view_crop.py

import cv2
import numpy as np
from key_codes import is_escape, is_enter

_F  = cv2.FONT_HERSHEY_PLAIN
_st = {}

def on_enter(frames):
    _st.clear()
    _st.update({
        "frames": list(frames),
        "drag":   {"active":False,"done":False,"x0":0,"y0":0,"x1":0,"y1":0},
        "status": "Drag to select crop region | Enter=apply | Esc=cancel",
    })

def render(canvas, ww, wh, events):
    frames = _st["frames"]
    drag   = _st["drag"]
    if not frames:
        return {"to":"scrub","frames":frames}

    _, ref = frames[0]
    fh, fw = ref.shape[:2]
    hint_h = 20
    img_h  = wh - hint_h
    scale  = min(ww/max(1,fw), img_h/max(1,fh))
    nw     = max(1,int(fw*scale)); nh = max(1,int(fh*scale))
    ox     = (ww-nw)//2; oy = (img_h-nh)//2

    for ev,x,y,flags in events["mouse"]:
        if ev==cv2.EVENT_LBUTTONDOWN:
            drag.update({"active":True,"done":False,"x0":x,"y0":y,"x1":x,"y1":y})
        elif ev==cv2.EVENT_MOUSEMOVE and drag["active"]:
            drag["x1"]=x; drag["y1"]=y
        elif ev==cv2.EVENT_LBUTTONUP and drag["active"]:
            drag["x1"]=x; drag["y1"]=y
            drag["active"]=False; drag["done"]=True

    # draw reference frame
    resized=cv2.resize(ref,(nw,nh),interpolation=cv2.INTER_NEAREST)
    canvas[oy:oy+nh,ox:ox+nw]=resized

    if drag["active"] or drag["done"]:
        x0,y0=drag["x0"],drag["y0"]; x1,y1=drag["x1"],drag["y1"]
        rx0,ry0=min(x0,x1),min(y0,y1); rx1,ry1=max(x0,x1),max(y0,y1)
        if rx1>rx0 and ry1>ry0:
            dim=canvas.copy()
            dim=(dim*0.35).astype(np.uint8)
            canvas[:]=dim
            canvas[oy:oy+nh,ox:ox+nw]=resized
            mask=np.zeros((wh,ww),dtype=np.uint8)
            mask[ry0:ry1,rx0:rx1]=255
            dark=(canvas.astype(np.float32)*0.35).astype(np.uint8)
            canvas[mask==0]=dark[mask==0]
            cv2.rectangle(canvas,(rx0,ry0),(rx1,ry1),(55,218,255),1)
            fw_s=max(1,int((rx1-rx0)/scale)); fh_s=max(1,int((ry1-ry0)/scale))
            cv2.putText(canvas,f"{fw_s}x{fh_s}",(rx0+4,max(ry0-5,12)),_F,0.9,(55,218,255),1)

    cv2.putText(canvas,_st["status"],(8,wh-4),_F,0.85,(68,88,108),1)

    k=events["key"]
    if is_escape(k):
        return {"to":"scrub","frames":frames}
    if is_enter(k) and drag["done"]:
        x0,y0=drag["x0"],drag["y0"]; x1,y1=drag["x1"],drag["y1"]
        rx0=max(0,int((min(x0,x1)-ox)/scale)); ry0=max(0,int((min(y0,y1)-oy)/scale))
        rx1=min(fw,int((max(x0,x1)-ox)/scale)); ry1=min(fh,int((max(y0,y1)-oy)/scale))
        if rx1>rx0 and ry1>ry0:
            new_frames=[(ts,f[ry0:ry1,rx0:rx1].copy()) for ts,f in frames]
            return {"to":"scrub","frames":new_frames}
        return {"to":"scrub","frames":frames}

    return None