[gtk+/multitouch: 12/27] gtk-demo: Add multitouch demo

[Carlos Garnacho <carlosg src gnome org>]

commit 4e96974be30a8383bb4f79e815cf81f6d8da16f4
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri Mar 11 21:26:36 2011 +0100

    gtk-demo: Add multitouch demo
    
    Pretty much ignores pointer events currently, so you're out
    of luck to see anything happening at all if you don't have
    a multitouch device...

 demos/gtk-demo/Makefile.am  |    1 +
 demos/gtk-demo/multitouch.c |  514 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 515 insertions(+), 0 deletions(-)
---
diff --git a/demos/gtk-demo/Makefile.am b/demos/gtk-demo/Makefile.am
index e15a8c6..13136b3 100644
--- a/demos/gtk-demo/Makefile.am
+++ b/demos/gtk-demo/Makefile.am
@@ -28,6 +28,7 @@ demos =						\
 	links.c					\
 	list_store.c				\
 	menus.c					\
+	multitouch.c				\
 	offscreen_window.c			\
 	offscreen_window2.c			\
 	overlay.c				\
diff --git a/demos/gtk-demo/multitouch.c b/demos/gtk-demo/multitouch.c
new file mode 100644
index 0000000..79f1f7d
--- /dev/null
+++ b/demos/gtk-demo/multitouch.c
@@ -0,0 +1,514 @@
+/* Multitouch
+ *
+ * Demonstrates some general multitouch event handling,
+ * using GdkTouchCluster in order to get grouped motion
+ * events for the touches within a cluster.
+ */
+
+#include <math.h>
+#include <gtk/gtk.h>
+#include "demo-common.h"
+
+static GtkWidget *window = NULL;
+static GList *shapes = NULL;
+
+typedef struct {
+  GdkTouchCluster *cluster;
+  GdkRGBA color;
+
+  gdouble angle;
+  gdouble zoom;
+
+  gdouble center_x;
+  gdouble center_y;
+
+  gdouble x;
+  gdouble y;
+  gdouble width;
+  gdouble height;
+
+  gdouble base_zoom;
+  gdouble base_angle;
+  gdouble initial_distance;
+  gdouble initial_angle;
+
+  GdkPoint points[4];
+} ShapeInfo;
+
+static void
+calculate_rotated_point (gdouble  angle,
+                         gdouble  zoom,
+                         gdouble  center_x,
+                         gdouble  center_y,
+                         gdouble  point_x,
+                         gdouble  point_y,
+                         gdouble *ret_x,
+                         gdouble *ret_y)
+{
+  gdouble distance, xd, yd, ang;
+
+  if (angle == 0)
+    {
+      *ret_x = point_x;
+      *ret_y = point_y;
+      return;
+    }
+
+  xd = center_x - point_x;
+  yd = center_y - point_y;
+
+  if (xd == 0 && yd == 0)
+    {
+      *ret_x = center_x;
+      *ret_y = center_y;
+      return;
+    }
+
+  distance = sqrt ((xd * xd) + (yd * yd));
+  distance *= zoom;
+
+  ang = atan2 (xd, yd);
+
+  /* Invert angle */
+  ang = (2 * G_PI) - ang;
+
+  /* Shift it 270Â */
+  ang += 3 * (G_PI / 2);
+
+  /* And constraint it to 0Â-360Â */
+  ang = fmod (ang, 2 * G_PI);
+  ang += angle;
+
+  *ret_x = center_x + (distance * cos (ang));
+  *ret_y = center_y + (distance * sin (ang));
+}
+
+static void
+shape_info_allocate_input_rect (ShapeInfo *info)
+{
+  gint width, height, i;
+
+  width = info->width;
+  height = info->height;
+
+  /* Top/left */
+  info->points[0].x = info->x - info->center_x;
+  info->points[0].y = info->y - info->center_y;
+
+  /* Top/right */
