[gtksourceview] map: use a widget for the slider

[Christian Hergert <chergert src gnome org>]

commit cec3305b0bf8afaca154956402d93a64468ca9aa
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jan 16 23:58:34 2021 -0800

    map: use a widget for the slider
    
    This still needs some work because scrolling has some delay (possibly
    caused within textview). But it's better than it was before and actually
    grabs input now.

 gtksourceview/gtksourcemap.c | 106 +++++++++++++++++++++++--------------------
 1 file changed, 58 insertions(+), 48 deletions(-)
---
diff --git a/gtksourceview/gtksourcemap.c b/gtksourceview/gtksourcemap.c
index 9e57ab82..29ea73de 100644
--- a/gtksourceview/gtksourcemap.c
+++ b/gtksourceview/gtksourcemap.c
@@ -124,6 +124,26 @@
 
 #define DEFAULT_WIDTH 100
 
+struct _GtkSourceMapSlider
+{
+       GtkWidget parent_instance;
+};
+
+#define GTK_SOURCE_TYPE_MAP_SLIDER (gtk_source_map_slider_get_type())
+G_DECLARE_FINAL_TYPE (GtkSourceMapSlider, gtk_source_map_slider, GTK_SOURCE, MAP_SLIDER, GtkWidget)
+G_DEFINE_TYPE (GtkSourceMapSlider, gtk_source_map_slider, GTK_TYPE_WIDGET)
+
+static void
+gtk_source_map_slider_class_init (GtkSourceMapSliderClass *klass)
+{
+       gtk_widget_class_set_css_name (GTK_WIDGET_CLASS (klass), "slider");
+}
+
+static void
+gtk_source_map_slider_init (GtkSourceMapSlider *self)
+{
+}
+
 typedef struct
 {
        /*
@@ -154,6 +174,9 @@ typedef struct
        /* A weak pointer to the connected buffer */
        GtkTextBuffer *buffer;
 
+       /* The slider widget */
+       GtkSourceMapSlider *slider;
+
        /* The location of the scrubber in widget coordinate space. */
        GdkRectangle scrubber_area;
 
@@ -243,7 +266,6 @@ update_scrubber_position (GtkSourceMap *map)
        gint ignored;
        gint child_height;
        gint view_height;
-       gint y;
 
        priv = gtk_source_map_get_instance_private (map);
 
@@ -270,23 +292,31 @@ update_scrubber_position (GtkSourceMap *map)
        gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (priv->view), &iter,
                                            visible_area.x, visible_area.y);
        gtk_text_view_get_iter_location (GTK_TEXT_VIEW (map), &iter, &iter_area);
-       gtk_text_view_buffer_to_window_coords (GTK_TEXT_VIEW (map),
-                                              GTK_TEXT_WINDOW_WIDGET,
-                                              iter_area.x, iter_area.y,
-                                              NULL, &y);
 
        scrubber_area.x = 0;
        scrubber_area.width = alloc.width;
-       scrubber_area.y = y;
+       scrubber_area.y = iter_area.y;
        scrubber_area.height = ((gdouble)view_alloc.height /
                                (gdouble)view_height *
                                (gdouble)child_height) +
                               iter_area.height;
 
+       if (scrubber_area.height > alloc.height)
+       {
+               scrubber_area.height = alloc.height;
+       }
+
        if (memcmp (&scrubber_area, &priv->scrubber_area, sizeof scrubber_area) != 0)
        {
                priv->scrubber_area = scrubber_area;
-               gtk_widget_queue_draw (GTK_WIDGET (map));
+               gtk_widget_set_size_request (GTK_WIDGET (priv->slider),
+                                            scrubber_area.width,
+                                            scrubber_area.height);
+               gtk_text_view_move_overlay (GTK_TEXT_VIEW (map),
+                                           GTK_WIDGET (priv->slider),
+                                           scrubber_area.x,
+                                           scrubber_area.y);
+               gtk_widget_queue_allocate (GTK_WIDGET (map));
        }
 }
 
@@ -370,10 +400,15 @@ gtk_source_map_rebuild_css (GtkSourceMap *map)
        if (background != NULL)
        {
                g_string_append_printf (gstr,
-                                       "textview.scrubber {\n"
-                                       "\tbackground-color: %s;\n"
-                                       "\tborder-top: 1px solid shade(%s,0.9);\n"
-                                       "\tborder-bottom: 1px solid shade(%s,0.9);\n"
+                                       "slider {\n"
+                                       "\tbackground-color: alpha(%s,.3);\n"
+                                       "\tborder-radius: 3px;\n"
+                                       "\tborder: 1px solid alpha(shade(%s,.9),.3);\n"
+                                       "\tmargin-top: 1px;\n"
+                                       "\tmargin-bottom: 1px;\n"
+                                       "}\n"
+                                       "slider:hover {\n"
+                                       "\tbackground-color: alpha(%s,.5);\n"
                                        "}\n",
                                        background,
                                        background,
@@ -640,19 +675,6 @@ scroll_to_child_point (GtkSourceMap *map,
        }
 }
 
