Skip to content
Back to top

# Source code for gaphas.view.gtkview

    """This module contains everything to display a model on a screen."""

    from __future__ import annotations

    import asyncio
    from math import isclose
    from collections.abc import Collection, Iterable

    import cairo
    from gi.repository import Graphene, GObject, Gtk

    from gaphas.geometry import Rect, Rectangle
    from gaphas.item import Item
    from gaphas.matrix import Matrix
    from gaphas.model import Model
    from gaphas.painter import DefaultPainter, ItemPainter
    from gaphas.painter.painter import ItemPainterType, Painter
    from gaphas.quadtree import Quadtree, QuadtreeBucket
    from gaphas.selection import Selection
    from gaphas.view.scrolling import Scrolling

    # Handy debug flag for drawing bounding boxes around the items.
    DEBUG_DRAW_BOUNDING_BOX = False
    DEBUG_DRAW_QUADTREE = False

    # The tolerance for Cairo. Bigger values increase speed and reduce accuracy
    # (default: 0.1)
    PAINT_TOLERANCE = 0.8
    BOUNDING_BOX_TOLERANCE = 1.0

    class GtkView(Gtk.DrawingArea, Gtk.Scrollable):
        """GTK widget for rendering a gaphas.model.Model to a screen.  The view
        uses Tools to handle events and Painters to draw. Both are configurable.

        The widget already contains adjustment objects (`hadjustment`,
        `vadjustment`) to be used for scrollbars.

        This view registers itself on the model, so it will receive
        update events.
        """

        # Just defined a name to make GTK register this class.
        __gtype_name__ = "GaphasView"

        # properties required by Gtk.Scrollable
        __gproperties__ = {
            "hscroll-policy": (
                Gtk.ScrollablePolicy,
                "hscroll-policy",
                "hscroll-policy",
                Gtk.ScrollablePolicy.MINIMUM,
                GObject.ParamFlags.READWRITE,
            ),
            "hadjustment": (
                Gtk.Adjustment,
                "hadjustment",
                "hadjustment",
                GObject.ParamFlags.READWRITE,
            ),
            "vscroll-policy": (
                Gtk.ScrollablePolicy,
                "vscroll-policy",
                "vscroll-policy",
                Gtk.ScrollablePolicy.MINIMUM,
                GObject.ParamFlags.READWRITE,
            ),
            "vadjustment": (
                Gtk.Adjustment,
                "vadjustment",
                "vadjustment",
                GObject.ParamFlags.READWRITE,
            ),
        }

        def __init__(self, model: Model | None = None, selection: Selection | None = None):
            """Create a new view.

            Args:
                model (Model): optional model to be set on construction time.
                selection (Selection): optional selection object, in case the default
                    selection object (hover/select/focus) is not enough.
            """
            super().__init__()

            self._dirty_items: set[Item] = set()

            self._back_buffer: cairo.Surface | None = None
            self._back_buffer_needs_resizing = True

            self._update_task: asyncio.Task | None = None

            self._controllers: set[Gtk.EventController] = set()

            self.set_can_focus(True)
            self.set_focusable(True)
            self.connect_after("resize", GtkView.on_resize)

            def alignment_updated(x: float | None, y: float | None) -> None:
                if self._model:
                    if x is not None:
                        self.matrix.set(x0=x)
                    if y is not None:
                        self.matrix.set(y0=y)

            self._scrolling = Scrolling(alignment_updated)

            self._selection = selection or Selection()

            self._matrix = Matrix()
            self._painter: Painter = DefaultPainter(self)
            self._bounding_box_painter: ItemPainterType = ItemPainter(self._selection)

            # quadtree bounds are in canvas coordinates (not view!)
            self._qtree: Quadtree[Item, None] = Quadtree()

            self._model: Model | None = None
            if model:
                self.model = model

            self._selection.add_handler(self.on_selection_update)
            self._matrix.add_handler(self.on_matrix_update)

        def do_get_property(self, prop: str) -> object:
            return self._scrolling.get_property(prop)

        def do_set_property(self, prop: str, value: object) -> None:
            self._scrolling.set_property(prop, value)

        @property
        def matrix(self) -> Matrix:
            """Model root to view transformation matrix."""
            return self._matrix

        def get_matrix_i2v(self, item: Item) -> Matrix:
            """Get Item to View matrix for ``item``."""
            return item.matrix_i2c.multiply(self._matrix)

        def get_matrix_v2i(self, item: Item) -> Matrix:
            """Get View to Item matrix for ``item``."""
            m = self.get_matrix_i2v(item)
            m.invert()
            return m

