allow widgets to lock focus on themselves

2 files changed, 68 insertions, 40 deletions

diff --git a/gui/widget/focus.go b/gui/widget/focus.go
index e2d1074..f1bc06e 100644
--- a/gui/widget/focus.go
+++ b/gui/widget/focus.go
@@ -1,70 +1,98 @@
 package widget
 
-import "image"
+import (
+	"image"
+	"sync"
+)
 
-// Focus keeps track of the currently selected widget.
-// A widget receives true when it gains focus and false when it loses focus.
-type Focus struct {
-	Widgets [][]chan bool
-	p       image.Point // coordinates of currently focused widget
+type FocusMaster struct {
+	slaves [][]chan bool
+	mu     sync.Mutex
+	p      image.Point // coordinates of currently focused slave
 }
 
-func NewFocus(rows []int) Focus {
-	f := Focus{
+type FocusSlave struct {
+	Focus <-chan bool
+	Mu    *sync.Mutex
+}
+
+func NewFocusMaster(rows []int) FocusMaster {
+	f := FocusMaster{
 		make([][]chan bool, len(rows)),
+		sync.Mutex{},
 		image.Point{},
 	}
-	for i := range f.Widgets {
-		f.Widgets[i] = make([]chan bool, rows[i])
-		for j := range f.Widgets[i] {
-			f.Widgets[i][j] = make(chan bool)
+	for i := range f.slaves {
+		f.slaves[i] = make([]chan bool, rows[i])
+		for j := range f.slaves[i] {
+			f.slaves[i][j] = make(chan bool)
 		}
 	}
 	return f
 }
 
-func (f *Focus) Close() {
-	for i := range f.Widgets {
-		for j := range f.Widgets[i] {
-			close(f.Widgets[i][j])
+func (f *FocusMaster) Slave(y, x int) FocusSlave {
+	return FocusSlave{f.slaves[y][x], &f.mu}
+}
+
+func (f *FocusMaster) Close() {
+	for i := range f.slaves {
+		for j := range f.slaves[i] {
+			close(f.slaves[i][j])
 		}
 	}
 }
 
-func (f *Focus) Focus(focus bool) {
-	f.Widgets[f.p.Y][f.p.X] <- focus
+func (f *FocusMaster) Focus(focus bool) {
+	f.slaves[f.p.Y][f.p.X] <- focus
 }
 
-func (f *Focus) Left() {
+func (f *FocusMaster) TryLeft() {
+	if !f.mu.TryLock() {
+		return
+	}
+	defer f.mu.Unlock()
 	f.Focus(false)
 	if f.p.X <= 0 {
-		f.p.X = len(f.Widgets[f.p.Y]) - 1
+		f.p.X = len(f.slaves[f.p.Y]) - 1
 	} else {
 		f.p.X--
 	}
 	f.Focus(true)
 }
 
-func (f *Focus) Right() {
+func (f *FocusMaster) TryRight() {
+	if !f.mu.TryLock() {
+		return
+	}
+	defer f.mu.Unlock()
 	f.Focus(false)
-	f.p.X = (f.p.X + 1) % len(f.Widgets[f.p.Y])
+	f.p.X = (f.p.X + 1) % len(f.slaves[f.p.Y])
 	f.Focus(true)
 }
 
-func (f *Focus) Up() {
+func (f *FocusMaster) TryUp() {
+	if !f.mu.TryLock() {
+		return
+	}
+	defer f.mu.Unlock()
 	f.Focus(false)
 	if f.p.Y <= 0 {
-		f.p.Y = len(f.Widgets) - 1
+		f.p.Y = len(f.slaves) - 1
 	} else {
 		f.p.Y--
 	}
-	f.p.X = min(f.p.X, len(f.Widgets[f.p.Y])-1)
+	f.p.X = min(f.p.X, len(f.slaves[f.p.Y])-1)
 	f.Focus(true)
 }
 
-func (f *Focus) Down() {
+func (f *FocusMaster) TryDown() {
+	if !f.mu.TryLock() {
+		return
+	}
+	defer f.mu.Unlock()
 	f.Focus(false)
-	f.p.Y = (f.p.Y + 1) % len(f.Widgets)
-	f.p.X = min(f.p.X, len(f.Widgets[f.p.Y])-1)
+	f.p.Y = (f.p.Y + 1) % len(f.slaves)
+	f.p.X = min(f.p.X, len(f.slaves[f.p.Y])-1)
 	f.Focus(true)
 }
diff --git a/gui/widget/widget.go b/gui/widget/widget.go
index ae09160..8c80551 100644
--- a/gui/widget/widget.go
+++ b/gui/widget/widget.go
@@ -41,14 +41,14 @@ func Label(text string, r image.Rectangle, env gui.Env, wg *sync.WaitGroup) {
 	}
 }
 
-func Input(val chan<- uint, r image.Rectangle, focusChan <-chan bool, env gui.Env, wg *sync.WaitGroup) {
+func Input(val chan<- uint, r image.Rectangle, focus FocusSlave, env gui.Env, wg *sync.WaitGroup) {
 	defer wg.Done()
 	defer close(env.Draw())
 	defer close(val)
 
-	redraw := func(text []byte, focus bool) func(draw.Image) image.Rectangle {
+	redraw := func(text []byte, haveFocus bool) func(draw.Image) image.Rectangle {
 		return func(drw draw.Image) image.Rectangle {
-			if focus {
+			if haveFocus {
 				drawText(text, drw, r, GREEN, FOCUS_COLOR)
 			} else {
 				drawText(text, drw, r, GREEN, WHITE)
@@ -57,14 +57,14 @@ func Input(val chan<- uint, r image.Rectangle, focusChan <-chan bool, env gui.En
 		}
 	}
 	text := []byte{'0'}
-	focus := false
+	haveFocus := false
 
-	env.Draw() <- redraw(text, focus)
+	env.Draw() <- redraw(text, haveFocus)
 Loop:
 	for {
 		select {
-		case focus = <-focusChan:
-			env.Draw() <- redraw(text, focus)
+		case haveFocus = <-focus.Focus:
+			env.Draw() <- redraw(text, haveFocus)
 		case event, ok := <-env.Events():
 			if !ok { // channel closed
 				break Loop
@@ -72,18 +72,18 @@ Loop:
 			switch event := event.(type) {
 			case win.WiFocus:
 				if event.Focused {
-					env.Draw() <- redraw(text, focus)
+					env.Draw() <- redraw(text, haveFocus)
 				}
 			case win.KbType:
-				if focus && isDigit(event.Rune) {
+				if haveFocus && isDigit(event.Rune) {
 					text = fmt.Appendf(text, "%c", event.Rune)
-					env.Draw() <- redraw(text, focus)
+					env.Draw() <- redraw(text, haveFocus)
 					val <- atoi(text)
 				}
 			case win.KbDown:
-				if focus && event.Key == win.KeyBackspace && len(text) > 0 {
+				if haveFocus && event.Key == win.KeyBackspace && len(text) > 0 {
 					text = text[:len(text)-1]
-					env.Draw() <- redraw(text, focus)
+					env.Draw() <- redraw(text, haveFocus)
 					val <- atoi(text)
 				}
 			}