From 2560ce1acb0ecb910cc8f9045b0019f04cbf63d8 Mon Sep 17 00:00:00 2001
From: Alon Levy <alon@pobox.com>
Date: Mon, 6 Apr 2015 17:50:54 +0300
Subject: client: return zoom buttons, make zoom conserve center point

---
 src/client/buttons.js | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

(limited to 'src/client/buttons.js')

diff --git a/src/client/buttons.js b/src/client/buttons.js
index 8a0b6b7d..00554c8b 100644
--- a/src/client/buttons.js
+++ b/src/client/buttons.js
@@ -214,5 +214,39 @@ $('#btn_rzdoc__open').click(function() {
     cmd_bar.fadeToggle(400);
 });
 
+function log_scale(max_in, min_out, max_out) {
+    var t = (min_out * max_out - 1) / (min_out + max_out - 2),
+        k = 1 / max_in * Math.log((max_out - t) / (1 - t));
+
+    return function (x) { return (1 - t) * Math.exp(x * k) + t; };
+}
+
+function exp_scale(max_in, min_out, max_out) {
+    var t = (min_out * max_out - 1) / (min_out + max_out - 2),
+        k = 1 / max_in * Math.log((max_out - t) / (1 - t));
+
+    return function (y) { return (1 / k) * Math.log((y - t) / (1 - t)); };
+}
+
+function clip(min, max, v) {
+    return Math.max(min, Math.min(max, v));
+}
+
+var zoom_range = 10,
+    zoom_min = 0.1,
+    zoom_max = 3,
+    zoom_exp_to_linear = exp_scale(zoom_range, zoom_min, zoom_max);
+
+$('#btn_zoom_in').asEventStream('click')
+    .map(1)
+    .merge($('#btn_zoom_out').asEventStream('click').map(-1))
+    .map(function (change) {
+        return clip(-zoom_range, zoom_range, zoom_exp_to_linear(rz_core.main_graph_view.zoom_obj.scale()) + change);
+    })
+    .map(log_scale(zoom_range, zoom_min, zoom_max))
+    .onValue(function (val) {
+        rz_core.main_graph_view.scale__absolute(val);
+    });
+
 return {'buttons': 'nothing here'};
 }); // define
-- 
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