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Tracking cursor position in real-time with remote monitoring (without JavaScript)
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// Tracking cursor position in real-time without JavaScript | |
// Demo: https://twitter.com/davywtf/status/1124146339259002881 | |
package main | |
import ( | |
"fmt" | |
"net/http" | |
"strings" | |
) | |
const W = 50 | |
const H = 50 | |
var ch chan string | |
const head = `<head> | |
<style> | |
*{margin:0;padding:0} | |
html,body{width:100%;height:100%} | |
p{ | |
width:10px; | |
height:10px; | |
display:inline-block; | |
border-right:1px solid #666; | |
border-bottom:1px solid #666 | |
} | |
</style> | |
</head>` | |
func main() { | |
ch = make(chan string) | |
http.HandleFunc("/", handler) | |
http.ListenAndServe(":8080", nil) | |
} | |
func handler(w http.ResponseWriter, r *http.Request) { | |
p := r.URL.Path | |
if p == "/" { | |
index(w, r) | |
return | |
} else if p == "/watch" { | |
watch(w, r) | |
return | |
} else { | |
if strings.HasPrefix(p, "/c") && strings.HasSuffix(p, ".png") { | |
ch <- p[1 : len(p)-4] | |
} | |
} | |
} | |
func index(w http.ResponseWriter, r *http.Request) { | |
w.Header().Set("Content-Type", "text/html; charset=utf-8") | |
flusher, ok := w.(http.Flusher) | |
if !ok { | |
return | |
} | |
w.Write([]byte(head)) | |
flusher.Flush() | |
// Send <p> grid | |
w.Write([]byte("<body>\n")) | |
for i := 0; i < H; i++ { | |
w.Write([]byte("<div>")) | |
for j := 0; j < W; j++ { | |
w.Write([]byte(fmt.Sprintf("<p id=\"c%dx%d\"></p>", i, j))) | |
} | |
w.Write([]byte("</div>\n")) | |
} | |
w.Write([]byte("</body>\n")) | |
flusher.Flush() | |
// Send CSS | |
w.Write([]byte("<style>")) | |
for i := 0; i < H; i++ { | |
for j := 0; j < W; j++ { | |
id := fmt.Sprintf("c%dx%d", i, j) | |
s := fmt.Sprintf("#%s:hover{background:url(\"%s.png\")}", id, id) | |
w.Write([]byte(s)) | |
} | |
} | |
w.Write([]byte("</style>")) | |
flusher.Flush() | |
} | |
func watch(w http.ResponseWriter, r *http.Request) { | |
w.Header().Set("Content-Type", "text/html; charset=utf-8") | |
flusher, ok := w.(http.Flusher) | |
if !ok { | |
return | |
} | |
w.Write([]byte(head)) | |
flusher.Flush() | |
// Send <p> grid | |
w.Write([]byte("<body>\n")) | |
for i := 0; i < H; i++ { | |
w.Write([]byte("<div>")) | |
for j := 0; j < W; j++ { | |
w.Write([]byte(fmt.Sprintf("<p id=\"c%dx%d\"></p>", i, j))) | |
} | |
w.Write([]byte("</div>\n")) | |
} | |
w.Write([]byte("</body>\n")) | |
flusher.Flush() | |
// Listen to ch for updates and write to response | |
for p := range ch { | |
s := fmt.Sprintf("<style>#%s{background:#000}</style>\n", p) | |
_, err := w.Write([]byte(s)) | |
if err != nil { | |
return | |
} | |
flusher.Flush() | |
} | |
} |
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