Implement side-by-side tiling

Patch by Florian Müllner for Metacity
https://bugzilla.gnome.org/show_bug.cgi?id=607694

When dragging a window over a screen edge and dropping it there,
maximize it vertically and scale it horizontally to cover the
corresponding half of the current monitor.

Whenever a "hot area" which triggers this behavior is entered, an
indication of window's target size is displayed after a short delay
to avoid distraction when moving a window between monitors.

1 files changed, 251 insertions, 0 deletions

diff --git a/src/ui/tile-preview.c b/src/ui/tile-preview.c
new file mode 100644
index 00000000..e782e6a5
--- /dev/null
+++ b/src/ui/tile-preview.c
@@ -0,0 +1,251 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/* Mutter tile-preview marks the area a window will *ehm* snap to */
+
+/*
+ * Copyright (C) 2010 Florian Müllner
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <config.h>
+
+#include <gtk/gtk.h>
+#include <cairo.h>
+
+#include "tile-preview.h"
+#include "core.h"
+
+#define OUTLINE_WIDTH 5  /* frame width in non-composite case */
+
+
+struct _MetaTilePreview {
+  GtkWidget     *preview_window;
+
+  GdkColor      *preview_color;
+  guchar         preview_alpha;
+
+  MetaRectangle  tile_rect;
+
+  gboolean       has_alpha: 1;
+};
+
+static gboolean
+meta_tile_preview_expose (GtkWidget      *widget,
+                          GdkEventExpose *event,
+                          gpointer        user_data)
+{
+  MetaTilePreview *preview = user_data;
+  GdkWindow *window;
+  cairo_t *cr;
+
+  window = gtk_widget_get_window (widget);
+  cr = gdk_cairo_create (window);
+
+  cairo_set_line_width (cr, 1.0);
+
+  if (preview->has_alpha)
+    {
+
+      /* Fill the preview area with a transparent color */
+      cairo_set_source_rgba (cr,
+                             (double)preview->preview_color->red   / 0xFFFF,
+                             (double)preview->preview_color->green / 0xFFFF,
+                             (double)preview->preview_color->blue  / 0xFFFF,
+                             (double)preview->preview_alpha / 0xFF);
+
+      cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+      cairo_paint (cr);
+
+      /* Use the opaque color for the border */
+      gdk_cairo_set_source_color (cr, preview->preview_color);
+    }
+  else
+    {
+      GtkStyle *style = gtk_widget_get_style (preview->preview_window);
+
+      gdk_cairo_set_source_color (cr, &style->white);
+
+      cairo_rectangle (cr,
+                       OUTLINE_WIDTH - 0.5, OUTLINE_WIDTH - 0.5,
+                       preview->tile_rect.width - 2 * (OUTLINE_WIDTH - 1) - 1,
+                       preview->tile_rect.height - 2 * (OUTLINE_WIDTH - 1) - 1);
+      cairo_stroke (cr);
+    }
+
+  cairo_rectangle (cr,
+                   0.5, 0.5,
+                   preview->tile_rect.width - 1,
+                   preview->tile_rect.height - 1);
+  cairo_stroke (cr);
+
+  cairo_destroy (cr);
+
+  return FALSE;
+}
+
+static void
+on_preview_window_style_set (GtkWidget *widget,
+                             GtkStyle  *previous,
+                             gpointer   user_data)
+{
+  MetaTilePreview *preview = user_data;
+  GtkStyle *style;
+
+  style = gtk_rc_get_style_by_paths (gtk_widget_get_settings (widget),
+                                     "GtkWindow.GtkIconView",
+                                     "GtkWindow.GtkIconView",
+                                     GTK_TYPE_ICON_VIEW);
+
+  if (style != NULL)
+    g_object_ref (style);
+  else
+    style = gtk_style_new ();
+
+  gtk_style_get (style, GTK_TYPE_ICON_VIEW,
+                 "selection-box-color", &preview->preview_color,
+                 "selection-box-alpha", &preview->preview_alpha,
+                 NULL);
+  if (!preview->preview_color)
+    {
+      GdkColor selection = style->base[GTK_STATE_SELECTED];
+      preview->preview_color = gdk_color_copy (&selection);
+    }
+
+  g_object_unref (style);
