How do I create a special form to use ExtCreateRgn function ?

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I want to create a special form,covered by a bitmap absolutely.In my view ,the form consists of a lot of points,but ,according to the function ExtCreateRgn,a form is made up of more rectangle.Oh,How can I deal with it?

Posted 4-Jun-14 3:18am

codeprojectddx

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enhzflep 4-Jun-14 9:50am

Do you care to further elaborate on where you're stuck?
When it comes to screen coordinates, a 'point' refers to a single pixel - that is, a rectangle whose right and bottom coord are left+1 and top+1.

So, lets assume you wish to have a 5 pixel region that resembles an X. Lets also assume that the top,left of the region is at the origin (0,0)

■ = part of region
_ = blank (CP doesn't show the diagram properly if I use the space character ' ')

■_■
_■_
■_■

You'd need 5 RECTs, each with an area of just 1 pixel.
r0(left,top,right,bottom) = 0,0, 1,1
r1(left,top,right,bottom) = 2,0, 3,1
r2(left,top,right,bottom) = 1,1, 2,2
r3(left,top,right,bottom) = 0,2, 1,3
r4(left,top,right,bottom) = 2,2, 3,3

codeprojectddx 4-Jun-14 10:20am

thank you ,then How to use the function ExtCreateRgn,second element of the struct RGADATA ,char [1] that I do not understand what it means .

enhzflep 4-Jun-14 10:54am

You're welcome. Me either to be honest.
These links may help (I just searched for "ExtCreateRegion sample")

http://edais.mvps.org/Tutorials/GDI/DC/DCch6.html
http://forums.codeguru.com/showthread.php?26046-Nightmare-on-ExtCreateRegion()-street

Note particularly the answer to the question in the 2nd link. :)

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KarstenK · Accepted Answer · 2014-06-04T07:14:00

Solution 1

Here is the best article about regions and how to deal with them: Guide to WIN32 Regions

Posted 4-Jun-14 7:14am

KarstenK