zoom and pan support

2 files changed, 88 insertions, 20 deletions

diff --git a/lib/simulator.py b/lib/simulator.py
index 37747b10..610e4ee4 100644
--- a/lib/simulator.py
+++ b/lib/simulator.py
@@ -239,6 +239,8 @@ class DrawingPanel(wx.Panel):
 
         self.Bind(wx.EVT_PAINT, self.OnPaint)
         self.Bind(wx.EVT_SIZE, self.choose_zoom_and_pan)
+        self.Bind(wx.EVT_LEFT_DOWN, self.on_left_mouse_button_down)
+        self.Bind(wx.EVT_MOUSEWHEEL, self.on_mouse_wheel)
 
         # wait for layouts so that panel size is set
         wx.CallLater(50, self.load, self.stitch_plan)
@@ -420,6 +422,72 @@ class DrawingPanel(wx.Panel):
     def one_stitch_backward(self):
         self.set_current_stitch(self.current_stitch - 1)
 
+    def on_left_mouse_button_down(self, event):
+        self.CaptureMouse()
+        self.drag_start = event.GetPosition()
+        self.drag_original_pan = self.pan
+        self.Bind(wx.EVT_MOTION, self.on_drag)
+        self.Bind(wx.EVT_MOUSE_CAPTURE_LOST, self.on_drag_end)
+        self.Bind(wx.EVT_LEFT_UP, self.on_drag_end)
+
+    def on_drag(self, event):
+        if self.HasCapture() and event.Dragging():
+            delta = event.GetPosition()
+            offset = (delta[0] - self.drag_start[0], delta[1] - self.drag_start[1])
+            self.pan = (self.drag_original_pan[0] + offset[0], self.drag_original_pan[1] + offset[1])
+            self.Refresh()
+
+    def on_drag_end(self, event):
+        if self.HasCapture():
+            self.ReleaseMouse()
+
+        self.Unbind(wx.EVT_MOTION)
+        self.Unbind(wx.EVT_MOUSE_CAPTURE_LOST)
+        self.Unbind(wx.EVT_LEFT_UP)
+
+    def on_mouse_wheel(self, event):
+        if event.GetWheelRotation() > 0:
+            zoom_delta = 1.03
+        else:
+            zoom_delta = 0.97
+
+        # If we just change the zoom, the design will appear to move on the
+        # screen.  We have to adjust the pan to compensate.  We want to keep
+        # the part of the design under the mouse pointer in the same spot
+        # after we zoom, so that we appar to be zooming centered on the
+        # mouse pointer.
+
+        # This will create a matrix that takes a point in the design and
+        # converts it to screen coordinates:
+        matrix = wx.AffineMatrix2D()
+        matrix.Translate(*self.pan)
+        matrix.Scale(self.zoom, self.zoom)
+
+        # First, figure out where the mouse pointer is in the coordinate system
+        # of the design:
+        pos = event.GetPosition()
+        inverse_matrix = wx.AffineMatrix2D()
+        inverse_matrix.Set(*matrix.Get())
+        inverse_matrix.Invert()
+        pos = inverse_matrix.TransformPoint(*pos)
+
+        # Next, see how that point changes position on screen before and after
+        # we apply the zoom change:
+        x_old, y_old = matrix.TransformPoint(*pos)
+        matrix.Scale(zoom_delta, zoom_delta)
+        x_new, y_new = matrix.TransformPoint(*pos)
+        x_delta = x_new - x_old
+        y_delta = y_new - y_old
+
+        # Finally, compensate for that change in position:
+        self.pan = (self.pan[0] - x_delta, self.pan[1] - y_delta)
+
+
+        self.zoom *= zoom_delta
+
+
+        self.Refresh()
+
 
 class SimulatorPanel(wx.Panel):
     """"""
diff --git a/messages.po b/messages.po
index 86f93f36..405b3bec 100644
--- a/messages.po
+++ b/messages.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PROJECT VERSION\n"
 "Report-Msgid-Bugs-To: EMAIL@ADDRESS\n"
-"POT-Creation-Date: 2018-08-26 16:41-0400\n"
+"POT-Creation-Date: 2018-08-26 23:34-0400\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -674,79 +674,79 @@ msgstr ""
 msgid "Generate INX files"
 msgstr ""
 
-#: lib/simulator.py:540
+#: lib/simulator.py:608
 msgid "<<"
 msgstr ""
 
-#: lib/simulator.py:540
+#: lib/simulator.py:608
 msgid "Play reverse (arrow left)"
 msgstr ""
 
-#: lib/simulator.py:541
+#: lib/simulator.py:609
 msgid "-"
 msgstr ""
 
-#: lib/simulator.py:541
+#: lib/simulator.py:609
 msgid "Play one frame backward (+)"
 msgstr ""
 
-#: lib/simulator.py:542
+#: lib/simulator.py:610
 msgid "+"
 msgstr ""
 
-#: lib/simulator.py:542
+#: lib/simulator.py:610
 msgid "Play one frame forward (+)"
 msgstr ""
 
-#: lib/simulator.py:543
+#: lib/simulator.py:611
 msgid ">>"
 msgstr ""
 
-#: lib/simulator.py:543
+#: lib/simulator.py:611
 msgid "Play forward (arrow right)"
 msgstr ""
 
-#: lib/simulator.py:544
+#: lib/simulator.py:612
 msgid "^"
 msgstr ""
 
-#: lib/simulator.py:544
+#: lib/simulator.py:612
 msgid "Speed up (arrow up)"
 msgstr ""
 
-#: lib/simulator.py:545
+#: lib/simulator.py:613
 msgid "v"
 msgstr ""
 
-#: lib/simulator.py:545
+#: lib/simulator.py:613
 msgid "Slow down (arrow down)"
 msgstr ""
 
-#: lib/simulator.py:546
+#: lib/simulator.py:614
 msgid "Pause"
 msgstr ""
 
-#: lib/simulator.py:546
+#: lib/simulator.py:614
 msgid "Pause (P)"
 msgstr ""
 
-#: lib/simulator.py:547
+#: lib/simulator.py:615
 msgid "Restart"
 msgstr ""
 
-#: lib/simulator.py:547
+#: lib/simulator.py:615
 msgid "Restart (R)"
 msgstr ""
 
-#: lib/simulator.py:548
+#: lib/simulator.py:616
 msgid "Quit"
 msgstr ""
 
-#: lib/simulator.py:548
+#: lib/simulator.py:616
 msgid "Close (Q)"
 msgstr ""
 
-#: lib/simulator.py:726
+#: lib/simulator.py:794
 msgid "Stitch # "
 msgstr ""