Simplified logic using a grid. It looks ugly but we don't care right now.

sugar/graphics/spreadbox.py

@@ -16,117 +16,47 @@
 # Boston, MA 02111-1307, USA.
 
 import random
-import math
 
-import cairo
 import hippo
+import gtk
 
-_DISTANCE_THRESHOLD = 10.0
-_FORCE_CONSTANT = 0.1
+from sugar.graphics import units
 
-class SpreadBox(hippo.CanvasBox, hippo.CanvasItem):
-    __gtype_name__ = 'SugarSpreadBox'
+_CELL_WIDTH  = units.grid_to_pixels(1)
+_CELL_HEIGHT = units.grid_to_pixels(1)
+_GRID_WIDTH  = gtk.gdk.screen_width() / _CELL_WIDTH
+_GRID_HEIGHT = gtk.gdk.screen_height() / _CELL_HEIGHT
 
+class SpreadBox(hippo.CanvasBox):
     def __init__(self, **kwargs):
         hippo.CanvasBox.__init__(self, **kwargs)
 
-        self._items_to_position = []
-        self._stable = False
+        self._grid = []
 
-    def add_item(self, item):
-        self._items_to_position.append(item)
-        self.append(item, hippo.PACK_FIXED)
-
-    def remove_item(self, item):
-        if self._items_to_position.count(item) > 0:
-            self._items_to_position.remove(item)
-        self.remove(item)
-
-    def _get_item_radius(self, item):
-        [width, height] = item.get_request()
-        return math.sqrt(width ** 2  + height ** 2) / 2
-
-    def _get_item_center(self, item):
-        [width, height] = item.get_request()
-        [x, y] = self.get_position(item)
-
-        c_x = int(x + float(width) / 2.0)
-        c_y = int(y + float(height) / 2.0)
-
-        return [c_x, c_y]
-
-    def _get_repulsion(self, icon1, icon2):
-        [c1_x, c1_y] = self._get_item_center(icon1)
-        [c2_x, c2_y] = self._get_item_center(icon2)
-
-        a = c2_x - c1_x
-        b = c2_y - c1_y
-
-        r1 = self._get_item_radius(icon1)
-        r2 = self._get_item_radius(icon2)
-        distance = math.sqrt(a ** 2  + b ** 2) - r1 - r2
-
-        if distance < _DISTANCE_THRESHOLD:
-            f_x = int(math.ceil(-_FORCE_CONSTANT * float(a)))
-            f_y = int(math.ceil(-_FORCE_CONSTANT * float(b)))
-        else:
-            f_x = 0
-            f_y = 0
-
-        return [f_x, f_y]
+        for i in range(0, _GRID_WIDTH * _GRID_HEIGHT):
+            self._grid.append(None)
 
-    def _clamp_position(self, icon, x, y):
-        x = max(0, x)
-        y = max(0, y)
-
-        [item_w, item_h] = icon.get_request()
-        [box_w, box_h] = self.get_allocation()
-
-        x = min(box_w - item_w, x)
-        y = min(box_h - item_h, y)
-
-        return [x, y]
-
-    def _spread_icons(self):
-        self._stable = True
-
-        for icon1 in self.get_children():
-            vx = 0
-            vy = 0
-
-            for icon2 in self.get_children():
-                if icon1 != icon2:
-                    [f_x, f_y] = self._get_repulsion(icon1, icon2)
-                    if f_x != 0 or f_y != 0:
-                        self._stable = False
-                        vx += f_x
-                        vy += f_y
-
-            if vx != 0 or vy != 0:
-                [x, y] = self.get_position(icon1)
-                new_x = x + vx
-                new_y = y + vy
-
-                [new_x, new_y] = self._clamp_position(icon1, new_x, new_y)
-
-                self.set_position(icon1, new_x, new_y)
-
-    def do_allocate(self, width, height, origin_changed):
-        hippo.CanvasBox.do_allocate(self, width, height, origin_changed)
+    def add_item(self, item):
+        start_pos = int(random.random() * len(self._grid))
 
-        for item in self._items_to_position:
-            [item_w, item_h] = item.get_request()
+        pos = start_pos
+        while self._grid[pos] != None:
+            pos = pos + 1
+            if pos == len(self._grid):
+                pos = 0
+            elif pos == start_pos:
+                break
 
-            x = int(random.random() * width - item_w)
-            y = int(random.random() * height - item_h)
+        self._grid[pos] = item
 
-            [x, y] = self._clamp_position(item, x, y)
-            self.set_position(item, x, y)
+        self.append(item, hippo.PACK_FIXED)
 
-        self._items_to_position = []
+        cell_y = int(pos / _GRID_WIDTH)
+        cell_x = pos - cell_y * _GRID_WIDTH
+        self.set_position(item, cell_x * _CELL_WIDTH, cell_y * _CELL_HEIGHT)
 
-        tries = 20
-        self._spread_icons()
-        while not self._stable and tries > 0:
-            self._spread_icons()
-            tries -= 1
+    def remove_item(self, item):
+        for i in range(0, len(self._grid)):
+            if self._grid[i] == item:
+                self._grid[i] = None
+        self.remove(item)