Add zoomview(). Store glOrtho plot view ranges in instance variables.

src/Plot.H

@@ -49,6 +49,8 @@ class Fl_Plot : public Fl_Gl_Window {
   char *xtitle() const { return xtitle_; }
   char *ytitle() const { return ytitle_; }
 
+  float zoomview( float zoomin, int xev = 0, int yev = 0 );
+
   int inpick() const { return inpick_; } // draw()ers: am I in GL_SELECT mode?
   void picksize( float width, float height );
   void pickbuffer( int words, GLuint *buf );
@@ -74,8 +76,10 @@ class Fl_Plot : public Fl_Gl_Window {
 
  protected:
   float x0_, x1_, y0_, y1_;
+  float initx0_, inity0_, initx1_, inity1_;
   char *xtitle_, *ytitle_;
 
+  float orthox0_, orthox1_, orthoy0_, orthoy1_;
   void (*pickcb_)( Fl_Gl_Window *, int hits, int nents, GLuint *buf, void *arg );
   int inpick_;
   float pickx_, picky_, pickwidth_, pickheight_;
@@ -122,6 +126,12 @@ class Fl_Plot : public Fl_Gl_Window {
     drawers_ = NULL;
     inpick_ = 0;
     pickwidth_ = 2, pickheight_ = 2;
+
+    orthox0_ = -.15;
+    orthox1_ = 1.05;
+    orthoy0_ = -.15;
+    orthoy1_ = 1.05;
+
     picknents_ = sizeof(tpickbuf) / sizeof(tpickbuf[0]);
     pickbuf_ = tpickbuf;
     pickarg_ = NULL;