[gtk/wip/otte/texttile: 2/3] Add GtkTextTile

[Benjamin Otte <otte src gnome org>]

commit d2d54d4378d44b7d810a50e13881a1103aecc949
Author: Benjamin Otte <otte redhat com>
Date:   Thu May 19 06:44:23 2022 +0200

    Add GtkTextTile
    
    A label alternative that renders itself into a given rectangle.
    
    The main use case is cells in column view.

 gtk/gtk.h         |   1 +
 gtk/gtktexttile.c | 362 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtktexttile.h |  48 ++++++++
 gtk/meson.build   |   2 +
 4 files changed, 413 insertions(+)
---
diff --git a/gtk/gtk.h b/gtk/gtk.h
index 0d4521e4ac..3d981b8560 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -256,6 +256,7 @@
 #include <gtk/gtktextmark.h>
 #include <gtk/gtktexttag.h>
 #include <gtk/gtktexttagtable.h>
+#include <gtk/gtktexttile.h>
 #include <gtk/gtktextview.h>
 #include <gtk/gtktogglebutton.h>
 #include <gtk/gtktooltip.h>
diff --git a/gtk/gtktexttile.c b/gtk/gtktexttile.c
new file mode 100644
index 0000000000..8154ddf895
--- /dev/null
+++ b/gtk/gtktexttile.c
@@ -0,0 +1,362 @@
+/*
+ * Copyright © 2022 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte gnome org>
+ */
+
+#include "config.h"
+
+#include "gtktexttile.h"
+
+#include "gtkcssstylechangeprivate.h"
+#include "gtksnapshot.h"
+#include "gtkwidgetprivate.h"
+
+/**
+ * GtkTextTile:
+ *
+ * `GtkTextTile` is a widget to show text in a predefined area.
+ *
+ * You likely want to use `GtkLabel` instead as this widget is for a small subset
+ * of use cases. The main use case is usage inside lists such as `GtkColumnView`.
+ *
+ * While a `GtkLabel` sizes itself according to the text that is displayed,
+ * `GtkTextTile` is given a size and fits the given text into that size as good
+ * as it can.
+ *
+ * As it is a common occurence that text doesn't fit, users of this widget should
+ * plan for that case.
+ */
+
+/* 3 chars are enough to display ellipsizing "..." */
+#define DEFAULT_MIN_CHARS 3
+/* This means we request no natural size and fall back to min size */
+#define DEFAULT_NAT_CHARS 0
+/* 1 line is what people want in 90% of cases */
+#define DEFAULT_MIN_LINES 1
+/* This means we request no natural size and fall back to min size */
+#define DEFAULT_NAT_LINES 0
+
+struct _GtkTextTile
+{
+  GtkWidget parent_instance;
+
+  char *text;
+  int min_chars;
+  int nat_chars;
+  int min_lines;
+  int nat_lines;
+
+  PangoLayout *layout;
+};
+
+enum
+{
+  PROP_0,
+  PROP_TEXT,
+
+  N_PROPS
+};
+
+G_DEFINE_TYPE (GtkTextTile, gtk_text_tile, GTK_TYPE_WIDGET)
+
+static GParamSpec *properties[N_PROPS] = { NULL, };
+
+static void
+gtk_text_tile_dispose (GObject *object)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (object);
+
+  g_clear_pointer (&self->text, g_free);
+
+  G_OBJECT_CLASS (gtk_text_tile_parent_class)->dispose (object);
+}
+
+static void
+gtk_text_tile_finalize (GObject *object)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (object);
+
+  g_clear_object (&self->layout);
+
+  G_OBJECT_CLASS (gtk_text_tile_parent_class)->finalize (object);
+}
+
+static void
+gtk_text_tile_get_property (GObject    *object,
+                            guint       property_id,
+                            GValue     *value,
+                            GParamSpec *pspec)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (object);
+
+  switch (property_id)
+    {
+    case PROP_TEXT:
+      g_value_set_string (value, self->text);
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_text_tile_set_property (GObject      *object,
+                            guint         property_id,
+                            const GValue *value,
+                            GParamSpec   *pspec)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (object);
+
+  switch (property_id)
+    {
+    case PROP_TEXT:
+      gtk_text_tile_set_text (self, g_value_get_string (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
+      break;
+    }
+}
+
+static void
+gtk_text_tile_css_changed (GtkWidget         *widget,
+                           GtkCssStyleChange *change)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (widget);
