WHOLE CHARACTER
画huà
to draw; to paint (绘图); picture; painting (图像); stroke (of a character) (笔画)
画 is to draw and the picture you draw: 画家 'painter', 画面 'the picture on screen', and every 笔画 'stroke' of a character.
ZDIC 字形分析 is 象形 — the source names no components. The modern shape splits as a 凵 frame plus a top line around the 田 piece; shown as a visual aid only.
PARTIAL OUTER FRAME: THE BOTTOM AND TWO SIDE WALLS
凵kǎn
an open container frame
The open-box bound radical form; where it appears as a frame piece, that page states the role; not a standalone word.
In 画: partial outer frame: the bottom and two side walls The open-box bound radical form; not a standalone page.
TOP LINE THAT CLOSES THE FRAME (ITS ENDS MEET THE SIDE WALLS)
一yī
one
Structural source piece in 百; not every visible stroke-like piece is taught as a separate word.
In 画: top line that closes the frame (its ends meet the side walls) Shown with its documented or clearly limited role.
THE ENCLOSED PIECE, WRITTEN LIKE THE FIELD GRAPH 田
田tián
field; farmland
Standalone meaning is kept separate from its role in other characters.
In 画: the enclosed piece, written like the field graph 田 No field meaning is claimed for it inside 画.