Implement a more convenient drag and drop

CMakeLists.txt

@@ -20,7 +20,7 @@ aux_source_directory("gds-parser" PARSER_SOURCES)
 aux_source_directory("latex-output" LATEX_SOURCES)
 aux_source_directory("cairo-output" CAIRO_SOURCES)
 aux_source_directory("trigonometric" TRIG_SOURCES)
-set(SOURCE "main.c" "layer-selector.c" "mapping-parser.c" "command-line.c" "main-window.c" "external-renderer.c")
+set(SOURCE "main.c" "layer-selector.c" "layer-selector-dnd.c" "mapping-parser.c" "command-line.c" "main-window.c" "external-renderer.c")
 
 set(SOURCE
   ${SOURCE}

layer-selector-dnd.c

@@ -0,0 +1,231 @@
+/*
+ * GDSII-Converter
+ * Copyright (C) 2019  Mario Hüttel <mario.huettel@gmx.net>
+ *
+ * This file is part of GDSII-Converter.
+ *
+ * GDSII-Converter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * GDSII-Converter 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 GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Original Drag and Drop Code taken from:
+ * https://gitlab.gnome.org/GNOME/gtk/blob/gtk-3-22/tests/testlist3.c
+ */
+
+/**
+ * @file layer-selector-dnd.c
+ * @brief This file implements the drag and drop functions regarding the list box containing the layer elements
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+#include "layer-selector-dnd.h"
+
+static GtkTargetEntry entries[] = {
+	{ "GTK_LIST_BOX_ROW", GTK_TARGET_SAME_APP, 0 }
+};
+
+static GtkListBoxRow *layer_selector_get_last_row (GtkListBox *list)
+{
+	int i;
+	GtkListBoxRow *row;
+
+	row = NULL;
+	for (i = 0; ; i++) {
+		GtkListBoxRow *tmp;
+		tmp = gtk_list_box_get_row_at_index(list, i);
+		if (tmp == NULL)
+			break;
+		row = tmp;
+	}
+
+	return row;
+}
+
+
+static GtkListBoxRow *layer_selector_get_row_before (GtkListBox *list, GtkListBoxRow *row)
+{
+	int pos;
+
+	pos = gtk_list_box_row_get_index (row);
+	return gtk_list_box_get_row_at_index (list, pos - 1);
+}
+
+static GtkListBoxRow *layer_selector_get_row_after (GtkListBox *list, GtkListBoxRow *row)
+{
+	int pos;
+
+	pos = gtk_list_box_row_get_index(row);
+	return gtk_list_box_get_row_at_index(list, pos + 1);
+}
+
+static void layer_selector_drag_data_received(GtkWidget *widget, GdkDragContext *context, gint x, gint y,
+					     GtkSelectionData *selection_data, guint info, guint32 time,
+					     gpointer data)
+{
+	GtkWidget *row_before, *row_after;
+	GtkWidget *row;
+	GtkWidget *source;
+	int pos;
+
+	row_before = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-before"));
+	row_after = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-after"));
+
+	g_object_set_data(G_OBJECT(widget), "row-before", NULL);
+	g_object_set_data(G_OBJECT(widget), "row-after", NULL);
+
+	if (row_before)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_before), "drag-hover-bottom");
+	if (row_after)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_after), "drag-hover-top");
+
+	row = (gpointer) *((gpointer *)gtk_selection_data_get_data(selection_data));
+	source = gtk_widget_get_ancestor(row, GTK_TYPE_LIST_BOX_ROW);
+
+	if (source == row_after)
+		return;
+
+	g_object_ref(source);
+	gtk_container_remove(GTK_CONTAINER(gtk_widget_get_parent(source)), source);
+
+	if (row_after)
+		pos = gtk_list_box_row_get_index(GTK_LIST_BOX_ROW(row_after));
+	else
+		pos = gtk_list_box_row_get_index(GTK_LIST_BOX_ROW(row_before)) + 1;
+
+	gtk_list_box_insert(GTK_LIST_BOX(widget), source, pos);
+	g_object_unref(source);
+}
+
+static gboolean layer_selector_drag_motion(GtkWidget *widget, GdkDragContext *context, int x, int y, guint time)
+{
+	GtkAllocation alloc;
+	GtkWidget *row;
+	int hover_row_y;
+	int hover_row_height;
+	GtkWidget *drag_row;
+	GtkWidget *row_before;
+	GtkWidget *row_after;
+
+	row = GTK_WIDGET(gtk_list_box_get_row_at_y(GTK_LIST_BOX(widget), y));
+
+	drag_row = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "drag-row"));
+	row_after = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-after"));
