From 4c5bfc86d540c22606e9d7fd5055b306cbff5eae Mon Sep 17 00:00:00 2001
From: kushalkolar <kushalkolar@gmail.com>
Date: Tue, 17 Sep 2024 02:30:04 -0400
Subject: [PATCH] start crosshair tool

---
 fastplotlib/tools/_crosshair.py | 97 +++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 fastplotlib/tools/_crosshair.py

diff --git a/fastplotlib/tools/_crosshair.py b/fastplotlib/tools/_crosshair.py
new file mode 100644
index 000000000..ea43eec64
--- /dev/null
+++ b/fastplotlib/tools/_crosshair.py
@@ -0,0 +1,97 @@
+from functools import partial
+
+import numpy as np
+
+import pygfx
+
+
+from ..graphics._features import VertexPositions, UniformColor, Thickness
+from ..layouts._subplot import Subplot
+
+
+class CrosshairTool:
+    def __init__(
+            self,
+            subplots: Subplot | list[Subplot],
+            thickness: float = 1.0,
+            style: str = "+",
+            color: str | tuple | np.ndarray = "w",
+            alpha: float = 0.5,
+    ):
+        self._subplots = list()
+        self._subplot_callbacks = dict()
+
+        self._world_objects: list[pygfx.Line] = list()
+
+        self._thickness = thickness
+        self._style = style
+        self._color = color
+        self._alpha = alpha
+
+    @property
+    def subplots(self) -> tuple[Subplot, ...]:
+        return tuple(self._subplots)
+
+    @property
+    def thickness(self) -> float:
+        return self._thickness
+
+    @property
+    def style(self) -> str:
+        return self._style
+
+    def add_subplot(self, subplot: Subplot):
+        if subplot.camera.fov > 0:
+            # TODO: worry about perspective projections later
+            raise TypeError("Crosshair currently only supported for Orthographic projections")
+
+        if subplot in self.subplots:
+            raise ValueError("subplot already registered")
+
+        if len(self._world_objects) < 1:
+            # get center of subplot to initialize crosshair lines
+
+            self._hline = pygfx.Line(
+                geometry=pygfx.Geometry
+            )
+
+        callback = partial(self._pointer_moved, subplot)
+        self._subplot_callbacks[subplot] = callback
+        subplot.renderer.add_event_handler(callback, "pointer_move")
+
+    def remove_subplot(self, subplot: Subplot):
+        if subplot not in self.subplots:
+            raise ValueError
+
+        callback = self._subplot_callbacks.pop(subplot)
+        subplot.renderer.remove_event_handler(callback)
+
+        self._subplots.remove(subplot)
+
+    def set_intersection(self, pos: tuple[float, float, float]):
+        """set intersection in world space"""
+        pass
+
+    def _pointer_moved(self, subplot: Subplot, ev: pygfx.PointerEvent):
+        world_pos = subplot.map_screen_to_world(ev)
+
+        # get bbox of subplot, code taken from axes
+        # TODO: perhaps this should be moved to utils or something?
+        xpos, ypos, width, height = subplot.get_rect()
+        # orthographic projection, get ranges using inverse
+
+        # get range of screen space by getting the corners
+        xmin, xmax = xpos, xpos + width
+        ymin, ymax = ypos + height, ypos
+
+        min_vals = subplot.map_screen_to_world((xmin, ymin))
+        max_vals = subplot.map_screen_to_world((xmax, ymax))
+
+        if min_vals is None or max_vals is None:
+            return
+
+        world_xmin, world_ymin, _ = min_vals
+        world_xmax, world_ymax, _ = max_vals
+
+        # world range to set endpoints of crosshair
+