Creating the Color Drop Casual Puzzle Game - The Essential Guide to Flash Games - page 357

Our big while loop lasts as long as there are Block objects in the blocksToCheck array. Since we
seeded it with blockToMatch (the Block the user clicked), we drop into the loop and get started with
it. The first thing we do in the loop is pop the last Block out of the blocksToCheck array and put it into
tempBlock . We then check the color value of tempBlock ( tempBlock.blockColor ) to see if it matches
the color of the Block the user clicked ( colorToMatch ).
Since we got the value for colorToMatch from the first Block , which also happens to be
tempBlock , this comparison will be true . We then push tempBlock into the blocksMatched array
(because it did indeed match) and call tempBlock.makeBlockClicked , which will light up the Block
by adding the glow filter we created in the Block class. This test is only guaranteed to evaluate
true the first time through the while loop. All subsequent iterations will be actual tests on Block
objects other than the Block the user clicked.
while(blocksToCheck.length > 0) {
tempBlock = blocksToCheck.pop();
if (tempBlock.blockColor == colorToMatch) {
blocksMatched.push(tempBlock);
tempBlock.makeBlockClicked();
}
Now we are going to test all the Block objects that surround tempBlock . Recall that we created
two arrays, rowList and colList, and their values relate to the Blocks in Figure 8-5. First, we
create a temporary Block object, tempBlock2, to use for this operation. Next, we create a for
loop that iterates through the rowList array. Since rowList and colList have the same number of
values, we don't need to specifically iterate through it, we will use the index (i) from the rowList
iteration for colList.
The next if statement tests to see if the Block represented by rowList[i] , colList[i] is within
the bounds of the board . The values must be greater than 0 and less than BLOCK_ROWS and
BLOCK_COLS (for columns and rows respectively). If we do not do this, an “array out of bounds
exception” will be thrown at runtime.
var tempBlock2:Block;
for (var i:int = 0;i < rowList.length;i++) {
if ((tempBlock.row + rowList[i]) >= 0 && (tempBlock.row + rowList[i])

< BLOCK_ROWS && (tempBlock.col + colList[i]) >= 0 &&

(tempBlock.col + colList[i]) < BLOCK_COLS ) {
So now that we know we are looking at a legitimate place in the board 2D array, we set tr equal
to the row calculation and tc equal to the column calculation. We now have two values that
represent one of the Block s in Figure 8-5. We set tempBlock2 equal to the Block object in the
board array represented by the tr and tc indexes ( board[tr][tc]; ).
var tr:int = tempBlock.row + rowList[i];
var tc:int = tempBlock.col + colList[i];
tempBlock2 = board[tr][tc];
Now, we are ready for our most important test. If the blockColor property of tempBlock2 is equal
to colorToMatch (the color of the clicked Block), we are in business.
However, we are not ready to push this Block into the blocksToCheck array just yet. We also need
to check to see if this Block is already in either blocksToCheck or blocksTested . If we did not
check this, the same Block would be pushed into blocksToCheck multiple times, and this function
would never complete.