Irregular image drawing

Hi, ive been building a 3d renderer and I am wandering how would I render a 32 by 32 bitmap onto an irregular square for example filling this square
http://gyazo.com/5ab752c502aa6e03fc6a4eaf670bfcd5
with a bitmap image that is 32 by 32.

I did have two ideas. idea 1 fill the square before rotating and scaling it , idea 2 draw lines across to fill the image but Im not to sure how I would implement either these two methods.

Thanks.

I imagine the line filling idea (although interesting) wouldnt be as fast as other options.
Could you just find the rotationg/scale of the square and then transform/scale/rotate a AffineTransform and the create a filter from the AffineTransform and apply the filter to a bufferedimage to be drawn?

Ive ran through methods currently the line drawing one is the most efficient . drawing 32 * 6 * 4000 is more efficient that 32326*4000 There is only one 32 because only rendering from left to right and doing 32 calculations otherwise you would need to do 32 * more.

So drawing with the line method is 768000 calculations for 4000 blocks being rendered. or 24576000 for rendering each pixel then manipulating it.

Oh I see. That makes sense.

with the second one having less pixel draws because its pre scaled unlike rotating every pixel it just skips the ones it doesnt need to render.