Reduce the number of calculation for label size

zhongwuzw · zhongwuzw · commit 99bb911c0313 · 2018-04-12T23:32:16.000+08:00
diff --git a/Sources/Layout/MessageSizeCalculator.swift b/Sources/Layout/MessageSizeCalculator.swift
@@ -186,13 +186,10 @@ open class MessageSizeCalculator: CellSizeCalculator {
     }
 
     internal func labelSize(for attributedText: NSAttributedString, considering maxWidth: CGFloat) -> CGSize {
-        let estimatedHeight = attributedText.height(considering: maxWidth)
-        let estimatedWidth = attributedText.width(considering: estimatedHeight)
+        let constraintBox = CGSize(width: maxWidth, height: .greatestFiniteMagnitude)
+        let rect = attributedText.boundingRect(with: constraintBox, options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil).integral
 
-        let finalHeight = ceil(estimatedHeight)
-        let finalWidth = estimatedWidth > maxWidth ? maxWidth : ceil(estimatedWidth)
-
-        return CGSize(width: finalWidth, height: finalHeight)
+        return rect.size
     }
 }
 

Original file line number	Diff line number	Diff line change
`@@ -186,13 +186,10 @@ open class MessageSizeCalculator: CellSizeCalculator {`
`186`	`186`	`}`
`187`	`187`
`188`	`188`	`internal func labelSize(for attributedText: NSAttributedString, considering maxWidth: CGFloat) -> CGSize {`
`189`		`- let estimatedHeight = attributedText.height(considering: maxWidth)`
`190`		`- let estimatedWidth = attributedText.width(considering: estimatedHeight)`
	`189`	`+ let constraintBox = CGSize(width: maxWidth, height: .greatestFiniteMagnitude)`
	`190`	`+ let rect = attributedText.boundingRect(with: constraintBox, options: [.usesLineFragmentOrigin, .usesFontLeading], context: nil).integral`
`191`	`191`
`192`		`- let finalHeight = ceil(estimatedHeight)`
`193`		`- let finalWidth = estimatedWidth > maxWidth ? maxWidth : ceil(estimatedWidth)`
`194`		`-`
`195`		`- return CGSize(width: finalWidth, height: finalHeight)`
	`192`	`+ return rect.size`
`196`	`193`	`}`
`197`	`194`	`}`
`198`	`195`