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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package widget
import (
"golang.org/x/exp/shiny/unit"
"golang.org/x/exp/shiny/widget/node"
"golang.org/x/exp/shiny/widget/theme"
)
// Padder is a shell widget that adds a margin to the inner widget's measured
// size. That margin may be added horizontally (left and right), vertically
// (top and bottom) or both, determined by the Padder's axis.
//
// That marginal space is not considered part of the inner widget's geometry.
// For example, to make that space 'clickable', construct the Padder inside of
// an event handling widget instead of vice versa.
type Padder struct {
node.ShellEmbed
Axis Axis
Margin unit.Value
}
// NewPadder returns a new Padder widget.
func NewPadder(a Axis, margin unit.Value, inner node.Node) *Padder {
w := &Padder{
Axis: a,
Margin: margin,
}
w.Wrapper = w
if inner != nil {
w.Insert(inner, nil)
}
return w
}
func (w *Padder) Measure(t *theme.Theme, widthHint, heightHint int) {
margin2 := t.Pixels(w.Margin).Round() * 2
if w.Axis.Horizontal() && widthHint >= 0 {
widthHint -= margin2
if widthHint < 0 {
widthHint = 0
}
}
if w.Axis.Vertical() && heightHint >= 0 {
heightHint -= margin2
if heightHint < 0 {
heightHint = 0
}
}
w.ShellEmbed.Measure(t, widthHint, heightHint)
if w.Axis.Horizontal() {
w.MeasuredSize.X += margin2
}
if w.Axis.Vertical() {
w.MeasuredSize.Y += margin2
}
}
func (w *Padder) Layout(t *theme.Theme) {
if c := w.FirstChild; c != nil {
r := w.Rect.Sub(w.Rect.Min)
inset := r.Inset(t.Pixels(w.Margin).Round())
if w.Axis.Horizontal() {
r.Min.X = inset.Min.X
r.Max.X = inset.Max.X
}
if w.Axis.Vertical() {
r.Min.Y = inset.Min.Y
r.Max.Y = inset.Max.Y
}
c.Rect = r
c.Wrapper.Layout(t)
}
}
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