+	row_before = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-before"));
+
+	gtk_style_context_remove_class(gtk_widget_get_style_context(drag_row), "drag-hover");
+	if (row_before)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_before), "drag-hover-bottom");
+	if (row_after)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_after), "drag-hover-top");
+
+	if (row) {
+		gtk_widget_get_allocation(row, &alloc);
+		hover_row_y = alloc.y;
+		hover_row_height = alloc.height;
+
+		if (y < hover_row_y + hover_row_height/2) {
+			row_after = row;
+			row_before = GTK_WIDGET(layer_selector_get_row_before(GTK_LIST_BOX(widget), GTK_LIST_BOX_ROW(row)));
+		} else {
+			row_before = row;
+			row_after = GTK_WIDGET(layer_selector_get_row_after(GTK_LIST_BOX(widget), GTK_LIST_BOX_ROW(row)));
+		}
+	} else {
+		row_before = GTK_WIDGET(layer_selector_get_last_row(GTK_LIST_BOX(widget)));
+		row_after = NULL;
+	}
+
+	g_object_set_data(G_OBJECT(widget), "row-before", row_before);
+	g_object_set_data(G_OBJECT(widget), "row-after", row_after);
+
+	if (drag_row == row_before || drag_row == row_after) {
+		gtk_style_context_add_class(gtk_widget_get_style_context(drag_row), "drag-hover");
+		return FALSE;
+	}
+
+	if (row_before)
+		gtk_style_context_add_class(gtk_widget_get_style_context(row_before), "drag-hover-bottom");
+	if (row_after)
+		gtk_style_context_add_class(gtk_widget_get_style_context(row_after), "drag-hover-top");
+
+	return TRUE;
+}
+
+static void layer_selector_drag_leave(GtkWidget *widget, GdkDragContext *context, guint time)
+{
+	GtkWidget *drag_row;
+	GtkWidget *row_before;
+	GtkWidget *row_after;
+
+	drag_row = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "drag-row"));
+	row_before = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-before"));
+	row_after = GTK_WIDGET(g_object_get_data(G_OBJECT(widget), "row-after"));
+
+	gtk_style_context_remove_class(gtk_widget_get_style_context(drag_row), "drag-hover");
+	if (row_before)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_before), "drag-hover-bottom");
+	if (row_after)
+		gtk_style_context_remove_class(gtk_widget_get_style_context(row_after), "drag-hover-top");
+
+}
+
+static const char *dnd_additional_css =
+  ".row:not(:first-child) { "
+  "  border-top: 1px solid alpha(gray,0.5); "
+  "  border-bottom: 1px solid transparent; "
+  "}"
+  ".row:first-child { "
+  "  border-top: 1px solid transparent; "
+  "  border-bottom: 1px solid transparent; "
+  "}"
+  ".row:last-child { "
+  "  border-top: 1px solid alpha(gray,0.5); "
+  "  border-bottom: 1px solid alpha(gray,0.5); "
+  "}"
+  ".row.drag-icon { "
+  "  background: white; "
+  "  border: 1px solid black; "
+  "}"
+  ".row.drag-row { "
+  "  color: gray; "
+  "  background: alpha(gray,0.2); "
+  "}"
+  ".row.drag-row.drag-hover { "
+  "  border-top: 1px solid #4e9a06; "
+  "  border-bottom: 1px solid #4e9a06; "
+  "}"
+  ".row.drag-hover image, "
+  ".row.drag-hover label { "
+  "  color: #4e9a06; "
+  "}"
+  ".row.drag-hover-top {"
+  "  border-top: 1px solid #4e9a06; "
+  "}"
+  ".row.drag-hover-bottom {"
+  "  border-bottom: 1px solid #4e9a06; "
+  "}";
+
+void layer_selector_list_box_setup_dnd(GtkListBox *box)
+{
+	GtkCssProvider *provider;
+
+	provider = gtk_css_provider_new ();
+	gtk_css_provider_load_from_data (provider, dnd_additional_css, -1, NULL);
+	gtk_style_context_add_provider_for_screen (gdk_screen_get_default (), GTK_STYLE_PROVIDER (provider), 800);
+
+	gtk_drag_dest_set(box, GTK_DEST_DEFAULT_MOTION | GTK_DEST_DEFAULT_DROP, entries, 1, GDK_ACTION_MOVE);
+	g_signal_connect(box, "drag-data-received", G_CALLBACK(layer_selector_drag_data_received), NULL);
+	g_signal_connect(box, "drag-motion", G_CALLBACK(layer_selector_drag_motion), NULL);
+	g_signal_connect(box, "drag-leave", G_CALLBACK(layer_selector_drag_leave), NULL);
+
+}

