98 lines
2.6 KiB
Go
98 lines
2.6 KiB
Go
package drawing
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// Liner receive segment definition
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type Liner interface {
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// LineTo Draw a line from the current position to the point (x, y)
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LineTo(x, y float64)
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}
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// Flattener receive segment definition
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type Flattener interface {
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// MoveTo Start a New line from the point (x, y)
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MoveTo(x, y float64)
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// LineTo Draw a line from the current position to the point (x, y)
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LineTo(x, y float64)
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// LineJoin add the most recent starting point to close the path to create a polygon
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LineJoin()
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// Close add the most recent starting point to close the path to create a polygon
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Close()
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// End mark the current line as finished so we can draw caps
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End()
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}
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// Flatten convert curves into straight segments keeping join segments info
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func Flatten(path *Path, flattener Flattener, scale float64) {
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// First Point
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var startX, startY float64
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// Current Point
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var x, y float64
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var i int
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for _, cmp := range path.Components {
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switch cmp {
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case MoveToComponent:
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x, y = path.Points[i], path.Points[i+1]
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startX, startY = x, y
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if i != 0 {
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flattener.End()
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}
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flattener.MoveTo(x, y)
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i += 2
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case LineToComponent:
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x, y = path.Points[i], path.Points[i+1]
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flattener.LineTo(x, y)
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flattener.LineJoin()
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i += 2
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case QuadCurveToComponent:
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// we include the previous point for the start of the curve
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TraceQuad(flattener, path.Points[i-2:], 0.5)
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x, y = path.Points[i+2], path.Points[i+3]
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flattener.LineTo(x, y)
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i += 4
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case CubicCurveToComponent:
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TraceCubic(flattener, path.Points[i-2:], 0.5)
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x, y = path.Points[i+4], path.Points[i+5]
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flattener.LineTo(x, y)
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i += 6
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case ArcToComponent:
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x, y = TraceArc(flattener, path.Points[i], path.Points[i+1], path.Points[i+2], path.Points[i+3], path.Points[i+4], path.Points[i+5], scale)
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flattener.LineTo(x, y)
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i += 6
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case CloseComponent:
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flattener.LineTo(startX, startY)
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flattener.Close()
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}
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}
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flattener.End()
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}
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// SegmentedPath is a path of disparate point sectinos.
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type SegmentedPath struct {
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Points []float64
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}
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// MoveTo implements the path interface.
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func (p *SegmentedPath) MoveTo(x, y float64) {
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p.Points = append(p.Points, x, y)
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// TODO need to mark this point as moveto
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}
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// LineTo implements the path interface.
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func (p *SegmentedPath) LineTo(x, y float64) {
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p.Points = append(p.Points, x, y)
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}
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// LineJoin implements the path interface.
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func (p *SegmentedPath) LineJoin() {
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// TODO need to mark the current point as linejoin
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}
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// Close implements the path interface.
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func (p *SegmentedPath) Close() {
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// TODO Close
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}
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// End implements the path interface.
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func (p *SegmentedPath) End() {
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// Nothing to do
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}
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