Steal kernel.org's libravatar lua.

cgit.css

@@ -897,3 +897,31 @@ div#cgit table.ssdiff td.space {
 div#cgit table.ssdiff td.space div {
 	min-height: 3em;
 }
+div#cgit span.libravatar img.onhover {
+        display: none;
+        border: 1px solid gray;
+        padding: 0px;
+        -webkit-border-radius: 4px;
+        -moz-border-radius: 4px;
+        border-radius: 4px;
+        width: 128px;
+        height: 128px;
+}
+
+div#cgit span.libravatar img.inline {
+        -webkit-border-radius: 3px;
+        -moz-border-radius: 3px;
+        border-radius: 3px;
+        width: 13px;
+        height: 13px;
+        margin-right: 0.2em;
+        opacity: 0.6;
+}
+
+div#cgit span.libravatar:hover > img.onhover {
+        display: block;
+        position: absolute;
+        margin-left: 1.5em;
+        background-color: #eeeeee;
+        box-shadow: 2px 2px 7px rgba(100,100,100,0.75);
+}

filters/email-libravatar-hover.lua

@@ -0,0 +1,25 @@
+local digest = require("openssl.digest")
+
+function md5_hex(input)
+	local b = digest.new("md5"):final(input)
+	local x = ""
+	for i = 1, #b do
+		x = x .. string.format("%.2x", string.byte(b, i))
+	end
+	return x
+end
+
+function filter_open(email, page)
+	buffer = ""
+	hexdigest = md5_hex(email:sub(2, -2):lower())
+end
+
+function filter_close()
+	baseurl = os.getenv("HTTPS") and "https://seccdn.libravatar.org/" or "http://cdn.libravatar.org/"
+	html("<span class='libravatar'><img class='inline' src='" .. baseurl .. "avatar/" .. hexdigest .. "?s=13&amp;d=retro' /><img class='onhover' src='" .. baseurl .. "avatar/" .. hexdigest .. "?s=128&amp;d=retro' /></span>" .. buffer)
+	return 0
+end
+
+function filter_write(str)
+	buffer = buffer .. str
+end