More reliable mouse cursor when cropping/scaling with zoom or hidpi

issue #214

docs/index.html

@@ -97,7 +97,7 @@ <h3>Recommended method</h3>
           <h3>Alternative methods for Ubuntu</h3>
           <p>
             <a href="https://launchpad.net/~cartes/+archive/ubuntu/drawing/">
-              PPA repository (version 0.4.13)
+              PPA repository (version 0.4.14)
             </a>
           </p>
           <p>

src/image.py

@@ -549,6 +549,19 @@ def get_corrected_coords(self, x1, x2, y1, y2, with_selection, with_zoom):
 		# the zoom is not 1.0
 		return x1, x2, y1, y2
 
+	def get_nineths_sizes(self, apply_to_selection):
+		"""Returns the sizes of the 'nineths' of the image used for example by
+		'scale' or 'crop' to decide the cursor they'll show."""
+		height = self.temp_pixbuf.get_height()
+		width = self.temp_pixbuf.get_width()
+		w_left, w_right, h_top, h_bottom = self.get_corrected_coords(0, width, \
+		                                    0, height, apply_to_selection, True)
+		w_left += 0.4 * width * self.zoom_level
+		w_right -= 0.4 * width * self.zoom_level
+		h_top += 0.4 * height * self.zoom_level
+		h_bottom -= 0.4 * height * self.zoom_level
+		return w_left, w_right, h_top, h_bottom
+
 	def on_scroll_on_area(self, area, event):
 		# TODO https://lazka.github.io/pgi-docs/index.html#Gdk-3.0/classes/EventScroll.html#Gdk.EventScroll
 		ctrl_is_used = (event.state & Gdk.ModifierType.CONTROL_MASK) == Gdk.ModifierType.CONTROL_MASK

src/tools/canvas_tools/abstract_canvas_tool.py

@@ -113,15 +113,8 @@ def get_handle_cursor_name(self, event_x, event_y):
 		"""Return the name of the accurate cursor for tools such as `scale` or
 		`crop`, with or without an active selection, depending on the size and
 		position of the resized/cropped area."""
-		height = self.get_image().temp_pixbuf.get_height()
-		width = self.get_image().temp_pixbuf.get_width()
-		w_left, w_right, h_top, h_bottom = self.get_image().get_corrected_coords(\
-		                     0, width, 0, height, self.apply_to_selection, True)
-		# Comment to help the debug:
-		h_top += 0.4 * height
-		h_bottom -= 0.4 * height
-		w_left += 0.4 * width
-		w_right -= 0.4 * width
+		w_left, w_right, h_top, h_bottom = self.get_image().get_nineths_sizes( \
+		                                                self.apply_to_selection)
 		# print("get_handle_cursor_name", w_left, w_right, h_top, h_bottom)
 
 		cursor_name = ''