PLT-4277: Allow larger custom emojis by resizing (#4447)

Add function to resize image using resize.Thumbnail. Add function to
resize gif using previous function. Add function to convert image.Image
to image.Palleted. Add logic to identify image type and resize them if
they are larger than MaxEmojiHeight or MaxEmojiWidth. Also increase
MaxEmojiFileSize.

* fix: Add github.com/nfnt to vendor

* fix: Fix max file size and if logic in resizeEmoji

* test: Fix and add new tests for new resize feature

* fix: Fix and update translations to fit new feature

* fix: Add requested changes

2 files changed, 133 insertions, 13 deletions

diff --git a/api/emoji.go b/api/emoji.go
index 39f57a3c8..9108db2ad 100644
--- a/api/emoji.go
+++ b/api/emoji.go
@@ -6,23 +6,26 @@ package api
 import (
 	"bytes"
 	"image"
-	_ "image/gif"
+	"image/draw"
+	"image/gif"
 	_ "image/jpeg"
-	_ "image/png"
+	"image/png"
 	"io"
 	"mime/multipart"
 	"net/http"
 	"strings"
 
 	l4g "github.com/alecthomas/log4go"
+	"github.com/disintegration/imaging"
 	"github.com/gorilla/mux"
 	"github.com/mattermost/platform/einterfaces"
 	"github.com/mattermost/platform/model"
 	"github.com/mattermost/platform/utils"
+	"image/color/palette"
 )
 
 const (
-	MaxEmojiFileSize = 64 * 1024 // 64 KB
+	MaxEmojiFileSize = 1000 * 1024 // 1 MB
 	MaxEmojiWidth    = 128
 	MaxEmojiHeight   = 128
 )
@@ -147,11 +150,39 @@ func uploadEmojiImage(id string, imageData *multipart.FileHeader) *model.AppErro
 	if config, _, err := image.DecodeConfig(bytes.NewReader(buf.Bytes())); err != nil {
 		return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.image.app_error", nil, err.Error())
 	} else if config.Width > MaxEmojiWidth || config.Height > MaxEmojiHeight {
-		return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.large_image.app_error", nil, "")
-	}
-
-	if err := WriteFile(buf.Bytes(), getEmojiImagePath(id)); err != nil {
-		return err
+		data := buf.Bytes()
+		newbuf := bytes.NewBuffer(nil)
+		if info, err := model.GetInfoForBytes(imageData.Filename, data); err != nil {
+			return err
+		} else if info.MimeType == "image/gif" {
+			if gif_data, err := gif.DecodeAll(bytes.NewReader(data)); err != nil {
+				return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.large_image.gif_decode_error", nil, "")
+			} else {
+				resized_gif := resizeEmojiGif(gif_data)
+				if err := gif.EncodeAll(newbuf, resized_gif); err != nil {
+					return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.large_image.gif_encode_error", nil, "")
+				}
+				if err := WriteFile(newbuf.Bytes(), getEmojiImagePath(id)); err != nil {
+					return err
+				}
+			}
+		} else {
+			if img, _, err := image.Decode(bytes.NewReader(data)); err != nil {
+				return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.large_image.decode_error", nil, "")
+			} else {
+				resized_image := resizeEmoji(img, config.Width, config.Height)
+				if err := png.Encode(newbuf, resized_image); err != nil {
+					return model.NewLocAppError("uploadEmojiImage", "api.emoji.upload.large_image.encode_error", nil, "")
+				}
+				if err := WriteFile(newbuf.Bytes(), getEmojiImagePath(id)); err != nil {
+					return err
+				}
+			}
+		}
+	} else {
+		if err := WriteFile(buf.Bytes(), getEmojiImagePath(id)); err != nil {
+			return err
+		}
 	}
 
 	return nil
@@ -252,3 +283,43 @@ func getEmojiImage(c *Context, w http.ResponseWriter, r *http.Request) {
 func getEmojiImagePath(id string) string {
 	return "emoji/" + id + "/image"
 }
+
+func resizeEmoji(img image.Image, width int, height int) image.Image {
+	emojiWidth := float64(width)
+	emojiHeight := float64(height)
+
+	var emoji image.Image
+	if emojiHeight <= MaxEmojiHeight && emojiWidth <= MaxEmojiWidth {
+		emoji = img
+	} else {
+		emoji = imaging.Fit(img, MaxEmojiWidth, MaxEmojiHeight, imaging.Lanczos)
+	}
+	return emoji
+}
+
+func resizeEmojiGif(gifImg *gif.GIF) *gif.GIF {
+	// Create a new RGBA image to hold the incremental frames.
+	firstFrame := gifImg.Image[0].Bounds()
+	b := image.Rect(0, 0, firstFrame.Dx(), firstFrame.Dy())
+	img := image.NewRGBA(b)
+
+	resizedImage := image.Image(nil)
+	// Resize each frame.
+	for index, frame := range gifImg.Image {
+		bounds := frame.Bounds()
+		draw.Draw(img, bounds, frame, bounds.Min, draw.Over)
+		resizedImage = resizeEmoji(img, firstFrame.Dx(), firstFrame.Dy())
+		gifImg.Image[index] = imageToPaletted(resizedImage)
+	}
+	// Set new gif width and height
+	gifImg.Config.Width = resizedImage.Bounds().Dx()
+	gifImg.Config.Height = resizedImage.Bounds().Dy()
+	return gifImg
+}
+
+func imageToPaletted(img image.Image) *image.Paletted {
+	b := img.Bounds()
+	pm := image.NewPaletted(b, palette.Plan9)
+	draw.FloydSteinberg.Draw(pm, b, img, image.ZP)
+	return pm
+}
diff --git a/api/emoji_test.go b/api/emoji_test.go
index fb23cc439..efe4fd363 100644
--- a/api/emoji_test.go
+++ b/api/emoji_test.go
@@ -177,8 +177,8 @@ func TestCreateEmoji(t *testing.T) {
 		CreatorId: th.BasicUser.Id,
 		Name:      model.NewId(),
 	}
-	if _, err := Client.CreateEmoji(emoji, createTestGif(t, 1000, 10), "image.gif"); err == nil {
-		t.Fatal("shouldn't be able to create an emoji that's too wide")
+	if _, err := Client.CreateEmoji(emoji, createTestGif(t, 1000, 10), "image.gif"); err != nil {
+		t.Fatal("should be able to create an emoji that's too wide by resizing it")
 	}
 
