fix(scrollbar): show in small viewport (#515)

Co-authored-by: Pier CeccoPierangioliEugenio <ceccopierangiolieugenio@users.noreply.github.com>

libs/pyTermTk/TermTk/TTkAbstract/abstractscrollarea.py

@@ -106,7 +106,7 @@ class TTkAbstractScrollArea(TTkContainer):
     @pyTTkSlot()
     def _viewportChanged(self) -> None:
         ''' Internal slot to handle viewport changes and update scroll bar ranges and visibility '''
-        if not self._viewport or not self.isVisible(): return
+        if self._processing or not self._viewport or not self.isVisible(): return
         w,h = self.size()
         fw, fh = self._viewport.viewFullAreaSize()
         dw, dh = self._viewport.viewDisplayedSize()
@@ -126,10 +126,9 @@ class TTkAbstractScrollArea(TTkContainer):
         self._horizontalScrollBar.setValue(ox)
 
         if self._verticalScrollBarPolicy == TTkK.ScrollBarAsNeeded:
-            if h<=4 or w<=1 or vrange<=0:
+            if w<=self._verticalScrollBar.minimumWidth() or vrange<=0:
                 self._verticalScrollBar.hide()
-            elif dh>self._verticalScrollBar.minimumHeight()+1:
+            elif dh>=self._verticalScrollBar.minimumHeight():
-                # we need enough space to display the bar to avoid endless loop
                 self._verticalScrollBar.show()
         elif self._verticalScrollBarPolicy == TTkK.ScrollBarAlwaysOn:
             self._verticalScrollBar.show()
@@ -137,10 +136,9 @@ class TTkAbstractScrollArea(TTkContainer):
             self._verticalScrollBar.hide()
 
         if self._horizontalScrollBarPolicy == TTkK.ScrollBarAsNeeded:
-            if w<=4 or h<=1 or hrange<=0:
+            if h<=self._horizontalScrollBar.minimumHeight() or hrange<=0:
                 self._horizontalScrollBar.hide()
-            elif dw>self._horizontalScrollBar.minimumWidth()+1:
+            elif dw>=self._horizontalScrollBar.minimumWidth():
-                # we need enough space to display the bar to avoid endless loop
                 self._horizontalScrollBar.show()
         elif self._horizontalScrollBarPolicy == TTkK.ScrollBarAlwaysOn:
             self._horizontalScrollBar.show()

libs/pyTermTk/TermTk/TTkCore/canvas.py

@@ -390,16 +390,15 @@ class TTkCanvas():
                 self._set(y,x+i, TTkCfg.theme.hscroll[1], color)
             for i in range(f,t): # Slider
                 self._set(y,x+i, TTkCfg.theme.hscroll[2], color)
-            self._set(y,x, TTkCfg.theme.hscroll[0], color)        # Left Arrow
             self._set(y,x+size-1, TTkCfg.theme.hscroll[3], color) # Right Arrow
+            self._set(y,x, TTkCfg.theme.hscroll[0], color)        # Left Arrow
         else:
             for i in range(y+1,y+size-1): # V line
                 self._set(y+i,x, TTkCfg.theme.vscroll[1], color)
             for i in range(f,t): # Slider
                 self._set(y+i,x, TTkCfg.theme.vscroll[2], color)
-            self._set(y,x, TTkCfg.theme.vscroll[0], color)        # Up Arrow
             self._set(y+size-1,x, TTkCfg.theme.vscroll[3], color) # Down Arrow
-        pass
+            self._set(y,x, TTkCfg.theme.vscroll[0], color)        # Up Arrow
 
     def drawTabMenuButton(
             self, pos, size, text, slim=False,

libs/pyTermTk/TermTk/TTkWidgets/scrollbar.py

@@ -84,12 +84,7 @@ class TTkScrollBar(TTkWidget):
 
         TTkWidget.__init__(self, **kwargs)
 
-        if self._orientation == TTkK.VERTICAL:
+        self.setMinimumSize(1,1)
-            self.setMaximumWidth(1)
-            self.setMinimumSize(1,3)
-        else:
-            self.setMaximumHeight(1)
-            self.setMinimumSize(3,1)
         self.setFocusPolicy(TTkK.ClickFocus)
 
     def orientation(self):
@@ -181,7 +176,7 @@ class TTkScrollBar(TTkWidget):
 
         size2 = size-2
         asciiStep = self._screenScroller[1] - self._screenScroller[0]
-        asciiDrawingSize = size2 - asciiStep
+        asciiDrawingSize = max(1, size2 - asciiStep)
 
         a =  aa * (self._maximum - self._minimum) // asciiDrawingSize