+  info->points[1].x = info->x - info->center_x + width;
+  info->points[1].y = info->y - info->center_y;
+
+  /* Bottom/right */
+  info->points[2].x = info->x - info->center_x + width;
+  info->points[2].y = info->y - info->center_y + height;
+
+  /* Bottom/left */
+  info->points[3].x = info->x - info->center_x;
+  info->points[3].y = info->y - info->center_y + height;
+
+  for (i = 0; i < 4; i++)
+    {
+      gdouble ret_x, ret_y;
+
+      calculate_rotated_point (info->angle,
+                               info->zoom,
+                               info->x,
+                               info->y,
+                               (gdouble) info->points[i].x,
+                               (gdouble) info->points[i].y,
+                               &ret_x,
+                               &ret_y);
+
+      info->points[i].x = (gint) ret_x;
+      info->points[i].y = (gint) ret_y;
+    }
+}
+
+static void
+shape_info_bounding_rect (ShapeInfo    *info,
+                          GdkRectangle *rect)
+{
+  gint i, left, right, top, bottom;
+
+  left = top = G_MAXINT;
+  right = bottom = 0;
+
+  for (i = 0; i < 4; i++)
+    {
+      if (info->points[i].x < left)
+        left = info->points[i].x;
+
+      if (info->points[i].x > right)
+        right = info->points[i].x;
+
+      if (info->points[i].y < top)
+        top = info->points[i].y;
+
+      if (info->points[i].y > bottom)
+        bottom = info->points[i].y;
+    }
+
+  rect->x = left - 20;
+  rect->y = top - 20;
+  rect->width = right - left + 40;
+  rect->height = bottom - top + 40;
+}
+
+static gboolean
+shape_info_point_in (ShapeInfo *info,
+                     gint       x,
+                     gint       y)
+{
+  GdkPoint *left, *right, *top, *bottom;
+  gint i;
+
+  left = right = top = bottom = NULL;
+
+  for (i = 0; i < 4; i++)
+    {
+      GdkPoint *p = &info->points[i];
+
+      if (!left ||
+          p->x < left->x ||
+          (p->x == left->x && p->y > left->y))
+        left = p;
+
+      if (!right ||
+          p->x > right->x ||
+          (p->x == right->x && p->y < right->y))
+        right = p;
+    }
+
+  for (i = 0; i < 4; i++)
+    {
+      GdkPoint *p = &info->points[i];
+
+      if (p == left || p == right)
+        continue;
+
+      if (!top ||
+          p->y < top->y)
+        top = p;
+
+      if (!bottom ||
+          p->y > bottom->y)
+        bottom = p;
+    }
+
+  g_assert (left && right && top && bottom);
+
+  if (x < left->x ||
+      x > right->x ||
+      y < top->y ||
+      y > bottom->y)
+    return FALSE;
+
+  /* Check whether point is above the sides
+   * between leftmost and topmost, and
+   * topmost and rightmost corners.
+   */
+  if (x <= top->x)
+    {
+      if (left->y - ((left->y - top->y) * (((gdouble) x - left->x) / (top->x - left->x))) > y)
+        return FALSE;
+    }
+  else
+    {
+      if (top->y + ((right->y - top->y) * (((gdouble) x - top->x) / (right->x - top->x))) > y)
+        return FALSE;
+    }
+
+  /* Check whether point is below the sides
+   * between leftmost and bottom, and
+   * bottom and rightmost corners.
