libgui/GuiCanvasPanel.py:_updateScrollBars(): split from resize().

libgui/GuiCanvasPanel.py:_updateScrollBars(): reduce flickering induced by calling SetVirtualSize() when scrollbars are not required.
libgui/GuiCanvasPanel.py:{resize,update}(): updated.
libgui/GuiCanvasWxBackend.py:{reset,__init__}(): removes obsolete reset().

libgui/GuiCanvasPanel.py

@@ -16,6 +16,17 @@ class GuiCanvasPanel(wx.ScrolledWindow):
             patchDeltaCell = self.canvas.map[patch[1]][patch[0]]; patchDelta = [*patch[0:2], *patchDeltaCell];
             self.canvas.journal.pushCursor(patchDelta)
     # }}}
+    # {{{ _updateScrollBars(self)
+    def _updateScrollBars(self):
+        clientSize = self.GetClientSize()
+        if   (self.winSize[0] > clientSize[0])      \
+        or   (self.winSize[1] > clientSize[1]):
+            self.scrollFlag = True; super().SetVirtualSize(self.winSize);
+        elif self.scrollFlag                        \
+        and  ((self.winSize[0] <= clientSize[0])    \
+        or    (self.winSize[1] <= clientSize[1])):
+            self.scrollFlag = False; super().SetVirtualSize((0, 0));
+    # }}}
 
     # {{{ dispatchDeltaPatches(self, deltaPatches)
     def dispatchDeltaPatches(self, deltaPatches):
@@ -38,16 +49,13 @@ class GuiCanvasPanel(wx.ScrolledWindow):
         oldSize = [0, 0] if self.canvas.map == None else self.canvas.size
         deltaSize = [b - a for a, b in zip(oldSize, newSize)]
         if self.canvas.resize(newSize, commitUndo):
-            self.winSize = [a * b for a, b in zip(newSize, self.backend.cellSize)]
+            self.winSize = [a * b for a, b in zip(newSize, self.backend.cellSize)]; self._updateScrollBars();
-            self.SetMinSize(self.winSize)
+            self.SetMinSize(self.winSize); self.SetSize(wx.DefaultCoord, wx.DefaultCoord, *self.winSize);
-            self.SetSize(wx.DefaultCoord, wx.DefaultCoord, *self.winSize)
-            self.SetVirtualSize(self.winSize)
             curWindow = self
             while curWindow != None:
                 curWindow.Layout(); curWindow = curWindow.GetParent();
             self.backend.resize(newSize, self.backend.cellSize)
-            eventDc = self.backend.getDeviceContext(self, self.GetViewStart())
+            viewRect = self.GetViewStart(); eventDc = self.backend.getDeviceContext(self, viewRect);
-            viewRect = self.GetViewStart()
             if deltaSize[0] > 0:
                 for numRow in range(oldSize[1]):
                     for numNewCol in range(oldSize[0], newSize[0]):
@@ -56,7 +64,6 @@ class GuiCanvasPanel(wx.ScrolledWindow):
                 for numNewRow in range(oldSize[1], newSize[1]):
                     for numNewCol in range(newSize[0]):
                         self._drawPatch(eventDc, False, [numNewCol, numNewRow, 1, 1, 0, " "], viewRect)
-            del eventDc; wx.SafeYield();
             self.interface.update(size=newSize, undoLevel=self.canvas.journal.patchesUndoLevel)
     # }}}
     # {{{ update(self, newSize, commitUndo=True, newCanvas=None)
@@ -67,7 +74,6 @@ class GuiCanvasPanel(wx.ScrolledWindow):
         for numRow in range(newSize[1]):
             for numCol in range(newSize[0]):
                 self.backend.drawPatch(eventDc, [numCol, numRow, *self.canvas.map[numRow][numCol]], self.GetViewStart())
-        wx.SafeYield()
     # }}}
 
     # {{{ onPanelClose(self, event)
@@ -113,7 +119,8 @@ class GuiCanvasPanel(wx.ScrolledWindow):
         self.backend, self.interface = backend(defaultCanvasSize, defaultCellSize), interface(self, parentFrame)
         self.brushColours, self.brushPos, self.brushSize = [4, 1], [0, 0], [1, 1]
         self.canvas, self.canvasPos, self.defaultCanvasPos, self.defaultCanvasSize, self.defaultCellSize = canvas, defaultCanvasPos, defaultCanvasPos, defaultCanvasSize, defaultCellSize
-        self.dirty, self.parentFrame = False, parentFrame
+        self.dirty, self.parentFrame, self.scrollFlag = False, parentFrame, False
+        self.SetScrollRate(*defaultCellSize); self._updateScrollBars();
 
         self.Bind(wx.EVT_CLOSE, self.onPanelClose)
         self.Bind(wx.EVT_LEAVE_WINDOW, self.onPanelLeaveWindow)
@@ -121,6 +128,5 @@ class GuiCanvasPanel(wx.ScrolledWindow):
         for eventType in (wx.EVT_LEFT_DOWN, wx.EVT_MOTION, wx.EVT_RIGHT_DOWN):
             self.Bind(eventType, self.onPanelInput)
         self.Bind(wx.EVT_PAINT, self.onPanelPaint)
-        self.SetScrollRate(*defaultCellSize); self.SetVirtualSize(self.winSize);
 
 # vim:expandtab foldmethod=marker sw=4 ts=4 tw=120

libgui/GuiCanvasWxBackend.py

@@ -120,10 +120,6 @@ class GuiCanvasWxBackend():
                 canvasDc.SelectObject(wx.NullBitmap); viewDc.SelectObject(wx.NullBitmap);
                 eventDc = wx.BufferedPaintDC(panelWindow, viewBitmap)
     # }}}
-    # {{{ reset(self, canvasSize, cellSize):
-    def reset(self, canvasSize, cellSize):
-        self.resize(canvasSize, cellSize)
-    # }}}
     # {{{ resize(self, canvasSize, cellSize):
     def resize(self, canvasSize, cellSize):
         winSize = [a * b for a, b in zip(canvasSize, cellSize)]
@@ -158,6 +154,6 @@ class GuiCanvasWxBackend():
     def __init__(self, canvasSize, cellSize):
         self._brushes, self._font, self._lastBrush, self._lastPen, self._pens = None, None, None, None, None
         self.canvasBitmap, self.cellSize = None, None
-        self._initBrushesAndPens(); self.reset(canvasSize, cellSize);
+        self._initBrushesAndPens(); self.resize(canvasSize, cellSize);
 
 # vim:expandtab foldmethod=marker sw=4 ts=4 tw=120