502 lines
13 KiB
Go
502 lines
13 KiB
Go
// Copyright 2014 beego Author. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package captcha
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import (
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"bytes"
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"image"
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"image/color"
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"image/png"
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"io"
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"math"
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)
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const (
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fontWidth = 11
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fontHeight = 18
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blackChar = 1
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// Standard width and height of a captcha image.
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stdWidth = 240
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stdHeight = 80
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// Maximum absolute skew factor of a single digit.
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maxSkew = 0.7
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// Number of background circles.
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circleCount = 20
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)
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var font = [][]byte{
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{ // 0
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0,
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1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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},
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{ // 1
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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},
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{ // 2
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0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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},
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{ // 3
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0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0,
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},
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{ // 4
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0,
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0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0,
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0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0,
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1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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},
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{ // 5
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0,
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},
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{ // 6
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0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0,
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0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0,
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0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0,
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1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0,
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1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 0,
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1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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},
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{ // 7
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0,
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0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0,
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},
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{ // 8
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0,
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0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0,
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0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0,
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0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0,
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1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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},
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{ // 9
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0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0,
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0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0,
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1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1,
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0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1,
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0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0,
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0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0,
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0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0,
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0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
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},
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}
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// Image struct
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type Image struct {
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*image.Paletted
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numWidth int
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numHeight int
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dotSize int
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}
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var prng = &siprng{}
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// randIntn returns a pseudorandom non-negative int in range [0, n).
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func randIntn(n int) int {
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return prng.Intn(n)
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}
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// randInt returns a pseudorandom int in range [from, to].
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func randInt(from, to int) int {
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return prng.Intn(to+1-from) + from
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}
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// randFloat returns a pseudorandom float64 in range [from, to].
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func randFloat(from, to float64) float64 {
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return (to-from)*prng.Float64() + from
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}
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func randomPalette() color.Palette {
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p := make([]color.Color, circleCount+1)
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// Transparent color.
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p[0] = color.RGBA{0xFF, 0xFF, 0xFF, 0x00}
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// Primary color.
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prim := color.RGBA{
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uint8(randIntn(129)),
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uint8(randIntn(129)),
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uint8(randIntn(129)),
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0xFF,
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}
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p[1] = prim
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// Circle colors.
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for i := 2; i <= circleCount; i++ {
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p[i] = randomBrightness(prim, 255)
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}
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return p
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}
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// NewImage returns a new captcha image of the given width and height with the
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// given digits, where each digit must be in range 0-9.
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func NewImage(digits []byte, width, height int) *Image {
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m := new(Image)
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m.Paletted = image.NewPaletted(image.Rect(0, 0, width, height), randomPalette())
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m.calculateSizes(width, height, len(digits))
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// Randomly position captcha inside the image.
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maxx := width - (m.numWidth+m.dotSize)*len(digits) - m.dotSize
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maxy := height - m.numHeight - m.dotSize*2
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var border int
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if width > height {
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border = height / 5
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} else {
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border = width / 5
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}
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x := randInt(border, maxx-border)
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y := randInt(border, maxy-border)
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// Draw digits.
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for _, n := range digits {
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m.drawDigit(font[n], x, y)
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x += m.numWidth + m.dotSize
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}
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// Draw strike-through line.
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m.strikeThrough()
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// Apply wave distortion.
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m.distort(randFloat(5, 10), randFloat(100, 200))
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// Fill image with random circles.
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m.fillWithCircles(circleCount, m.dotSize)
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return m
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}
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// encodedPNG encodes an image to PNG and returns
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// the result as a byte slice.
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func (m *Image) encodedPNG() []byte {
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var buf bytes.Buffer
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if err := png.Encode(&buf, m.Paletted); err != nil {
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panic(err.Error())
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}
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return buf.Bytes()
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}
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// WriteTo writes captcha image in PNG format into the given writer.
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func (m *Image) WriteTo(w io.Writer) (int64, error) {
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n, err := w.Write(m.encodedPNG())
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return int64(n), err
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}
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func (m *Image) calculateSizes(width, height, ncount int) {
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// Goal: fit all digits inside the image.
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var border int
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if width > height {
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border = height / 4
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} else {
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border = width / 4
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}
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// Convert everything to floats for calculations.
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w := float64(width - border*2)
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h := float64(height - border*2)
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// fw takes into account 1-dot spacing between digits.
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fw := float64(fontWidth + 1)
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fh := float64(fontHeight)
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nc := float64(ncount)
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// Calculate the width of a single digit taking into account only the
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// width of the image.
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nw := w / nc
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// Calculate the height of a digit from this width.
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nh := nw * fh / fw
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// Digit too high?
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if nh > h {
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// Fit digits based on height.
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nh = h
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nw = fw / fh * nh
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}
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// Calculate dot size.
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m.dotSize = int(nh / fh)
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if m.dotSize < 1 {
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m.dotSize = 1
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}
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// Save everything, making the actual width smaller by 1 dot to account
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// for spacing between digits.
