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https://github.com/gohugoio/hugo.git
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39 lines
1.2 KiB
Go
39 lines
1.2 KiB
Go
// Copyright 2023 The Hugo Authors. 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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// 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 images
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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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"github.com/disintegration/gift"
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)
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var _ gift.Filter = (*opacityFilter)(nil)
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type opacityFilter struct {
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opacity float32
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}
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func (f opacityFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
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// 0 is fully transparent and 255 is opaque.
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alpha := uint8(f.opacity * 255)
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mask := image.NewUniform(color.Alpha{alpha})
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draw.DrawMask(dst, dst.Bounds(), src, image.Point{}, mask, image.Point{}, draw.Over)
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}
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func (f opacityFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
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return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
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}
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