pyTermTk/TermTk/TTkAbstract/abstractscrollarea.py

# MIT License
#
# Copyright (c) 2021 Eugenio Parodi <ceccopierangiolieugenio AT googlemail DOT com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

__all__ = ['TTkAbstractScrollArea']

from TermTk.TTkCore.constant import TTkK
# from TermTk.TTkCore.log import TTkLog
from TermTk.TTkCore.signal import pyTTkSlot
from TermTk.TTkWidgets.widget import TTkWidget
from TermTk.TTkWidgets.container import TTkContainer
from TermTk.TTkWidgets.scrollbar import TTkScrollBar
from TermTk.TTkLayouts.gridlayout import TTkGridLayout
from TermTk.TTkAbstract.abstractscrollview import TTkAbstractScrollViewInterface

class TTkAbstractScrollArea(TTkContainer):
    __slots__ = (
        '_processing', # this flag is required to avoid unnecessary loop on edge cases
        '_viewport',
        '_verticalScrollBar',   '_verticalScrollBarPolicy',
        '_horizontalScrollBar', '_horizontalScrollBarPolicy',)

    def __init__(self, *args, **kwargs):
        self._processing = False
        self._viewport = None
        # self.setLayout(TTkGridLayout())
        self._verticalScrollBar = TTkScrollBar(orientation=TTkK.VERTICAL, visible=False)
        self._horizontalScrollBar = TTkScrollBar(orientation=TTkK.HORIZONTAL, visible=False)
        self._verticalScrollBarPolicy   = kwargs.get("verticalScrollBarPolicy",  TTkK.ScrollBarAsNeeded)
        self._horizontalScrollBarPolicy = kwargs.get("horizontalScrollBarPolicy",TTkK.ScrollBarAsNeeded)
        super().__init__(*args, **kwargs)
        self.layout().addWidget(self._verticalScrollBar)
        self.layout().addWidget(self._horizontalScrollBar)

    def _resizeEvent(self):
        if self._processing: return
        self._processing = True
        w,h = self.size()
        vert = 1 if self._verticalScrollBar.isVisible() else 0
        hori = 1 if self._horizontalScrollBar.isVisible() else 0
        if vert:
            self._verticalScrollBar.setGeometry(w-1,0,1,h-hori)
        if hori:
            self._horizontalScrollBar.setGeometry(0,h-1,w-vert,1)
        if self._viewport:
            self._viewport.setGeometry(0,0,w-vert,h-hori)
        self._processing = False

    def resizeEvent(self, w: int, h: int):
        self._resizeEvent()

    @pyTTkSlot()
    def _viewportChanged(self):
        if not self.isVisible(): return
        w,h = self.size()
        fw, fh = self._viewport.viewFullAreaSize()
        dw, dh = self._viewport.viewDisplayedSize()
        ox, oy = self._viewport.getViewOffsets()
        if 0 in [fw,fh,dw,dh]:
            return
        hpage = dw
        vpage = dh
        hrange = fw - dw
        vrange = fh - dh
        # TTkLog.debug(f"f:{fw,fh=}, d:{dw,dh=}, o:{ox,oy=}")
        self._verticalScrollBar.setPageStep(vpage)
        self._verticalScrollBar.setRange(0, vrange)
        self._verticalScrollBar.setValue(oy)
        self._horizontalScrollBar.setPageStep(hpage)
        self._horizontalScrollBar.setRange(0, hrange)
        self._horizontalScrollBar.setValue(ox)

        if self._verticalScrollBarPolicy == TTkK.ScrollBarAsNeeded:
            if h<=4 or w<=1 or vrange<=0:
                self._verticalScrollBar.hide()
            elif dh>self._verticalScrollBar.minimumHeight()+1:
                # we need enough space to display the bar to avoid endless loop
                self._verticalScrollBar.show()
        elif self._verticalScrollBarPolicy == TTkK.ScrollBarAlwaysOn:
            self._verticalScrollBar.show()
        else:
            self._verticalScrollBar.hide()

        if self._horizontalScrollBarPolicy == TTkK.ScrollBarAsNeeded:
            if w<=4 or h<=1 or hrange<=0:
                self._horizontalScrollBar.hide()
            elif dw>self._horizontalScrollBar.minimumWidth()+1:
                # we need enough space to display the bar to avoid endless loop
                self._horizontalScrollBar.show()
        elif self._horizontalScrollBarPolicy == TTkK.ScrollBarAlwaysOn:
            self._horizontalScrollBar.show()
        else:
            self._horizontalScrollBar.hide()
        self._resizeEvent()

    @pyTTkSlot(int)
    def _vscrollMoved(self, val):
        ox, _ = self._viewport.getViewOffsets()
        self._viewport.viewMoveTo(ox, val)

    @pyTTkSlot(int)
    def _hscrollMoved(self, val):
        _, oy = self._viewport.getViewOffsets()
        self._viewport.viewMoveTo(val, oy)

    def setViewport(self, viewport):
        if not isinstance(viewport, TTkAbstractScrollViewInterface):
            raise TypeError("TTkAbstractScrollViewInterface is required in TTkAbstractScrollArea.setVewport(viewport)")
        if self._viewport:
            self._viewport.viewChanged.disconnect(self._viewportChanged)
            # TODO: Remove this check once
            #  unified  "addWidget" and "addItem" in the TTKGridLayout
            if isinstance(viewport, TTkWidget):
                self.layout().removeWidget(self._viewport)
            else:
                self.layout().removeItem(self._viewport)
        self._viewport = viewport
        self._viewport.viewChanged.connect(self._viewportChanged)
        self._verticalScrollBar.sliderMoved.connect(self._vscrollMoved)
        self._horizontalScrollBar.sliderMoved.connect(self._hscrollMoved)
        # TODO: Remove this check once
        #  unified  "addWidget" and "addItem" in the TTKGridLayout
        if isinstance(viewport, TTkWidget):
            self.layout().addWidget(viewport)
        else:
            self.layout().addItem(viewport)
        self._resizeEvent()

    def setVerticalScrollBarPolicy(self, policy):
        if policy != self._verticalScrollBarPolicy:
            self._verticalScrollBarPolicy = policy
            self._viewportChanged()

    def setHorizontalScrollBarPolicy(self, policy):
        if policy != self._horizontalScrollBarPolicy:
            self._horizontalScrollBarPolicy = policy
            self._viewportChanged()

    def viewport(self):
        return self._viewport

    def update(self, repaint=True, updateLayout=False, updateParent=False):
        if self._viewport:
            self._viewport.update(repaint, updateLayout, updateParent=False)
        return super().update(repaint, updateLayout, updateParent)