More improvements to zooming - sensible cursor drawing at high zoom levels, better zoom speeds at high zoom.

Author: Robert D. Vincent

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.
     //////////////////////////////////

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;
 

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();