User interface toolkit for Go with support for SDL2 and HTML Canvas render targets.
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package ui
import (
"fmt"
"strings"
"git.kirsle.net/go/render"
"git.kirsle.net/go/ui/style"
)
// DefaultFont is the default font settings used for a Label.
var DefaultFont = render.Text{
Size: 12,
Color: render.Black,
}
// Label is a simple text label widget.
type Label struct {
BaseWidget
// Configurable fields for the constructor.
Text string
TextVariable *string
IntVariable *int
Font render.Text
style *style.Label
width int
height int
lineHeight int
}
// NewLabel creates a new label.
func NewLabel(c Label) *Label {
w := &Label{
Text: c.Text,
TextVariable: c.TextVariable,
IntVariable: c.IntVariable,
Font: DefaultFont,
}
w.SetStyle(Theme.Label)
if !c.Font.IsZero() {
w.Font = c.Font
}
w.IDFunc(func() string {
return fmt.Sprintf(`Label<"%s">`, w.text().Text)
})
return w
}
// SetStyle sets the label's default style.
func (w *Label) SetStyle(v *style.Label) {
if v == nil {
v = &style.DefaultLabel
}
w.style = v
w.SetBackground(w.style.Background)
w.Font.Color = w.style.Foreground
}
// text returns the label's displayed text, coming from the TextVariable if
// available or else the Text attribute instead.
func (w *Label) text() render.Text {
if w.TextVariable != nil {
w.Font.Text = *w.TextVariable
return w.Font
} else if w.IntVariable != nil {
w.Font.Text = fmt.Sprintf("%d", *w.IntVariable)
return w.Font
}
w.Font.Text = w.Text
return w.Font
}
// Value returns the current text value displayed in the widget, whether it was
// the hardcoded value or a TextVariable.
func (w *Label) Value() string {
return w.text().Text
}
// Compute the size of the label widget.
func (w *Label) Compute(e render.Engine) {
text := w.text()
lines := strings.Split(text.Text, "\n")
// Max rect to encompass all lines of text.
var maxRect = render.Rect{}
for _, line := range lines {
if line == "" {
line = "<empty>"
}
text.Text = line // only this line at this time.
rect, err := e.ComputeTextRect(text)
if err != nil {
panic(fmt.Sprintf("%s: failed to compute text rect: %s", w, err)) // TODO return an error
}
if rect.W > maxRect.W {
maxRect.W = rect.W
}
maxRect.H += rect.H
w.lineHeight = int(rect.H)
}
var (
padX = w.Font.Padding + w.Font.PadX
padY = w.Font.Padding + w.Font.PadY
)
if !w.FixedSize() {
w.ResizeAuto(render.Rect{
W: maxRect.W + (padX * 2),
H: maxRect.H + (padY * 2),
})
}
// Call the BaseWidget Compute in case we have subscribers.
w.BaseWidget.Compute(e)
}
// Present the label widget.
func (w *Label) Present(e render.Engine, P render.Point) {
if w.Hidden() {
return
}
border := w.BoxThickness(1)
var (
text = w.text()
padX = w.Font.Padding + w.Font.PadX
padY = w.Font.Padding + w.Font.PadY
)
w.DrawBox(e, P)
for i, line := range strings.Split(text.Text, "\n") {
text.Text = line
e.DrawText(text, render.Point{
X: P.X + border + padX,
Y: P.Y + border + padY + (i * w.lineHeight),
})
}
// Call the BaseWidget Present in case we have subscribers.
w.BaseWidget.Present(e, P)
}