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a8fd76557b
This PR fixes the builtin avatar generator. 1. The random background color makes some images very dirty. So now we only use white background for avatars. 2. We use left-right mirror avatars to satisfy #14799 3. Fix a small padding error in the algorithm
69 lines
2.2 KiB
Go
69 lines
2.2 KiB
Go
// Copyright 2021 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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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 int, 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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