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@ryannhg

ryannhg/main.go Secret

Created Jan 13, 2022
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SEO Image Gen Script
package main
import (
"fmt"
"image"
"image/draw"
"image/jpeg"
"image/png"
"log"
"path/filepath"
"strings"
"os"
)
// TERMINAL CONST
const RESET = "\033[0m"
const RED = "\033[31m"
const GREEN = "\033[32m"
const YELLOW = "\033[33m"
const CYAN = "\033[36m"
// This script is a modified version of this:
// https://www.golangprograms.com/how-to-add-watermark-or-merge-two-image.html
func main() {
// Step 1: Load background gradient JPEG
bgImage := loadBackgroundImage()
// Step 2: Make sure the output folder exists
ensureOuputFolderExists()
// Step 3: Create a new file for each PNG image
count := createImagesWithBackground(bgImage)
// Step 4: Print out a success message
printSuccessMessage(count)
}
func loadBackgroundImage() image.Image {
bgFile, err := os.Open("backgrounds/square.png")
if err != nil {
log.Fatalf("failed to open: %s", err)
}
bgImage, err := png.Decode(bgFile)
if err != nil {
log.Fatalf("failed to decode: %s", err)
}
defer bgFile.Close()
return bgImage
}
func ensureOuputFolderExists() {
os.MkdirAll("../../static/gen/seo", os.ModePerm)
}
func createImagesWithBackground(bgImage image.Image) int {
// Read all files in the "static/images" folder
files, err := os.ReadDir("../../static/images")
if err != nil {
log.Fatalf("failed to read folder: %s", err)
}
// Will track how many files were generated
count := 0
for _, file := range files {
// Get filename, without extension
nameWithExt := file.Name()
filename := strings.TrimSuffix(nameWithExt, filepath.Ext(nameWithExt))
// Ignore non-PNG files
if filepath.Ext(nameWithExt) == ".png" {
count++
createCombinedFile(bgImage, filename)
}
}
return count
}
func printSuccessMessage(count int) {
log.Printf(
"\n\n %s%d%s SEO images generated!\n\n",
GREEN,
count,
RESET,
)
}
// Creates a single file
func createCombinedFile(bgImage image.Image, filename string) {
// Define input/output paths
inputFilepath := fmt.Sprintf("../../static/images/%s.png", filename)
outputFilepath := fmt.Sprintf("../../static/gen/seo/%s.jpg", filename)
// Load foreground PNG image
fgFile, err := os.Open(inputFilepath)
if err != nil {
log.Fatalf("failed to open: %s", err)
}
fgImage, err := png.Decode(fgFile)
if err != nil {
log.Fatalf("failed to decode: %s", err)
}
defer fgFile.Close()
// Describe expected image dimensions
bgBounds := image.Rect(0, 0, 256, 256)
fgOffset := image.Pt(64, 64)
fgBounds := image.Rect(0, 0, 128, 128).Add(fgOffset)
// Validate against actual image dimensions
actualFgBounds := fgImage.Bounds().Size()
// Exit with helpful error if a PNG is the wrong size
if actualFgBounds.X != 128 || actualFgBounds.Y != 128 {
printInvalidImageError(filename, actualFgBounds)
}
// Create a composite image
combinedImage := image.NewRGBA(bgBounds)
draw.Draw(combinedImage, bgBounds, bgImage, image.Point{}, draw.Src)
draw.Draw(combinedImage, fgBounds, fgImage, image.Point{}, draw.Over)
// Write output to the filesystem
combinedFile, err := os.Create(outputFilepath)
if err != nil {
log.Fatalf("failed to create: %s", err)
}
jpeg.Encode(combinedFile, combinedImage, &jpeg.Options{Quality: jpeg.DefaultQuality})
defer combinedFile.Close()
}
func printInvalidImageError(filename string, actualBounds image.Point) {
log.Fatalf(
"\n\n Problem with %s./static/images/%s.png%s :\n\n Expected size %s128x128%s, found %s%dx%d%s\n\n",
YELLOW,
filename,
RESET,
GREEN,
RESET,
CYAN,
actualBounds.X,
actualBounds.Y,
RESET,
)
}
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