/
overlayImage.go
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/
overlayImage.go
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package filters
import (
"github.com/zalando-stups/skrop/parse"
"github.com/zalando/skipper/filters"
"github.com/h2non/bimg"
"io/ioutil"
"os"
)
const (
// OverlayImageName is the name of the filter
OverlayImageName = "overlayImage"
// NE North East
NE = "NE"
// NC North Center
NC = "NC"
// NW North West
NW = "NW"
// CE Centre East
CE = "CE"
// CC Centre Center
CC = "CC"
// CW Centre West
CW = "CW"
// SE South East
SE = "SE"
// SC South Center
SC = "SC"
// SW South West
SW = "SW"
)
var (
gravityType = map[string]bool{
NE: true,
NC: true,
NW: true,
CE: true,
CC: true,
CW: true,
SE: true,
SC: true,
SW: true,
}
verticalGravity = map[string]bimg.Gravity{
NE: bimg.GravityNorth,
NC: bimg.GravityNorth,
NW: bimg.GravityNorth,
CE: bimg.GravityCentre,
CC: bimg.GravityCentre,
CW: bimg.GravityCentre,
SE: bimg.GravitySouth,
SC: bimg.GravitySouth,
SW: bimg.GravitySouth,
}
horizontalGravity = map[string]bimg.Gravity{
NE: bimg.GravityEast,
NC: bimg.GravityCentre,
NW: bimg.GravityWest,
CE: bimg.GravityEast,
CC: bimg.GravityCentre,
CW: bimg.GravityWest,
SE: bimg.GravityEast,
SC: bimg.GravityCentre,
SW: bimg.GravityWest,
}
)
type overlay struct {
file string
opacity float64
verticalGravity bimg.Gravity
horizontalGravity bimg.Gravity
rightMargin int
leftMargin int
topMargin int
bottomMargin int
}
// NewOverlayImage creates a new filter of this type
func NewOverlayImage() filters.Spec {
return &overlay{}
}
func (f *overlay) Name() string {
return OverlayImageName
}
func (f *overlay) CreateOptions(imageContext *ImageFilterContext) (*bimg.Options, error) {
origSize, err := imageContext.Image.Size()
if err != nil {
return nil, err
}
overArr, err := readImage(f.file)
if err != nil {
return nil, err
}
overImage := bimg.NewImage(overArr)
overSize, err := overImage.Size()
if err != nil {
return nil, err
}
var x, y int
switch f.verticalGravity {
case bimg.GravityNorth:
y = f.topMargin
case bimg.GravityCentre:
y = f.topMargin + int(float64(origSize.Height-f.topMargin-f.bottomMargin)/2) - int(
float64(overSize.Height)/2)
case bimg.GravitySouth:
y = origSize.Height - f.bottomMargin - overSize.Height
}
switch f.horizontalGravity {
case bimg.GravityWest:
x = f.leftMargin
case bimg.GravityCentre:
x = f.leftMargin + int(float64(origSize.Width-f.leftMargin-f.rightMargin)/2) - int(float64(overSize.Width)/2)
case bimg.GravityEast:
x = origSize.Width - f.rightMargin - overSize.Width
}
return &bimg.Options{WatermarkImage: bimg.WatermarkImage{Buf: overArr,
Opacity: float32(f.opacity),
Left: x,
Top: y,
}}, nil
}
func (f *overlay) CanBeMerged(other *bimg.Options, self *bimg.Options) bool {
zero := bimg.WatermarkImage{}
//it can be merged if the background was not set (in options or in self) or if they are set to the same value
return other.Width == 0 && other.Height == 0 && (equals(other.WatermarkImage, zero) || equals(other.WatermarkImage, self.WatermarkImage))
}
func equals(one bimg.WatermarkImage, two bimg.WatermarkImage) bool {
return one.Opacity == two.Opacity &&
one.Top == two.Top &&
one.Left == two.Left &&
len(one.Buf) == len(two.Buf)
}
func (f *overlay) Merge(other *bimg.Options, self *bimg.Options) *bimg.Options {
other.WatermarkImage = self.WatermarkImage
return other
}
func readImage(file string) ([]byte, error) {
img, err := os.Open(file)
if err != nil {
return nil, err
}
defer img.Close()
buf, err := ioutil.ReadAll(img)
if err != nil {
return nil, err
}
return buf, nil
}
func (f *overlay) CreateFilter(args []interface{}) (filters.Filter, error) {
//imageOverlay(<filename>, <opacity>, <gravity>, <right_margin>, <left_margin>, <top_margin>, <bottom_margin>)
//imageOverlay("filename", 1.0, NE, 0, 0, 0, 0)
//imageOverlay("filename", 1.0, NE)
var err error
if len(args) != 3 && len(args) != 7 {
return nil, filters.ErrInvalidFilterParameters
}
o := &overlay{}
o.file, err = parse.EskipStringArg(args[0])
if err != nil {
return nil, err
}
o.opacity, err = parse.EskipFloatArg(args[1])
if err != nil {
return nil, err
}
if o.opacity < 0 {
o.opacity = 0
} else if o.opacity > 1.0 {
o.opacity = 1
}
gravity, err := parse.EskipStringArg(args[2])
if err != nil {
return nil, err
}
if !gravityType[gravity] {
return nil, filters.ErrInvalidFilterParameters
}
o.verticalGravity = verticalGravity[gravity]
o.horizontalGravity = horizontalGravity[gravity]
if len(args) == 3 {
return o, nil
}
o.topMargin, err = parse.EskipIntArg(args[3])
if err != nil {
return nil, err
}
o.rightMargin, err = parse.EskipIntArg(args[4])
if err != nil {
return nil, err
}
o.bottomMargin, err = parse.EskipIntArg(args[5])
if err != nil {
return nil, err
}
o.leftMargin, err = parse.EskipIntArg(args[6])
if err != nil {
return nil, err
}
return o, nil
}
func (f *overlay) Request(ctx filters.FilterContext) {}
func (f *overlay) Response(ctx filters.FilterContext) {
HandleImageResponse(ctx, f)
}