ebiten/internal/graphicsutil/copy.go

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// Copyright 2017 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package graphicsutil
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import (
"image"
"image/color"
"image/draw"
)
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// CopyImage copies origImg to a new RGBA image.
//
// Basically CopyImage just calls draw.Draw.
// If origImg is a paletted image, an optimized copying method is used.
//
// CopyImage is used only internally but it is exposed for testing.
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//
// TODO: CopyImage should return []byte (#521)
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func CopyImage(origImg image.Image) *image.RGBA {
size := origImg.Bounds().Size()
w, h := size.X, size.Y
newImg := image.NewRGBA(image.Rect(0, 0, w, h))
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switch origImg := origImg.(type) {
case *image.Paletted:
b := origImg.Bounds()
x0 := b.Min.X
y0 := b.Min.Y
x1 := b.Max.X
y1 := b.Max.Y
palette := make([]uint8, len(origImg.Palette)*4)
for i, c := range origImg.Palette {
rgba := color.RGBAModel.Convert(c).(color.RGBA)
palette[4*i] = rgba.R
palette[4*i+1] = rgba.G
palette[4*i+2] = rgba.B
palette[4*i+3] = rgba.A
}
index0 := 0
index1 := 0
d0 := origImg.Stride - (x1 - x0)
d1 := newImg.Stride - (x1-x0)*4
pix0 := origImg.Pix
pix1 := newImg.Pix
for j := 0; j < y1-y0; j++ {
for i := 0; i < x1-x0; i++ {
p := int(pix0[index0])
pix1[index1] = palette[4*p]
pix1[index1+1] = palette[4*p+1]
pix1[index1+2] = palette[4*p+2]
pix1[index1+3] = palette[4*p+3]
index0++
index1 += 4
}
index0 += d0
index1 += d1
}
default:
draw.Draw(newImg, image.Rect(0, 0, w, h), origImg, origImg.Bounds().Min, draw.Src)
}
return newImg
}