"""
summary: paint on top of the navigation band

description:
  Using an "event filter", we will intercept paint events
  targeted at the navigation band widget, let it paint itself,
  and then add our own markers on top.

level: intermediate
"""

import random

from PySide6 import QtCore
from PySide6 import QtGui
from PySide6 import QtWidgets

import ida_kernwin
import ida_segment

import idc

class painter_t(QtCore.QObject):
    def __init__(self):
        QtCore.QObject.__init__(self)
        self.target = ida_kernwin.PluginForm.FormToPyQtWidget(ida_kernwin.open_navband_window(idc.here(), 1))
        self.target.installEventFilter(self)
        self.items = []
        self.painting = False

    def add_item(self, ea, radius, color):
        self.items.append((ea, radius, color))
        self.target.update()

    def add_random_item(self):
        R = random.random
        s = ida_segment.getnseg(int(ida_segment.get_segm_qty() * R()))
        ea = s.start_ea + int((s.end_ea - s.start_ea) * R())
        radius = 4 + int(R() * 8)
        color = QtGui.QColor(int(255 * R()), int(255 * R()), int(255 * R()))
        self.add_item(ea, radius, color)

    def eventFilter(self, receiver, event):
        if not self.painting and \
           self.target == receiver and \
           event.type() == QtCore.QEvent.Paint:

            # Send a paint event that we won't intercept
            self.painting = True
            try:
                pev = QtGui.QPaintEvent(self.target.rect())
                QtWidgets.QApplication.instance().sendEvent(self.target, pev)
            finally:
                self.painting = False

            # now we can paint our items
            for ea, radius, color in self.items:
                painter = QtGui.QPainter(receiver)
                painter.setRenderHints(QtGui.QPainter.Antialiasing)
                pxl, is_vertical = ida_kernwin.get_navband_pixel(ea)
                if pxl >= 0:
                    x = (self.target.width() // 2) if is_vertical else pxl
                    y = pxl if is_vertical else (self.target.height() // 2)
                    painter.setPen(color)
                    painter.setBrush(color)
                    painter.drawEllipse(QtCore.QPoint(x, y), radius, radius)
                painter.end()

            # ...and prevent the widget form painting itself again
            return True
        return QtCore.QObject.eventFilter(self, receiver, event)

painter = painter_t()

# Try the following:
# for i in range(100): painter.add_random_item()