doodle/pkg/uix/canvas_strokes.go
Noah Petherbridge c8620f871e Drawing Strokes and Undo/Redo Functionality
* Add new pkg/drawtool with utilities to abstract away drawing actions
  into Strokes and track undo/redo History for them.
* The freehand Pencil tool in EditorMode has been refactored to create a
  Stroke of Shape=Freehand and queue up its world pixels there instead
  of directly modifying the level chunker in real time. When the mouse
  button is released, the freehand Stroke is committed to the level
  chunker and added to the UndoHistory.
* UndoHistory is (temporarily) stored with the level.Level so it can
  survive trips to PlayScene and back, but is not stored as JSON on
  disk.
* Ctrl-Z and Ctrl-Y in EditorMode for undo and redo, respectively.
2019-07-03 16:25:23 -07:00

113 lines
3.1 KiB
Go

package uix
import (
"git.kirsle.net/apps/doodle/lib/render"
"git.kirsle.net/apps/doodle/lib/ui"
"git.kirsle.net/apps/doodle/pkg/balance"
"git.kirsle.net/apps/doodle/pkg/drawtool"
"git.kirsle.net/apps/doodle/pkg/level"
"git.kirsle.net/apps/doodle/pkg/log"
)
// canvas_strokes.go: functions related to drawtool.Stroke and the Canvas.
// AddStroke installs a new Stroke to be superimposed over drawing data
// in the canvas.
//
// The stroke is added to the canvas's map by its ID so it can be removed later.
// The stroke must have a non-zero ID value set or this function will panic.
// drawtool.NewStroke() creates an initialized Stroke object to use here.
func (w *Canvas) AddStroke(stroke *drawtool.Stroke) {
if stroke.ID == 0 {
panic("Canvas.AddStroke: the Stroke is missing an ID; was it initialized properly?")
}
w.strokes[stroke.ID] = stroke
}
// RemoveStroke uninstalls a Stroke from the canvas using its ID.
//
// Returns true if the stroke existed to begin with, false if not.
func (w *Canvas) RemoveStroke(stroke *drawtool.Stroke) bool {
if _, ok := w.strokes[stroke.ID]; ok {
delete(w.strokes, stroke.ID)
return true
}
return false
}
// UndoStroke rolls back the level's UndoHistory and deletes the pixels last
// added to the level. Returns false and emits a warning to the log if the
// canvas has no level loaded properly.
func (w *Canvas) UndoStroke() bool {
if w.level == nil {
log.Error("Canvas.UndoStroke: no Level currently available to the canvas")
return false
}
latest := w.level.UndoHistory.Latest()
if latest != nil {
for point := range latest.IterPoints() {
w.chunks.Delete(point)
}
}
return w.level.UndoHistory.Undo()
}
// RedoStroke rolls the level's UndoHistory forwards again and replays the
// recently undone changes.
func (w *Canvas) RedoStroke() bool {
if w.level == nil {
log.Error("Canvas.UndoStroke: no Level currently available to the canvas")
return false
}
ok := w.level.UndoHistory.Redo()
if !ok {
return false
}
latest := w.level.UndoHistory.Latest()
// We stored the ActiveSwatch on this stroke as we drew it. Recover it
// and place the pixels back down.
if swatch, ok := latest.ExtraData.(*level.Swatch); ok {
for point := range latest.IterPoints() {
w.chunks.Set(point, swatch)
}
return true
}
log.Error("Canvas.UndoStroke: undo was successful but no Swatch was stored on the Stroke.ExtraData!")
return ok
}
// presentStrokes is called as part of Present() and draws the strokes whose
// pixels are currently visible within the viewport.
func (w *Canvas) presentStrokes(e render.Engine) {
var (
P = ui.AbsolutePosition(w) // w.Point() // Canvas point in UI
VP = w.ViewportRelative() // Canvas scroll viewport
)
for _, stroke := range w.strokes {
for point := range stroke.IterPoints() {
if !point.Inside(VP) {
continue
}
dest := render.Point{
X: P.X + w.Scroll.X + w.BoxThickness(1) + point.X,
Y: P.Y + w.Scroll.Y + w.BoxThickness(1) + point.Y,
}
if balance.DebugCanvasStrokeColor != render.Invisible {
e.DrawPoint(balance.DebugCanvasStrokeColor, dest)
} else {
e.DrawPoint(stroke.Color, dest)
}
}
}
}