fix flex layout calculation (#53)

flex.go

@@ -485,7 +485,7 @@ func (f *flexEmbed) layout(width, height int, container *containerEmbed) {
 		line := &lines[l]
 		for _, child := range line.child {
 			if f.AlignItems == AlignItemStretch &&
-				f.crossSize(child.node.item.Width, child.node.item.Height) == 0 &&
+				!f.isCrossSizeFixed(child.node.item) &&
 				child.crossSize < line.crossSize {
 				crossMargin := child.crossMargin[0] + child.crossMargin[1]
 				child.crossSize = line.crossSize - crossMargin
@@ -743,6 +743,17 @@ func (f *flexEmbed) setMainSize(v int) {
 	}
 }
 
+func (f *flexEmbed) isCrossSizeFixed(v *View) bool {
+	switch f.Direction {
+	case Row:
+		return v.isHeightFixed()
+	case Column:
+		return v.isWidthFixed()
+	default:
+		panic(fmt.Sprint("flex: bad direction ", f.Direction))
+	}
+}
+
 func (f *flexEmbed) crossSize(x, y int) int {
 	switch f.Direction {
 	case Row:

view.go

@@ -183,13 +183,21 @@ func (v *View) addChild(cv *View) *View {
 	return v
 }
 
+func (v *View) isWidthFixed() bool {
+	return v.Width != 0 || v.WidthInPct != 0
+}
+
 func (v *View) width() int {
 	if v.Width == 0 {
 		return v.calculatedWidth
 	}
 	return v.Width
 }
 
+func (v *View) isHeightFixed() bool {
+	return v.Height != 0 || v.HeightInPct != 0
+}
+
 func (v *View) height() int {
 	if v.Height == 0 {
 		return v.calculatedHeight