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m.numWidth = int(nw) - m.dotSize
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m.numHeight = int(nh)
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}
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func (m *Image) drawHorizLine(fromX, toX, y int, colorIdx uint8) {
|
|
for x := fromX; x <= toX; x++ {
|
|
m.SetColorIndex(x, y, colorIdx)
|
|
}
|
|
}
|
|
|
|
func (m *Image) drawCircle(x, y, radius int, colorIdx uint8) {
|
|
f := 1 - radius
|
|
dfx := 1
|
|
dfy := -2 * radius
|
|
xo := 0
|
|
yo := radius
|
|
|
|
m.SetColorIndex(x, y+radius, colorIdx)
|
|
m.SetColorIndex(x, y-radius, colorIdx)
|
|
m.drawHorizLine(x-radius, x+radius, y, colorIdx)
|
|
|
|
for xo < yo {
|
|
if f >= 0 {
|
|
yo--
|
|
dfy += 2
|
|
f += dfy
|
|
}
|
|
xo++
|
|
dfx += 2
|
|
f += dfx
|
|
m.drawHorizLine(x-xo, x+xo, y+yo, colorIdx)
|
|
m.drawHorizLine(x-xo, x+xo, y-yo, colorIdx)
|
|
m.drawHorizLine(x-yo, x+yo, y+xo, colorIdx)
|
|
m.drawHorizLine(x-yo, x+yo, y-xo, colorIdx)
|
|
}
|
|
}
|
|
|
|
func (m *Image) fillWithCircles(n, maxradius int) {
|
|
maxx := m.Bounds().Max.X
|
|
maxy := m.Bounds().Max.Y
|
|
for i := 0; i < n; i++ {
|
|
colorIdx := uint8(randInt(1, circleCount-1))
|
|
r := randInt(1, maxradius)
|
|
m.drawCircle(randInt(r, maxx-r), randInt(r, maxy-r), r, colorIdx)
|
|
}
|
|
}
|
|
|
|
func (m *Image) strikeThrough() {
|
|
maxx := m.Bounds().Max.X
|
|
maxy := m.Bounds().Max.Y
|
|
y := randInt(maxy/3, maxy-maxy/3)
|
|
amplitude := randFloat(5, 20)
|
|
period := randFloat(80, 180)
|
|
dx := 2.0 * math.Pi / period
|
|
for x := 0; x < maxx; x++ {
|
|
xo := amplitude * math.Cos(float64(y)*dx)
|
|
yo := amplitude * math.Sin(float64(x)*dx)
|
|
for yn := 0; yn < m.dotSize; yn++ {
|
|
r := randInt(0, m.dotSize)
|
|
m.drawCircle(x+int(xo), y+int(yo)+(yn*m.dotSize), r/2, 1)
|
|
}
|
|
}
|
|
}
|
|
|
|
func (m *Image) drawDigit(digit []byte, x, y int) {
|
|
skf := randFloat(-maxSkew, maxSkew)
|
|
xs := float64(x)
|
|
r := m.dotSize / 2
|
|
y += randInt(-r, r)
|
|
for yo := 0; yo < fontHeight; yo++ {
|
|
for xo := 0; xo < fontWidth; xo++ {
|
|
if digit[yo*fontWidth+xo] != blackChar {
|
|
continue
|
|
}
|
|
m.drawCircle(x+xo*m.dotSize, y+yo*m.dotSize, r, 1)
|
|
}
|
|
xs += skf
|
|
x = int(xs)
|
|
}
|
|
}
|
|
|
|
func (m *Image) distort(amplude float64, period float64) {
|
|
w := m.Bounds().Max.X
|
|
h := m.Bounds().Max.Y
|
|
|
|
oldm := m.Paletted
|
|
newm := image.NewPaletted(image.Rect(0, 0, w, h), oldm.Palette)
|
|
|
|
dx := 2.0 * math.Pi / period
|
|
for x := 0; x < w; x++ {
|
|
for y := 0; y < h; y++ {
|
|
xo := amplude * math.Sin(float64(y)*dx)
|
|
yo := amplude * math.Cos(float64(x)*dx)
|
|
newm.SetColorIndex(x, y, oldm.ColorIndexAt(x+int(xo), y+int(yo)))
|
|
}
|
|
}
|
|
m.Paletted = newm
|
|
}
|
|
|
|
func randomBrightness(c color.RGBA, max uint8) color.RGBA {
|
|
minc := min3(c.R, c.G, c.B)
|
|
maxc := max3(c.R, c.G, c.B)
|
|
if maxc > max {
|
|
return c
|
|
}
|
|
n := randIntn(int(max-maxc)) - int(minc)
|
|
return color.RGBA{
|
|
uint8(int(c.R) + n),
|
|
uint8(int(c.G) + n),
|
|
uint8(int(c.B) + n),
|
|
c.A,
|
|
}
|
|
}
|
|
|
|
func min3(x, y, z uint8) (m uint8) {
|
|
m = x
|
|
if y < m {
|
|
m = y
|
|
}
|
|
if z < m {
|
|
m = z
|
|
}
|
|
return
|
|
}
|
|
|
|
func max3(x, y, z uint8) (m uint8) {
|
|
m = x
|
|
if y > m {
|
|
m = y
|
|
}
|
|
if z > m {
|
|
m = z
|
|
}
|
|
return
|
|
}
|