Merge branch 'devel' into 243-formdemo

CHANGELOG.md

@@ -28,6 +28,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   func (*BarChart) Mouse(m *terminalapi.Mouse, meta *widgetapi.EventMeta) error { ... }
   ```
 
+### Fixed
+
+- `termdash` no longer crashes when `tcell` is used and the terminal window
+  downsizes while content is being drawn.
+
 ### Added
 
 #### Infrastructure changes
@@ -38,6 +43,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - containers can register into separate focus groups and specific keyboard keys
   can be configured to move the focus within each focus group.
 - widgets can now request keyboard events exclusively when focused.
+- users can now set a `container` as focused using the new `container.Focused`
+  option.
 
 #### Updates to the `button` widget
 

container/focus_test.go

@@ -541,7 +541,7 @@ func TestFocusTrackerNextAndPrevious(t *testing.T) {
 		wantProcessed int
 	}{
 		{
-			desc: "initially the root is focused",
+			desc: "initially the root is focused by default",
 			container: func(ft *faketerm.Terminal) (*Container, error) {
 				return New(
 					ft,
@@ -554,6 +554,49 @@ func TestFocusTrackerNextAndPrevious(t *testing.T) {
 			},
 			wantFocused: contLocA,
 		},
+		{
+			desc: "focus root explicitly",
+			container: func(ft *faketerm.Terminal) (*Container, error) {
+				return New(
+					ft,
+					Focused(),
+					SplitVertical(
+						Left(),
+						Right(),
+					),
+					KeyFocusNext(keyNext),
+				)
+			},
+			wantFocused: contLocA,
+		},
+		{
+			desc: "focus can be set to a container other than root",
+			container: func(ft *faketerm.Terminal) (*Container, error) {
+				return New(
+					ft,
+					SplitVertical(
+						Left(Focused()),
+						Right(),
+					),
+					KeyFocusNext(keyNext),
+				)
+			},
+			wantFocused: contLocB,
+		},
+		{
+			desc: "option Focused used on multiple containers, the last one takes effect",
+			container: func(ft *faketerm.Terminal) (*Container, error) {
+				return New(
+					ft,
+					SplitVertical(
+						Left(Focused()),
+						Right(Focused()),
+					),
+					KeyFocusNext(keyNext),
+				)
+			},
+			wantFocused: contLocC,
+		},
 		{
 			desc: "keyNext does nothing when only root exists",
 			container: func(ft *faketerm.Terminal) (*Container, error) {

container/options.go

@@ -1033,3 +1033,14 @@ func KeyFocusGroupsPrevious(key keyboard.Key, groups ...FocusGroup) Option {
 		return nil
 	})
 }
+
+// Focused moves the keyboard focus to this container.
+// If not specified, termdash will start with the root container focused.
+// If specified on multiple containers, the last container with this option
+// will be focused.
+func Focused() Option {
+	return option(func(c *Container) error {
+		c.focusTracker.setActive(c)
+		return nil
+	})
+}

private/canvas/canvas.go

@@ -195,21 +195,14 @@ func (c *Canvas) copyTo(offset image.Point, dstSetCell setCellFunc) error {
 }
 
 // Apply applies the canvas to the corresponding area of the terminal.
-// Guarantees to stay within limits of the area the canvas was created with.
 func (c *Canvas) Apply(t terminalapi.Terminal) error {
-	termArea, err := area.FromSize(t.Size())
-	if err != nil {
-		return err
-	}
-
-	bufArea, err := area.FromSize(c.buffer.Size())
-	if err != nil {
-		return err
-	}
-
-	if !bufArea.In(termArea) {
-		return fmt.Errorf("the canvas area %+v doesn't fit onto the terminal %+v", bufArea, termArea)
-	}
+	// Note - the size of the terminal might have changed since we started
+	// drawing, since terminal windows are inherently racy (the user can resize
+	// them at any time).
+	//
+	// This is ok, since the underlying terminal layer will just ignore cells
+	// that are out of bounds and termdash will redraw again once it receives
+	// the resize event. Regression for #281.
 
 	// The image.Point{0, 0} of this canvas isn't always exactly at
 	// image.Point{0, 0} on the terminal.