backends/x/window.go

@@ -89,7 +89,7 @@ func (window *Window) Adopt (child tomo.Element) {
 		child.SetParentHooks (tomo.ParentHooks {
 			Draw: window.childDrawCallback,
 			MinimumSizeChange: window.childMinimumSizeChangeCallback,
-			ExpandingHeightChange: window.resizeChildToFit,
+			FlexibleHeightChange: window.resizeChildToFit,
 			SelectionRequest: window.childSelectionRequestCallback,
 		})
 		

element.go

@@ -16,9 +16,9 @@ type ParentHooks struct {
 	// event.
 	MinimumSizeChange func (width, height int)
 
-	// ExpandingHeightChange is called when the parameters affecting the
+	// FlexibleHeightChange is called when the parameters affecting the
 	// element's expanding height have changed.
-	ExpandingHeightChange func ()
+	FlexibleHeightChange func ()
 	
 	// SelectionRequest is called when the child element element wants
 	// itself to be selected. If the parent element chooses to grant the
@@ -46,11 +46,11 @@ func (hooks ParentHooks) RunMinimumSizeChange (width, height int) {
 	}
 }
 
-// RunExpandingHeightChange runs the ExpandingHeightChange hook if it is not
+// RunFlexibleHeightChange runs the ExpandingHeightChange hook if it is not
 // nil. If it is nil, it does nothing.
-func (hooks ParentHooks) RunExpandingHeightChange () {
+func (hooks ParentHooks) RunFlexibleHeightChange () {
-	if hooks.ExpandingHeightChange != nil {
+	if hooks.FlexibleHeightChange != nil {
-		hooks.ExpandingHeightChange()
+		hooks.FlexibleHeightChange()
 	}
 }
 

elements/basic/container.go

@@ -18,6 +18,7 @@ type Container struct {
 	warping    bool
 	selected   bool
 	selectable bool
+	flexible   bool
 }
 
 // NewContainer creates a new container.
@@ -49,6 +50,7 @@ func (element *Container) Adopt (child tomo.Element, expand bool) {
 		MinimumSizeChange: func (int, int) {
 			element.updateMinimumSize()
 		},
+		FlexibleHeightChange: element.updateMinimumSize,
 		SelectionRequest: func () (granted bool) {
 			child, selectable := child.(tomo.Selectable)
 			if !selectable { return }
@@ -68,7 +70,7 @@ func (element *Container) Adopt (child tomo.Element, expand bool) {
 	})
 
 	element.updateMinimumSize()
-	element.updateSelectable()
+	element.reflectChildProperties()
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
@@ -113,7 +115,7 @@ func (element *Container) Disown (child tomo.Element) {
 	}
 
 	element.updateMinimumSize()
-	element.updateSelectable()
+	element.reflectChildProperties()
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
@@ -126,7 +128,7 @@ func (element *Container) DisownAll () {
 	element.children = nil
 
 	element.updateMinimumSize()
-	element.updateSelectable()
+	element.reflectChildProperties()
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
@@ -183,8 +185,6 @@ func (element *Container) Resize (width, height int) {
 	element.draw()
 }
 
-// TODO: implement KeyboardTarget
-
 func (element *Container) HandleMouseDown (x, y int, button tomo.Button) {
 	child, handlesMouse := element.ChildAt(image.Pt(x, y)).(tomo.MouseTarget)
 	if !handlesMouse { return }
@@ -230,7 +230,7 @@ func (element *Container) HandleKeyDown (
 	})
 }
 
-func (element *Container) HandleKeyUp(key tomo.Key, modifiers tomo.Modifiers) {
+func (element *Container) HandleKeyUp (key tomo.Key, modifiers tomo.Modifiers) {
 	element.forSelected (func (child tomo.Selectable) bool {
 		child0, handlesKeyboard := child.(tomo.KeyboardTarget)
 		if handlesKeyboard {
@@ -300,6 +300,11 @@ func (element *Container) HandleSelection (direction tomo.SelectionDirection) (o
 	return false
 }
 
+// TODO: fix this!
+// func (element *Container) MinimumHeightFor (width int) (height int) {
+	// return element.layout.MinimumHeightFor(element.children, width)
+// }
+
 func (element *Container) HandleDeselection () {
 	element.selected = false
 	element.forSelected (func (child tomo.Selectable) bool {
@@ -326,6 +331,15 @@ func (element *Container) forSelectable (callback func (child tomo.Selectable) b
 	}
 }
 
+func (element *Container) forFlexible (callback func (child tomo.Flexible) bool) {
+	for _, entry := range element.children {
+		child, selectable := entry.Element.(tomo.Flexible)
+		if selectable {
+			if !callback(child) { break }
+		}
+	}
+}
+
 func (element *Container) forSelectableBackward (callback func (child tomo.Selectable) bool) {
 	for index := len(element.children) - 1; index >= 0; index -- {
 		child, selectable := element.children[index].Element.(tomo.Selectable)
@@ -345,12 +359,17 @@ func (element *Container) firstSelected () (index int) {
 	return -1
 }
 