+
+  GTK_WIDGET_CLASS (gtk_text_tile_parent_class)->css_changed (widget, change);
+
+  if (gtk_css_style_change_affects (change, GTK_CSS_AFFECTS_TEXT_ATTRS))
+    {
+      PangoAttrList *new_attrs;
+
+      new_attrs = gtk_css_style_get_pango_attributes (gtk_css_style_change_get_new_style (change));
+      pango_layout_set_attributes (self->layout, new_attrs);
+      pango_attr_list_unref (new_attrs);
+
+      gtk_widget_queue_draw (widget);
+    }
+}
+
+static int
+get_char_pixels (PangoLayout *layout)
+{
+  PangoContext *context;
+  PangoFontMetrics *metrics;
+  int char_width, digit_width;
+
+  context = pango_layout_get_context (layout);
+  metrics = pango_context_get_metrics (context, NULL, NULL);
+  char_width = pango_font_metrics_get_approximate_char_width (metrics);
+  digit_width = pango_font_metrics_get_approximate_digit_width (metrics);
+  pango_font_metrics_unref (metrics);
+
+  return MAX (char_width, digit_width);
+}
+
+static void
+gtk_text_tile_measure_width (GtkTextTile *self,
+                             int         *minimum,
+                             int         *natural)
+{
+  int char_pixels = get_char_pixels (self->layout);
+
+  *minimum = self->min_chars * char_pixels;
+  *natural = MAX (self->min_chars, self->nat_chars) * char_pixels;
+}
+
+static void
+gtk_text_tile_measure_height (GtkTextTile *self,
+                              int         *minimum,
+                              int         *natural,
+                              int         *minimum_baseline,
+                              int         *natural_baseline)
+{
+  PangoContext *context;
+  PangoFontMetrics *metrics;
+  int ascent, descent;
+
+  if (self->min_lines == 0 && self->nat_lines == 0)
+    return;
+
+  context = gtk_widget_get_pango_context (GTK_WIDGET (self));
+  metrics = pango_context_get_metrics (context, NULL, NULL);
+
+  ascent = pango_font_metrics_get_ascent (metrics);
+  descent = pango_font_metrics_get_descent (metrics);
+
+  *minimum = self->min_lines * (ascent + descent);
+  *natural = MAX (self->min_lines, self->nat_lines) * (ascent + descent);
+
+  if (minimum_baseline)
+    *minimum_baseline = self->min_lines ? ascent : 0;
+  if (natural_baseline)
+    *natural_baseline = MAX (self->min_lines, self->nat_lines) ? ascent : 0;
+}
+
+static void
+gtk_text_tile_measure (GtkWidget      *widget,
+                       GtkOrientation  orientation,
+                       int             for_size,
+                       int            *minimum,
+                       int            *natural,
+                       int            *minimum_baseline,
+                       int            *natural_baseline)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (widget);
+
+  /* We split this into 2 functions explicitly, so nobody gets the idea
+   * of adding height-for-width to this.
+   * This is meant to be fast, so that is a big no-no.
+   */
+  if (orientation == GTK_ORIENTATION_HORIZONTAL)
+    gtk_text_tile_measure_width (self, minimum, natural);
+  else
+    gtk_text_tile_measure_height (self, minimum, natural, minimum_baseline, natural_baseline);
+
+  *minimum = PANGO_PIXELS_CEIL (*minimum);
+  *natural = PANGO_PIXELS_CEIL (*natural);
+  if (*minimum_baseline > 0)
+    *minimum_baseline = PANGO_PIXELS_CEIL (*minimum_baseline);
+  if (*natural_baseline > 0)
+    *natural_baseline = PANGO_PIXELS_CEIL (*natural_baseline);
+}
+
+static void
+gtk_text_tile_snapshot (GtkWidget   *widget,
+                        GtkSnapshot *snapshot)
+{
+  GtkTextTile *self = GTK_TEXT_TILE (widget);
+  GtkStyleContext *context;
+
+  if (!self->text || (*self->text == '\0'))
+    return;
+
+  context = _gtk_widget_get_style_context (widget);
+
+  gtk_snapshot_render_layout (snapshot, context, 0, 0, self->layout);
+}
+
+static void
+gtk_text_tile_class_init (GtkTextTileClass *klass)
+{
+  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  gobject_class->dispose = gtk_text_tile_dispose;
+  gobject_class->finalize = gtk_text_tile_finalize;
+  gobject_class->get_property = gtk_text_tile_get_property;