+   */
+  if (x <= bottom->x)
+    {
+      if (left->y + ((bottom->y - left->y) * (((gdouble) x - left->x) / (bottom->x - left->x))) < y)
+        return FALSE;
+    }
+  else
+    {
+      if (bottom->y - ((bottom->y - right->y) * (((gdouble) x - bottom->x) / (right->x - bottom->x))) < y)
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static ShapeInfo *
+shape_info_new (gdouble  x,
+                gdouble  y,
+                gdouble  width,
+                gdouble  height,
+                GdkRGBA *color)
+{
+  ShapeInfo *info;
+
+  info = g_slice_new0 (ShapeInfo);
+  info->cluster = NULL;
+  info->color = *color;
+
+  info->x = x;
+  info->y = y;
+  info->width = width;
+  info->height = height;
+
+  info->angle = 0;
+  info->zoom = 1;
+
+  info->base_zoom = 1;
+  info->base_angle = 0;
+  info->initial_distance = 0;
+  info->initial_angle = 0;
+
+  shape_info_allocate_input_rect (info);
+
+  shapes = g_list_prepend (shapes, info);
+
+  return info;
+}
+
+static void
+shape_info_free (ShapeInfo *info)
+{
+  g_slice_free (ShapeInfo, info);
+}
+
+static void
+shape_info_draw (cairo_t   *cr,
+                 ShapeInfo *info)
+{
+  cairo_save (cr);
+
+  cairo_translate (cr, info->points[0].x, info->points[0].y);
+  cairo_scale (cr, info->zoom, info->zoom);
+  cairo_rotate (cr, info->angle);
+
+  cairo_rectangle (cr, 0, 0, info->width, info->height);
+  gdk_cairo_set_source_rgba (cr, &info->color);
+  cairo_fill_preserve (cr);
+
+  cairo_set_line_width (cr, 6);
+  cairo_set_source_rgb (cr, 0, 0, 0);
+  cairo_stroke (cr);
+
+  cairo_restore (cr);
+}
+
+static gboolean
+draw_cb (GtkWidget *widget,
+         cairo_t   *cr,
+         gpointer   user_data)
+{
+  GList *l;
+
+  for (l = shapes; l; l = l->next)
+    shape_info_draw (cr, l->data);
+
+  return FALSE;
+}
+
+static gboolean
+button_press_cb (GtkWidget *widget,
+                 GdkEvent  *event,
+                 gpointer   user_data)
+{
+  ShapeInfo *shape = NULL;
+  guint touch_id;
+
+  if (gdk_event_get_touch_id (event, &touch_id))
+    {
+      GList *l;
+
+      for (l = shapes; l; l = l->next)
+        {
+          ShapeInfo *info = l->data;
+
+          if (shape_info_point_in (info,
+                                   (gint) event->button.x,
+                                   (gint) event->button.y))
+            shape = info;
+        }
+
+      if (!shape)
+        return FALSE;
+
+      if (!shape->cluster)
+        shape->cluster = gdk_window_create_touch_cluster (gtk_widget_get_window (widget));
+
+      /* Only change cluster device if there were no touches or no device */
+      if (!gdk_touch_cluster_get_device (shape->cluster) ||
+          !gdk_touch_cluster_get_touches (shape->cluster))
+        gdk_touch_cluster_set_device (shape->cluster,
+                                      gdk_event_get_source_device (event));
+
+      gdk_touch_cluster_add_touch (shape->cluster, touch_id);
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
+static gboolean
+multitouch_cb (GtkWidget *widget,
+               GdkEvent  *event,
+               gpointer   user_data)
+{
+  ShapeInfo *info = NULL;
+  gboolean new_center = FALSE;
+  gboolean new_position = FALSE;
+  gdouble event_x, event_y;
+  cairo_region_t *region;
+  GdkRectangle rect;
+  GList *l;
+
+  for (l = shapes; l; l = l->next)
+    {
+      ShapeInfo *shape = l->data;
+
+      if (event->multitouch.group == shape->cluster)
+        {
+          info = shape;
+          break;
+        }
+    }
+
+  if (!info)
+    return FALSE;
+
+  shape_info_bounding_rect (info, &rect);
+  region = cairo_region_create_rectangle ((cairo_rectangle_int_t *) &rect);
+
+  if (event->multitouch.n_events == 1)
+    {
+      /* Update center if we just got to
+       * this situation from either way */
+      if (event->type == GDK_MULTITOUCH_ADDED ||
+          event->type == GDK_MULTITOUCH_REMOVED)
+        new_center = TRUE;
+
