Hi every one. I am tying to build a Zooming application that is a zoom by level type. i manege to create the following: first i to build a zoom Meter that spited overall zoom into Levels and sub zooms for each level. each level represent a set of divided image increasing by level and ordered by Level,column and row. and i create procedure that shift image to zoom center by this transformation: Z(x1,y1)=(x1-x2,y1-y2):x1,y1 center before zoom;x2,y2:center after zoom. then i create a procedure that combine's the image. and procedure to calculate Subtractive of a point in other level by this transformation: S(x1,y1)=((x1*d2)/d1,(y1*d`2)/d`1):x1,y1 target point; d1,d2 old dimension;d`1,d`2: new dimension. and procedure that detects the viewed parts of image in the view port(putting the result in two dimension array of Boolean [Column][Row]) then during my analysis to the program i ran into many problems like: what is the effective methods to creates fixed frame (by dimensions of the form) that represent a 'view' part of the image, that capable to pan throw the total image ,zoom from /to image plus move throw the levels, with 'aware' for border updates. effective algorithms for transformation like(move ,zoom) for my levels; if you please, i need some help in this manner ,please put some hint to solve my problem. thank you very much for reading may request.