Skip to content

DataGraph: add faint trend line #1531

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
kolunmi wants to merge 2 commits into
base: main
Choose a base branch
from
Open

DataGraph: add faint trend line #1531

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
1ddbedf
DataGraph: add faint trend line
kolunmi May 21, 2026
8b3e689
make trend line thinner and dashed
kolunmi May 21, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
109 changes: 95 additions & 14 deletions src/bz-data-graph.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,10 +21,10 @@
#include "config.h"

#include <adwaita.h>
#include <math.h>

#include "bz-data-graph.h"
#include "bz-data-point.h"
#include <math.h>

#define LABEL_MARGIN 75.0
#define LABEL_MARGIN_RIGHT 35.0
Expand All @@ -48,6 +48,9 @@ struct _BzDataGraph
GskPath *path;
GskPathMeasure *path_measure;

GskPath *trend;
GskPathMeasure *trend_measure;

GskRenderNode *other;
GskRenderNode *graph;
GskRenderNode *overlay;
Expand Down Expand Up @@ -131,6 +134,8 @@ bz_data_graph_dispose (GObject *object)
g_clear_pointer (&self->tooltip_prefix, g_free);
g_clear_pointer (&self->path, gsk_path_unref);
g_clear_pointer (&self->path_measure, gsk_path_measure_unref);
g_clear_pointer (&self->trend, gsk_path_unref);
g_clear_pointer (&self->trend_measure, gsk_path_measure_unref);
g_clear_pointer (&self->other, gsk_render_node_unref);
g_clear_pointer (&self->graph, gsk_render_node_unref);
g_clear_pointer (&self->overlay, gsk_render_node_unref);
Expand Down Expand Up @@ -749,6 +754,10 @@ refresh_path (BzDataGraph *self,
double min_independent = 0.0;
double max_independent = 0.0;
double max_dependent = 0.0;
double sum_independent = 0.0;
double sum_dependent = 0.0;
double mean_independent = 0.0;
double mean_dependent = 0.0;
PangoContext *pango = NULL;
PangoFontMetrics *metrics = NULL;
double font_height = 0.0;
Expand All @@ -758,12 +767,20 @@ refresh_path (BzDataGraph *self,
g_autoptr (GskPathBuilder) grid_builder = NULL;
g_autoptr (GskPath) grid = NULL;
g_autoptr (GskStroke) grid_stroke = NULL;
double trend_slope_numerator = 0.0;
double trend_slope_denominator = 0.0;
double trend_slope = 0.0;
double trend_intercept = 0.0;
g_autoptr (GskPathBuilder) trend_builder = NULL;
g_autoptr (GskPath) trend = NULL;
double rounded_axis_max = 0.0;
double tick_spacing = 0.0;
int num_ticks = 0;

g_clear_pointer (&self->path, gsk_path_unref);
g_clear_pointer (&self->path_measure, gsk_path_measure_unref);
g_clear_pointer (&self->trend, gsk_path_unref);
g_clear_pointer (&self->trend_measure, gsk_path_measure_unref);
g_clear_pointer (&self->other, gsk_render_node_unref);

if (self->model == NULL)
Expand Down Expand Up @@ -797,10 +814,16 @@ refresh_path (BzDataGraph *self,
max_independent = MAX (independent, max_independent);
max_dependent = MAX (dependent, max_dependent);
}

sum_independent += independent;
sum_dependent += dependent;
}

rounded_axis_max = calculate_axis_tick_value (max_dependent, TRUE);

mean_independent = sum_independent / (double) n_items;
mean_dependent = sum_dependent / (double) n_items;

pango = gtk_widget_get_pango_context (GTK_WIDGET (self));
metrics = pango_context_get_metrics (pango, NULL, NULL);
font_height = (double) (int) PANGO_PIXELS_CEIL (pango_font_metrics_get_height (metrics));
Expand Down Expand Up @@ -892,6 +915,9 @@ refresh_path (BzDataGraph *self,
gsk_path_builder_move_to (grid_builder, x, height);
gsk_path_builder_line_to (grid_builder, x, height + TICK_LENGTH);
}

trend_slope_numerator += (independent - mean_independent) * (dependent - mean_dependent);
trend_slope_denominator += (independent - mean_independent) * (independent - mean_independent);
}

gsk_path_builder_move_to (grid_builder, 0.0, height);
Expand Down Expand Up @@ -947,22 +973,42 @@ refresh_path (BzDataGraph *self,
gtk_snapshot_append_stroke (snapshot, grid, grid_stroke, &(GdkRGBA){ 1.0, 1.0, 1.0, 1.0 });
gtk_snapshot_restore (snapshot);

