55 lines
1.8 KiB
Go
55 lines
1.8 KiB
Go
/*
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Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
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Permission to use, copy, modify, and/or distribute this software for any purpose
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with or without fee is hereby granted, provided that the above copyright notice
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and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
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REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
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THIS SOFTWARE.
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*/
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package resize
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import (
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"image"
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)
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// Thumbnail will downscale provided image to max width and height preserving
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// original aspect ratio and using the interpolation function interp.
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// It will return original image, without processing it, if original sizes
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// are already smaller than provided constraints.
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func Thumbnail(maxWidth, maxHeight uint, img image.Image, interp InterpolationFunction) image.Image {
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origBounds := img.Bounds()
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origWidth := uint(origBounds.Dx())
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origHeight := uint(origBounds.Dy())
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newWidth, newHeight := origWidth, origHeight
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// Return original image if it have same or smaller size as constraints
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if maxWidth >= origWidth && maxHeight >= origHeight {
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return img
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}
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// Preserve aspect ratio
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if origWidth > maxWidth {
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newHeight = uint(origHeight * maxWidth / origWidth)
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if newHeight < 1 {
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newHeight = 1
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}
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newWidth = maxWidth
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}
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if newHeight > maxHeight {
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newWidth = uint(newWidth * maxHeight / newHeight)
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if newWidth < 1 {
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newWidth = 1
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}
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newHeight = maxHeight
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}
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return Resize(newWidth, newHeight, img, interp)
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}
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