From 401af5e6a1291b60f7167e4aa2d80939276c5ae8 Mon Sep 17 00:00:00 2001
From: "Robert D. Vincent" <robert.d.vincent@mcgill.ca>
Date: Fri, 22 Apr 2016 00:43:50 -0400
Subject: [PATCH 1/2] Set a reasonable initial zoom level.

---
 src/brainbrowser/volume-viewer/lib/panel.js       |  1 +
 .../volume-viewer/volume-loaders/minc.js          | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/brainbrowser/volume-viewer/lib/panel.js b/src/brainbrowser/volume-viewer/lib/panel.js
index 7a1bc55e..ddf4175a 100644
--- a/src/brainbrowser/volume-viewer/lib/panel.js
+++ b/src/brainbrowser/volume-viewer/lib/panel.js
@@ -497,6 +497,7 @@
 
     if (panel.volume) {
       setSlice(panel, panel.volume.slice(panel.axis));
+      panel.zoom = panel.volume.getPreferredZoom(panel.canvas.width, panel.canvas.height);
     }
 
     return panel;
diff --git a/src/brainbrowser/volume-viewer/volume-loaders/minc.js b/src/brainbrowser/volume-viewer/volume-loaders/minc.js
index 0676f8b9..9682cc63 100644
--- a/src/brainbrowser/volume-viewer/volume-loaders/minc.js
+++ b/src/brainbrowser/volume-viewer/volume-loaders/minc.js
@@ -372,6 +372,21 @@
       },
       getVoxelMax: function() {
         return volume.header.voxel_max;
+      },
+      /* given a width and height (from the panel), this function returns the "best"
+       * single zoom level that will guarantee that the image fits exactly into the
+       * current panel.
+       */
+      getPreferredZoom: function(width, height) {
+        var header = volume.header;
+        var x_fov = header.xspace.space_length * Math.abs(header.xspace.step);
+        var y_fov = header.yspace.space_length * Math.abs(header.yspace.step);
+        var z_fov = header.zspace.space_length * Math.abs(header.xspace.step);
+        var xw = width / x_fov;
+        var yw = width / y_fov;
+        var yh = height / y_fov;
+        var zh = height / z_fov;
+        return Math.min(yw, xw, zh, yh);
       }
     };
     return volume;

From 4c1e83c7c965ec994e37f61b2217c7fd859950e8 Mon Sep 17 00:00:00 2001
From: "Robert D. Vincent" <robert.d.vincent@mcgill.ca>
Date: Mon, 25 Apr 2016 08:45:02 -0400
Subject: [PATCH 2/2] More improvements to zooming - sensible cursor drawing at
 high zoom levels, better zoom speeds at high zoom.

---
 examples/volume-viewer-demo.js                    |  7 +++++++
 src/brainbrowser/volume-viewer/lib/panel.js       | 13 ++++++++-----
 src/brainbrowser/volume-viewer/modules/loading.js |  5 +++--
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/examples/volume-viewer-demo.js b/examples/volume-viewer-demo.js
index eec6a1a1..009cf43e 100644
--- a/examples/volume-viewer-demo.js
+++ b/examples/volume-viewer-demo.js
@@ -285,6 +285,13 @@ $(function() {
       });
     });
 
+    $(document).keypress(function(e) {
+      if (e.keyCode === 114) {
+        // Reset displays if user presses 'r' key.
+        viewer.resetDisplays();
+        viewer.redrawVolumes();
+      }
+    });
     //////////////////////////////////
     // Per volume UI hooks go in here.
     //////////////////////////////////
diff --git a/src/brainbrowser/volume-viewer/lib/panel.js b/src/brainbrowser/volume-viewer/lib/panel.js
index ddf4175a..1826e265 100644
--- a/src/brainbrowser/volume-viewer/lib/panel.js
+++ b/src/brainbrowser/volume-viewer/lib/panel.js
@@ -295,9 +295,10 @@
       * ```
       */
       reset: function() {
-        panel.zoom = 1;
+        panel.zoom = panel.default_zoom;
         panel.image_center.x = panel.canvas.width / 2;
         panel.image_center.y = panel.canvas.height / 2;
+        panel.updated = true;
       },
 
       /**
@@ -496,8 +497,10 @@
     }
 
     if (panel.volume) {
-      setSlice(panel, panel.volume.slice(panel.axis));
-      panel.zoom = panel.volume.getPreferredZoom(panel.canvas.width, panel.canvas.height);
+      var volume = panel.volume;
+      setSlice(panel, volume.slice(panel.axis));
+      panel.default_zoom = volume.getPreferredZoom(panel.canvas.width, panel.canvas.height);
+      panel.zoom = panel.default_zoom;
     }
 
     return panel;
@@ -518,7 +521,7 @@
     var context = panel.context;
     var cursor = panel.getCursorPosition();
     var zoom = panel.zoom;
-    var length = 8 * zoom;
+    var length = 8 * (zoom / panel.default_zoom);
     var x, y, space;
     var distance;
     var dx, dy;
@@ -529,7 +532,7 @@
     context.strokeStyle = color;
     context.fillStyle = color;
 
-    space = zoom;
+    space = 1;
     x = cursor.x;
     y = cursor.y;
 
diff --git a/src/brainbrowser/volume-viewer/modules/loading.js b/src/brainbrowser/volume-viewer/modules/loading.js
index 18ddbc8b..10bb6eda 100644
--- a/src/brainbrowser/volume-viewer/modules/loading.js
+++ b/src/brainbrowser/volume-viewer/modules/loading.js
@@ -646,7 +646,7 @@ BrainBrowser.VolumeViewer.modules.loading = function(viewer) {
 
           last_touch_distance = null;
         }
-        
+
         canvas.addEventListener("mousedown", function(event) {
           event.preventDefault();
 
@@ -696,7 +696,8 @@ BrainBrowser.VolumeViewer.modules.loading = function(viewer) {
         }
 
         function zoom(delta) {
-          panel.zoom = Math.max(panel.zoom + delta * 0.05, 0.05);
+          panel.zoom *= (delta < 0) ? 1/1.05 : 1.05;
+          panel.zoom = Math.max(panel.zoom, 0.25);
           panel.updateVolumePosition();
           panel.updateSlice();