-func (element *Container) updateSelectable () {
+func (element *Container) reflectChildProperties () {
 	element.selectable = false
 	element.forSelectable (func (tomo.Selectable) bool {
 		element.selectable = true
 		return false
 	})
+	element.flexible = false
+	element.forFlexible (func (tomo.Flexible) bool {
+		element.flexible = true
+		return false
+	})
 	if !element.selectable {
 		element.selected = false
 	}
@@ -374,8 +393,11 @@ func (element *Container) childSelectionRequestCallback (
 }
 
 func (element *Container) updateMinimumSize () {
-	element.core.SetMinimumSize (
+	width, height := element.layout.MinimumSize(element.children)
-		element.layout.MinimumSize(element.children, 1e9))
+	if element.flexible {
+		height = element.layout.MinimumHeightFor(element.children, width)
+	}
+	element.core.SetMinimumSize(width, height)
 }
 
 func (element *Container) recalculate () {

elements/basic/label.go

@@ -88,7 +88,7 @@ func (element *Label) updateMinimumSize () {
 		if em < 1 { em = theme.Padding() }
 		element.core.SetMinimumSize (
 			em, element.drawer.LineHeight().Round())
-		element.core.NotifyExpandingHeightChange()
+		element.core.NotifyFlexibleHeightChange()
 	} else {
 		bounds := element.drawer.LayoutBounds()
 		element.core.SetMinimumSize(bounds.Dx(), bounds.Dy())

elements/core/core.go

@@ -144,10 +144,10 @@ func (control CoreControl) SetMinimumSize (width, height int) {
 	}
 }
 
-// NotifyExpandingHeightChange notifies the parent element that this element's
+// NotifyFlexibleHeightChange notifies the parent element that this element's
-// expanding height has changed.
+// flexible height has changed.
-func (control CoreControl) NotifyExpandingHeightChange () {
+func (control CoreControl) NotifyFlexibleHeightChange () {
-	control.core.hooks.RunExpandingHeightChange()
+	control.core.hooks.RunFlexibleHeightChange()
 }
 
 // ConstrainSize contstrains the specified width and height to the minimum width

examples/verticalLayout/main.go

@@ -17,7 +17,7 @@ func run () {
 	container := basic.NewContainer(layouts.Vertical { true, true })
 	window.Adopt(container)
 
-	label    := basic.NewLabel("it is a label hehe", false)
+	label    := basic.NewLabel("it is a label hehe", true)
 	button   := basic.NewButton("drawing pad")
 	okButton := basic.NewButton("OK")
 	button.OnClick (func () {

layout.go

@@ -20,8 +20,11 @@ type Layout interface {
 	Arrange (entries []LayoutEntry, width, height int)
 
 	// MinimumSize returns the minimum width and height that the layout
-	// needs to properly arrange the given slice of layout entries, given a
+	// needs to properly arrange the given slice of layout entries.
-	// "suqeeze" width so that the height can be determined for elements
+	MinimumSize (entries []LayoutEntry) (width, height int)
-	// fulfilling the Expanding interface.
+
-	MinimumSize (entries []LayoutEntry, squeeze int) (width, height int)
+	// MinimumHeightFor Returns the minimum height the layout needs to lay
+	// out the specified elements at the given width, taking into account
+	// flexible elements.
+	MinimumHeightFor (entries []LayoutEntry, squeeze int) (height int)
 }

layouts/vertical.go

@@ -25,17 +25,22 @@ func (layout Vertical) Arrange (entries []tomo.LayoutEntry, width, height int) {
 	freeSpace := height
 	expandingElements := 0
 
-	// TODO: find the width first, then store the minumum height of
-	// everything in a list, then arrange everything.
-	// minimumHeights := make([]int, len(entries))
-
 	// count the number of expanding elements and the amount of free space
-	// for them to collectively occupy
+	// for them to collectively occupy, while gathering minimum heights.
+	minimumHeights := make([]int, len(entries))
 	for index, entry := range entries {
+		var entryMinHeight int
+
+		if child, flexible := entry.Element.(tomo.Flexible); flexible {
+			entryMinHeight = child.MinimumHeightFor(width)
+		} else {
+			_, entryMinHeight = entry.MinimumSize()
+		}
+		minimumHeights[index] = entryMinHeight
+		
 		if entry.Expand {
 			expandingElements ++
 		} else {
-			_, entryMinHeight := entry.MinimumSize()
 			freeSpace -= entryMinHeight
 		}
 		if index > 0 && layout.Gap {
@@ -62,7 +67,7 @@ func (layout Vertical) Arrange (entries []tomo.LayoutEntry, width, height int) {
 		if entry.Expand {
 			entryHeight = expandingElementHeight
 		} else {
-			_, entryHeight = entry.MinimumSize()
+			entryHeight = minimumHeights[index]
 		}
 		y += entryHeight
 		entryBounds := entry.Bounds()
@@ -76,7 +81,6 @@ func (layout Vertical) Arrange (entries []tomo.LayoutEntry, width, height int) {
 // arrange the given list of entries.
 func (layout Vertical) MinimumSize (
 	entries []tomo.LayoutEntry,
-	squeeze int,
 ) (
 	width, height int,
 ) {
@@ -97,3 +101,31 @@ func (layout Vertical) MinimumSize (
 	}
 	return
 }
+
+// MinimumHeightFor Returns the minimum height the layout needs to lay out the
+// specified elements at the given width, taking into account flexible elements.
+func (layout Vertical) MinimumHeightFor (
+	entries []tomo.LayoutEntry,
+	squeeze int,
+) (
+	height int,
+) {
+	for index, entry := range entries {
+		child, flexible := entry.Element.(tomo.Flexible)
+		if flexible {
+			height += child.MinimumHeightFor(squeeze)
+		} else {
+			_, entryHeight := entry.MinimumSize()
+			height += entryHeight
+		}
+		
+		if layout.Gap && index > 0 {
+			height += theme.Padding()
+		}
+	}
+
+	if layout.Pad {
+		height += theme.Padding() * 2
+	}
+	return
+}