+  gobject_class->set_property = gtk_text_tile_set_property;
+
+  widget_class->css_changed = gtk_text_tile_css_changed;
+  widget_class->measure = gtk_text_tile_measure;
+  widget_class->snapshot = gtk_text_tile_snapshot;
+
+  /**
+   * GtkTextTile:text: (attributes org.gtk.Property.get=gtk_text_tile_get_text 
org.gtk.Property.set=gtk_text_tile_set_text)
+   *
+   * The displayed text.
+   *
+   * Since: 4.8
+   */
+  properties[PROP_TEXT] =
+    g_param_spec_string ("text", NULL, NULL,
+                         NULL,
+                         G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS);
+
+  g_object_class_install_properties (gobject_class, N_PROPS, properties);
+}
+
+static void
+gtk_text_tile_init (GtkTextTile *self)
+{
+  self->min_chars = DEFAULT_MIN_CHARS;
+  self->nat_chars = DEFAULT_NAT_CHARS;
+  self->min_lines = DEFAULT_MIN_LINES;
+  self->nat_lines = DEFAULT_NAT_LINES;
+
+  self->layout = gtk_widget_create_pango_layout (GTK_WIDGET (self), NULL);
+}
+
+/**
+ * gtk_text_tile_new:
+ * @text: (nullable): The text to display.
+ *
+ * Creates a new `GtkTextTile` with the given text.
+ *
+ * Returns: a new `GtkTextTile`
+ *
+ * Since: 4.8
+ */
+GtkWidget *
+gtk_text_tile_new (const char *text)
+{
+  return g_object_new (GTK_TYPE_TEXT_TILE,
+                       "text", text,
+                       NULL);
+}
+
+/**
+ * gtk_text_tile_set_text: (attributes org.gtk.Method.set_property=text)
+ * @self: a `GtkTextTile`
+ * @text: (nullable): The text to display
+ *
+ * Sets the text to be displayed.
+ *
+ * Since: 4.8
+ */
+void
+gtk_text_tile_set_text (GtkTextTile *self,
+                        const char  *text)
+{
+  g_return_if_fail (GTK_IS_TEXT_TILE (self));
+
+  if (g_strcmp0 (self->text, text) == 0)
+    return;
+
+  g_free (self->text);
+  self->text = g_strdup (text);
+
+  pango_layout_set_text (self->layout, self->text, -1);
+
+  /* This here not being a gtk_widget_queue_resize() is why this widget exists */
+  gtk_widget_queue_draw (GTK_WIDGET (self));
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TEXT]);
+}
+
+/**
+ * gtk_text_tile_get_text: (attributes org.gtk.Method.get_property=text)
+ * @self: a `GtkTextTile`
+ *
+ * Gets the text that is displayed.
+ *
+ * Returns: (nullable) (transfer none): The displayed text
+ *
+ * Since: 4.8
+ */
+const char *
+gtk_text_tile_get_text (GtkTextTile *self)
+{
+  g_return_val_if_fail (GTK_IS_TEXT_TILE (self), NULL);
+
+  return self->text;
+}
+
diff --git a/gtk/gtktexttile.h b/gtk/gtktexttile.h
new file mode 100644
index 0000000000..55afc28d35
--- /dev/null
+++ b/gtk/gtktexttile.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright © 2022 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte gnome org>
+ */
+
+#ifndef __GTK_TEXT_TILE_H__
+#define __GTK_TEXT_TILE_H__
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gtk/gtkmediastream.h>
+#include <gtk/gtkwidget.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_TEXT_TILE         (gtk_text_tile_get_type ())
+
+GDK_AVAILABLE_IN_4_8
+G_DECLARE_FINAL_TYPE (GtkTextTile, gtk_text_tile, GTK, TEXT_TILE, GtkWidget)
+
+GDK_AVAILABLE_IN_4_8
+GtkWidget *     gtk_text_tile_new                       (const char             *text);
+
+GDK_AVAILABLE_IN_4_8
+const char *    gtk_text_tile_get_text                  (GtkTextTile            *self);
+GDK_AVAILABLE_IN_4_8
+void            gtk_text_tile_set_text                  (GtkTextTile            *self,
+                                                         const char             *text);
+
+G_END_DECLS
+
+#endif  /* __GTK_TEXT_TILE_H__ */
diff --git a/gtk/meson.build b/gtk/meson.build
index 322badc1ad..3d50d21e3f 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -405,6 +405,7 @@ gtk_public_sources = files([
   'gtktextsegment.c',
   'gtktexttag.c',
   'gtktexttagtable.c',
+  'gtktexttile.c',
   'gtktexttypes.c',
   'gtktextutil.c',
   'gtktextview.c',
@@ -673,6 +674,7 @@ gtk_public_headers = files([
   'gtktextmark.h',
   'gtktexttag.h',
   'gtktexttagtable.h',
+  'gtktexttile.h',
   'gtktextview.h',
   'gtktogglebutton.h',
   'gtktooltip.h',