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Source files keep their SPDX-License-Identifier and Hanzo copyright line; the Gitea, Gogs and LFS Test Server copyrights they used to repeat now live once in NOTICE, alongside LICENSE. The header lint accepts any copyright line above the SPDX line, so it no longer demands an upstream one. Co-authored-by: Hanzo Dev <[email protected]>
69 lines
2.1 KiB
Go
69 lines
2.1 KiB
Go
// Copyright 2026 Hanzo AI, Inc. All rights reserved.
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// SPDX-License-Identifier: MIT
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// Copied and modified from https://github.com/issue9/identicon/ (MIT License)
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package identicon
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var (
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// cos(0),cos(90),cos(180),cos(270)
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cos = []int{1, 0, -1, 0}
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// sin(0),sin(90),sin(180),sin(270)
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sin = []int{0, 1, 0, -1}
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)
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// rotate the points by center point (x,y)
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// angle: [0,1,2,3] means [0，90，180，270] degree
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func rotate(points []int, x, y, angle int) {
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// the angle is only used internally, and it has been guaranteed to be 0/1/2/3, so we do not check it again
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for i := 0; i < len(points); i += 2 {
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px, py := points[i]-x, points[i+1]-y
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points[i] = px*cos[angle] - py*sin[angle] + x
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points[i+1] = px*sin[angle] + py*cos[angle] + y
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}
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}
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// check whether the point is inside the polygon (defined by the points)
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// the first and the last point must be the same
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func pointInPolygon(x, y int, polygonPoints []int) bool {
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if len(polygonPoints) < 8 { // a valid polygon must have more than 2 points
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return false
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}
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// reference: nonzero winding rule, https://en.wikipedia.org/wiki/Nonzero-rule
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// split the plane into two by the check point horizontally:
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// y>0，includes (x>0 && y==0)
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// y<0，includes (x<0 && y==0)
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//
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// then scan every point in the polygon.
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//
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// if current point and previous point are in different planes (eg: curY>0 && prevY<0),
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// check the clock-direction from previous point to current point (use check point as origin).
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// if the direction is clockwise, then r++, otherwise then r--
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// finally, if 2==abs(r), then the check point is inside the polygon
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r := 0
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prevX, prevY := polygonPoints[0], polygonPoints[1]
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prev := (prevY > y) || ((prevX > x) && (prevY == y))
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for i := 2; i < len(polygonPoints); i += 2 {
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currX, currY := polygonPoints[i], polygonPoints[i+1]
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curr := (currY > y) || ((currX > x) && (currY == y))
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if curr == prev {
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prevX, prevY = currX, currY
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continue
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}
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if mul := (prevX-x)*(currY-y) - (currX-x)*(prevY-y); mul >= 0 {
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r++
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} else { // mul < 0
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r--
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}
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prevX, prevY = currX, currY
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prev = curr
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}
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return r == 2 || r == -2
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}
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