78 lines
2.0 KiB
Go
78 lines
2.0 KiB
Go
package drawtool
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import "git.kirsle.net/apps/doodle/lib/render"
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/*
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Stroke holds temporary pixel data with a shape and color.
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It is used for myriad purposes:
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- As a staging area for drawing new pixels to the drawing without committing
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them until completed.
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- As a unit of work for the Undo/Redo History when editing a drawing.
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- As imaginary visual lines superimposed on top of a drawing, for example to
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visualize the link between two doodads or to draw collision hitboxes and other
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debug lines to the drawing.
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*/
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type Stroke struct {
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ID int // Unique ID per each stroke
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Shape Shape
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Color render.Color
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ExtraData interface{} // arbitrary storage for extra data to attach
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// Start and end points for Lines, Rectangles, etc.
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PointA render.Point
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PointB render.Point
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// Array of points for Freehand shapes.
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Points []render.Point
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uniqPoint map[render.Point]interface{} // deduplicate points added
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}
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var nextStrokeID int
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// NewStroke initializes a new Stroke with a shape and a color.
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func NewStroke(shape Shape, color render.Color) *Stroke {
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nextStrokeID++
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return &Stroke{
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ID: nextStrokeID,
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Shape: shape,
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Color: color,
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// Initialize data structures.
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Points: []render.Point{},
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uniqPoint: map[render.Point]interface{}{},
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}
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}
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// IterPoints returns an iterator of points represented by the stroke.
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//
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// For a Line, returns all of the points between PointA and PointB. For freehand,
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// returns every point added to the stroke.
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func (s *Stroke) IterPoints() chan render.Point {
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ch := make(chan render.Point)
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go func() {
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switch s.Shape {
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case Freehand:
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for _, point := range s.Points {
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ch <- point
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}
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case Line:
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for point := range render.IterLine2(s.PointA, s.PointB) {
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ch <- point
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}
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}
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close(ch)
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}()
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return ch
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}
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// AddPoint adds a point to the stroke, for freehand shapes.
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func (s *Stroke) AddPoint(p render.Point) {
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if _, ok := s.uniqPoint[p]; ok {
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return
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}
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s.uniqPoint[p] = nil
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s.Points = append(s.Points, p)
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}
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