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1/* batteryviewer: Display battery metrics
2 * Copyright (C) 2023 Scott Worley <scottworley@scottworley.com>
3 *
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, version 3.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <https://www.gnu.org/licenses/>.
15 *
16 *
17 *
18 * h/t https://ptomato.name/advanced-gtk-techniques/html/custom-container.html
19 * for examples of how to make GTK widgets
20 */
21
22#include "chart.h"
23#include <float.h>
24#include <gtk/gtk.h>
25
26#define BV_CHART_PRIVATE(obj) \
27 (G_TYPE_INSTANCE_GET_PRIVATE((obj), BV_CHART_TYPE, BVChartPrivate))
28
29typedef struct _BVChartPrivate BVChartPrivate;
30
31struct _BVChartPrivate {
32 GArray *points;
33 float minx, miny, maxx, maxy;
34};
35
36struct BVChartPoint {
37 float x, y;
38};
39
40struct ScreenPoint {
41 float x, y;
42};
43
44G_DEFINE_TYPE_WITH_CODE(BVChart, bv_chart, GTK_TYPE_DRAWING_AREA,
45 G_ADD_PRIVATE(BVChart))
46
47typedef void (*cairo_draw_func)(cairo_t *cr, double x, double y);
48
49static struct ScreenPoint to_screen(BVChartPrivate *priv,
50 GtkAllocation *allocation,
51 struct BVChartPoint *p) {
52 int margin = 3;
53 float xscale = (allocation->width - 2 * margin) / (priv->maxx - priv->minx);
54 float yscale = (allocation->height - 2 * margin) / (priv->miny - priv->maxy);
55 struct ScreenPoint screen_p = {
56 .x = xscale * (p->x - priv->minx) + margin,
57 .y = yscale * (p->y - priv->maxy) + margin,
58 };
59 return screen_p;
60}
61
62static void draw_data(BVChartPrivate *priv, cairo_t *cr,
63 GtkAllocation *allocation) {
64 cairo_set_source_rgb(cr, 0.0, 0.0, 1.0);
65 float gap_threshold = 3.0;
66 float prevx = 0.0;
67 for (guint i = 0; i < priv->points->len; i++) {
68 struct BVChartPoint *p =
69 &g_array_index(priv->points, struct BVChartPoint, i);
70 gboolean is_gap = p->x - prevx > gap_threshold;
71 cairo_draw_func f = is_gap ? cairo_move_to : cairo_line_to;
72 struct ScreenPoint screen_p = to_screen(priv, allocation, p);
73 f(cr, screen_p.x, screen_p.y);
74 prevx = p->x;
75 }
76 cairo_stroke(cr);
77}
78
79static void draw_axis(BVChartPrivate *priv, cairo_t *cr,
80 GtkAllocation *allocation) {
81 if (priv->miny < 0.0 && priv->maxy > 0.0) {
82 cairo_set_source_rgb(cr, 0.0, 0.0, 0.0);
83 struct BVChartPoint p = {.x = priv->minx, .y = 0.0};
84 struct ScreenPoint screen_p = to_screen(priv, allocation, &p);
85 cairo_move_to(cr, screen_p.x, screen_p.y);
86 p.x = priv->maxx;
87 screen_p = to_screen(priv, allocation, &p);
88 cairo_line_to(cr, screen_p.x, screen_p.y);
89 cairo_stroke(cr);
90 }
91}
92
93static gboolean bv_chart_draw(GtkWidget *widget, cairo_t *cr) {
94 BVChart *chart = BV_CHART(widget);
95 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
96
97 cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
98 cairo_paint(cr);
99
100 if (priv->points->len < 2)
101 return TRUE;
102
103 GtkAllocation allocation;
104 gtk_widget_get_allocation(widget, &allocation);
105
106 draw_data(priv, cr, &allocation);
107 draw_axis(priv, cr, &allocation);
108
109 return TRUE;
110}
111
112static void bv_chart_class_init(BVChartClass *klass) {
113 GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
114 widget_class->draw = bv_chart_draw;
115}
116
117static void bv_chart_init(BVChart *chart) {
118 gtk_widget_set_has_window(GTK_WIDGET(chart), FALSE);
119 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
120 gboolean zero_terminated = FALSE;
121 gboolean clear_ = FALSE;
122 priv->points =
123 g_array_new(zero_terminated, clear_, sizeof(struct BVChartPoint));
124 priv->minx = FLT_MAX;
125 priv->miny = FLT_MAX;
126 priv->maxx = FLT_MIN;
127 priv->maxy = FLT_MIN;
128}
129
130GtkWidget *bv_chart_new() {
131 return GTK_WIDGET(g_object_new(bv_chart_get_type(), NULL));
132}
133
134void bv_chart_add_point(BVChart *chart, float x, float y) {
135 BVChartPrivate *priv = bv_chart_get_instance_private(chart);
136 if (x < priv->minx)
137 priv->minx = x;
138 if (y < priv->miny)
139 priv->miny = y;
140 if (x > priv->maxx)
141 priv->maxx = x;
142 if (y > priv->maxy)
143 priv->maxy = y;
144 struct BVChartPoint p = {.x = x, .y = y};
145 g_array_append_val(priv->points, p);
146}