make --alt-y-grid work properly in many more cases than before

git-svn-id: svn://svn.oetiker.ch/rrdtool/branches/1.2@633 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/program/src/rrd_graph.c b/program/src/rrd_graph.c
index ebd91fb0c07d3aa2981db2f83e983c6d63aa8263..7259eef6c7e4155fe474e518d75e90e770f92137 100644 (file)
--- a/program/src/rrd_graph.c
+++ b/program/src/rrd_graph.c
@@ -394,7 +394,7 @@ expand_range(image_desc_t *im)
              delt = im->maxval - im->minval;
              adj = delt * 0.1;
              fact = 2.0 * pow(10.0,
-                   floor(log10(max(fabs(im->minval), fabs(im->maxval)))) - 2);
+                   floor(log10(max(fabs(im->minval), fabs(im->maxval))/im->magfact)) - 2);
              if (delt < fact) {
                adj = (fact - delt) * 0.55;
 #ifdef DEBUG
@@ -432,10 +432,6 @@ expand_range(image_desc_t *im)
                    -sensiblevalues[i] >=scaled_max)
                    im->maxval = -sensiblevalues[i]*(im->magfact);
            }
-           /* no sensiblevalues found. we switch to ALTYGRID mode */
-           if (sensiblevalues[i] == 0){
-               im->extra_flags |= ALTYGRID;
-           }           
        }
     } else {
        /* adjust min and max to the grid definition if there is one */
@@ -1549,21 +1545,12 @@ calc_horizontal_grid(image_desc_t   *im)
     if(isnan(im->ygridstep)){
        if(im->extra_flags & ALTYGRID) {
            /* find the value with max number of digits. Get number of digits */
-           decimals = ceil(log10(max(fabs(im->maxval), fabs(im->minval))));
+           decimals = ceil(log10(max(fabs(im->maxval), fabs(im->minval))*im->viewfactor/im->magfact));
            if(decimals <= 0) /* everything is small. make place for zero */
                decimals = 1;
            
-           fractionals = floor(log10(range));
-           if(fractionals < 0) { /* small amplitude. */
-               int len = decimals - fractionals + 1;
-               if (im->unitslength < len) im->unitslength = len;
-               sprintf(im->ygrid_scale.labfmt, "%%%d.%df", len, -fractionals + 1);
-           } else {
-               int len = decimals + 1;
-               if (im->unitslength < len) im->unitslength = len;
-               sprintf(im->ygrid_scale.labfmt, "%%%d.1f", len);
-           }
-           im->ygrid_scale.gridstep = pow((double)10, (double)fractionals);
+           im->ygrid_scale.gridstep = pow((double)10, floor(log10(range)));
+           
            if(im->ygrid_scale.gridstep == 0) /* range is one -> 0.1 is reasonable scale */
                im->ygrid_scale.gridstep = 0.1;
            /* should have at least 5 lines but no more then 15 */
@@ -1580,6 +1567,16 @@ calc_horizontal_grid(image_desc_t   *im)
                im->ygrid_scale.gridstep /= 5;
                im->ygrid_scale.labfact = 5;
            }
+           fractionals = floor(log10(im->ygrid_scale.gridstep*(double)im->ygrid_scale.labfact*im->viewfactor/im->magfact));
+           if(fractionals < 0) { /* small amplitude. */
+               int len = decimals - fractionals + 1;
+               if (im->unitslength < len+2) im->unitslength = len+2;
+               sprintf(im->ygrid_scale.labfmt, "%%%d.%df%s", len, -fractionals,(im->symbol != ' ' ? " %c" : ""));
+           } else {
+               int len = decimals + 1;
+               if (im->unitslength < len+2) im->unitslength = len+2;
+               sprintf(im->ygrid_scale.labfmt, "%%%d.1f%s", len, ( im->symbol != ' ' ? " %c" : "" ));
+           }
        }
        else {
            for(i=0;ylab[i].grid > 0;i++){
@@ -1624,23 +1621,27 @@ int draw_horizontal_grid(image_desc_t *im)
        if ( Y0 >= im->yorigin-im->ysize
                 && Y0 <= im->yorigin){       
            if(i % im->ygrid_scale.labfact == 0){               
-               if (i==0 || im->symbol == ' ') {
-                   if(MaxY < 10) {
-                       if(im->extra_flags & ALTYGRID) {
-                           sprintf(graph_label,im->ygrid_scale.labfmt,scaledstep*im->viewfactor*i);
-                       }
-                       else {
-                           sprintf(graph_label,"%4.1f",scaledstep*im->viewfactor*i);
-                       }
-                   } else {
-                       sprintf(graph_label,"%4.0f",scaledstep*im->viewfactor*i);
-                   }
+               if (im->symbol == ' ') {
+                   if(im->extra_flags & ALTYGRID) {
+                       sprintf(graph_label,im->ygrid_scale.labfmt,scaledstep*im->viewfactor*i);
+                    } else {
+                        if(MaxY < 10) {
+                          sprintf(graph_label,"%4.1f",scaledstep*im->viewfactor*i);
+                       } else {
+                          sprintf(graph_label,"%4.0f",scaledstep*im->viewfactor*i);
+                       }
+                    }
                }else {
-                   if(MaxY < 10){
-                       sprintf(graph_label,"%4.1f %c",scaledstep*im->viewfactor*i, im->symbol);
-                   } else {
-                       sprintf(graph_label,"%4.0f %c",scaledstep*im->viewfactor*i, im->symbol);
-                   }
+                   char sisym = ( i == 0  ? ' ' : im->symbol);
+                   if(im->extra_flags & ALTYGRID) {
+                       sprintf(graph_label,im->ygrid_scale.labfmt,scaledstep*im->viewfactor*i,sisym);
+                    } else {
+                       if(MaxY < 10){
+                         sprintf(graph_label,"%4.1f %c",scaledstep*im->viewfactor*i, sisym);
+                       } else {
+                         sprintf(graph_label,"%4.0f %c",scaledstep*im->viewfactor*i, sisym);
+                       }
+                    }
                }
 
               gfx_new_text ( im->canvas,