        @property
        def model(self) -> Model | None:
            """The model."""
            return self._model

        @model.setter
        def model(self, model: Model | None) -> None:
            if self._model:
                self._model.unregister_view(self)
                self._selection.clear()
                self._dirty_items.clear()
                self._qtree.clear()
                if self._update_task:
                    self._update_task.cancel()

            self._model = model

            if self._model:
                self._model.register_view(self)
                self.request_update(self._model.get_all_items())

        @property
        def painter(self) -> Painter:
            """Painter for drawing the view."""
            return self._painter

        @painter.setter
        def painter(self, painter: Painter) -> None:
            self._painter = painter

        @property
        def bounding_box_painter(self) -> ItemPainterType:
            """Special painter for calculating item bounding boxes."""
            return self._bounding_box_painter

        @bounding_box_painter.setter
        def bounding_box_painter(self, painter: ItemPainterType) -> None:
            self._bounding_box_painter = painter

        @property
        def selection(self) -> Selection:
            """Selected, focused and hovered items."""
            return self._selection

        @selection.setter
        def selection(self, selection: Selection) -> None:
            """Selected, focused and hovered items."""
            self._selection = selection
            if self._model:
                self.request_update(self._model.get_all_items())

        @property
        def bounding_box(self) -> Rectangle:
            """The bounding box of the complete view, relative to the view port."""
            return Rectangle(*transform_rectangle(self._matrix, self._qtree.soft_bounds))

        @property
        def hadjustment(self) -> Gtk.Adjustment:
            """Gtk adjustment object for use with a scrollbar."""
            return self._scrolling.hadjustment

        @property
        def vadjustment(self) -> Gtk.Adjustment:
            """Gtk adjustment object for use with a scrollbar."""
            return self._scrolling.vadjustment

        def clamp_item(self, item):
            """Update adjustments so the item is located inside the view port."""
            x, y, w, h = self.get_item_bounding_box(item).tuple()
            self.hadjustment.clamp_page(x, x + w)
            self.vadjustment.clamp_page(y, y + h)

        def add_controller(self, *controllers: Gtk.EventController) -> None:
            """Add a controller."""
            for controller in controllers:
                super().add_controller(controller)
            self._controllers.update(controllers)

        def remove_controller(self, controller: Gtk.EventController) -> bool:
            """Remove a controller."""
            super().remove_controller(controller)
            if controller in self._controllers:
                self._controllers.discard(controller)
                return True
            return False

        def remove_all_controllers(self) -> None:
            """Remove all registered controllers."""
            for controller in set(self._controllers):
                self.remove_controller(controller)

        def zoom(self, factor: float) -> None:
            """Zoom in/out by factor ``factor``."""
            assert self._model
            self.matrix.scale(factor, factor)
            self.request_update(self._model.get_all_items())

        def get_items_in_rectangle(
            self, rect: Rect, contain: bool = False
        ) -> Iterable[Item]:
            """Return the items in the rectangle 'rect' (in view coordinates).

            Items are automatically sorted in model's processing order.
            """
            assert self._model
            crect = transform_rectangle(self._matrix.inverse(), rect)
            items = (
                self._qtree.find_inside(crect)
                if contain
                else self._qtree.find_intersect(crect)
            )
            return self._model.sort(items)

        def get_item_bounding_box(self, item: Item) -> Rectangle:
            """Get the bounding box for the item, in view coordinates."""
            return Rectangle(
                *transform_rectangle(self._matrix, self._qtree.get_bounds(item))
            )

        def request_update(
            self,
            items: Iterable[Item],
            removed_items: Iterable[Item] = (),
        ) -> None:
            """Request update for items."""
            if items:
                self._dirty_items.update(items)

            if removed_items:
                selection = self._selection
                self._dirty_items.difference_update(removed_items)

                for item in removed_items:
                    self._qtree.remove(item)
                    selection.unselect_item(item)

            if items or removed_items:
                self.update()

        def update(self) -> asyncio.Task:
            """Update view status according to the items updated in the model."""

