import dearpygui.dearpygui as dpg
import cv2 as cv
import numpy as np

def flat_img(mat):
    return np.true_divide(np.asfarray(np.ravel(np.flip(mat,2)), dtype='f'), 255.0)

#full size image
_img = cv.imread('./test.jpg')


_imgdata = flat_img(_img)
#window scaled image
img = _img.copy()
imgdata = _imgdata.copy()

win_dimensions = [800,500]
tag_n = 0

#updating a texture with new dimension
def resize_window_img(tag, dimensions, _img, flat):
    img_dim = np.flip(_img.shape[:-1])
    scale = 1
    if (dimensions[0] >= dimensions[1]):
        scale = dimensions[0]/img_dim[0]
    else: scale = dimensions[1]/img_dim[1]
    img_dim[0]*=scale
    img_dim[1]*=scale

    global img
    global imgdata
    img = cv.resize(_img, img_dim)
    imgdata = flat_img(img)
    # delete window, add new texture+tag to registry, re-add window
    # dpg.delete_item(tag)
    with dpg.texture_registry(show=False):
        global tag_n
        tag_n +=1
        tex_tag = "texture_tag"+str(tag_n)
        dpg.configure_item(img.shape[1], img.shape[0], imgdata, tag=tex_tag, format=dpg.mvFormat_Float_rgb)
    with dpg.window(tag="imgwindow"):
        dpg.add_image(tex_tag)
        dpg.set_primary_window("imgwindow", True)

def handle_float(sender, data):
    dpg.set_value("texture_tag"+str(tag_n), np.multiply(imgdata, data))

def afteredit_cb(sender, data):
    f = dpg.get_value(data)
    # print(f"{f}, {data}")

def viewport_resize_cb(sender, data):
    win_dimensions[0] = data[2:][0]
    win_dimensions[1] = data[2:][1]

def resize_button_cb(sender, data):
    resize_window_img("imgwindow", win_dimensions, _img, _imgdata)

dpg.create_context()
dpg.create_viewport(title='img gui', width=win_dimensions[0], height=win_dimensions[1])

with dpg.item_handler_registry(tag="float handler") as handler:
    dpg.add_item_deactivated_after_edit_handler(callback=afteredit_cb)

with dpg.texture_registry(show=False):
    dpg.add_raw_texture(img.shape[1], img.shape[0], imgdata, tag="texture_tag"+str(tag_n), format=dpg.mvFormat_Float_rgb)

with dpg.window(tag="ctlnwindow", label="img", no_close=True):
    dpg.add_slider_float(label="float", tag="fbar", default_value=0., max_value=1, callback=handle_float)
    dpg.add_button(label="fit image to window", tag="resizebutton", callback=resize_button_cb)

with dpg.window(tag="imgwindow"):
    dpg.add_image("texture_tag"+str(tag_n))
    dpg.set_primary_window("imgwindow", True)

dpg.setup_dearpygui()
dpg.show_viewport()
dpg.bind_item_handler_registry("fbar", "float handler")
dpg.set_viewport_resize_callback(viewport_resize_cb)
dpg.start_dearpygui()
dpg.destroy_context()