Use alpha-0 colors to erase previous scribbles

smbct · Oct 26, 2020 · 1ffcedc · 1ffcedc
1 parent a180222
commit 1ffcedc
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Showing 4 changed files with 95 additions and 20 deletions.
diff --git a/pympress/scribble.py b/pympress/scribble.py
@@ -48,6 +48,8 @@ class Scribbler(builder.Builder):
     scribbling_mode = False
     #: `list` of scribbles to be drawn, as tuples of color :class:`~Gdk.RGBA`, width `int`, and a `list` of points.
     scribble_list = []
+    #: `list` of undone scribbles to possibly redo
+    scribble_redo_list = []
     #: Whether the current mouse movements are drawing strokes or should be ignored
     scribble_drawing = False
     #: :class:`~Gdk.RGBA` current color of the scribbling tool
@@ -66,6 +68,13 @@ class Scribbler(builder.Builder):
     #: :class:`~Gtk.AspectFrame` for the slide in the Presenter's highlight mode
     scribble_p_frame = None
 
+    #: :class:`~Gtk.Button` for removing the last drawn scribble
+    scribble_undo = None
+    #: :class:`~Gtk.Button` for drawing the last removed scribble
+    scribble_redo = None
+    #: :class:`~Gtk.Button` for removing all drawn scribbles
+    scribble_clear = None
+
     #: A :class:`~Gtk.OffscreenWindow` where we render the scribbling interface when it's not shown
     off_render = None
     #: :class:`~Gtk.Box` in the Presenter window, where we insert scribbling.
@@ -141,6 +150,8 @@ def nav_scribble(self, name, ctrl_pressed, command = None):
             return False
         elif command == 'undo_scribble':
             self.pop_scribble()
+        elif command == 'redo_scribble':
+            self.pop_scribble()
         elif command == 'cancel':
             self.disable_scribbling()
         else:
@@ -160,7 +171,9 @@ def track_scribble(self, widget, event):
         """
         if self.scribble_drawing:
             self.scribble_list[-1][2].append(self.get_slide_point(widget, event))
+            self.scribble_redo_list.clear()
 
+            self.adjust_buttons()
             self.redraw_current_slide()
             return True
         else:
@@ -201,19 +214,26 @@ def draw_scribble(self, widget, cairo_context):
         """
         ww, wh = widget.get_allocated_width(), widget.get_allocated_height()
 
+        cairo_context.push_group()
         cairo_context.set_line_cap(cairo.LINE_CAP_ROUND)
 
         for color, width, points in self.scribble_list:
             points = [(p[0] * ww, p[1] * wh) for p in points]
 
+            # alpha == 0 -> Eraser mode
+            cairo_context.set_operator(cairo.OPERATOR_OVER if color.alpha else cairo.OPERATOR_CLEAR)
             cairo_context.set_source_rgba(*color)
             cairo_context.set_line_width(width)
+
             cairo_context.move_to(*points[0])
 
             for p in points[1:]:
                 cairo_context.line_to(*p)
             cairo_context.stroke()
 
+        cairo_context.pop_group_to_source()
+        cairo_context.paint()
+
 
     def update_color(self, widget):
         """ Callback for the color chooser button, to set scribbling color.
@@ -237,20 +257,40 @@ def update_width(self, widget, event, value):
         self.config.set('scribble', 'width', str(self.scribble_width))
 
 
+    def adjust_buttons(self):
+        """ Properly enable and disable buttons based on scribblings lists.
+        """
+        self.scribble_undo.set_sensitive(bool(self.scribble_list))
+        self.scribble_clear.set_sensitive(bool(self.scribble_list))
+        self.scribble_redo.set_sensitive(bool(self.scribble_redo_list))
+
+
     def clear_scribble(self, *args):
         """ Callback for the scribble clear button, to remove all scribbles.
         """
-        del self.scribble_list[:]
+        self.scribble_list.clear()
 
         self.redraw_current_slide()
+        self.adjust_buttons()
 
 
     def pop_scribble(self, *args):
         """ Callback for the scribble undo button, to undo the last scribble.
         """
         if self.scribble_list:
-            self.scribble_list.pop()
+            self.scribble_redo_list.append(self.scribble_list.pop())
+
+        self.adjust_buttons()
+        self.redraw_current_slide()
+
+
+    def redo_scribble(self, *args):
+        """ Callback for the scribble undo button, to undo the last scribble.
+        """
+        if self.scribble_redo_list:
+            self.scribble_list.append(self.scribble_redo_list.pop())
 
+        self.adjust_buttons()
         self.redraw_current_slide()
 
