91 lines
2.2 KiB
Go
91 lines
2.2 KiB
Go
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// Copyright 2017 The Ebiten Authors
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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 ebiten
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import (
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"image"
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"image/color"
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"image/draw"
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)
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// imageToBytes gets RGBA bytes from img.
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//
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// Basically imageToBytes just calls draw.Draw.
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// If img is a paletted image, an optimized copying method is used.
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//
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// If img is *image.RGBA and its length is same as 4*width*height, imageToBytes returns its Pix.
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func imageToBytes(img image.Image) []byte {
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size := img.Bounds().Size()
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w, h := size.X, size.Y
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switch img := img.(type) {
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case *image.Paletted:
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bs := make([]byte, 4*w*h)
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b := img.Bounds()
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x0 := b.Min.X
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y0 := b.Min.Y
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x1 := b.Max.X
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y1 := b.Max.Y
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palette := make([]uint8, len(img.Palette)*4)
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for i, c := range img.Palette {
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rgba := color.RGBAModel.Convert(c).(color.RGBA)
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palette[4*i] = rgba.R
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palette[4*i+1] = rgba.G
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palette[4*i+2] = rgba.B
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palette[4*i+3] = rgba.A
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}
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// Even img is a subimage of another image, Pix starts with 0-th index.
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idx0 := 0
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idx1 := 0
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d := img.Stride - (x1 - x0)
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for j := 0; j < y1-y0; j++ {
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for i := 0; i < x1-x0; i++ {
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p := int(img.Pix[idx0])
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bs[idx1] = palette[4*p]
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bs[idx1+1] = palette[4*p+1]
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bs[idx1+2] = palette[4*p+2]
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bs[idx1+3] = palette[4*p+3]
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idx0++
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idx1 += 4
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}
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idx0 += d
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}
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return bs
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case *image.RGBA:
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if len(img.Pix) == 4*w*h {
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return img.Pix
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}
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return imageToBytesSlow(img)
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default:
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return imageToBytesSlow(img)
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}
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}
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func imageToBytesSlow(img image.Image) []byte {
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size := img.Bounds().Size()
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w, h := size.X, size.Y
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bs := make([]byte, 4*w*h)
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dstImg := &image.RGBA{
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Pix: bs,
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Stride: 4 * w,
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Rect: image.Rect(0, 0, w, h),
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}
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draw.Draw(dstImg, image.Rect(0, 0, w, h), img, img.Bounds().Min, draw.Src)
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return bs
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}
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