layer-selector-dnd.h

@@ -0,0 +1,33 @@
+/*
+ * GDSII-Converter
+ * Copyright (C) 2019  Mario Hüttel <mario.huettel@gmx.net>
+ *
+ * This file is part of GDSII-Converter.
+ *
+ * GDSII-Converter is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * GDSII-Converter 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 GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @file layer-selector-dnd.h
+ * @brief Header for drag and drop of layer selector
+ * @author Mario Hüttel <mario.huettel@gmx.net>
+ */
+
+#ifndef _LAYER_SELECTOR_DND_H_
+#define _LAYER_SELECTOR_DND_H_
+
+#include <gtk/gtk.h>
+
+void layer_selector_list_box_setup_dnd(GtkListBox *box);
+
+#endif /* _LAYER_SELECTOR_DND_H_ */

main-window.c

@@ -40,6 +40,7 @@
 #include "version/version.h"
 #include "tree-renderer/lib-cell-renderer.h"
 #include "gds-parser/gds-tree-checker.h"
+#include "layer-selector-dnd.h"
 
 /**
  * @brief User data supplied to callback function of the open button
@@ -441,6 +442,9 @@ GtkWindow *create_main_window()
 	g_signal_connect(conv_button, "clicked", G_CALLBACK(on_convert_clicked), &conv_data);
 
 	listbox = GTK_WIDGET(gtk_builder_get_object(main_builder, "layer-list"));
+	/* Set up the list box sided callbacks for drag and drop */
+	layer_selector_list_box_setup_dnd(GTK_LIST_BOX(listbox));
+
 	open_data.layer_box = GTK_LIST_BOX(listbox);
 
 	/* Set buttons fpr layer mapping GUI */

widgets/layer-element.c

@@ -17,9 +17,16 @@
  * along with GDSII-Converter.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+/*
+ * The drag and drop implementation is adapted from
+ * https://gitlab.gnome.org/GNOME/gtk/blob/gtk-3-22/tests/testlist3.c
+ *
+ * Thanks to the GTK3 people for creating these examples.
+ */
+
 /**
  * @file layer-element.c
- * @brief Omplementation of the layer element used for configuring layer colors etc.
+ * @brief Implementation of the layer element used for configuring layer colors etc.
  * @author Mario Hüttel <mario.huettel@gmx.net>
  */
 
@@ -65,14 +72,14 @@ static void layer_element_drag_begin(GtkWidget *widget,
 	int x, y;
 	(void)data;
 
-	row = gtk_widget_get_ancestor (widget, GTK_TYPE_LIST_BOX_ROW);
+	row = gtk_widget_get_ancestor(widget, GTK_TYPE_LIST_BOX_ROW);
-	gtk_widget_get_allocation (row, &alloc);
+	gtk_widget_get_allocation(row, &alloc);
-	surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, alloc.width, alloc.height);
+	surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, alloc.width, alloc.height);
-	cr = cairo_create (surface);
+	cr = cairo_create(surface);
 
