ncplot: support legend styling

NEWS.md

@@ -19,6 +19,9 @@ rearrangements of Notcurses.
     RGB in a channel (they were originally in the attrword).
   * Added `ncdirect_flush()`, mainly for the benefit of FFI that might not
     have a native interface to `fflush(3)`.
+  * The `ncplot_options` struct has a new field, `legendstyle`. If the
+    dependent variable is being labeled, this style will be applied to the
+    legend. Without NCPLOT_OPTION_LABELTICKSD, this value is ignored.
 
 * 1.6.15 (2020-08-16)
   * Styles now work properly with `ncdirect`, which apparently has never

doc/man/man3/notcurses_plot.3.md

@@ -11,15 +11,19 @@ notcurses_plot - high level widget for plotting
 **#include <notcurses/notcurses.h>**
 
 ```c
-#define NCPLOT_OPTION_LABELTICKSD  0x0001
-#define NCPLOT_OPTION_EXPONENTIALD 0x0002
-#define NCPLOT_OPTION_VERTICALI    0x0004
+#define NCPLOT_OPTION_LABELTICKSD   0x0001u
+#define NCPLOT_OPTION_EXPONENTIALD  0x0002u
+#define NCPLOT_OPTION_VERTICALI     0x0004u
+#define NCPLOT_OPTION_NODEGRADE     0x0008u
+#define NCPLOT_OPTION_DETECTMAXONLY 0x0010u
 
 typedef struct ncplot_options {
   // channels for the maximum and minimum levels.
   // lerp across the domain between these two.
   uint64_t maxchannel;
   uint64_t minchannel;
+  // styling used for labels (NCPLOT_OPTION_LABELTICKSD)
+  uint16_t legendstyle;
   // number of "pixels" per row x column
   ncblitter_e gridtype;
   // independent variable is a contiguous range
@@ -81,9 +85,14 @@ how the braille glyphs will look in a given font.
 The same **ncplot_options** struct can be used with all ncplot types. The
 **flags** field is a bitmask composed of:
 
-* **NCPLOT_OPTION_LABELTICKSD**: Label dependent axis ticks.
-* **NCPLOT_OPTION_EXPONENTIALD**: Use an exponential dependent axis.
-* **NCPLOT_OPTION_VERTICALI**: Vertical independent axis.
+* **NCPLOT_OPTION_LABELTICKSD**: Label dependent axis ticks
+* **NCPLOT_OPTION_EXPONENTIALD**: Use an exponential dependent axis
+* **NCPLOT_OPTION_VERTICALI**: Vertical independent axis
+* **NCPLOT_OPTION_NODEGRADE**: Fail rather than degrade blitter
+* **NCPLOT_OPTION_DETECTMAXONLY**: Detect only max domain, not min
+
+If **NCPLOT_OPTION_LABELTICKSD** is supplied, the **legendstyle** field will be
+used to style the labels. It is otherwise ignored.
 
 # NOTES
 

include/notcurses/notcurses.h

@@ -2868,17 +2868,19 @@ API int ncmenu_destroy(struct ncmenu* n);
 //
 // This options structure works for both the ncuplot (uint64_t) and ncdplot
 // (double) types.
-#define NCPLOT_OPTION_LABELTICKSD   0x0001ull // show labels for dependent axis
-#define NCPLOT_OPTION_EXPONENTIALD  0x0002ull // exponential dependent axis
-#define NCPLOT_OPTION_VERTICALI     0x0004ull // independent axis is vertical
-#define NCPLOT_OPTION_NODEGRADE     0x0008ull // fail rather than degrade blitter
-#define NCPLOT_OPTION_DETECTMAXONLY 0x0010ull // use domain detection only for max
+#define NCPLOT_OPTION_LABELTICKSD   0x0001u // show labels for dependent axis
+#define NCPLOT_OPTION_EXPONENTIALD  0x0002u // exponential dependent axis
+#define NCPLOT_OPTION_VERTICALI     0x0004u // independent axis is vertical
+#define NCPLOT_OPTION_NODEGRADE     0x0008u // fail rather than degrade blitter
+#define NCPLOT_OPTION_DETECTMAXONLY 0x0010u // use domain detection only for max
 
 typedef struct ncplot_options {
   // channels for the maximum and minimum levels. linear or exponential
   // interpolation will be applied across the domain between these two.
   uint64_t maxchannel;
   uint64_t minchannel;
+  // styling used for the legend, if NCPLOT_OPTION_LABELTICKSD is set
+  uint16_t legendstyle;
   // if you don't care, pass NCBLIT_DEFAULT and get NCBLIT_8x1 (assuming
   // UTF8) or NCBLIT_1x1 (in an ASCII environment)
   ncblitter_e gridtype; // number of "pixels" per row x column

python/src/notcurses/build_notcurses.py

@@ -350,6 +350,7 @@ bool ncplane_translate_abs(const struct ncplane* n, int* y, int* x);
 typedef struct ncplot_options {
   uint64_t maxchannel;
   uint64_t minchannel;
+  uint16_t legendstyle;
   ncblitter_e gridtype;
   uint64_t rangex;
   unsigned flags;

src/lib/plot.h

@@ -64,6 +64,7 @@ class ncppplot {
    if(dimx < ncpp->rangex){
      ncpp->slotcount = scaleddim;
    }
+   ncpp->legendstyle = opts->legendstyle;
    if( (ncpp->labelaxisd = opts->flags & NCPLOT_OPTION_LABELTICKSD) ){
      if(ncpp->slotcount + scaledprefixlen > scaleddim){
        if(scaleddim > scaledprefixlen){
@@ -128,6 +129,7 @@ class ncppplot {
    const int finalx = (slotcount < scaleddim - 1 - (startx * scale) ? startx + (slotcount / scale) - 1 : dimx - 1);
    if(labelaxisd){
      // show the *top* of each interval range
+     ncplane_set_attr(ncp, legendstyle);
      for(int y = 0 ; y < dimy ; ++y){
        uint64_t channels = 0;
        calc_gradient_channels(&channels, maxchannel, maxchannel,
@@ -145,6 +147,7 @@ class ncppplot {
        }
        ncplane_printf_yx(ncp, dimy - y - 1, PREFIXCOLUMNS - strlen(buf), "%s", buf);
      }
+     ncplane_set_attr(ncp, NCSTYLE_NONE);
    }
    if(finalx < startx){ // exit on pathologically narrow planes
      return 0;
@@ -362,6 +365,7 @@ class ncppplot {
 
  uint64_t maxchannel;
  uint64_t minchannel;
+ uint16_t legendstyle;
  bool vertical_indep; // not yet implemented FIXME
  const struct blitset* bset;
  // requested number of slots. 0 for automatically setting the number of slots

src/libcpp/Plot.cc

@@ -6,6 +6,7 @@ using namespace ncpp;
 ncplot_options PlotD::default_options = {
 	0, // maxchannel
 	0, // minchannel
+  0, // legendstyle
 	ncblitter_e::NCBLIT_1x1, // ncblitter_e
 	0, // rangex
 	0, // flags
@@ -14,6 +15,7 @@ ncplot_options PlotD::default_options = {
 ncplot_options PlotU::default_options = {
 	0, // maxchannel
 	0, // minchannel
+  0, // legendstyle
 	ncblitter_e::NCBLIT_1x1, // ncblitter_e
 	0, // rangex
 	0, // flags