CTFrameGetLineOrigins 中的错误？

Question

我使用 Apple 的 SimpleTextInput 示例中的以下代码来确定光标的框架。我正在使用CTFrameGetLineOrigins，我注意到它返回的 y 值不正确（无论在哪一行，它都显示 .336）。我的应用程序与SimpleTextInput 略有不同，因为我将文本垂直居中，因此文本框架不会直接从原点开始。但是，为什么它给我每一行的这个价值？这是一个错误吗？

for (int i = 0; i < [lines count]; i++) 
{
    CTLineRef line = (CTLineRef) [lines objectAtIndex:i];
    CFRange range = CTLineGetStringRange(line);
    NSInteger localIndex = index - range.location;

    if (localIndex >= 0 && localIndex <= range.length) 
    {
        CGPoint origin;
        CGFloat ascent, descent;
        CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
        CTFrameGetLineOrigins(self.textFrame, CFRangeMake(i, 0), &origin);
        CGFloat xPos = origin.x + CTLineGetOffsetForStringIndex(line, index, NULL);
        return CGRectMake(xPos, origin.y - descent, 3, ascent + descent);
    }
}

- (void) drawRect:(CGRect)rect
{
    CTFramesetterRef textFramesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)self.text);
    CGMutablePathRef textFrameMutablePath = CGPathCreateMutable();
    CGPathAddRect(textFrameMutablePath, NULL, self.bounds);
    self.textFrame = CTFramesetterCreateFrame(textFramesetter, CFRangeMake(0, 0), textFrameMutablePath, NULL);

    CGFloat textFrameHeight = [self calculateHeightForTextFrame];
    CGRect textFrameRect = CGRectMake(0, (self.bounds.size.height / 2) - (textFrameHeight / 2), self.bounds.size.width, textFrameHeight);

    CGPathRelease(textFrameMutablePath);
    textFrameMutablePath = NULL;

    CFRelease(self.textFrame);
    self.textFrame = NULL;

    textFrameMutablePath = CGPathCreateMutable();
    CGPathAddRect(textFrameMutablePath, NULL, textFrameRect);
    self.textFrame = CTFramesetterCreateFrame(textFramesetter, CFRangeMake(0, 0), textFrameMutablePath, NULL);

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    CGContextTranslateCTM(context, 0, self.bounds.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    CTFrameDraw(self.textFrame, context); 

    CGPathRelease(textFrameMutablePath);
    CFRelease(textFramesetter);

    [self cursorPositionChanged];
}

Answer 1

Take out CTFrameGetLineOrigins() out of loop to get all line origins like :

NSArray *lines = (__bridge id)CTFrameGetLines(frame);
CGPoint origins[lines.count];
CTFrameGetLineOrigins(frame, CFRangeMake(0, lines.count), origins); //this will fill all line origins in origins[] buffer.

for (int i = 0; i < [lines count]; i++)
{
    CTLineRef line = (__bridge CTLineRef) [lines objectAtIndex:i];
    CFRange range = CTLineGetStringRange(line);

    // CGPoint origin; // moved out of loop
    CGFloat ascent, descent;
    CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
    // CTFrameGetLineOrigins(frame, CFRangeMake(i, 1), &origin); // moved to out of loop
    CGFloat xPos = origins[i].x; //  + CTLineGetOffsetForStringIndex(line, index, NULL);
    NSLog(@"%@", NSStringFromCGRect(CGRectMake(xPos + origins[i].x, origins[i].y - descent, 3, ascent + descent)));
}

Answer 2

您的范围是 0 个元素长：

CFRangeMake(i, 0)

你的意思是让它长 1 个元素：

CFRangeMake(i, 1)

---

编辑：

我刚刚尝试了以下代码，并且为每一行获取不同的来源没有问题。我取出了你的“索引”代码，因为我不知道应该设置什么索引，我想证明我可以得到所有的行来源（我可以）。

CTFramesetterRef
      framesetter = CTFramesetterCreateWithAttributedString(attrString);


  CFArrayRef paths = [self copyPaths];
  CFIndex pathCount = CFArrayGetCount(paths);
  CFIndex charIndex = 0;
  for (CFIndex pathIndex = 0; pathIndex < pathCount; ++pathIndex) {
    CGPathRef path = CFArrayGetValueAtIndex(paths, pathIndex);

    CTFrameRef
        frame = CTFramesetterCreateFrame(framesetter,
                                         CFRangeMake(charIndex, 0),
                                         path,
        NULL);

    NSArray *lines = (__bridge id)CTFrameGetLines(frame);
    for (int i = 0; i < [lines count]; i++)
    {
      CTLineRef line = (__bridge CTLineRef) [lines objectAtIndex:i];
      CFRange range = CTLineGetStringRange(line);

      CGPoint origin;
      CGFloat ascent, descent;
      CTLineGetTypographicBounds(line, &ascent, &descent, NULL);
      CTFrameGetLineOrigins(frame, CFRangeMake(i, 1), &origin);
      CGFloat xPos = origin.x; //  + CTLineGetOffsetForStringIndex(line, index, NULL);
      NSLog(@"%@", NSStringFromCGRect(CGRectMake(xPos, origin.y - descent, 3, ascent + descent)));
    }

在我的情况下输出：

2012-03-21 18:28:19.834 Columns[9370:f803] {{0, 929.24}, {3, 12}}
2012-03-21 18:28:19.835 Columns[9370:f803] {{0, 914.24}, {3, 12}}
2012-03-21 18:28:19.835 Columns[9370:f803] {{0, 899.24}, {3, 12}}
2012-03-21 18:28:19.836 Columns[9370:f803] {{0, 884.24}, {3, 12}}
2012-03-21 18:28:19.836 Columns[9370:f803] {{0, 869.24}, {3, 12}}
2012-03-21 18:28:19.836 Columns[9370:f803] {{0, 854.24}, {3, 12}}
2012-03-21 18:28:19.837 Columns[9370:f803] {{0, 839.24}, {3, 12}}
2012-03-21 18:28:19.837 Columns[9370:f803] {{0, 824.24}, {3, 12}}
2012-03-21 18:28:19.838 Columns[9370:f803] {{0, 809.24}, {3, 12}}
2012-03-21 18:28:19.838 Columns[9370:f803] {{0, 794.24}, {3, 12}}
2012-03-21 18:28:19.838 Columns[9370:f803] {{0, 779.24}, {3, 12}}
2012-03-21 18:28:19.839 Columns[9370:f803] {{0, 764.24}, {3, 12}}
...

Answer 3

奇怪的是，我似乎已经通过替换解决了这个问题：

CGPathAddRect(textFrameMutablePath, NULL, self.bounds);

与

CGPathAddRect(textFrameMutablePath, NULL, CGRectInset(self.bounds, self.horizontalInset, self.verticalInset));

不知道为什么，但它有效。