ui/functions.go

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package ui
import (
"git.kirsle.net/go/render"
)
// AbsolutePosition computes a widget's absolute X,Y position on the
// window on screen by crawling its parent widget tree.
func AbsolutePosition(w Widget) render.Point {
abs := w.Point()
var (
node = w
ok bool
)
for {
node, ok = node.Parent()
if !ok { // reached the top of the tree
return abs
}
abs.Add(node.Point())
}
}
// AbsoluteRect returns a Rect() offset with the absolute position.
func AbsoluteRect(w Widget) render.Rect {
var (
P = AbsolutePosition(w)
R = w.Rect()
)
return render.Rect{
X: P.X,
Y: P.Y,
W: R.W + P.X,
H: R.H, // TODO: the Canvas in EditMode lets you draw pixels
// below the status bar if we do `+ R.Y` here.
}
}
// widgetInFocusedWindow returns whether a widget (like a Button) is a
// descendant of a Window that is being Window Managed by Supervisor, and
// said window is in a Focused state.
//
// This is used by Supervisor to decide whether the widget should be given
// events or not: a widget in a non-focused window ignores events, so that a
// button in a "lower" window could not be clicked through a "higher" window
// that overlaps it.
func widgetInFocusedWindow(w Widget) (isManaged, isFocused bool) {
var node = w
for {
// Is the node a Window?
if window, ok := node.(*Window); ok {
return true, window.Focused()
}
node, _ = node.Parent()
if node == nil {
return false, true // reached the root
}
}
}
// WidgetInManagedWindow returns true if the widget is owned by a ui.Window
// which is being Window Managed by the Supervisor.
//
// Returns true if any parent widget is a Window with managed=true. This
// boolean is set when you call .Supervise() on the window to be managed by
// Supervisor.
func WidgetInManagedWindow(w Widget) bool {
var node = w
for {
// Is the node a Window?
if window, ok := node.(*Window); ok {
if window.managed {
return true
}
}
node, _ = node.Parent()
if node == nil {
return false // reached the root
}
}
}