rewrite code a bit

Signed-off-by: Naman Sood <mail@nsood.in>

common/common.go

@@ -0,0 +1,77 @@
+package common
+
+import (
+	"io"
+	"time"
+
+	"github.com/fogleman/gg"
+)
+
+const (
+	BlogTitle   = "Prose"
+	BlogURL     = "https://prose.nsood.in"
+	BlogSummary = "Where I infodump in Markdown and nobody can stop me."
+)
+
+func RSSDatetime(timestamp int64) string {
+	return time.Unix(timestamp, 0).Format("Mon, 02 Jan 2006 15:04:05 MST")
+}
+
+func CreateImage(title, summary, url string, out io.Writer) error {
+	imgWidth, imgHeight, imgPaddingX, imgPaddingY := 1200, 600, 50, 100
+	accentHeight, spacerHeight := 12.5, 20.0
+	titleSize, summarySize, urlSize := 63.0, 42.0, 27.0
+	lineHeight := 1.05
+	textWidth := float64(imgWidth - 2*imgPaddingX)
+
+	draw := gg.NewContext(imgWidth, imgHeight)
+
+	titleFont, err := gg.LoadFontFace("static/fonts/Nunito-Bold.ttf", titleSize)
+	if err != nil {
+		return err
+	}
+	summaryFont, err := gg.LoadFontFace("static/fonts/Nunito-LightItalic.ttf", summarySize)
+	if err != nil {
+		return err
+	}
+	urlFont, err := gg.LoadFontFace("static/fonts/JetBrainsMono-ExtraLight.ttf", urlSize)
+	if err != nil {
+		return err
+	}
+
+	draw.SetFontFace(titleFont)
+	wrappedTitle := draw.WordWrap(title, textWidth)
+	draw.SetFontFace(summaryFont)
+	wrappedSummary := draw.WordWrap(summary, textWidth)
+
+	draw.SetHexColor("#fff")
+	draw.DrawRectangle(0, 0, float64(imgWidth), float64(imgHeight))
+	draw.Fill()
+	draw.SetHexColor("#3498db")
+	draw.DrawRectangle(0, float64(imgHeight)-accentHeight, float64(imgWidth), accentHeight)
+	draw.Fill()
+
+	offset := float64(imgPaddingY)
+
+	draw.SetFontFace(titleFont)
+	draw.SetHexColor("#333")
+	for _, line := range wrappedTitle {
+		draw.DrawString(line, float64(imgPaddingX), offset)
+		offset += lineHeight * titleSize
+	}
+	offset += spacerHeight
+
+	draw.SetFontFace(summaryFont)
+	draw.SetHexColor("#999")
+	for _, line := range wrappedSummary {
+		draw.DrawString(line, float64(imgPaddingX), offset)
+		offset += lineHeight * summarySize
+	}
+
+	draw.SetHexColor("#333")
+	draw.SetFontFace(urlFont)
+	urlY := float64(imgHeight - imgPaddingY)
+	draw.DrawStringWrapped(url, float64(imgPaddingX), urlY, 0, 0, textWidth, lineHeight, gg.AlignRight)
+
+	return draw.EncodePNG(out)
+}