working out the sold area of a grid

terryoleary1981

i'm trying to create an application similar to a pixel ad site. I've created some ajax that record the x,y corordinate of the top left corner of the advert on a grid, along with the width and height of the area selected.

I have done this relatively straight forwardly... the problem i now have is checking the purchased areas during a users selection of an advertising area.

I need to ensure the area selected is not one previously sold.... I'm having problems working out how to work out the pixels/ grid squares sold from just the information i have... I know other sites have achieved this in the same way but I'm a little lossed having tried several things and failed.

Can anyone help? please let me know or I can give more info or msn me on unofficialfan@hotmail.co.uk

Thanks in advance

big_nerd

You can setup a database to and save records based on their xy coordinates, since they do not change there will be no duplicates..

If you have an SQL Server available on your server, find out what type (most likely MySQL) and version info. As well what version of php you are using.

You can most likely setup a table with all of the information you would need, from IF it is sold, to who, and for how long.

terryoleary1981

hi,

yeah i have the information stored in a DB, I'm trying to figure out the logic in order to check what pixels / area of the grid is already purchased so new users dont select an area already taken

jmack159

it seems like you could do something like this:

say cust1 ordered an area starting at (10,50) and the area is 100X100. then the four corners of the box are then {(10,50), (110,50), (110,150), (10,150)}. so if cust2 orders a box starting at (100,50) and 100X100 it should fail because the left edge is overlapping right? so you have a range of two number, one for the x, one for the y, that the new points cannot be within. so cust2's x must be 110 < x < 10, while at the same time the y must be 150 < y < 50. i would suggest that maybe you grey out areas that have already been bought, it seems more intuitive for the user, cus they don't know whats in you db. have you tried drawing a picture? i herd somewhere that its worth like a thousand words or something! 🙂

big_nerd

Good Suggestion.

Draw the map out on paper, or on the computer and print it.

If you want you can even label each sector as a map.

Map A is Coordinates 100, 150 and its a 100x100, etc etc.

You can keep your grid map for reference.

Take something complicated and make it easier, if you have a set "area" (kind of like a newspaper) label the areas, draw it out, keep the regions that are sellable a different color than the "content" section.

Label each area and note on your map the size, in your DB label them as you wish, A, B, C, D, E or something.

You can reference "A" and have a record for "available".

You will eventually know the map off by heart and it will be easy.