canvas.py

# helper function for canvas.

__author__           = "Dilawar Singh"
__copyright__        = "Copyright 2019-, Dilawar Singh"
__maintainer__       = "Dilawar Singh"
__email__            = "dilawars@ncbs.res.in"

from collections import deque
from pathlib import Path
from PIL.ImageTk import PhotoImage
from PIL import Image

figs_, txt_ = [None]*2, ""

def canvasWH(canvas):
    W, H = canvas.winfo_width(), canvas.winfo_height()
    return W, H

def addToGlobalList(obj):
    global figs_
    figs_.append(obj)
    del figs_[0]

def getLastElemFromGlobalList():
    return figs_[-1]

def drawNumpyOnCanvas(canvas, frames, data=[]):
    global txt_
    W, H = canvasWH(canvas)
    canvas.delete("all")
    for i, img in enumerate(frames):
        photo = PhotoImage(image = Image.fromarray(img))
        canvas.create_image(W//2, H//2, image=photo)
        addToGlobalList(photo)
        if txt_:
            canvas.delete(txt_)
        if data:
            txt_ = canvas.create_text(0, 10, text=data[i].strip(), anchor="nw")
        canvas.update()

def showImageFileOnCanvas(canvas, imgpath : Path):
    img = Image.open(str(imgpath))
    W, H = canvasWH(canvas)
    w, h = img.size
    scale = min(W/w, H/h, 1)  # scale to fit canvas.
    if scale < 1 and W > 1 and H > 1:
        w *= scale
        h *= scale
        img = img.resize((int(w),int(h)), Image.ANTIALIAS)
    photo = PhotoImage(img)
    addToGlobalList(photo)    # else it won't display.
    canvas.delete("all")
    # Resize image to canvas size.
    canvas.create_image(0, 0, image=photo, anchor='nw')
    canvas.update()