libsysprof-gtk: start on chart + layers

The goal here is to be able to connect data series such as
SysprofTimeSeries or SysprofXYSeries to various chart layers. Those
chart layers get stacked in a SysprofChart.

Some glue code will be necessary to go from frames into data series but
we can experiment with how to automate that later on.

src/libsysprof-gtk/sysprof-depth-layer.c

@@ -0,0 +1,234 @@
+/* sysprof-depth-layer.c
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "config.h"
+
+#include "sysprof-depth-layer.h"
+
+struct _SysprofDepthLayer
+{
+  SysprofChartLayer parent_instance;
+  SysprofXYSeries *series;
+  GdkRGBA color;
+};
+
+enum {
+  PROP_0,
+  PROP_COLOR,
+  PROP_SERIES,
+  N_PROPS
+};
+
+G_DEFINE_FINAL_TYPE (SysprofDepthLayer, sysprof_depth_layer, SYSPROF_TYPE_CHART_LAYER)
+
+static GParamSpec *properties [N_PROPS];
+
+static void
+sysprof_depth_layer_snapshot (GtkWidget   *widget,
+                              GtkSnapshot *snapshot)
+{
+  SysprofDepthLayer *self = (SysprofDepthLayer *)widget;
+  const SysprofXYSeriesValue *values;
+  guint n_values;
+  float min_x, max_x;
+  int line_width;
+  int width;
+  int height;
+
+  g_assert (SYSPROF_IS_DEPTH_LAYER (self));
+  g_assert (GTK_IS_SNAPSHOT (snapshot));
+
+  if (self->series == NULL || self->color.alpha == 0)
+    return;
+
+  if (!(values = sysprof_xy_series_get_values (self->series, &n_values)))
+    return;
+
+  sysprof_xy_series_get_range (self->series, &min_x, NULL, &max_x, NULL);
+
+  width = gtk_widget_get_width (widget);
+  height = gtk_widget_get_width (widget);
+
+  line_width = MAX (1, (max_x - min_x) / width);
+
+  for (guint i = 0; i < n_values; i++)
+    {
+      const SysprofXYSeriesValue *v = &values[i];
+
+      gtk_snapshot_append_color (snapshot,
+                                 &self->color,
+                                 &GRAPHENE_RECT_INIT (v->x * width,
+                                                      height,
+                                                      line_width,
+                                                      height - (v->y * height)));
+    }
+}
+
+static void
+sysprof_depth_layer_dispose (GObject *object)
+{
+  SysprofDepthLayer *self = (SysprofDepthLayer *)object;
+
+  g_clear_pointer (&self->series, sysprof_xy_series_unref);
+
+  G_OBJECT_CLASS (sysprof_depth_layer_parent_class)->dispose (object);
+}
+
+static void
+sysprof_depth_layer_get_property (GObject    *object,
+                                  guint       prop_id,
+                                  GValue     *value,
+                                  GParamSpec *pspec)
+{
+  SysprofDepthLayer *self = SYSPROF_DEPTH_LAYER (object);
+
+  switch (prop_id)
+    {
+    case PROP_COLOR:
+      g_value_set_boxed (value, &self->color);
+      break;
+
+    case PROP_SERIES:
+      g_value_set_boxed (value, self->series);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+sysprof_depth_layer_set_property (GObject      *object,
+                                  guint         prop_id,
+                                  const GValue *value,
+                                  GParamSpec   *pspec)
+{
+  SysprofDepthLayer *self = SYSPROF_DEPTH_LAYER (object);
+
+  switch (prop_id)
+    {
+    case PROP_COLOR:
+      sysprof_depth_layer_set_color (self, g_value_get_boxed (value));
+      break;
+
+    case PROP_SERIES:
+      sysprof_depth_layer_set_series (self, g_value_get_boxed (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+sysprof_depth_layer_class_init (SysprofDepthLayerClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->dispose = sysprof_depth_layer_dispose;
+  object_class->get_property = sysprof_depth_layer_get_property;
+  object_class->set_property = sysprof_depth_layer_set_property;
+
+  widget_class->snapshot = sysprof_depth_layer_snapshot;
+
+  properties[PROP_COLOR] =
+    g_param_spec_boxed ("color", NULL, NULL,
+                         GDK_TYPE_RGBA,
+                         (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  properties[PROP_SERIES] =
+    g_param_spec_boxed ("series", NULL, NULL,
+                         SYSPROF_TYPE_XY_SERIES,
+                         (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_properties (object_class, N_PROPS, properties);
+}
+
+static void
+sysprof_depth_layer_init (SysprofDepthLayer *self)
+{
+  self->color.alpha = 1;
+}
+
+SysprofChartLayer *
+sysprof_depth_layer_new (void)
+{
+  return g_object_new (SYSPROF_TYPE_DEPTH_LAYER, NULL);
+}
+
+const GdkRGBA *
+sysprof_depth_layer_get_color (SysprofDepthLayer *self)
+{
+  return &self->color;
+}
+
+void
+sysprof_depth_layer_set_color (SysprofDepthLayer *self,
+                               const GdkRGBA     *color)
+{
+  static const GdkRGBA black = {0,0,0,1};
+
+  g_return_if_fail (SYSPROF_IS_DEPTH_LAYER (self));
+
+  if (color == NULL)
+    color = &black;
+
+  if (!gdk_rgba_equal (&self->color, color))
+    {
+      self->color = *color;
+      g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_COLOR]);
+    }
+}
+
+/**
+ * sysprof_depth_layer_get_series:
+ * @self: a #SysprofDepthLayer
+ *
+ * Gets the data series to be drawn.
+ *
+ * Returns: (transfer none) (nullable): a #SysprofXYSeries or %NULL
+ */
+SysprofXYSeries *
+sysprof_depth_layer_get_series (SysprofDepthLayer *self)
+{
+  g_return_val_if_fail (SYSPROF_IS_DEPTH_LAYER (self), NULL);
+
+  return self->series;
+}
+
+void
+sysprof_depth_layer_set_series (SysprofDepthLayer *self,
+                                SysprofXYSeries   *series)
+{
+  g_return_if_fail (SYSPROF_IS_DEPTH_LAYER (self));
+
+  if (series == self->series)
+    return;
+
+  g_clear_pointer (&self->series, sysprof_xy_series_unref);
+
+  if (series)
+    self->series = sysprof_xy_series_ref (series);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_SERIES]);
+
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+}