+}
+
+MetaTilePreview *
+meta_tile_preview_new (int      screen_number,
+                       gboolean composited)
+{
+  MetaTilePreview *preview;
+  GdkColormap *rgba_colormap;
+  GdkScreen *screen;
+
+  screen = gdk_display_get_screen (gdk_display_get_default (), screen_number);
+  rgba_colormap = gdk_screen_get_rgba_colormap (screen);
+
+  preview = g_new (MetaTilePreview, 1);
+
+  preview->preview_window = gtk_window_new (GTK_WINDOW_POPUP);
+
+  gtk_window_set_screen (GTK_WINDOW (preview->preview_window), screen);
+  gtk_widget_set_app_paintable (preview->preview_window, TRUE);
+
+  preview->preview_color = NULL;
+  preview->preview_alpha = 0xFF;
+
+  preview->tile_rect.x = preview->tile_rect.y = 0;
+  preview->tile_rect.width = preview->tile_rect.height = 0;
+
+  preview->has_alpha = rgba_colormap && composited;
+
+  if (preview->has_alpha)
+    {
+      gtk_widget_set_colormap (preview->preview_window, rgba_colormap);
+
+      g_signal_connect (preview->preview_window, "style-set",
+                        G_CALLBACK (on_preview_window_style_set), preview);
+    }
+
+  gtk_widget_realize (preview->preview_window);
+  gdk_window_set_back_pixmap (gtk_widget_get_window (preview->preview_window),
+                              NULL, FALSE);
+
+  g_signal_connect (preview->preview_window, "expose-event",
+                    G_CALLBACK (meta_tile_preview_expose), preview);
+
+  return preview;
+}
+
+void
+meta_tile_preview_free (MetaTilePreview *preview)
+{
+  gtk_widget_destroy (preview->preview_window);
+
+  if (preview->preview_color)
+    gdk_color_free (preview->preview_color);
+
+  g_free (preview);
+}
+
+void
+meta_tile_preview_show (MetaTilePreview *preview,
+                        MetaRectangle   *tile_rect)
+{
+  GdkWindow *window;
+  GdkRectangle old_rect;
+
+  if (gtk_widget_get_visible (preview->preview_window)
+      && preview->tile_rect.x == tile_rect->x
+      && preview->tile_rect.y == tile_rect->y
+      && preview->tile_rect.width == tile_rect->width
+      && preview->tile_rect.height == tile_rect->height)
+    return; /* nothing to do */
+
+  gtk_widget_show (preview->preview_window);
+  window = gtk_widget_get_window (preview->preview_window);
+  meta_core_lower_beneath_focus_window (gdk_display,
+                                        GDK_WINDOW_XWINDOW (window),
+                                        gtk_get_current_event_time ());
+
+  old_rect.x = old_rect.y = 0;
+  old_rect.width = preview->tile_rect.width;
+  old_rect.height = preview->tile_rect.height;
+
+  gdk_window_invalidate_rect (window, &old_rect, FALSE);
+
+  preview->tile_rect = *tile_rect;
+
+  gdk_window_move_resize (window,
+                          preview->tile_rect.x, preview->tile_rect.y,
+                          preview->tile_rect.width, preview->tile_rect.height);
+
+  if (!preview->has_alpha)
+    {
+      GdkRectangle outer_rect, inner_rect;
+      GdkRegion *outer_region, *inner_region;
+      GdkColor black;
+
+      black = gtk_widget_get_style (preview->preview_window)->black;
+      gdk_window_set_background (window, &black);
+
+      outer_rect.x = outer_rect.y = 0;
+      outer_rect.width = preview->tile_rect.width;
+      outer_rect.height = preview->tile_rect.height;
+
+      inner_rect.x = OUTLINE_WIDTH;
+      inner_rect.y = OUTLINE_WIDTH;
+      inner_rect.width = outer_rect.width - 2 * OUTLINE_WIDTH;
+      inner_rect.height = outer_rect.height - 2 * OUTLINE_WIDTH;
+
+      outer_region = gdk_region_rectangle (&outer_rect);
+      inner_region = gdk_region_rectangle (&inner_rect);
+
+      gdk_region_subtract (outer_region, inner_region);
+      gdk_region_destroy (inner_region);
+
+      gdk_window_shape_combine_region (window, outer_region, 0, 0);
+      gdk_region_destroy (outer_region);
+    }
+}
+
+void
+meta_tile_preview_hide (MetaTilePreview *preview)
+{
+  gtk_widget_hide (preview->preview_window);
+}
\ No newline at end of file