Support configuring image size

cmd/wfgraphic-cli/main.go

@@ -14,6 +14,8 @@ import (
 	"flag"
 	"io/ioutil"
 	"os"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/writeas/text-pic"
@@ -25,6 +27,7 @@ var (
 	font       = flag.String("font", "serif", "Post font (options: \"serif\", \"sans\", \"mono\")")
 	instance   = flag.String("i", "write.as", "WriteFreely instance hostname (e.g. pencil.writefree.ly)")
 	author     = flag.String("u", "", "WriteFreely author username (for multi-user instances)")
+	size       = flag.String("size", "1024", "Image size, either a single number for a square (e.g. \"900\") or a combined width and height (e.g. \"1080x1920\")")
 )
 
 func main() {
@@ -36,6 +39,34 @@ func main() {
 		log.Info("Invalid font given. Options: \"serif\", \"sans\", \"mono\"")
 		os.Exit(1)
 	}
+	// Parse image dimensions and validate
+	var w, h int
+	if strings.ContainsRune(*size, 'x') {
+		parts := strings.Split(*size, "x")
+		if len(parts) != 2 {
+			log.Info("Invalid --size given. Must be a single number for a square (e.g. \"900\") or a combined width and height (e.g. \"1080x1920\")")
+			os.Exit(1)
+		}
+		var err error
+		w, err = strconv.Atoi(parts[0])
+		if err != nil {
+			log.Info("Unable to parse --size dimension '%s': %s", parts[0], err)
+			os.Exit(1)
+		}
+		h, err = strconv.Atoi(parts[1])
+		if err != nil {
+			log.Info("Unable to parse --size dimension '%s': %s", parts[1], err)
+			os.Exit(1)
+		}
+	} else {
+		sq, err := strconv.Atoi(*size)
+		if err != nil {
+			log.Info("Unable to parse --size: %s", err)
+			os.Exit(1)
+		}
+		w = sq
+		h = sq
+	}
 
 	log.Info("Reading input...")
 	in, err := ioutil.ReadAll(os.Stdin)
@@ -46,7 +77,7 @@ func main() {
 
 	log.Info("Generating image...")
 	start := time.Now()
-	err = textpic.GenerateImage(textpic.NewContentOptions(*instance, *author, false, *font, string(in)), *outputFile)
+	err = textpic.GenerateImage(textpic.NewContentOptions(*instance, *author, false, *font, string(in)), w, h, *outputFile)
 	if err != nil {
 		log.Error("%s", err)
 		os.Exit(1)

textpic.go

@@ -33,9 +33,7 @@ func loadFont(dc *gg.Context, fontFace string, bold bool, points float64) error
 	return nil
 }
 
-func GenerateImage(opt *ContentOptions, outputFilename string) error {
-	w := 900
-	h := 900
+func GenerateImage(opt *ContentOptions, w, h int, outputFilename string) error {
 	wf := float64(w)
 	hf := float64(h)
 	dc := gg.NewContext(w, h)