allow widgets to lock focus on themselves

1 files changed, 56 insertions, 28 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)
 }