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// Copyright 2024 The Hugo Authors. All rights reserved.
//
// 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.
package images
import (
"image"
"image/color"
"image/draw"
"github.com/disintegration/gift"
)
var _ gift.Filter = (*opacityFilter)(nil)
type opacityFilter struct {
opacity float32
}
func (f opacityFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
// 0 is fully transparent and 255 is opaque.
alpha := uint8(f.opacity * 255)
mask := image.NewUniform(color.Alpha{alpha})
draw.DrawMask(dst, dst.Bounds(), src, image.Point{}, mask, image.Point{}, draw.Over)
}
func (f opacityFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
}
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