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SEO Image Gen Script
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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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