User interface toolkit for Go with support for SDL2 and HTML Canvas render targets.
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package ui
import (
"errors"
"fmt"
"git.kirsle.net/go/render"
"git.kirsle.net/go/ui/style"
)
// Button is a clickable button.
type Button struct {
BaseWidget
Name string
child Widget
style *style.Button
// Set this true to hard-set a color for this button;
// it will not adjust on mouse-over or press.
FixedColor bool
// Private options.
hovering bool
clicked bool
}
// NewButton creates a new Button.
func NewButton(name string, child Widget) *Button {
w := &Button{
Name: name,
child: child,
style: &style.DefaultButton,
}
w.IDFunc(func() string {
return fmt.Sprintf("Button<%s>", w.Name)
})
w.SetStyle(Theme.Button)
w.Handle(MouseOver, func(e EventData) error {
w.hovering = true
if !w.FixedColor {
w.SetBackground(w.style.HoverBackground)
if label, ok := w.child.(*Label); ok {
label.Font.Color = w.style.HoverForeground
}
}
return nil
})
w.Handle(MouseOut, func(e EventData) error {
w.hovering = false
if !w.FixedColor {
w.SetBackground(w.style.Background)
if label, ok := w.child.(*Label); ok {
label.Font.Color = w.style.Foreground
}
}
return nil
})
w.Handle(MouseDown, func(e EventData) error {
w.clicked = true
w.SetBorderStyle(BorderSunken)
return nil
})
w.Handle(MouseUp, func(e EventData) error {
w.clicked = false
w.SetBorderStyle(BorderStyle(w.style.BorderStyle))
return nil
})
return w
}
// SetStyle sets the button style.
func (w *Button) SetStyle(v *style.Button) {
if v == nil {
v = &style.DefaultButton
}
w.style = v
w.Configure(Config{
BorderSize: w.style.BorderSize,
BorderStyle: BorderStyle(w.style.BorderStyle),
OutlineSize: w.style.OutlineSize,
OutlineColor: w.style.OutlineColor,
Background: w.style.Background,
})
// If the child is a Label, apply the foreground color.
if label, ok := w.child.(*Label); ok {
label.Font.Color = w.style.Foreground
}
}
// GetStyle gets the button style.
func (w *Button) GetStyle() *style.Button {
return w.style
}
// Children returns the button's child widget.
func (w *Button) Children() []Widget {
return []Widget{w.child}
}
// Compute the size of the button.
func (w *Button) Compute(e render.Engine) {
// Compute the size of the inner widget first.
w.child.Compute(e)
// Auto-resize only if we haven't been given a fixed size.
if !w.FixedSize() {
size := w.child.Size()
w.Resize(render.Rect{
W: size.W + w.BoxThickness(2),
H: size.H + w.BoxThickness(2),
})
}
w.BaseWidget.Compute(e)
}
// SetText conveniently sets the button text, for Label children only.
func (w *Button) SetText(text string) error {
if label, ok := w.child.(*Label); ok {
label.Text = text
}
return errors.New("child is not a Label widget")
}
// Present the button.
func (w *Button) Present(e render.Engine, P render.Point) {
if w.Hidden() {
return
}
w.Compute(e)
var (
S = w.Size()
ChildSize = w.child.Size()
)
// Draw the widget's border and everything.
w.DrawBox(e, P)
// Offset further if we are currently sunken.
var clickOffset int
if w.clicked {
clickOffset++
}
// Where to place the child widget.
moveTo := render.Point{
X: P.X + w.BoxThickness(1) + clickOffset,
Y: P.Y + w.BoxThickness(1) + clickOffset,
}
// If we're bigger than we need to be, center the child widget.
if S.Bigger(ChildSize) {
moveTo.X = P.X + (S.W / 2) - (ChildSize.W / 2)
}
// Draw the text label inside.
w.child.Present(e, moveTo)
w.BaseWidget.Present(e, P)
}