artist/text.go

@@ -165,6 +165,7 @@ func (drawer *TextDrawer) LineHeight () (height fixed.Int26_6) {
 // have its maximum width set to the given width. This does not alter the
 // drawer's state.
 func (drawer *TextDrawer) ReccomendedHeightFor (width int) (height int) {
+	if drawer.face == nil { return }
 	if !drawer.layoutClean { drawer.recalculate() }
 	metrics := drawer.face.Metrics()
 	dot := fixed.Point26_6 { 0, metrics.Height }

config/config.go

@@ -50,3 +50,44 @@ func (Default) ScrollVelocity () int {
 func (Default) ThemePath () (string) {
 	return ""
 }
+
+// Wrapped wraps a configuration and uses Default if it is nil.
+type Wrapped struct {
+	Config
+}
+
+// Padding returns the amount of internal padding elements should have.
+// An element's inner content (such as text) should be inset by this
+// amount, in addition to the inset returned by the pattern of its
+// background.
+func (wrapped Wrapped) Padding () int {
+	return wrapped.ensure().Padding()
+}
+
+// Margin returns how much space should be put in between elements.
+func (wrapped Wrapped) Margin () int {
+	return wrapped.ensure().Margin()
+}
+
+// HandleWidth returns how large grab handles should typically be. This
+// is important for accessibility reasons.
+func (wrapped Wrapped) HandleWidth () int {
+	return wrapped.ensure().HandleWidth()
+}
+
+// ScrollVelocity returns how many pixels should be scrolled every time
+// a scroll button is pressed.
+func (wrapped Wrapped) ScrollVelocity () int {
+	return wrapped.ensure().ScrollVelocity()
+}
+
+// ThemePath returns the directory path to the theme.
+func (wrapped Wrapped) ThemePath () string {
+	return wrapped.ensure().ThemePath()
+}
+
+func (wrapped Wrapped) ensure () (real Config) {
+	real = wrapped.Config
+	if real == nil { real = Default { } }
+	return
+}

elements/basic/button.go

@@ -18,18 +18,16 @@ type Button struct {
 	pressed bool
 	text    string
 	
-	config config.Config
+	config config.Wrapped
-	theme  theme.Theme
+	theme  theme.Wrapped
-	c      theme.Case
 	
 	onClick func ()
 }
 
 // NewButton creates a new button with the specified label text.
 func NewButton (text string) (element *Button) {
-	element = &Button {
+	element = &Button { }
-		c: theme.C("basic", "button"),
+	element.theme.Case = theme.C("basic", "button")
-	}
 	element.Core, element.core = core.NewCore(element.draw)
 	element.FocusableCore,
 	element.focusableControl = core.NewFocusableCore(element.redo)
@@ -103,18 +101,19 @@ func (element *Button) SetText (text string) {
 
 // SetTheme sets the element's theme.
 func (element *Button) SetTheme (new theme.Theme) {
-	element.theme = new
+	if new == element.theme.Theme { return }
+	element.theme.Theme = new
 	element.drawer.SetFace (element.theme.FontFace (
 		theme.FontStyleRegular,
-		theme.FontSizeNormal,
+		theme.FontSizeNormal))
-		element.c))
 	element.updateMinimumSize()
 	element.redo()
 }
 
 // SetConfig sets the element's configuration.
 func (element *Button) SetConfig (new config.Config) {
-	element.config = new
+	if new == element.config.Config { return }
+	element.config.Config = new
 	element.updateMinimumSize()
 	element.redo()
 }
@@ -141,7 +140,7 @@ func (element *Button) draw () {
 		Pressed:  element.pressed,
 	}
 
-	pattern := element.theme.Pattern(theme.PatternButton, element.c, state)
+	pattern := element.theme.Pattern(theme.PatternButton, state)
 
 	artist.FillRectangle(element, pattern, bounds)