 	// try to create an emoji that's too tall
@@ -186,8 +186,8 @@ func TestCreateEmoji(t *testing.T) {
 		CreatorId: th.BasicUser.Id,
 		Name:      model.NewId(),
 	}
-	if _, err := Client.CreateEmoji(emoji, createTestGif(t, 10, 1000), "image.gif"); err == nil {
-		t.Fatal("shouldn't be able to create an emoji that's too tall")
+	if _, err := Client.CreateEmoji(emoji, createTestGif(t, 10, 1000), "image.gif"); err != nil {
+		t.Fatal("should be able to create an emoji that's too tall by resizing it")
 	}
 
 	// try to create an emoji that's too large
@@ -195,7 +195,7 @@ func TestCreateEmoji(t *testing.T) {
 		CreatorId: th.BasicUser.Id,
 		Name:      model.NewId(),
 	}
-	if _, err := Client.CreateEmoji(emoji, createTestAnimatedGif(t, 100, 100, 4000), "image.gif"); err == nil {
+	if _, err := Client.CreateEmoji(emoji, createTestAnimatedGif(t, 100, 100, 10000), "image.gif"); err == nil {
 		t.Fatal("shouldn't be able to create an emoji that's too large")
 	}
 
@@ -424,3 +424,52 @@ func TestGetEmojiImage(t *testing.T) {
 		t.Fatal("should've failed to get image for deleted emoji")
 	}
 }
+
+func TestResizeEmoji(t *testing.T) {
+	// try to resize a jpeg image within MaxEmojiWidth and MaxEmojiHeight
+	small_img_data := createTestJpeg(t, MaxEmojiWidth, MaxEmojiHeight)
+	if small_img, _, err := image.Decode(bytes.NewReader(small_img_data)); err != nil {
+		t.Fatal("failed to decode jpeg bytes to image.Image")
+	} else {
+		resized_img := resizeEmoji(small_img, small_img.Bounds().Dx(), small_img.Bounds().Dy())
+		if resized_img.Bounds().Dx() > MaxEmojiWidth || resized_img.Bounds().Dy() > MaxEmojiHeight {
+			t.Fatal("resized jpeg width and height should not be greater than MaxEmojiWidth or MaxEmojiHeight")
+		}
+		if resized_img != small_img {
+			t.Fatal("should've returned small_img itself")
+		}
+	}
+	// try to resize a jpeg image
+	jpeg_data := createTestJpeg(t, 256, 256)
+	if jpeg_img, _, err := image.Decode(bytes.NewReader(jpeg_data)); err != nil {
+		t.Fatal("failed to decode jpeg bytes to image.Image")
+	} else {
+		resized_jpeg := resizeEmoji(jpeg_img, jpeg_img.Bounds().Dx(), jpeg_img.Bounds().Dy())
+		if resized_jpeg.Bounds().Dx() > MaxEmojiWidth || resized_jpeg.Bounds().Dy() > MaxEmojiHeight {
+			t.Fatal("resized jpeg width and height should not be greater than MaxEmojiWidth or MaxEmojiHeight")
+		}
+	}
+	// try to resize a png image
+	png_data := createTestJpeg(t, 256, 256)
+	if png_img, _, err := image.Decode(bytes.NewReader(png_data)); err != nil {
+		t.Fatal("failed to decode png bytes to image.Image")
+	} else {
+		resized_png := resizeEmoji(png_img, png_img.Bounds().Dx(), png_img.Bounds().Dy())
+		if resized_png.Bounds().Dx() > MaxEmojiWidth || resized_png.Bounds().Dy() > MaxEmojiHeight {
+			t.Fatal("resized png width and height should not be greater than MaxEmojiWidth or MaxEmojiHeight")
+		}
+	}
+	// try to resize an animated gif
+	gif_data := createTestAnimatedGif(t, 256, 256, 10)
+	if gif_img, err := gif.DecodeAll(bytes.NewReader(gif_data)); err != nil {
+		t.Fatal("failed to decode gif bytes to gif.GIF")
+	} else {
+		resized_gif := resizeEmojiGif(gif_img)
+		if resized_gif.Config.Width > MaxEmojiWidth || resized_gif.Config.Height > MaxEmojiHeight {
+			t.Fatal("resized gif width and height should not be greater than MaxEmojiWidth or MaxEmojiHeight")
+		}
+		if len(resized_gif.Image) != len(gif_img.Image) {
+			t.Fatal("resized gif should have the same number of frames as original gif")
+		}
+	}
+}