+      event_x = event->multitouch.events[0]->x;
+      event_y = event->multitouch.events[0]->y;
+      new_position = TRUE;
+    }
+  else if (event->multitouch.n_events == 2)
+    {
+      gdouble distance, angle;
+
+      gdk_events_get_center ((GdkEvent *) event->multitouch.events[0],
+                             (GdkEvent *) event->multitouch.events[1],
+                             &event_x, &event_y);
+
+      gdk_events_get_distance ((GdkEvent *) event->multitouch.events[0],
+                               (GdkEvent *) event->multitouch.events[1],
+                               &distance);
+
+      gdk_events_get_angle ((GdkEvent *) event->multitouch.events[0],
+                            (GdkEvent *) event->multitouch.events[1],
+                            &angle);
+
+      if (event->type == GDK_MULTITOUCH_ADDED)
+        {
+          /* Second touch was just added, update base zoom/angle */
+          info->base_zoom = info->zoom;
+          info->base_angle = info->angle;
+          info->initial_angle = angle;
+          info->initial_distance = distance;
+          new_center = TRUE;
+        }
+
+      info->zoom = MAX (info->base_zoom * (distance / info->initial_distance), 1.0);
+      info->angle = info->base_angle + (angle - info->initial_angle);
+      new_position = TRUE;
+    }
+
+  if (new_center)
+    {
+      gdouble origin_x, origin_y;
+
+      origin_x = info->x - info->center_x;
+      origin_y = info->y - info->center_y;
+
+      calculate_rotated_point (- info->angle,
+                               1 / info->zoom,
+                               info->x - origin_x,
+                               info->y - origin_y,
+                               event_x - origin_x,
+                               event_y - origin_y,
+                               &info->center_x,
+                               &info->center_y);
+    }
+
+  if (new_position)
+    {
+      info->x = event_x;
+      info->y = event_y;
+    }
+
+  shape_info_allocate_input_rect (info);
+
+  shape_info_bounding_rect (info, &rect);
+  cairo_region_union_rectangle (region, (cairo_rectangle_int_t *) &rect);
+  gdk_window_invalidate_region (gtk_widget_get_window (widget), region, FALSE);
+
+  return TRUE;
+}
+
+GtkWidget *
+do_multitouch (GtkWidget *do_widget)
+{
+  if (!window)
+    {
+      GdkRGBA color;
+
+      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+      gtk_window_set_title (GTK_WINDOW (window), "Multitouch demo");
+      gtk_window_set_default_size (GTK_WINDOW (window), 600, 600);
+
+      gtk_window_set_screen (GTK_WINDOW (window),
+			     gtk_widget_get_screen (do_widget));
+
+      gtk_widget_add_events (window,
+                             GDK_TOUCH_MASK |
+                             GDK_POINTER_MOTION_MASK |
+                             GDK_BUTTON_PRESS_MASK |
+                             GDK_BUTTON_RELEASE_MASK);
+
+      gtk_widget_set_app_paintable (window, TRUE);
+
+      g_signal_connect (window, "draw",
+                        G_CALLBACK (draw_cb), NULL);
+      g_signal_connect (window, "button-press-event",
+                        G_CALLBACK (button_press_cb), NULL);
+      g_signal_connect (window, "multitouch-event",
+                        G_CALLBACK (multitouch_cb), NULL);
+
+      gdk_rgba_parse (&color, "red");
+      color.alpha = 0.5;
+      shape_info_new (100, 50, 100, 140, &color);
+
+      gdk_rgba_parse (&color, "green");
+      color.alpha = 0.5;
+      shape_info_new (200, 100, 120, 90, &color);
+
+      gdk_rgba_parse (&color, "blue");
+      color.alpha = 0.5;
+      shape_info_new (150, 190, 140, 90, &color);
+    }
+
+  if (!gtk_widget_get_visible (window))
+    gtk_widget_show (window);
+  else
+    {
+      gtk_widget_destroy (window);
+      window = NULL;
+
+      g_list_foreach (shapes, (GFunc) shape_info_free, NULL);
+      g_list_free (shapes);
+      shapes = NULL;
+    }
+
+  return window;
+}