Gdiplus [41]: igpregion Region

// Create a region: tgpregion. create (); {the parameter can be a rectangle, path, hrgn, or region data, or no parameter} tgpregion. fromhrgn (); {initialize from hrgn} // calculate the region (rectangle, path, or another region): igpregion. intersect (); {intersection} igpregion. union (); {Union} igpregion. exclude (); {minus} igpregion. exclusiveor (); {minus intersection} igpregion. complement (); {non-intersection} // others: igpregion. isvisible (); {judge whether the specified vertex or rectangle is in the region} igpregion. getdata; {obtain region data (igpbuffer), which contains data pointer and data size} igpregion. getregionscans (); {Get the rectangle array from the region, float type} igpregion. getregionscansi (); {Get a rectangle array from the region, integer} igpregion. translate (); {offset} igpregion. transform (); {matrix transformation} igpregion. makeinfinite; {initialized to infinitely large} igpregion. makeempty; {Initialization is empty} igpregion. isempty (); {determines whether the region is empty} igpregion. isinfinite (); {determines whether the region is infinitely large} igpregion. getbounds (); {Get boundary rectangle} igpregion. gethrgn (); {obtain hrgn (Windows region handle)} igpregion. clone; {copy} igpregion. equals (); {judge whether it is the same}

  
 

Two important uses of a region:

1. igpregion. isvisible ();

2. igpgraphics. Clip or igpgraphics. setclip ();

Isvisible test:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs; Type tform1 = Class (tform) Procedure formcreate (Sender: tobject ); procedure formpaint (Sender: tobject); Procedure formmousemove (Sender: tobject; shift: tshiftstate; X, Y: integer); end; var form1: tform1; implementation {$ R *. DFM} uses gdiplus, gdiplushelpers; Var region: igpregion; Procedure tform1.formcreate (Sender: tobject); var rect: tgprect; Path: igpgraphicspath; begin rect. initialize (clientrect); rect. inflate (-20,-20); region: = tgpregion. create (rect); rect. inflate (-2,-2); Path: = tgpgraphicspath. create (); Path. addellipse (rect); region. exclude (PATH); end; Procedure tform1.formpaint (Sender: tobject); var brush: igphatchbrush; begin brush: = tgphatchbrush. create (hatchstylemin, tgpcolor. silver, tgpcolor. red); canvas. togpgraphics. fillregion (brush, region); end; Procedure tform1.formmousemove (Sender: tobject; shift: tshiftstate; X, Y: integer); begin text: = 'form1 '; If region. isvisible (x, y) then text: = 'in the region'; end.
 
   
 

Cut area test:

 
Uses gdiplus; Procedure tform1.formpaint (Sender: tobject); const PTS: array [0 .. 3] of tgppoint = (X: 10; Y: 10), (X: 150; Y: 10), (X: 100; Y: 75), (X: 100; Y: 150); var graphics: igpgraphics; Path: igpgraphicspath; region: igpregion; pen: igppen; Font: igpfont; brush: igpbrush; begin graphics: = tgpgraphics. create (handle); Path: = tgpgraphicspath. create; Path. addpolygon (PTS); region: = tgpregion. create (PATH); pen: = tgppen. create ($ ff000000); graphics. drawpath (pen, PATH); graphics. clip: = region; // graphics. setclip (region); // or such Font: = tgpfont. create ('arial', 36, [fontstylebold], unitpixel); brush: = tgpsolidbrush. create ($ ffff0000); graphics. drawstring ('a Clipping Region ', Font, tgppointf. create (15, 25), brush); graphics. drawstring ('a Clipping Region ', Font, tgppointf. create (15, 68), brush); end;