11 files changed, 197 insertions, 111 deletions

diff --git a/src/controller/callbacks/mouse_wheel.c b/src/controller/callbacks/mouse_wheel.c
index 52d3c8b..9ca73bc 100644
--- a/src/controller/callbacks/mouse_wheel.c
+++ b/src/controller/callbacks/mouse_wheel.c
@@ -1,44 +1,74 @@
 #include "mouse_wheel.h"
 #include "../actions/zoom.h"
+#include "../../view/state0.h"
 #include <GL/glut.h>
+#include <math.h>
+
+#define S state0
 
 void 
 mouse_wheel (int button, int dir, int x, int y)
 {
   /*
-   * Get the current coordinates, substract some fixed amount and
-   * then perform the zoom.
+   * Start at the origin of the window.  An alternative would be to
+   * start at the position of the mouse.  Calculate a bounding box
+   * that will be the selection and zoom to it.
    */
-  GLint viewport[4];
-  glGetIntegerv (GL_VIEWPORT, viewport);
+  double width = fabs(S.ortho.max_x - S.ortho.min_x);
+  double height = fabs(S.ortho.max_y - S.ortho.min_y);
 
   /*
-   * The step size could be either a fixed number of pixels or a percentage.
+   * Box the smaller of the two dimensions.
    */
-  //  int step = 5;
-  int step = (viewport[3] - viewport[1]) * 0.10;
+  double box = 0.0;
+  if (width <= height)
+    box = width;
+  else
+    box = height;
 
   /*
-   * Not that the focus of the zoom is currently the center of the
-   * window but could alternatively be the mouse pointer's position.
+   * The step size could be either a fixed number of pixels or a
+   * percentage.  Here we take 10% of the size of the box.
    */
+  double step = box * 0.10;
+
+  double x1 = 0.0;
+  double y1 = 0.0;
+  double x2 = 0.0;
+  double y2 = 0.0;
+
+  if (width < height)
+    {
+      x1 = S.ortho.min_x;
+      x2 = S.ortho.max_x;
+      y1 = ((S.ortho.max_y + S.ortho.min_y) / 2.0) - (0.5 * width);
+      y2 = ((S.ortho.max_y + S.ortho.min_y) / 2.0) + (0.5 * width);
+    }
+  else if (width > height)
+    {
+      x1 = ((S.ortho.max_x + S.ortho.min_x) / 2.0) - (0.5 * height);
+      x2 = ((S.ortho.max_x + S.ortho.min_x) / 2.0) + (0.5 * height);
+      y1 = S.ortho.min_y;
+      y2 = S.ortho.max_y;
+    }
+  else
+    {
+      x1 = S.ortho.min_x;
+      x2 = S.ortho.max_x;
+      y1 = S.ortho.min_y;
+      y2 = S.ortho.max_y;
+    }
 
   // Zoom in
-  if (dir > 0)
+  if (dir > 0) 
     {
-      zoom (step,
-	    step,
-	    viewport[3] - step,
-	    viewport[3] - step);		   
+      zoom (x1 + step, y1 + step, x2 - step, y2 - step);
     }
 
   // Zoom out
   else
     {
-      zoom (-step,
-	    -step,
-	    viewport[3] + step,
-	    viewport[3] + step);		   
+      zoom (x1 - step, y1 - step, x2 + step, y2 + step);
     }
 
   return;