Add a Clear/Erase All tool

Problem: It is problematic to remove all bodies in the canvas, one by one,
to get a clear screen. A clear all tool is certainly needed.

Solution: Implement a Clear All tool, which also asks for confirmation before
destroying everything.

Fixes #1615

3 files changed, 153 insertions, 0 deletions

diff --git a/activity.py b/activity.py
index d7a3d76..9994dea 100644
--- a/activity.py
+++ b/activity.py
@@ -32,6 +32,7 @@ from sugar.activity.widgets import ActivityToolbarButton
 from sugar.activity.widgets import StopButton
 from sugar.graphics.radiotoolbutton import RadioToolButton
 from sugar.graphics.toolbutton import ToolButton
+from sugar.graphics.alert import ConfirmationAlert
 from sugar.graphics.toolbarbox import ToolbarBox
 from sugar.graphics.toolbarbox import ToolbarButton
 from sugar.graphics.style import GRID_CELL_SIZE
@@ -120,6 +121,12 @@ class PhysicsActivity(activity.Activity):
         self._insert_stop_play_button(toolbar_box.toolbar)
 
         separator = gtk.SeparatorToolItem()
+        toolbar_box.toolbar.insert(separator, -1)
+        separator.show()
+
+        self._insert_clear_all_button(toolbar_box.toolbar)
+
+        separator = gtk.SeparatorToolItem()
         separator.props.draw = False
         separator.set_size_request(0, -1)
         separator.set_expand(True)
@@ -149,6 +156,14 @@ class PhysicsActivity(activity.Activity):
         toolbar.insert(self.stop_play, -1)
         self.stop_play.show()
 
+    def _insert_clear_all_button(self, toolbar):
+        self.clear_all = ToolButton('clear_all')
+        self.clear_all.set_tooltip(_("Erase All"))
+        self.clear_all.set_accelerator(_('<ctrl>a'))
+        self.clear_all.connect('clicked', self.clear_all_cb)
+        toolbar.insert(self.clear_all, -1)
+        self.clear_all.show()
+
     def _insert_create_tools(self, create_toolbar):
 
         def _insert_item(toolbar, item, pos=-1):
@@ -186,6 +201,21 @@ class PhysicsActivity(activity.Activity):
             self.stop_play.set_icon('media-playback-start')
             self.stop_play.set_tooltip(_("Start"))
 
+    def clear_all_cb(self, button):
+        clear_all_alert = ConfirmationAlert()
+        clear_all_alert.props.title=_('Are You Sure?')
+        clear_all_alert.props.msg = _('All you work will be discarded. This cannot be undone!')
+        clear_all_alert.connect('response', self.clear_all_alert_cb)
+        self.add_alert(clear_all_alert)
+
+    def clear_all_alert_cb(self, alert, response_id):
+        self.remove_alert(alert)
+        if response_id is gtk.RESPONSE_OK:
+            pygame.event.post(pygame.event.Event(pygame.USEREVENT,
+                                             action="clear_all"))
+        else:
+            pass
+
     def radioClicked(self, button):
         pygame.event.post(pygame.event.Event(pygame.USEREVENT,
                                              action=self.radioList[button]))
diff --git a/icons/clear_all.svg b/icons/clear_all.svg
new file mode 100644
index 0000000..4316a3a
--- /dev/null
+++ b/icons/clear_all.svg
@@ -0,0 +1,115 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="48px"
+   height="48px"
+   id="svg2985"
+   version="1.1"
+   inkscape:version="0.48.3.1 r9886"
+   sodipodi:docname="clear_all.svg">
+  <defs
+     id="defs2987" />
+  <sodipodi:namedview
+     id="base"
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1.0"
+     inkscape:pageopacity="0.0"
+     inkscape:pageshadow="2"
+     inkscape:zoom="7"
+     inkscape:cx="-1.1428571"
+     inkscape:cy="24"
+     inkscape:current-layer="layer1"
+     showgrid="true"
+     inkscape:grid-bbox="true"
+     inkscape:document-units="px"
+     gridtolerance="10"
+     inkscape:snap-global="false"
+     guidetolerance="10"
+     inkscape:window-width="1360"
+     inkscape:window-height="744"
+     inkscape:window-x="0"
+     inkscape:window-y="24"
+     inkscape:window-maximized="1" />
+  <metadata
+     id="metadata2990">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
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+  <g
+     id="layer1"
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer">
+    <rect
+       style="fill:none;fill-opacity:1;fill-rule:nonzero;stroke:#ffffff;stroke-width:3.899;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3821"
+       width="30.772253"
+       height="29.05797"
+       x="9.1853018"
+       y="14.328158" />
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+       style="fill:none;stroke:#ffffff;stroke-width:1.75924551;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3823"
+       width="38.669331"
+       height="1.6693259"
+       x="5.02248"
+       y="12.593908" />
+    <rect
+       style="fill:none;stroke:#ffffff;stroke-width:1.25541639;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3825"
+       width="1.2017266"
+       height="14.344584"
+       x="15.970565"
+       y="21.399136" />
+    <rect
+       style="fill:none;stroke:#ffffff;stroke-width:1.25541639;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3825-4"
+       width="1.2017266"
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+       x="24.11342"
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+    <rect
+       style="fill:none;stroke:#ffffff;stroke-width:1.25541639;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3825-1"
+       width="1.2017266"
+       height="14.344584"
+       x="31.970564"
+       y="21.256279" />
+    <rect
+       style="fill:none;stroke:#ffffff;stroke-width:3.599;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3908"
+       width="24.428572"
+       height="0.14285715"
+       x="12.571428"
+       y="6.5714283" />
+    <rect
+       style="fill:none;stroke:#ffffff;stroke-width:3.599;stroke-linejoin:round;stroke-miterlimit:4;stroke-opacity:1;stroke-dasharray:none"
+       id="rect3910"
+       width="0.14285715"
+       height="5.1428571"
+       x="12.571428"
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+</svg>
diff --git a/tools.py b/tools.py
index 358e1fe..62aba05 100644
--- a/tools.py
+++ b/tools.py
@@ -49,6 +49,14 @@ class Tool(object):
                     # Stop/start simulation
                     toggle = self.game.world.run_physics
                     self.game.world.run_physics = not toggle
+                elif event.action == "clear_all":
+                    if len(self.game.world.world.GetBodyList()) > 1:
+                        # Get bodies and destroy them too
+                        for body in self.game.world.world.GetBodyList():
+                            self.game.world.world.DestroyBody(body)
+
+                        # Add ground, because we destroyed it before
+                        self.game.world.add.ground()
                 elif event.action == "focus_in":
                     self.game.in_focus = True
                 elif event.action == "focus_out":