Workshop › Klondike Solitaire › Step 31 of 40

Drop it where you want

What we are doing

On release, a card that did not move is still a tap. A dragged card goes to the pile under the middle of the held card, not under the pointer: that feels right however you grabbed it. If tryMove refuses, the card simply appears back in its pile, because it never left it.

```js
const { from, index, moved } = drag
if (!moved) autoMove(from, index)
else {
  // Drop on the pile under the middle of the held card.
  const target = hit(drag.x - drag.dx + CW / 2, drag.y - drag.dy + CH / 2)
  if (target) tryMove(from, index, target.key)
}
```

What it means

• moved is taken out of drag too.
• Not moved: a tap, autoMove.
• Moved: the held card's corner is (x - dx, y - dy); adding half a card gives its middle. hit finds the pile there, and tryMove tries it.

Your turn

In the pointerup listener, replace the two lines const { from, index } = drag and autoMove(from, index) with the new lines.

Skills: Keyboard and mouse input, Collision detection

← Draw the held cards at the pointer Drop a king into an empty column →

All steps

1. The green table
2. Draw one card
3. The face of a card
4. Red and black
5. A deck of 52
6. Shuffle
7. Piles in one object
8. Deal the seven columns
9. A place for every pile
10. Put the piles on the table
11. Fan out the columns
12. Outlines for empty places
13. Turn over a card
14. Space turns a card
15. Go through the stock again
16. What is under the pointer?
17. Hitting a card in a column
18. Tap the stock
19. Rule 1: building a column
20. Rule 2: building a foundation
21. Move cards by the rules
22. Turn over the uncovered card
23. Find where a card goes
24. Pick up a card
25. Tap to move
26. A move counter
27. Count the moves
28. Where did you grab it?
29. Follow the pointer
30. Draw the held cards at the pointer
31. Drop it where you want
32. Drop a king into an empty column
33. A clock
34. Winning
35. You won!
36. A new game
37. The best time
38. Snapshots of the table
39. Undo
40. Build it yourself: finish by itself