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status_indicator.go
56 lines (46 loc) · 1.42 KB
/
status_indicator.go
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package images
import (
"bytes"
"image"
"image/color"
"image/png"
"math"
"github.com/fogleman/gg"
)
func AddStatusIndicatorToImage(inputImage []byte, innerColor color.Color, indicatorSize, indicatorBorder, indicatorCenterToEdge float64) ([]byte, error) {
// decode the input image
img, _, err := image.Decode(bytes.NewReader(inputImage))
if err != nil {
return nil, err
}
// get the dimensions of the image
width := img.Bounds().Max.X
height := img.Bounds().Max.Y
indicatorOuterRadius := (indicatorSize / 2) + indicatorBorder
// calculate the center point
x := float64(width) - indicatorCenterToEdge
y := float64(height) - indicatorCenterToEdge
// create a new gg.Context instance
dc := gg.NewContext(width, height)
dc.DrawImage(img, 0, 0)
// Loop through each pixel in the hole and set it to transparent
dc.SetColor(color.Transparent)
for i := x - indicatorOuterRadius; i <= x+indicatorOuterRadius; i++ {
for j := y - indicatorOuterRadius; j <= y+indicatorOuterRadius; j++ {
if math.Pow(i-x, 2)+math.Pow(j-y, 2) <= math.Pow(indicatorOuterRadius, 2) {
dc.SetPixel(int(i), int(j))
}
}
}
// draw inner circle
dc.DrawCircle(x, y, indicatorOuterRadius-indicatorBorder)
dc.SetColor(innerColor)
dc.Fill()
// encode the modified image as PNG and return as []byte
var outputImage bytes.Buffer
err = png.Encode(&outputImage, dc.Image())
if err != nil {
return nil, err
}
return outputImage.Bytes(), nil
}