git.scottworley.com Git - batteryviewer/blob - chart.c

   1 /*
   2  * h/t https://ptomato.name/advanced-gtk-techniques/html/custom-container.html
   3  * for examples of how to make GTK widgets
   4  */
   5
   6 #include "chart.h"
   7 #include <float.h>
   8 #include <gtk/gtk.h>
   9
  10 #define BV_CHART_PRIVATE(obj)                                                  \
  11   (G_TYPE_INSTANCE_GET_PRIVATE((obj), BV_CHART_TYPE, BVChartPrivate))
  12
  13 typedef struct _BVChartPrivate BVChartPrivate;
  14
  15 struct _BVChartPrivate {
  16   GArray *points;
  17   float minx, miny, maxx, maxy;
  18 };
  19
  20 struct BVChartPoint {
  21   float x, y;
  22 };
  23
  24 G_DEFINE_TYPE_WITH_CODE(BVChart, bv_chart, GTK_TYPE_DRAWING_AREA,
  25                         G_ADD_PRIVATE(BVChart))
  26
  27 static gboolean bv_chart_draw(GtkWidget *widget, cairo_t *cr) {
  28   BVChart *chart = BV_CHART(widget);
  29   BVChartPrivate *priv = bv_chart_get_instance_private(chart);
  30
  31   cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
  32   cairo_paint(cr);
  33
  34   if (priv->points->len < 2)
  35     return TRUE;
  36
  37   GtkAllocation allocation;
  38   gtk_widget_get_allocation(widget, &allocation);
  39
  40   float xscale = allocation.width / (priv->maxx - priv->minx);
  41   float yscale = allocation.height / (priv->miny - priv->maxy);
  42   cairo_set_source_rgb(cr, 0.0, 0.0, 1.0);
  43   struct BVChartPoint *start =
  44       &g_array_index(priv->points, struct BVChartPoint, 0);
  45   cairo_move_to(cr, xscale * (start->x - priv->minx),
  46                 yscale * (start->y - priv->maxy));
  47   for (guint i = 1; i < priv->points->len; i++) {
  48     struct BVChartPoint *p =
  49         &g_array_index(priv->points, struct BVChartPoint, i);
  50     cairo_line_to(cr, xscale * (p->x - priv->minx),
  51                   yscale * (p->y - priv->maxy));
  52   }
  53   cairo_stroke(cr);
  54
  55   return TRUE;
  56 }
  57
  58 static void bv_chart_class_init(BVChartClass *klass) {
  59   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
  60   widget_class->draw = bv_chart_draw;
  61 }
  62
  63 static void bv_chart_init(BVChart *chart) {
  64   gtk_widget_set_has_window(GTK_WIDGET(chart), FALSE);
  65   BVChartPrivate *priv = bv_chart_get_instance_private(chart);
  66   gboolean zero_terminated = FALSE;
  67   gboolean clear_ = FALSE;
  68   priv->points =
  69       g_array_new(zero_terminated, clear_, sizeof(struct BVChartPoint));
  70   priv->minx = FLT_MAX;
  71   priv->miny = FLT_MAX;
  72   priv->maxx = FLT_MIN;
  73   priv->maxy = FLT_MIN;
  74 }
  75
  76 GtkWidget *bv_chart_new() {
  77   return GTK_WIDGET(g_object_new(bv_chart_get_type(), NULL));
  78 }
  79
  80 void bv_chart_add_point(BVChart *chart, float x, float y) {
  81   BVChartPrivate *priv = bv_chart_get_instance_private(chart);
  82   if (x < priv->minx)
  83     priv->minx = x;
  84   if (y < priv->miny)
  85     priv->miny = y;
  86   if (x > priv->maxx)
  87     priv->maxx = x;
  88   if (y > priv->maxy)
  89     priv->maxy = y;
  90   struct BVChartPoint p = {.x = x, .y = y};
  91   g_array_append_val(priv->points, p);
  92 }