28 lines
474 B
Go
28 lines
474 B
Go
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package main
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import (
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"image"
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"image/color"
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)
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type circle struct {
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p image.Point
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r int
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}
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func (c *circle) ColorModel() color.Model {
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return color.AlphaModel
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}
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func (c *circle) Bounds() image.Rectangle {
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return image.Rect(c.p.X-c.r, c.p.Y-c.r, c.p.X+c.r, c.p.Y+c.r)
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}
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func (c *circle) At(x, y int) color.Color {
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xx, yy, rr := float64(x-c.p.X)+0.5, float64(y-c.p.Y)+0.5, float64(c.r)
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if xx*xx+yy*yy < rr*rr {
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return color.Alpha{255}
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}
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return color.Alpha{0}
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}
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