self->path = gsk_path_builder_to_path (curve_builder);
self->path_measure = gsk_path_measure_new (self->path);
self->other = gtk_snapshot_to_node (snapshot);
if (!G_APPROX_VALUE (trend_slope_denominator, 0.0, 0.00001))
trend_slope = trend_slope_numerator / trend_slope_denominator;
trend_intercept = mean_dependent - trend_slope * mean_independent;

trend_builder = gsk_path_builder_new ();
gsk_path_builder_move_to (
trend_builder,
0.0,
(1.0 - (trend_intercept + trend_slope * min_independent) /
rounded_axis_max) *
height);
gsk_path_builder_line_to (
trend_builder,
width,
(1.0 - (trend_intercept + trend_slope * max_independent) /
rounded_axis_max) *
height);

self->path = gsk_path_builder_to_path (curve_builder);
self->path_measure = gsk_path_measure_new (self->path);
self->trend = gsk_path_builder_to_path (trend_builder);
self->trend_measure = gsk_path_measure_new (self->trend);
self->other = gtk_snapshot_to_node (snapshot);
}

static void
refresh_graph (BzDataGraph *self)
{
double widget_width = 0.0;
double widget_height = 0.0;
AdwStyleManager *style_manager = NULL;
g_autoptr (GdkRGBA) accent_color = NULL;
GdkRGBA widget_color = { 0 };
g_autoptr (GskPath) transitioning = NULL;
g_autoptr (GskStroke) stroke = NULL;
g_autoptr (GtkSnapshot) snapshot = NULL;
double widget_width = 0.0;
double widget_height = 0.0;
AdwStyleManager *style_manager = NULL;
g_autoptr (GdkRGBA) accent_color = NULL;
GdkRGBA widget_color = { 0 };
g_autoptr (GskPath) transitioning = NULL;
g_autoptr (GskPath) trend_transitioning = NULL;
g_autoptr (GtkSnapshot) snapshot = NULL;

if (self->path == NULL)
{
Expand Down Expand Up @@ -993,16 +1039,30 @@ refresh_graph (BzDataGraph *self)
gsk_path_builder_add_segment (builder, self->path, &point0, &point1);
transitioning = gsk_path_builder_to_path (builder);
}
if (self->transition_progress > 0.0 && self->transition_progress < 1.0)
{
GskPathPoint point0 = { 0 };
double path_distance = 0.0;
GskPathPoint point1 = { 0 };
g_autoptr (GskPathBuilder) builder = NULL;

stroke = gsk_stroke_new (3.0);
gsk_stroke_set_line_cap (stroke, GSK_LINE_CAP_ROUND);
gsk_path_get_start_point (self->trend, &point0);
path_distance = gsk_path_measure_get_length (self->trend_measure) * self->transition_progress;
gsk_path_measure_get_point (self->trend_measure, path_distance, &point1);

builder = gsk_path_builder_new ();
gsk_path_builder_add_segment (builder, self->trend, &point0, &point1);
trend_transitioning = gsk_path_builder_to_path (builder);
}

snapshot = gtk_snapshot_new ();
gtk_snapshot_save (snapshot);
gtk_snapshot_translate (snapshot, &GRAPHENE_POINT_INIT (LABEL_MARGIN, 0.0));

if (self->transition_progress > 0.0)
{
g_autoptr (GskStroke) stroke = NULL;
g_autoptr (GskStroke) trend_stroke = NULL;
g_autoptr (GskPathBuilder) builder = NULL;
GskPathPoint point0 = { 0 };
GskPathPoint point1 = { 0 };
Expand Down Expand Up @@ -1059,6 +1119,19 @@ refresh_graph (BzDataGraph *self)
},
},
};
const GdkRGBA trend_color = {
.red = widget_color.red,
.green = widget_color.green,
.blue = widget_color.blue,
.alpha = 0.8,
};

stroke = gsk_stroke_new (3.0);
gsk_stroke_set_line_cap (stroke, GSK_LINE_CAP_ROUND);

trend_stroke = gsk_stroke_new (2.0);
gsk_stroke_set_line_cap (trend_stroke, GSK_LINE_CAP_ROUND);
gsk_stroke_set_dash (trend_stroke, (const float[]){ 12, 16 }, 2);

gtk_snapshot_append_stroke (
snapshot,
Expand Down Expand Up @@ -1142,6 +1215,14 @@ refresh_graph (BzDataGraph *self)

gtk_snapshot_pop (snapshot); /* Push Mask (image) */
gtk_snapshot_pop (snapshot); /* Push Fill */

/* Trend line */
gtk_snapshot_append_stroke (
snapshot,
trend_transitioning != NULL
? trend_transitioning
: self->trend,
trend_stroke, &trend_color);
}
gtk_snapshot_restore (snapshot);

Expand Down
Loading