFrameOfStringInRange:(CTFrameRef)frameRef range:(CFRange)range{
    CFRange frameRefRange = CTFrameGetStringRange(frameRef);
    range = [self wkj_cfRangeInsection:frameRefRange range:range];
    if ([self wkj_cfRangeEqualToRange:range range:CFRangeZero]) {
        return nil;
    }
    
    NSArray *lines = (NSArray*)CTFrameGetLines(frameRef);
    NSInteger lineCount = [lines count];
    //獲取整個CTFrame的大小
    CGPathRef path = CTFrameGetPath(frameRef);
    CGRect frameRefRect = CGPathGetBoundingBox(path);
    //獲取所有行的起點
    CGPoint *origins = (CGPoint*)malloc(lineCount * sizeof(CGPoint));
    CTFrameGetLineOrigins(frameRef, CFRangeMake(0, 0), origins);
    NSMutableArray *rects = [NSMutableArray array];
    for (CFIndex index = 0; index<lines.count; index++) {
        CTLineRef line = (__bridge CTLineRef)[lines objectAtIndex:index];
        CFRange rangeOfLine = CTLineGetStringRange(line);
        CFRange rangeOfInsection = [self wkj_cfRangeInsection:rangeOfLine range:range];
        if (![self wkj_cfRangeEqualToRange:rangeOfInsection range:CFRangeZero]) {
            CGRect frame = [self wkj_lineGetFrame:line point:origins[index] range:rangeOfInsection];
            frame = CGRectOffset(frame, frameRefRect.origin.x, frameRefRect.origin.y);
            
            [rects addObject:[NSValue valueWithCGRect:frame]];
        }
    }
    free(origins);
    return [rects copy];
}

+ (CGRect)wkj_lineGetFrame:(CTLineRef)line
                     point:(CGPoint)origin
                     range:(CFRange)range{
    CFRange lineRange = CTLineGetStringRange(line);
    range = [self wkj_cfRangeInsection:lineRange range:range];
    CGFloat trailingWhitespaceWidth = CTLineGetTrailingWhitespaceWidth(line);
    if ([self wkj_cfRangeGetEndLocation:range]==[self wkj_cfRangeGetEndLocation:lineRange]&&trailingWhitespaceWidth>0) {
        --range.length;
    }
    CGFloat xStart = CTLineGetOffsetForStringIndex(line, range.location, NULL);
    CGFloat xEnd = CTLineGetOffsetForStringIndex(line, [self wkj_cfRangeGetEndLocation:range]+1, NULL);
    
    CGFloat ascent, descent, leading;
    
    CTLineGetTypographicBounds(line, &ascent, &descent, &leading);
    CGRect selectionRect = CGRectMake(origin.x + xStart,
                                      origin.y - descent,
                                      xEnd - xStart,
                                      ascent + descent + leading);
    
    return selectionRect;
}

+ (CFRange)wkj_cfRangeInsection:(CFRange)range1 range:(CFRange)range2{
    if ([self wkj_cfRangeGreaterThanRange:range1 range:range2]||[self wkj_cfRangeGreaterThanRange:range2 range:range1]) {
        return CFRangeZero;
    }
    CFIndex beginLocation = MAX(range1.location, range2.location);
    CFIndex endLocation = MIN([self wkj_cfRangeGetEndLocation:range1], [self wkj_cfRangeGetEndLocation:range2]);
    
    return [self wkj_cfRangeMakeWithInterval:beginLocation endIndex:endLocation];
}

+ (BOOL)wkj_cfRangeGreaterThanRange:(CFRange)range1 range:(CFRange)range2{
    return range1.location>[self wkj_cfRangeGetEndLocation:range2];
}
+ (CFIndex)wkj_cfRangeGetEndLocation:(CFRange)range{
    return range.location+range.length-1;
}
+ (CFRange)wkj_cfRangeMakeWithInterval:(CFIndex)startIndex endIndex:(CFIndex)endIndex{
    return CFRangeMake(startIndex, endIndex - startIndex + 1);
}
+ (BOOL)wkj_cfRangeEqualToRange:(CFRange)range1 range:(CFRange)range2{
    return range1.location == range2.location&&range1.length==range2.length;
}

3.塗色劃線

- (void)wkj_drawLineForSelectArea{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [[UIColor redColor] colorWithAlphaComponent:0.3].CGColor);
    for (NSValue *rectValue in _arraySelectRect) {
        CGRect rect = [rectValue CGRectValue];
        rect.origin.y -= 2.5;
        ///劃線時可設置高度為1  塗色是可根據字體大小設置
        rect.size.height = 1;
        rect.size.width -= 1.5;
        CGContextFillRect(context, rect);
    }
}

4.CoreText 分頁

#pragma mark 分頁
/**
 CoreText 分頁
 str: NSAttributedString屬性字元串
 textFrame: 繪製區域
 */

+ (NSArray *)wkj_coreTextPaging:(NSAttributedString *)str textArea:(CGRect)textFrame{
    ///分頁NSAttributedString結果
    // NSMutableArray *arrayPagingStr = [NSMutableArray array];
    ///分頁NSRange結果
    NSMutableArray *arrayPagingRange = [NSMutableArray array];
    
    CFAttributedStringRef cfStrRef = (__bridge CFAttributedStringRef)str;
    CTFramesetterRef framesetterRef = CTFramesetterCreateWithAttributedString(cfStrRef);
    CGPathRef path = CGPathCreateWithRect(textFrame, NULL);
    
    int textPos = 0;
    NSUInteger strLength = [str length];
    while (textPos < strLength)  {
        //設置路徑
        CTFrameRef frame = CTFramesetterCreateFrame(framesetterRef, CFRangeMake(textPos, 0), path, NULL);
        CFRange frameRange = CTFrameGetVisibleStringRange(frame);
        NSRange range = NSMakeRange(frameRange.location, frameRange.length);
        
        [arrayPagingRange addObject:[NSValue valueWithRange:range]];
        // [arrayPagingStr addObject:[str attributedSubstringFromRange:range]];
        //移動
        textPos += frameRange.length;
        CFRelease(frame);
    }
    CGPathRelease(path);
    CFRelease(framesetterRef);
    // return arrayPagingStr;
    return arrayPagingRange;
}

5.獲取繪製區域的高度

/**
 str:NSAttributedString 內容屬性
 width: 繪製的寬度
 */
+ (CGFloat)coretextContentHeight:(NSAttributedString *)str width:(CGFloat)width{
    //創建CTFramesetterRef
    CTFramesetterRef framesetterRef = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)str);
    // 獲得要繪製的區域高度
    CGSize restrictSize = CGSizeMake(width, CGFLOAT_MAX);
    CGSize coreTextSize = CTFramesetterSuggestFrameSizeWithConstraints(framesetterRef, CFRangeMake(0,0), nil, restrictSize, nil);
   return coreTextSize.height;
}