doodle/lib/ui/label.go
Noah Petherbridge cc1e441232 Eraser Tool, Brush Sizes
* Implement Brush Sizes for drawtool.Stroke and add a UI to the tools panel
  to control the brush size.
  * Brush sizes: 1, 2, 4, 8, 16, 24, 32, 48, 64
* Add the Eraser Tool to editor mode. It uses a default brush size of 16
  and a max size of 32 due to some performance issues.
* The Undo/Redo system now remembers the original color of pixels when
  you change them, so that Undo will set them back how they were instead
  of deleting the pixel entirely. Due to performance issues, this only
  happens when your Brush Size is 0 (drawing single-pixel shapes).
* UI: Add an IntVariable option to ui.Label to bind showing the value of
  an int reference.

Aforementioned performance issues:

* When we try to remember whole rects of pixels for drawing thick
  shapes, it requires a ton of scanning for each step of the shape. Even
  de-duplicating pixel checks, tons of extra reads are constantly
  checked.
* The Eraser is the only tool that absolutely needs to be able to
  remember wiped pixels AND have large brush sizes. The performance
  sucks and lags a bit if you erase a lot all at once, but it's a
  trade-off for now.
* So pixels aren't remembered when drawing lines in your level with
  thick brushes, so the Undo action will simply delete your pixels and not
  reset them. Only the Eraser can bring back pixels.
2019-07-11 19:07:46 -07:00

134 lines
2.7 KiB
Go

package ui
import (
"fmt"
"strings"
"git.kirsle.net/apps/doodle/lib/render"
)
// 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
width int32
height int32
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,
}
if !c.Font.IsZero() {
w.Font = c.Font
}
w.IDFunc(func() string {
return fmt.Sprintf(`Label<"%s">`, w.text().Text)
})
return w
}
// 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),
})
}
w.MoveTo(render.Point{
X: maxRect.X + w.BoxThickness(1),
Y: maxRect.Y + w.BoxThickness(1),
})
}
// 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 + int32(i*w.lineHeight),
})
}
}