Optimize ScatterPlot drag and drop

Author: martinRenou

examples/plotting.ipynb

@@ -36,6 +36,8 @@
     "\n",
     "        self.color = color\n",
     "        self.scheme = scheme\n",
+    "        \n",
+    "        self.background_color = '#f7f7f7'\n",
     "\n",
     "        self.init_plot(x, y)\n",
     "\n",
@@ -75,7 +77,7 @@
     "        background = self[0]\n",
     "\n",
     "        # Draw background\n",
-    "        background.fill_style = '#f7f7f7'\n",
+    "        background.fill_style = self.background_color\n",
     "        background.global_alpha = 0.3\n",
     "        background.fill_rect(drawarea_min_x, drawarea_min_y, drawarea_max_x, drawarea_max_y)\n",
     "        background.global_alpha = 1\n",
@@ -130,10 +132,13 @@
     "\n",
     "        self.n_marks = min(x.shape[0], y.shape[0], size.shape[0], color.shape[0])\n",
     "\n",
+    "        # Index of the dragged point\n",
+    "        self.i_mark = -1\n",
+    "\n",
     "        self[2].on_mouse_down(self.mouse_down_handler)\n",
     "        self[2].on_mouse_move(self.mouse_move_handler)\n",
     "        self[2].on_mouse_up(self.mouse_up_handler)\n",
-    "        \n",
+    "\n",
     "        self.draw()\n",
     "\n",
     "    def draw(self):\n",
@@ -161,6 +166,8 @@
     "            plot_layer.restore()\n",
     "\n",
     "    def mouse_down_handler(self, pixel_x, pixel_y):\n",
+    "        plot_layer = self[1]\n",
+    "\n",
     "        for idx in range(self.n_marks):\n",
     "            mark_x = self.x[idx]\n",
     "            mark_y = self.y[idx]\n",
@@ -170,18 +177,40 @@
     "                pixel_y > self.scale_y(mark_y) - mark_size and pixel_y < self.scale_y(mark_y) + mark_size):\n",
     "                self.i_mark = idx\n",
     "                self.dragging = True\n",
+    "\n",
+    "                with hold_canvas(plot_layer):\n",
+    "                    plot_layer.fill_style = self.background_color\n",
+    "                    plot_layer.stroke_style = self.colormap(self.color[self.i_mark])\n",
+    "\n",
+    "                    plot_layer.fill_arc(self.scale_x(mark_x), self.scale_y(mark_y), mark_size, 0, 2 * pi)\n",
+    "                    plot_layer.stroke_arc(self.scale_x(mark_x), self.scale_y(mark_y), mark_size, 0, 2 * pi)\n",
     "                break\n",
-    "                \n",
+    "\n",
     "    def mouse_move_handler(self, pixel_x, pixel_y):\n",
-    "        if self.dragging:\n",
+    "        if self.dragging and self.i_mark != -1:\n",
+    "            interaction_layer = self[2]\n",
+    "\n",
     "            unscaled_x = self.unscale_x(pixel_x)\n",
     "            unscaled_y = self.unscale_y(pixel_y)\n",
-    "            self.x[self.i_mark] = unscaled_x\n",
-    "            self.y[self.i_mark] = unscaled_y\n",
-    "            self.draw()\n",
-    "                    \n",
+    "\n",
+    "            with hold_canvas(interaction_layer):\n",
+    "                interaction_layer.clear()\n",
+    "                interaction_layer.fill_style = self.colormap(self.color[self.i_mark])\n",
+    "                interaction_layer.stroke_style = self.stroke_color\n",
+    "\n",
+    "                self.x[self.i_mark] = unscaled_x\n",
+    "                self.y[self.i_mark] = unscaled_y\n",
+    "\n",
+    "                interaction_layer.fill_arc(pixel_x, pixel_y, self.sizes[self.i_mark], 0, 2 * pi)\n",
+    "                interaction_layer.stroke_arc(pixel_x, pixel_y, self.sizes[self.i_mark], 0, 2 * pi)\n",
+    "\n",
     "    def mouse_up_handler(self, pixel_x, pixel_y):\n",
-    "        self.dragging = False"
+    "        self.dragging = False\n",
+    "\n",
+    "        self.draw()\n",
+    "\n",
+    "        interaction_layer = self[2]\n",
+    "        interaction_layer.clear()"
    ]
   },
   {