Corrections to Example 10-9: Password Entry Field on page 290.
The password example didn't correctly handle the delete key. It would delete the asterisks, but not the underlying password. Also, it wouldn't properly clear the password following an erroneous attempt to log in. Here is a corrected version that addresses these issues:
property pPassword property pMyMember on beginSprite me set pMyMember = the member of sprite (the spriteNum of me) -- Clear the password field set pPassword = EMPTY put EMPTY into member pMyMember end on keyDown me -- Mask the field with asterisks. set maskChar = "*" if the key = RETURN or the key = ENTER then -- Check the password when they hit RETURN or ENTER if verifyPassword (pPassword) = TRUE then -- Use this to jump to an appropriate frame in your movie go frame "Top Secret" else alert "Invalid Password" -- This is NEW to clear the field when the user entered -- the wrong password set pPassword = EMPTY put EMPTY into member pMyMember end if else if isArrowOrTabKey() then -- This is changed from the book. Allow the arrow or tab keys through. pass else if isDeleteKey() then -- Handle the delete and backspace keys specially if the selStart = 0 and the selEnd = 0 then -- If the cursor is already at the left edge, there is nothing -- to delete, so beep at the user. beep exit end if set insertPoint = max(1, the selStart) set endPoint = max(1, the selEnd) -- Delete the hilighted characters or the character to the left -- of the insertion point if insertPoint = endPoint then delete char insertPoint of pPassword else delete char insertPoint to endPoint of pPassword end if pass else -- Determine which portion of the field to replace set insertPoint = max(1, the selStart + 1) set endPoint = max(1, the selEnd) -- Insert the text at the cursor location if insertPoint = endPoint then -- In this case, no characters are hilighted. -- Add the keystroke to the secret password put the key before char insertPoint of pPassword -- But display the masking character (asterisk) in its place put maskChar before char insertPoint of member pMyMember else -- In this case, replace all the hilighted characters put the key into char insertPoint to endPoint of pPassword put maskChar into char insertPoint to endPoint of member pMyMember end if -- Update the cursor insertion point manually set the selEnd = insertPoint set the selStart = insertPoint end if end keyDown -- This handler is new. It detects the delete key, backspace key or -- keypad delete key. It replaces the "isEditingKey" handler from -- the example which is no longer needed in this context on isDeleteKey case (the key) of BACKSPACE: return TRUE end case case (the keyCode) of 51, 117: return TRUE otherwise: return FALSE end case end isDeleteKey -- This handler is new. It detects the arrow keys and the Tab key on isArrowOrTabKey case (the key) of TAB: return TRUE end case case (the keyCode) of 123, 124, 125, 126: return TRUE otherwise: return FALSE end case end isArrowOrTabKey -- Verify the password on verifyPassword password -- Store your password here if password = "platypus" then return TRUE else return FALSE end if end verifyPassword
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(The page last revised November 4, 1999)