73 lines
1.8 KiB
Go
73 lines
1.8 KiB
Go
/*
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* Copyright (C) 2022. Gardel <sunxinao@hotmail.com> and contributors
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package model
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import (
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"crypto/sha256"
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"encoding/hex"
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"image"
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"image/color"
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"time"
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)
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type Texture struct {
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Hash string `gorm:"size:64;primaryKey"`
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CreatedAt time.Time
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UpdatedAt time.Time
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Data []byte `gorm:"not null"`
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Used uint `gorm:"not null"`
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}
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func ComputeTextureId(img image.Image) string {
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digest := sha256.New()
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bound := img.Bounds()
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width := bound.Dx()
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height := bound.Dy()
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var buf [4096]byte
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putInt(buf[:], int32(width))
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putInt(buf[4:], int32(height))
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var pos = 8
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for x := 0; x < width; x++ {
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for y := 0; y < height; y++ {
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rgba := color.NRGBAModel.Convert(img.At(x, y)).(color.NRGBA)
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if rgba.A == 0 {
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copy(buf[pos:], []byte{0, 0, 0, 0})
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} else {
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copy(buf[pos:], []byte{rgba.A, rgba.R, rgba.G, rgba.B})
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}
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pos += 4
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if pos == len(buf) {
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pos = 0
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digest.Write(buf[:])
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}
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}
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}
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if pos > 0 {
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digest.Write(buf[:pos])
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}
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return hex.EncodeToString(digest.Sum(nil))
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}
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func putInt(buf []byte, n int32) {
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buf[0] = byte(n >> 24 & 0xff)
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buf[1] = byte(n >> 16 & 0xff)
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buf[2] = byte(n >> 8 & 0xff)
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buf[3] = byte(n & 0xff)
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}
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