From b0c5644b475a09704ea010025b491fd9211122c3 Mon Sep 17 00:00:00 2001
From: Bartek Szopka <bartek.szopka+github@gmail.com>
Date: Wed, 14 Mar 2012 22:53:17 +0000
Subject: [PATCH] "`goto` now accepts duration parameter"

---
 README.md     |  3 +++
 index.html    |  5 +++--
 js/impress.js | 27 +++++++++++++++------------
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/README.md b/README.md
index 060bfd610..040c7bd0a 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,9 @@ VERSION HISTORY
     - you can give it a number of step you want to go to: `impress().goto(7)`
     - or its id: `impress().goto("the-best-slide-ever")`
     - of course DOM element is still acceptable: `impress().goto( document.getElementById("overview") )`
+* and if it's not enough, `goto()` also accepts second parameter to define the transition duration in ms, for example
+  `impress().goto("make-it-quick", 300)` or `impress().goto("now", 0)`
+
 
 ### 0.4.1 ([browse](http://github.com/bartaz/impress.js/tree/0.4.1), [zip](http://github.com/bartaz/impress.js/zipball/0.4.1), [tar](http://github.com/bartaz/impress.js/tarball/0.4.1))
 
diff --git a/index.html b/index.html
index e81557eba..929d59d1d 100644
--- a/index.html
+++ b/index.html
@@ -340,8 +340,9 @@ <h1>impress.js<sup>*</sup></h1>
         `api.init()` - initializes the presentation,
         `api.next()` - moves to next step of the presentation,
         `api.prev()` - moves to previous step of the presentation,
-        `api.goto( idx | id | element )` - moves the presentation to the step given by its index number,
-                                           id or the DOM element.
+        `api.goto( idx | id | element, [duration] )` - moves the presentation to the step given by its index number
+                id or the DOM element; second parameter can be used to define duration of the transition in ms,
+                but it's optional - if not provided default transition duration for the presentation will be used.
     
     You can also simply call `impress()` again to get the API, so `impress().next()` is also allowed.
     Don't worry, it wont initialize the presentation again.
diff --git a/js/impress.js b/js/impress.js
index e06edbc06..7c1b28983 100644
--- a/js/impress.js
+++ b/js/impress.js
@@ -365,10 +365,10 @@
             return (step && step.id && stepsData["impress-" + step.id]) ? step : null;
         };
         
-        var goto = function ( el, force ) {
+        var goto = function ( el, duration ) {
             
-            if ( !initialized || !(el = getStep(el)) || (el === activeStep && !force) ) {
-                // selected element is not defined as step or is already active
+            if ( !initialized || !(el = getStep(el)) ) {
+                // presentation not initialized or given element is not a step
                 return false;
             }
             
@@ -409,12 +409,10 @@
             // check if the transition is zooming in or not
             var zoomin = target.scale >= currentState.scale;
             
-            // if presentation starts (nothing is active yet)
-            // don't animate (set duration to 0)
-            var duration = (activeStep) ? config.transitionDuration : 0,
-                delay = (config.transitionDuration / 2);
+            duration = toNumber(duration, config.transitionDuration);
+            var delay = (duration / 2);
             
-            if (force) {
+            if (el === activeStep) {
                 windowScale = computeWindowScale(config);
             }
             
@@ -486,6 +484,8 @@
         root.addEventListener("impress-init", function(){       
             // HASH CHANGE
             
+            var lastHash = "";
+            
             // `#/step-id` is used instead of `#step-id` to prevent default browser
             // scrolling to element in hash
             //
@@ -493,16 +493,19 @@
             // causes transtion being laggy
             // BUG: http://code.google.com/p/chromium/issues/detail?id=62820
             root.addEventListener("impress-step-enter", function (event) {
-                window.location.hash = "#/" + event.target.id;
+                window.location.hash = lastHash = "#/" + event.target.id;
             }, false);
             
             window.addEventListener("hashchange", function () {
-                goto( getElementFromUrl() );
+                // don't go twice to same element
+                if (window.location.hash !== lastHash) {
+                    goto( getElementFromUrl() );
+                }
             }, false);
             
             // START 
             // by selecting step defined in url or first step of the presentation
-            goto(getElementFromUrl() || steps[0]);
+            goto(getElementFromUrl() || steps[0], 0);
         }, false);
         
         body.classList.add("impress-disabled");
@@ -633,7 +636,7 @@
         // rescale presentation when window is resized
         window.addEventListener("resize", throttle(function () {
             // force going to active step again, to trigger rescaling
-            api.goto( document.querySelector(".active"), true );
+            api.goto( document.querySelector(".active"), 500 );
         }, 250), false);
         
     }, false);