snapshot of https://github.com/mattermost/mattermost.git (master, 2026-09-16; blobs > 131072B omitted)

server/channels/app/imaging/utils.go

@@ -0,0 +1,153 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package imaging
+
+import (
+	"image"
+	"image/color"
+
+	"github.com/boxes-ltd/imaging"
+)
+
+type rawImg interface {
+	Set(x, y int, c color.Color)
+	Opaque() bool
+}
+
+func isFullyTransparent(c color.Color) bool {
+	// TODO: This can be optimized by checking the color type and
+	// only extract the needed alpha value.
+	_, _, _, a := c.RGBA()
+	return a == 0
+}
+
+// FillImageTransparency fills in-place all the fully transparent pixels of the
+// input image with the given color.
+func FillImageTransparency(img image.Image, c color.Color) {
+	var i rawImg
+
+	bounds := img.Bounds()
+
+	fillFunc := func() {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			for x := bounds.Min.X; x < bounds.Max.X; x++ {
+				if isFullyTransparent(img.At(x, y)) {
+					i.Set(x, y, c)
+				}
+			}
+		}
+	}
+
+	switch raw := img.(type) {
+	case *image.Alpha:
+		i = raw
+	case *image.Alpha16:
+		i = raw
+	case *image.Gray:
+		i = raw
+	case *image.Gray16:
+		i = raw
+	case *image.NRGBA:
+		i = raw
+		col := color.NRGBAModel.Convert(c).(color.NRGBA)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					if raw.Pix[i+3] == 0x00 {
+						raw.Pix[i] = col.R
+						raw.Pix[i+1] = col.G
+						raw.Pix[i+2] = col.B
+						raw.Pix[i+3] = col.A
+					}
+				}
+			}
+		}
+	case *image.NRGBA64:
+		i = raw
+		col := color.NRGBA64Model.Convert(c).(color.NRGBA64)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
+					if a == 0 {
+						raw.Pix[i] = uint8(col.R >> 8)
+						raw.Pix[i+1] = uint8(col.R)
+						raw.Pix[i+2] = uint8(col.G >> 8)
+						raw.Pix[i+3] = uint8(col.G)
+						raw.Pix[i+4] = uint8(col.B >> 8)
+						raw.Pix[i+5] = uint8(col.B)
+						raw.Pix[i+6] = uint8(col.A >> 8)
+						raw.Pix[i+7] = uint8(col.A)
+					}
+				}
+			}
+		}
+	case *image.Paletted:
+		i = raw
+		fillFunc = func() {
+			for i := range raw.Palette {
+				if isFullyTransparent(raw.Palette[i]) {
+					raw.Palette[i] = c
+				}
+			}
+		}
+	case *image.RGBA:
+		i = raw
+		col := color.RGBAModel.Convert(c).(color.RGBA)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					if raw.Pix[i+3] == 0x00 {
+						raw.Pix[i] = col.R
+						raw.Pix[i+1] = col.G
+						raw.Pix[i+2] = col.B
+						raw.Pix[i+3] = col.A
+					}
+				}
+			}
+		}
+	case *image.RGBA64:
+		i = raw
+		col := color.RGBA64Model.Convert(c).(color.RGBA64)
+		fillFunc = func() {
+			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+				for x := bounds.Min.X; x < bounds.Max.X; x++ {
+					i := raw.PixOffset(x, y)
+					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
+					if a == 0 {
+						raw.Pix[i] = uint8(col.R >> 8)
+						raw.Pix[i+1] = uint8(col.R)
+						raw.Pix[i+2] = uint8(col.G >> 8)
+						raw.Pix[i+3] = uint8(col.G)
+						raw.Pix[i+4] = uint8(col.B >> 8)
+						raw.Pix[i+5] = uint8(col.B)
+						raw.Pix[i+6] = uint8(col.A >> 8)
+						raw.Pix[i+7] = uint8(col.A)
+					}
+				}
+			}
+		}
+	default:
+		return
+	}
+
+	if !i.Opaque() {
+		fillFunc()
+	}
+}
+
+// FillCenter creates an image with the specified dimensions and fills it with
+// the centered and scaled source image.
+func FillCenter(img image.Image, w, h int) *image.NRGBA {
+	return imaging.Fill(img, w, h, imaging.Center, imaging.Lanczos)
+}
+
+// Fit scales down the image to fit within the specified maximum dimensions,
+// preserving the aspect ratio.
+func Fit(img image.Image, maxW, maxH int) *image.NRGBA {
+	return imaging.Fit(img, maxW, maxH, imaging.Lanczos)
+}