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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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