 

diff --git a/pympress/share/defaults.conf b/pympress/share/defaults.conf
@@ -155,4 +155,5 @@ unzoom = u
 validate = Return KP_Enter
 cancel = Escape
 undo_scribble = <ctrl>z
+redo_scribble = <ctrl>r
 toggle_pointermode = l
diff --git a/pympress/share/xml/highlight.glade b/pympress/share/xml/highlight.glade
@@ -69,6 +69,7 @@
                 <property name="width_request">80</property>
                 <property name="height_request">80</property>
                 <property name="visible">True</property>
+                <property name="sensitive">False</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
                 <property name="always_show_image">True</property>
@@ -87,6 +88,7 @@
                 <property name="width_request">80</property>
                 <property name="height_request">80</property>
                 <property name="visible">True</property>
+                <property name="sensitive">False</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
                 <property name="always_show_image">True</property>
@@ -100,16 +102,17 @@
               </packing>
             </child>
             <child>
-              <object class="GtkColorButton" id="scribble_color">
+              <object class="GtkButton" id="scribble_redo">
+                <property name="label">gtk-redo</property>
                 <property name="width_request">80</property>
                 <property name="height_request">80</property>
                 <property name="visible">True</property>
+                <property name="sensitive">False</property>
                 <property name="can_focus">True</property>
                 <property name="receives_default">True</property>
                 <property name="use_stock">True</property>
                 <property name="always_show_image">True</property>
-                <property name="use_alpha">True</property>
-                <signal name="color-set" handler="update_color" swapped="no"/>
+                <signal name="clicked" handler="redo_scribble" swapped="no"/>
               </object>
               <packing>
                 <property name="expand">False</property>
@@ -118,21 +121,52 @@
               </packing>
             </child>
             <child>
-              <object class="GtkScale" id="scribble_width">
-                <property name="width_request">80</property>
-                <property name="height_request">160</property>
+              <object class="GtkBox">
                 <property name="visible">True</property>
-                <property name="can_focus">True</property>
+                <property name="can_focus">False</property>
+                <property name="valign">center</property>
                 <property name="orientation">vertical</property>
-                <property name="adjustment">scribble_width_adjust</property>
-                <property name="inverted">True</property>
-                <property name="digits">0</property>
-                <property name="draw_value">False</property>
-                <property name="value_pos">bottom</property>
-                <signal name="change-value" handler="update_width" swapped="no"/>
+                <child>
+                  <object class="GtkColorButton" id="scribble_color">
+                    <property name="width_request">80</property>
+                    <property name="height_request">80</property>
+                    <property name="visible">True</property>
+                    <property name="can_focus">True</property>
+                    <property name="receives_default">True</property>
+                    <property name="use_stock">True</property>
+                    <property name="always_show_image">True</property>
+                    <property name="use_alpha">True</property>
+                    <signal name="color-set" handler="update_color" swapped="no"/>
+                  </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">1</property>
+                  </packing>
+                </child>
+                <child>
+                  <object class="GtkScale" id="scribble_width">
+                    <property name="width_request">80</property>
+                    <property name="height_request">160</property>
+                    <property name="visible">True</property>
+                    <property name="can_focus">True</property>
+                    <property name="orientation">vertical</property>
+                    <property name="adjustment">scribble_width_adjust</property>
+                    <property name="inverted">True</property>
+                    <property name="digits">0</property>
+                    <property name="draw_value">False</property>
+                    <property name="value_pos">bottom</property>
+                    <signal name="change-value" handler="update_width" swapped="no"/>
+                  </object>
+                  <packing>
+                    <property name="expand">False</property>
+                    <property name="fill">True</property>
+                    <property name="position">2</property>
+                  </packing>
+                </child>
               </object>
               <packing>
-                <property name="expand">False</property>
+                <property name="expand">True</property>
                 <property name="fill">True</property>
                 <property name="position">4</property>
               </packing>
@@ -154,7 +188,7 @@
                 <property name="expand">False</property>
                 <property name="fill">True</property>
                 <property name="pack_type">end</property>
-                <property name="position">5</property>
+                <property name="position">7</property>
               </packing>
             </child>
             <child>
@@ -173,14 +207,14 @@
                 <property name="expand">False</property>
                 <property name="fill">True</property>
                 <property name="pack_type">end</property>
-                <property name="position">6</property>
+                <property name="position">8</property>
               </packing>
             </child>
           </object>
           <packing>
             <property name="expand">False</property>
             <property name="fill">True</property>
-            <property name="position">1</property>
+            <property name="position">2</property>
           </packing>
         </child>
       </object>

diff --git a/pympress/ui.py b/pympress/ui.py
@@ -987,7 +987,7 @@ def on_navigation(self, widget, event):
         elif command == 'toggle_pointermode':
             self.laser.toggle_pointermode()
         else:
-            if command and command not in {'cancel', 'validate', 'undo_scribble'}:
+            if command and command not in {'cancel', 'validate', 'undo_scribble', 'redo_scribble'}:
                 logger.error('ERROR: missing command "{}" for {}{}{}{}'
                              .format(command, 'ctrl + ' if ctrl_pressed else '', 'shift + ' if shift_pressed else '',
                                      'meta + ' if meta_pressed else '', name))