boundaryLineHeight class

Author: GaryQian

lib/ui/text.dart

@@ -431,6 +431,52 @@ enum TextDecorationStyle {
   wavy
 }
 
+/// Defines how the paragraph will handle the ascent of the first line and
+/// descent of the last line. These lines are referred to as "Boundary" lines.
+class BoundaryLineHeightBehavior {
+
+  /// Creates a new BoundaryLineHeightBehavior object.
+  ///
+  ///  * first: When true, the [TextStyle.height] modifier will be applied to
+  ///    to the ascent of the first line. When false, the font's default ascent
+  ///    will be used.
+  ///  * last: When true, the [TextStyle.height] modifier will be applied to
+  ///    to the descent of the last line. When false, the font's default descent
+  ///    will be used.
+  BoundaryLineHeightBehavior({
+    this.first = true,
+    this.last = true,
+  });
+
+  /// Creates a new BoundaryLineHeightBehavior object from an encoded form.
+  ///
+  /// See [encode] for the creation of the encoded form.
+  BoundaryLineHeightBehavior.fromEncoded(int encoded) : first = (encoded & 0x1) > 0,
+                                                        last = (encoded & 0x2) > 0;
+
+
+  /// Whether to apply the [TextStyle.height] modifier or not to the ascent of
+  /// the first line in the paragraph.
+  ///
+  /// When true, the [TextStyle.height] modifier will be applied to to the ascent
+  /// of the first line. When false, the font's default ascent will be used and
+  /// the [TextStyle.height] will have no effect on the ascent of the first line.
+  final bool first;
+
+  /// Whether to apply the [TextStyle.height] modifier or not to the descent of
+  /// the last line in the paragraph.
+  ///
+  /// When true, the [TextStyle.height] modifier will be applied to to the descent
+  /// of the last line. When false, the font's default descent will be used and
+  /// the [TextStyle.height] will have no effect on the descent of the last line.
+  final bool last;
+
+  /// Returns an encoded int representation of this object.
+  int encode() {
+    return 0 + (first ? 1 << 0 : 0) + (last ? 1 << 1 : 0);
+  }
+}
+
 /// Determines if lists [a] and [b] are deep equivalent.
 ///
 /// Returns true if the lists are both null, or if they are both non-null, have
@@ -765,7 +811,7 @@ Int32List _encodeParagraphStyle(
   String fontFamily,
   double fontSize,
   double height,
-  int boundingLineHeightBehavior,
+  BoundaryLineHeightBehavior boundaryLineHeightBehavior,
   FontWeight fontWeight,
   FontStyle fontStyle,
   StrutStyle strutStyle,
@@ -793,9 +839,9 @@ Int32List _encodeParagraphStyle(
     result[0] |= 1 << 5;
     result[5] = maxLines;
   }
-  if (boundingLineHeightBehavior != null) {
+  if (boundaryLineHeightBehavior != null) {
     result[0] |= 1 << 6;
-    result[6] = boundingLineHeightBehavior;
+    result[6] = boundaryLineHeightBehavior.encode();
   }
   if (fontFamily != null) {
     result[0] |= 1 << 7;
@@ -886,7 +932,7 @@ class ParagraphStyle {
     String fontFamily,
     double fontSize,
     double height,
-    int boundingLineHeightBehavior,
+    BoundaryLineHeightBehavior boundaryLineHeightBehavior,
     FontWeight fontWeight,
     FontStyle fontStyle,
     StrutStyle strutStyle,
@@ -899,7 +945,7 @@ class ParagraphStyle {
          fontFamily,
          fontSize,
          height,
-         boundingLineHeightBehavior,
+         boundaryLineHeightBehavior,
          fontWeight,
          fontStyle,
          strutStyle,