]> git.scottworley.com Git - batteryviewer/blob - chart.c
1fa76c542656f611eb2974fb1323f7d174cd8090
[batteryviewer] / 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 typedef void (*cairo_draw_func)(cairo_t *cr, double x, double y);
28
29 static gboolean bv_chart_draw(GtkWidget *widget, cairo_t *cr) {
30 BVChart *chart = BV_CHART(widget);
31 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
32
33 cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
34 cairo_paint(cr);
35
36 if (priv->points->len < 2)
37 return TRUE;
38
39 GtkAllocation allocation;
40 gtk_widget_get_allocation(widget, &allocation);
41
42 int margin = 3;
43 float xscale = (allocation.width - 2 * margin) / (priv->maxx - priv->minx);
44 float yscale = (allocation.height - 2 * margin) / (priv->miny - priv->maxy);
45 cairo_set_source_rgb(cr, 0.0, 0.0, 1.0);
46 float gap_threshold = 3.0;
47 float prevx = 0.0;
48 for (guint i = 0; i < priv->points->len; i++) {
49 struct BVChartPoint *p =
50 &g_array_index(priv->points, struct BVChartPoint, i);
51 gboolean is_gap = p->x - prevx > gap_threshold;
52 cairo_draw_func f = is_gap ? cairo_move_to : cairo_line_to;
53 float screen_x = xscale * (p->x - priv->minx) + margin;
54 float screen_y = yscale * (p->y - priv->maxy) + margin;
55 f(cr, screen_x, screen_y);
56 prevx = p->x;
57 }
58 cairo_stroke(cr);
59
60 return TRUE;
61 }
62
63 static void bv_chart_class_init(BVChartClass *klass) {
64 GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
65 widget_class->draw = bv_chart_draw;
66 }
67
68 static void bv_chart_init(BVChart *chart) {
69 gtk_widget_set_has_window(GTK_WIDGET(chart), FALSE);
70 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
71 gboolean zero_terminated = FALSE;
72 gboolean clear_ = FALSE;
73 priv->points =
74 g_array_new(zero_terminated, clear_, sizeof(struct BVChartPoint));
75 priv->minx = FLT_MAX;
76 priv->miny = FLT_MAX;
77 priv->maxx = FLT_MIN;
78 priv->maxy = FLT_MIN;
79 }
80
81 GtkWidget *bv_chart_new() {
82 return GTK_WIDGET(g_object_new(bv_chart_get_type(), NULL));
83 }
84
85 void bv_chart_add_point(BVChart *chart, float x, float y) {
86 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
87 if (x < priv->minx)
88 priv->minx = x;
89 if (y < priv->miny)
90 priv->miny = y;
91 if (x > priv->maxx)
92 priv->maxx = x;
93 if (y > priv->maxy)
94 priv->maxy = y;
95 struct BVChartPoint p = {.x = x, .y = y};
96 g_array_append_val(priv->points, p);
97 }