-static void
-gtk_source_map_size_allocate (GtkWidget *widget,
-                              int        width,
-                              int        height,
-                              int        baseline)
-{
-       GtkSourceMap *map = GTK_SOURCE_MAP (widget);
-
-       GTK_WIDGET_CLASS (gtk_source_map_parent_class)->size_allocate (widget, width, height, baseline);
-
-       update_scrubber_position (map);
-}
-
 static void
 connect_view (GtkSourceMap  *map,
               GtkSourceView *view)
@@ -799,31 +821,12 @@ gtk_source_map_snapshot_layer (GtkTextView      *text_view,
                               GtkTextViewLayer  layer,
                               GtkSnapshot      *snapshot)
 {
-       GtkSourceMap *map = (GtkSourceMap *)text_view;
-       GtkSourceMapPrivate *priv = gtk_source_map_get_instance_private (map);
-
-       g_assert (GTK_SOURCE_IS_MAP (map));
+       g_assert (GTK_SOURCE_IS_MAP (text_view));
        g_assert (GTK_IS_SNAPSHOT (snapshot));
 
        /* We avoid chaining up to draw layers from GtkSourceView. The details are
         * too small to see and significantly slow down rendering.
         */
-
-       if (layer == GTK_TEXT_VIEW_LAYER_BELOW_TEXT)
-       {
-               GtkStyleContext *style_context = gtk_widget_get_style_context (GTK_WIDGET (map));
-
-               gtk_style_context_save (style_context);
-               if (priv->had_color)
-                       gtk_style_context_add_class (style_context, "scrubber");
-               else
-                       gtk_style_context_add_class (style_context, "selection");
-               gtk_snapshot_render_background (snapshot,
-                                               style_context,
-                                               priv->scrubber_area.x, priv->scrubber_area.y,
-                                               priv->scrubber_area.width, priv->scrubber_area.height);
-               gtk_style_context_restore (style_context);
-       }
 }
 
 static void
@@ -1046,7 +1049,6 @@ gtk_source_map_class_init (GtkSourceMapClass *klass)
 
        widget_class->measure = gtk_source_map_measure;
        widget_class->hide = gtk_source_map_hide;
-       widget_class->size_allocate = gtk_source_map_size_allocate;
        widget_class->show = gtk_source_map_show;
        widget_class->state_flags_changed = gtk_source_map_state_flags_changed;
        widget_class->realize = gtk_source_map_realize;
@@ -1076,15 +1078,21 @@ gtk_source_map_init (GtkSourceMap *map)
        GtkSourceMapPrivate *priv;
        GtkSourceCompletion *completion;
        GtkEventController *scroll;
-       GtkStyleContext *context;
        GtkGesture *drag;
 
        priv = gtk_source_map_get_instance_private (map);
 
        priv->css_provider = gtk_css_provider_new ();
+        priv->slider = g_object_new (GTK_SOURCE_TYPE_MAP_SLIDER,
+                                    "width-request", 1,
+                                    "height-request", 1,
+                                    NULL);
+        gtk_text_view_add_overlay (GTK_TEXT_VIEW (map), GTK_WIDGET (priv->slider), 0, 0);
 
-       context = gtk_widget_get_style_context (GTK_WIDGET (map));
-       gtk_style_context_add_provider (context,
+       gtk_style_context_add_provider (gtk_widget_get_style_context (GTK_WIDGET (map)),
+                                       GTK_STYLE_PROVIDER (priv->css_provider),
+                                       GTK_SOURCE_STYLE_PROVIDER_PRIORITY + 1);
+       gtk_style_context_add_provider (gtk_widget_get_style_context (GTK_WIDGET (priv->slider)),
                                        GTK_STYLE_PROVIDER (priv->css_provider),
                                        GTK_SOURCE_STYLE_PROVIDER_PRIORITY + 1);
 
@@ -1105,6 +1113,8 @@ gtk_source_map_init (GtkSourceMap *map)
        gtk_source_map_set_font_name (map, "BuilderBlocks 1");
 
        drag = gtk_gesture_drag_new ();
+       gtk_event_controller_set_propagation_phase (GTK_EVENT_CONTROLLER (drag),
+                                                    GTK_PHASE_CAPTURE);
        g_signal_connect_swapped (drag,
                                  "drag-begin",
                                  G_CALLBACK (gtk_source_map_drag_begin),