Merge pull request #4 from yoursunny/scroll

processing: preserve scroll position while zooming

processing.pde

@@ -312,8 +312,10 @@ void mouseWheel(MouseEvent event) {
   if (mouseY>buttonY && mouseY <buttonY+buttonH &&
     mouseX>button4X && mouseX <button4X+smallButtonW) {
     //it is over the reducer button
+    xShift *= reducer;
     reducer-= wheel/10;
     reducer = constrain(reducer, 0.1, 9.9);
+    xShift /= reducer; // preserve scroll position
     getData();
   } else {        //move the graph
     xShift-=wheel*50;