overlay.go (1246B)
1 // Copyright 2020 The Hugo Authors. All rights reserved.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 // http://www.apache.org/licenses/LICENSE-2.0
7 //
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13
14 package images
15
16 import (
17 "fmt"
18 "image"
19 "image/draw"
20
21 "github.com/disintegration/gift"
22 )
23
24 var _ gift.Filter = (*overlayFilter)(nil)
25
26 type overlayFilter struct {
27 src ImageSource
28 x, y int
29 }
30
31 func (f overlayFilter) Draw(dst draw.Image, src image.Image, options *gift.Options) {
32 overlaySrc, err := f.src.DecodeImage()
33 if err != nil {
34 panic(fmt.Sprintf("failed to decode image: %s", err))
35 }
36
37 gift.New().Draw(dst, src)
38 gift.New().DrawAt(dst, overlaySrc, image.Pt(f.x, f.y), gift.OverOperator)
39 }
40
41 func (f overlayFilter) Bounds(srcBounds image.Rectangle) image.Rectangle {
42 return image.Rect(0, 0, srcBounds.Dx(), srcBounds.Dy())
43 }