catbase/plugins/gifmeme/gif.go

package gifmeme

import (
	"bytes"
	"github.com/andybons/gogif"
	"github.com/rs/zerolog/log"
	"github.com/velour/catbase/config"
	"github.com/velour/catbase/plugins/meme"
	"image"
	"image/gif"
	"net/http"
	"time"
)

const tpc = 5
const nColors = 64

func getGif(c *config.Config, s meme.Specification) ([]byte, int, int, error) {
	t0 := time.Now()
	resp, err := http.Get(s.ImageURL)
	if err != nil {
		return nil, 0, 0, err
	}
	g, err := gif.DecodeAll(resp.Body)
	if err != nil {
		return nil, 0, 0, err
	}
	log.Debug().Msgf("Len before adding text: %d", len(g.Image))
	err = addText(c, g, s.Configs)
	log.Debug().Msgf("Len after adding text: %d", len(g.Image))
	log.Debug().Msgf("%v elapsed adding text", time.Now().Sub(t0))
	if err != nil {
		return nil, 0, 0, err
	}
	out := bytes.NewBuffer([]byte{})
	t1 := time.Now()
	err = gif.EncodeAll(out, g)
	if err != nil {
		return nil, 0, 0, err
	}
	log.Debug().Msgf("%v elapsed encoding gif", time.Now().Sub(t1))
	w, h := g.Image[0].Bounds().Max.X, g.Image[0].Bounds().Max.Y
	return out.Bytes(), w, h, nil
}

func addText(c *config.Config, g *gif.GIF, text []meme.Text) error {
	totalTime := calcTime(g)
	framesNeeded, avgFrames := calcTextTime(text)
	loops := 1

	if totalTime < framesNeeded {
		loops = framesNeeded / totalTime
		totalTime = loops * totalTime
	} else {
		framesNeeded = totalTime
	}

	log.Debug().Msgf("We need %d loops for %d total time with %d frames",
		loops, totalTime, framesNeeded)

	frames := []*image.Paletted{}
	delays := []int{}

	idx := 0

	toicfg := meme.MkTextOnImageConfig(c)

	bounds := g.Image[0].Bounds()
	maxSz := max(bounds.Max.X, bounds.Max.Y)
	if toicfg.MaxSz > float64(maxSz) {
		toicfg.MaxSz = float64(maxSz)
	}

	currText := 0
	currTextFrames := 0

	log.Debug().Msgf("Writing text configs %+v on image", text)

	log.Debug().Msgf("Starting text with %+v", text[currText])

	for i := 0; i < framesNeeded; i++ {
		img := g.Image[idx]
		i, err := meme.TextOnImage(toicfg, img, []meme.Text{text[currText]})
		if err != nil {
			log.Error().Err(err).Msg("error encoding gif")
			return err
		}
		frames = append(frames, imgToPaletted(i))
		delays = append(delays, g.Delay[idx])
		idx = (idx + 1) % len(g.Image)
		currTextFrames++
		if currTextFrames > avgFrames {
			currText = (currText + 1) % len(text)
			currTextFrames = 0
			log.Debug().Msgf("Switching text to %+v", text[currText])
		}
	}

	g.Image = frames
	g.Delay = delays
	g.Disposal = nil
	g.Config = image.Config{}

	return nil
}

func calcTextTime(text []meme.Text) (int, int) {
	total := 1
	for _, frame := range text {
		total += tpc * len(frame.Text)
	}
	return total, total / len(text)
}

func calcTime(g *gif.GIF) int {
	total := 0
	for _, frameDelay := range g.Delay {
		total += frameDelay
	}
	return total
}

func imgToPaletted(i image.Image) *image.Paletted {
	bounds := i.Bounds()
	p := image.NewPaletted(bounds, nil)
	quantizer := gogif.MedianCutQuantizer{NumColor: nColors}
	quantizer.Quantize(p, bounds, i, image.Point{})
	return p
}

func max(x, y int) int {
	if x > y {
		return x
	}
	return y
}