react-native/ReactCommon/fabric/textlayoutmanager/RCTTextLayoutManager.mm

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/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#import "RCTTextLayoutManager.h"
#import "NSTextStorage+FontScaling.h"
#import "RCTAttributedTextUtils.h"
using namespace facebook::react;
@implementation RCTTextLayoutManager
static NSLineBreakMode RCTNSLineBreakModeFromWritingDirection(EllipsizeMode ellipsizeMode) {
switch (ellipsizeMode) {
case EllipsizeMode::Clip: return NSLineBreakByClipping;
case EllipsizeMode::Head: return NSLineBreakByTruncatingHead;
case EllipsizeMode::Tail: return NSLineBreakByTruncatingTail;
case EllipsizeMode::Middle: return NSLineBreakByTruncatingMiddle;
}
}
- (facebook::react::Size)measureWithAttributedString:(AttributedString)attributedString
paragraphAttributes:(ParagraphAttributes)paragraphAttributes
layoutConstraints:(LayoutConstraints)layoutConstraints
{
CGSize maximumSize = CGSize {layoutConstraints.maximumSize.width, layoutConstraints.maximumSize.height};
NSTextStorage *textStorage =
[self _textStorageAndLayoutManagerWithAttributesString:RCTNSAttributedStringFromAttributedString(attributedString)
paragraphAttributes:paragraphAttributes
size:maximumSize];
NSLayoutManager *layoutManager = textStorage.layoutManagers.firstObject;
NSTextContainer *textContainer = layoutManager.textContainers.firstObject;
[layoutManager ensureLayoutForTextContainer:textContainer];
CGSize size = [layoutManager usedRectForTextContainer:textContainer].size;
size = (CGSize){
MIN(size.width, maximumSize.width),
MIN(size.height, maximumSize.height)
};
return facebook::react::Size {size.width, size.height};
}
- (void)drawAttributedString:(AttributedString)attributedString
paragraphAttributes:(ParagraphAttributes)paragraphAttributes
frame:(CGRect)frame
{
NSTextStorage *textStorage =
[self _textStorageAndLayoutManagerWithAttributesString:RCTNSAttributedStringFromAttributedString(attributedString)
paragraphAttributes:paragraphAttributes
size:frame.size];
NSLayoutManager *layoutManager = textStorage.layoutManagers.firstObject;
NSTextContainer *textContainer = layoutManager.textContainers.firstObject;
NSRange glyphRange = [layoutManager glyphRangeForTextContainer:textContainer];
[layoutManager drawBackgroundForGlyphRange:glyphRange atPoint:frame.origin];
[layoutManager drawGlyphsForGlyphRange:glyphRange atPoint:frame.origin];
}
- (NSTextStorage *)_textStorageAndLayoutManagerWithAttributesString:(NSAttributedString *)attributedString
paragraphAttributes:(ParagraphAttributes)paragraphAttributes
size:(CGSize)size
{
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:size];
textContainer.lineFragmentPadding = 0.0; // Note, the default value is 5.
textContainer.lineBreakMode =
paragraphAttributes.maximumNumberOfLines > 0 ? RCTNSLineBreakModeFromWritingDirection(paragraphAttributes.ellipsizeMode) : NSLineBreakByClipping;
textContainer.maximumNumberOfLines = paragraphAttributes.maximumNumberOfLines;
NSLayoutManager *layoutManager = [NSLayoutManager new];
[layoutManager addTextContainer:textContainer];
NSTextStorage *textStorage =
[[NSTextStorage alloc] initWithAttributedString:attributedString];
[textStorage addLayoutManager:layoutManager];
if (paragraphAttributes.adjustsFontSizeToFit) {
CGFloat minimumFontSize = !isnan(paragraphAttributes.minimumFontSize) ? paragraphAttributes.minimumFontSize : 4.0;
CGFloat maximumFontSize = !isnan(paragraphAttributes.maximumFontSize) ? paragraphAttributes.maximumFontSize : 96.0;
[textStorage scaleFontSizeToFitSize:size
minimumFontSize:minimumFontSize
maximumFontSize:maximumFontSize];
}
return textStorage;
}
@end