#!/usr/bin/env python3
# Copyright (C) 2017-2020 Antoine Martin <antoine@xpra.org>
# Xpra is released under the terms of the GNU GPL v2, or, at your option, any
# later version. See the file COPYING for details.

from xpra.platform import program_context
from xpra.platform.gui import force_focus
from xpra.gtk.window import add_close_accel
from xpra.gtk.pixbuf import get_icon_pixbuf
from xpra.os_util import gi_import

from cairo import OPERATOR_CLEAR, OPERATOR_SOURCE  # pylint: disable=no-name-in-module

Gtk = gi_import("Gtk")
Gdk = gi_import("Gdk")
GLib = gi_import("GLib")


class ColorGradientWindow(Gtk.Window):

    def __init__(self):
        super().__init__()
        self.set_position(Gtk.WindowPosition.CENTER)
        self.set_default_size(1024, 768)
        self.set_app_paintable(True)
        self.set_events(Gdk.EventMask.KEY_PRESS_MASK | Gdk.EventMask.BUTTON_PRESS_MASK)
        icon = get_icon_pixbuf("encoding.png")
        if icon:
            self.set_icon(icon)
        self.bpc = 16
        self.update_title()
        drawing_area = Gtk.DrawingArea()
        drawing_area.connect("draw", self.area_draw)
        self.add(drawing_area)
        self.connect("configure_event", self.configure_event)
        # self.connect('resize', changed)
        self.connect("destroy", Gtk.main_quit)
        self.connect("key_press_event", self.on_key_press)
        self.connect("button-press-event", self.on_button_press)

    def update_title(self):
        self.set_title("Color Bit Depth: %i" % self.bpc)

    def show_with_focus(self):
        force_focus()
        self.show_all()
        super().present()

    def configure_event(self, *_args):
        self.queue_draw()

    def on_button_press(self, _widget, event):
        if event.type != Gdk.EventType.BUTTON_PRESS:
            return
        if event.button == 1:
            self.bpc += 1
        else:
            self.bpc -= 1
        self.bpc = (self.bpc + 16) % 16
        self.update_title()
        self.queue_draw()
        return True

    def on_key_press(self, _widget, key_event):
        if key_event.string == "-":
            self.bpc = ((self.bpc - 2) % 16) + 1
        else:
            self.bpc = (self.bpc % 16) + 1
        self.update_title()
        self.queue_draw()
        return True

    def do_expose_event(self, *_args):
        self.area_draw()

    def area_draw(self, *_args):
        cr = self.get_window().cairo_create()
        cr.save()
        cr.set_operator(OPERATOR_CLEAR)
        alloc = self.get_allocated_size()[0]
        w, h = alloc.width, alloc.height
        cr.rectangle(0, 0, w, h)
        cr.fill()
        cr.restore()

        blocks = 12
        bh = h // blocks
        M = 2 ** 16 - 1
        mask = 0
        for _ in range(16 - self.bpc):
            mask = mask * 2 + 1
        mask = 0xffff ^ mask

        def normv(v) -> float:
            assert 0 <= v <= M
            iv = int(v) & mask
            return max(0, iv / M)

        def paint_block(R=M, G=M, B=M, label="") -> None:
            y = h * self.index // blocks
            self.index += 1
            cr.set_operator(OPERATOR_SOURCE)
            for i in range(w):
                v = i / w
                cr.save()
                r = normv(R * v)
                g = normv(G * v)
                b = normv(B * v)
                cr.set_source_rgb(r, g, b)
                cr.rectangle(i, y, 1, bh)
                cr.fill()
                cr.restore()
            if label:
                cr.set_font_size(32)
                cr.set_source_rgb(1, 1, 1)
                cr.move_to(w // 2 - 12, y + bh // 2 + 8)
                cr.show_text(label)

        # top block for title, all white:
        cr.save()
        cr.set_source_rgb(1, 1, 1)
        cr.rectangle(0, 0, w, bh)
        cr.fill()
        cr.restore()
        # title
        cr.set_font_size(32)
        cr.set_source_rgb(0, 0, 0)
        txt = "Clipped to %i bits per channel" % self.bpc
        cr.move_to(w // 2 - 8 * len(txt), bh // 2 + 4)
        cr.show_text(txt)
        txt = "(click or press a key to increase)"
        cr.move_to(w // 2 - 3 * len(txt), bh // 2 + 20)
        cr.set_font_size(12)
        cr.show_text(txt)

        self.index = 1
        paint_block(M, 0, 0, "R")
        paint_block(0, M - 1, 0, "G")
        paint_block(0, 0, M - 2, "B")
        paint_block(0, M - 3, M - 3, "C")
        paint_block(M - 4, 0, M - 4, "M")
        paint_block(M - 5, M - 5, 0, "Y")
        paint_block(0, 0, 0, "K")
        # Black Shade Blocks:
        paint_block(M, M, M)
        paint_block(M // 2, M // 2, M // 2)
        paint_block(M // 4, M // 4, M // 4)
        paint_block(M // 8, M // 8, M // 8)
        paint_block(M // 16, M // 16, M // 16)


def main():
    from xpra.platform.gui import init, set_default_icon
    with program_context("colors-gradient", "Colors Gradient"):
        set_default_icon("encoding.png")
        init()

        from xpra.gtk.signals import quit_on_signals
        quit_on_signals("colros gradient test window")
        w = ColorGradientWindow()
        add_close_accel(w, Gtk.main_quit)
        GLib.idle_add(w.show_with_focus)
        Gtk.main()


if __name__ == "__main__":
    main()