-	gtk_style_context_add_class (gtk_widget_get_style_context (row), "drag-icon");
+	gtk_style_context_add_class (gtk_widget_get_style_context(row), "drag-icon");
 	gtk_widget_draw (row, cr);
-	gtk_style_context_remove_class (gtk_widget_get_style_context (row), "drag-icon");
+	gtk_style_context_remove_class(gtk_widget_get_style_context(row), "drag-icon");
 
 	gtk_widget_translate_coordinates (widget, row, 0, 0, &x, &y);
 	cairo_surface_set_device_offset (surface, -x, -y);
@@ -80,6 +87,21 @@ static void layer_element_drag_begin(GtkWidget *widget,
 
 	cairo_destroy (cr);
 	cairo_surface_destroy (surface);
+
+	g_object_set_data(G_OBJECT(gtk_widget_get_parent(row)), "drag-row", row);
+	gtk_style_context_add_class(gtk_widget_get_style_context(row), "drag-row");
+}
+
+static void layer_element_drag_end(GtkWidget *widget, GdkDragContext *context, gpointer data)
+{
+	GtkWidget *row;
+	(void)context;
+	(void)data;
+
+	row = gtk_widget_get_ancestor(widget, GTK_TYPE_LIST_BOX_ROW);
+	g_object_set_data(G_OBJECT(gtk_widget_get_parent(row)), "drag-row", NULL);
+	gtk_style_context_remove_class(gtk_widget_get_style_context(row), "drag-row");
+	gtk_style_context_remove_class(gtk_widget_get_style_context(row), "drag-hover");
 }
 
 static void layer_element_drag_data_get(GtkWidget *widget, GdkDragContext *context, GtkSelectionData *selection_data,
@@ -94,36 +116,6 @@ static void layer_element_drag_data_get(GtkWidget *widget, GdkDragContext *conte
 			       32, (const guchar *)&widget, sizeof(gpointer));
 }
 
-static void layer_element_drag_data_received(GtkWidget *widget, GdkDragContext *context, gint x, gint y,
-					     GtkSelectionData *selection_data, guint info, guint32 time,
-					     gpointer data)
-{
-	GtkWidget *target;
-	GtkWidget *row;
-	GtkWidget *source;
-	int pos;
-	(void)context;
-	(void)x;
-	(void)y;
-	(void)info;
-	(void)time;
-	(void)data;
-
-	target = widget;
-
-	pos = gtk_list_box_row_get_index (GTK_LIST_BOX_ROW (target));
-	row = (gpointer)(*(gpointer *)gtk_selection_data_get_data(selection_data));
-	source = gtk_widget_get_ancestor (row, GTK_TYPE_LIST_BOX_ROW);
-
-	if (source == target)
-		return;
-
-	g_object_ref (source);
-	gtk_container_remove (GTK_CONTAINER (gtk_widget_get_parent (source)), source);
-	gtk_list_box_insert (GTK_LIST_BOX (gtk_widget_get_parent (target)), source, pos);
-	g_object_unref (source);
-}
-
 static void layer_element_init(LayerElement *self)
 {
 	GtkBuilder *builder;
@@ -140,11 +132,11 @@ static void layer_element_init(LayerElement *self)
 	self->priv.event_handle = GTK_EVENT_BOX(gtk_builder_get_object(builder, "event-box"));
 
 	/* Setup drag and drop */
+	gtk_style_context_add_class (gtk_widget_get_style_context(GTK_WIDGET(self)), "row");
 	gtk_drag_source_set(GTK_WIDGET(self->priv.event_handle), GDK_BUTTON1_MASK, entries, 1, GDK_ACTION_MOVE);
 	g_signal_connect(self->priv.event_handle, "drag-begin", G_CALLBACK(layer_element_drag_begin), NULL);
 	g_signal_connect(self->priv.event_handle, "drag-data-get", G_CALLBACK(layer_element_drag_data_get), NULL);
-	gtk_drag_dest_set(GTK_WIDGET(self), GTK_DEST_DEFAULT_ALL, entries, 1, GDK_ACTION_MOVE);
+	g_signal_connect(self->priv.event_handle, "drag-end", G_CALLBACK(layer_element_drag_end), NULL);
-	g_signal_connect(GTK_WIDGET(self), "drag-data-received", G_CALLBACK(layer_element_drag_data_received), NULL);
 
 	g_object_unref(builder);
 }