From fb99d81cccc469b0457c877cd726ffb15c3179b6 Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Wed, 14 Apr 2010 12:03:01 -0500
Subject: [PATCH] Better hextile performance: index subrects instead of
 slicing/shifting.

- Many times better performance. Before this, browser was spending all
  it's time garbage collecting or doing something. Now the bottleneck
  is in set fillStyle and fillRect which is probably where it should
  be.
---
 vnc.js | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/vnc.js b/vnc.js
index 14a0ee1e..72b70922 100644
--- a/vnc.js
+++ b/vnc.js
@@ -227,7 +227,7 @@ init_msg: function () {
 display_raw: function () {
     console.log(">> display_raw");
     Canvas.rfbImage(FBU.x, FBU.y, FBU.width, FBU.height, RFB.d);
-    RFB.d.splice(0, FBU.width * FBU.height * RFB.fb_Bpp);
+    RFB.d.shiftBytes(FBU.width * FBU.height * RFB.fb_Bpp);
     FBU.rects --;
 },
 
@@ -331,6 +331,7 @@ display_hextile: function() {
         if (subencoding > -1) {
             /* We know the encoding and have a whole tile */
             FBU.subencoding = RFB.d.shift8();
+            FBU.bytes--;
             if (FBU.subencoding == 0) {
                 if (FBU.lastsubencoding & 0x01) {
                     /* Weird: ignore blanks after RAW */
@@ -343,37 +344,45 @@ display_hextile: function() {
                 }
             } else if (FBU.subencoding & 0x01) { // Raw
                 Canvas.rfbImage(x, y, w, h, RFB.d);
-                RFB.d.splice(0, FBU.bytes - 1);
             } else {
+                var idx = 0;
                 if (FBU.subencoding & 0x02) { // Background
-                    FBU.background = RFB.d.shiftBytes(RFB.fb_Bpp);
+                    FBU.background = RFB.d.slice(idx, idx + RFB.fb_Bpp);
+                    idx += RFB.fb_Bpp;
                     //console.log("   background: " + FBU.background);
                 }
                 if (FBU.subencoding & 0x04) { // Foreground
-                    FBU.foreground = RFB.d.shiftBytes(RFB.fb_Bpp);
+                    FBU.foreground = RFB.d.slice(idx, idx + RFB.fb_Bpp);
+                    idx += RFB.fb_Bpp;
                     //console.log("   foreground: " + FBU.foreground);
                 }
                 Canvas.rfbRect(x, y, w, h, FBU.background);
                 if (FBU.subencoding & 0x08) { // AnySubrects
-                    subrects = RFB.d.shift8();
+                    subrects = RFB.d[idx];
+                    idx++;
+                    var color, xy, sx, sy, wh, sw, sh;
                     for (var i = 0; i < subrects; i ++) {
                         if (FBU.subencoding & 0x10) { // SubrectsColoured
-                            var color = RFB.d.shiftBytes(RFB.fb_Bpp);
+                            color = RFB.d.slice(idx, idx + RFB.fb_Bpp);
+                            idx += RFB.fb_Bpp;
                         } else {
-                            var color = FBU.foreground;
+                            color = FBU.foreground;
                         }
-                        var xy = RFB.d.shift8();
-                        var sx = x + (xy >> 4);
-                        var sy = y + (xy & 0x0f);
+                        xy = RFB.d[idx];
+                        idx++;
+                        sx = x + (xy >> 4);
+                        sy = y + (xy & 0x0f);
 
-                        var wh = RFB.d.shift8();
-                        var sw = (wh >> 4)   + 1;
-                        var sh = (wh & 0x0f) + 1;
+                        wh = RFB.d[idx];
+                        idx++;
+                        sw = (wh >> 4)   + 1;
+                        sh = (wh & 0x0f) + 1;
 
                         Canvas.rfbRect(sx, sy, sw, sh, color);
                     }
                 }
             }
+            if (FBU.bytes > 0) RFB.d.shiftBytes(FBU.bytes);
             FBU.lastsubencoding = FBU.subencoding;
             FBU.subencoding = -1;
             FBU.tiles --;