            async def _update():
                model = self._model
                if not model:
                    return

                dirty_items = self.all_dirty_items()
                model.update_now(dirty_items)
                dirty_items |= self.all_dirty_items()

                old_bb = self._qtree.soft_bounds
                self.update_bounding_box(dirty_items)
                if self._qtree.soft_bounds != old_bb:
                    self.update_scrolling()
                self.update_back_buffer()

            def clear_task(task):
                self._update_task = None

            if not self._update_task:
                self._update_task = asyncio.create_task(_update())
                self._update_task.add_done_callback(clear_task)
            return self._update_task

        def all_dirty_items(self) -> set[Item]:
            """Return all dirty items, clearing the marked items."""
            model = self._model
            if not model:
                return set()

            def iterate_items(items: Iterable[Item]) -> Iterable[Item]:
                assert model
                for item in items:
                    parent = model.get_parent(item)
                    if parent is not None and parent in items:
                        # item's matrix will be updated thanks to parent's matrix update
                        continue

                    yield item

                    yield from iterate_items(set(model.get_children(item)))

            dirty_items = set(iterate_items(self._dirty_items))
            self._dirty_items.clear()
            return dirty_items

        def update_bounding_box(self, items: Collection[Item]) -> None:
            """Update the bounding boxes of the model items for this view, in model
            coordinates."""
            painter = self._bounding_box_painter
            qtree = self._qtree
            for item in items:
                surface = cairo.RecordingSurface(cairo.Content.COLOR_ALPHA, None)
                cr = cairo.Context(surface)
                cr.set_tolerance(BOUNDING_BOX_TOLERANCE)

                painter.paint_item(item, cr)
                x, y, w, h = surface.ink_extents()

                qtree.add(item=item, bounds=(x, y, w, h))

        def update_scrolling(self) -> None:
            matrix = Matrix(*self._matrix)  # type: ignore[misc]
            # When zooming the bounding box to view size, disregard current scroll offsets
            matrix.set(x0=0, y0=0)
            bounds = Rectangle(*transform_rectangle(matrix, self._qtree.soft_bounds))

            self._scrolling.update_adjustments(self.get_width(), self.get_height(), bounds)

        def _debug_draw_bounding_box(self, cr, width, height):
            for item in self.get_items_in_rectangle((0, 0, width, height)):
                try:
                    b = self.get_item_bounding_box(item)
                except KeyError:
                    pass  # No bounding box right now..
                else:
                    cr.save()
                    cr.identity_matrix()
                    cr.set_source_rgb(0.8, 0, 0)
                    cr.set_line_width(1.0)
                    cr.rectangle(*b)
                    cr.stroke()
                    cr.restore()

        def _debug_draw_quadtree(self, cr):
            def draw_qtree_bucket(bucket: QuadtreeBucket) -> None:
                cr.rectangle(*bucket.bounds)
                cr.stroke()
                for b in bucket._buckets:
                    draw_qtree_bucket(b)

            cr.set_source_rgb(0, 0, 0.8)
            cr.set_line_width(1.0)
            draw_qtree_bucket(self._qtree._bucket)

        def do_realize(self) -> None:
            Gtk.DrawingArea.do_realize(self)

            if self._model:
                # Ensure updates are propagated
                self._model.register_view(self)
                self.request_update(self._model.get_all_items())

        def do_unrealize(self) -> None:
            if self._model:
                self._model.unregister_view(self)

            Gtk.DrawingArea.do_unrealize(self)

        def on_selection_update(self, item: Item | None) -> None:
            if self._model:
                if item is None:
                    self.request_update(self._model.get_all_items())
                elif item in self._model.get_all_items():
                    self.request_update((item,))

        def on_matrix_update(self, matrix, old_matrix_values):
            # Test if scale or rotation changed
            if not all(map(isclose, matrix, old_matrix_values[:4])):
                self.update_scrolling()
            self._scrolling.update_position(matrix[4], matrix[5])
            self.update_back_buffer()

        def on_resize(self, _width: int, _height: int) -> None:
            self.update_scrolling()
            if self.get_realized():
                self._back_buffer_needs_resizing = True
                self.update_back_buffer()
            else:
                self._back_buffer = None

        def update_back_buffer(self) -> None:
            self.queue_draw()

        def do_snapshot(self, snapshot):
            if self.model:
                width = self.get_width()
                height = self.get_height()
                r = Graphene.Rect()
                r.init(0, 0, width, height)
                cr = snapshot.append_cairo(r)
                cr.set_matrix(self.matrix.to_cairo())
                cr.save()
                cr.set_tolerance(PAINT_TOLERANCE)
                items = self.get_items_in_rectangle((0, 0, width, height))
                self.painter.paint(list(items), cr)
                cr.restore()

                if DEBUG_DRAW_BOUNDING_BOX:
                    self._debug_draw_bounding_box(cr, width, height)

                if DEBUG_DRAW_QUADTREE:
                    self._debug_draw_quadtree(cr)

    def transform_rectangle(matrix: Matrix, rect: Rect) -> Rect:
        x, y, w, h = rect

        return matrix.transform_point(x, y) + matrix.transform_distance(w, h)