QCard DLL Lesson 7

See Lesson 1 for QCard DLL and WAV files needed for the demo code.

Checking for a Match

The game is not yet finished, but getting close. We must now check the two cards chosen by the user to see if they match. If there is a match, we must remove them from the table, otherwise we must return them to the face down position.

Two Cards per Turn

Because a memory card game allows the user to see only two card faces at a time, we'll create variables to keep track of the status of the current turn and the locations of the cards. We'll also keep track of the number of turns taken and the score. The score will reflect the number of pairs correctly identified by the player.

cardOne=0   'first card clicked by user
cardTwo=0   'second card clicked by user
cardOneX=0
cardTwoX=0
cardOneY=0
cardTwoY=0  'locations of cards clicked by user
turns=0     'record number of tries made by user
score=0     'record number of matches - 12 is max

This demo allows the user to click one card and then another. It checks to see if they match and removes them if they do. After two cards are revealed, there is a slight pause to allow the user
to see the result, then the 'turns' variable is incremented by 1.

When the user clicks on a card, we see if it's the first or second card in the turn. If it is the first card, we set the variables and return control to the user. If it's the second card we'll continue in the routine to check for a match.

   'check whether this is first or second card
    if cardOne=0 then
        cardOne=clickCard
        cardOneX=x
        cardOneY=y
        return  'leave first card up and return
    else
        cardTwo=clickCard
        cardTwoX=x
        cardTwoY=y
    end if

We'll turn off the mouse event handler and pause for two seconds to allow the player to see the cards he's selected.

    #1.g "when leftButtonUp" 'turn off mouse event while pausing
    call Pause 2000     '2 second pause to view cards
    #1.g "setfocus; when leftButtonUp [checkIndex]"

Removing Cards at the end of Turn

We first query the value and suit of the two cards, then remove them from the table. It is important to remove cards before dealing them again. If they are not placed on a blank table, the DLL records the image of the tabletop with the card displayed and uses that to replace the tabletop when the card is later removed. If we deal a card face up, for instance, then deal it in the same place face down, then remove it, the tabletop will appear to have a face up version of the card on it, even though no card is there.

    oneVal = GetCardValue(card(cardOne,1))
    twoVal = GetCardValue(card(cardTwo,1))
    'ace=1,deuce=2....jack=11,queen=12,king=13
    oneSuit = GetCardSuit(card(cardOne,1))
    twoSuit = GetCardSuit(card(cardTwo,1))
    'returns 1=Clubs, 2=Diamonds, 3=Hearts, 4=Spades.
 
    'Remove cards from table --
    'they will be redealt if they don't match.
    call RemoveCard hBox, card(cardOne,1)
    call RemoveCard hBox, card(cardTwo,1)
    turns=turns+1

Ending the Turn

If the cards match, the 'score' variable is incremented by one. When a card is turned up it is first removed from the table to restore the image of the tabletop, then dealt face up. After two cards are turned up, they are removed if they match one another. If they do not match, they are removed to restore the tabletop image, then redealt in the same location face down.

Variables were created to hold values for the first and second card clicked so that they can be evaluated for a match and redealt at the correct x,y location if they do not match. If the 'cardOne' variable is 0, then the card clicked is the first one to be drawn, otherwise it is the second one. These variables are reset to 0 after two cards are drawn and evaluated.

    'See if cards match each other in suit and value.
    'If they don't match, turn them face down and redeal them.
    if (oneVal<>twoVal) or (oneSuit<>twoSuit) then
        'set status of cards to 0, which is face down
        Call SetCardStatus card(cardOne,1), 0
        Call SetCardStatus card(cardTwo,1), 0
 
        'deal card face down
        Call DealCard hBox,card(cardOne,1),cardOneX,cardOneY
        Call DealCard hBox,card(cardTwo,1),cardTwoX,cardTwoY
    else
        'If cards match, increment score and don't
        'replace them on the table.
        'Set visible to 'off'
        card(cardOne,2)=0
        card(cardTwo,2)=0
        score=score+1
    end if
 
    cardOne=0   : cardTwo=0
    cardOneX=0  : cardTwoX=0
    cardOneY=0  : cardTwoY=0  'reset for next try
 
    msg$="Turns: ";turns;"        Score: ";score
    #1.g "place 10 420"
    #1.g "\" ; msg$; space$(400)
    RETURN

DEMO