Learn more about GDI + [5]: drawarc-draw an arc

In this example:

Code File:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls, spin, extctrls; Type tform1 = Class (tform) Panel1: tpanel; label1: tlabel; label2: tlabel; spinedit1: tspinedit; spinedit2: pushed; Procedure formcreate (Sender: tobject); Procedure destroy (Sender: tobject); end; var form1: tform1; implementation {$ R *. DFM} uses gdipobj, gdipapi; var a1, a2: integer; Procedure tform1.formcreate (Sender: tobject); begin A1: = 0; A2: = 360; spinedit1.text: = inttostr (A1); spinedit2.text: = inttostr (A2); spinedit1.increment: = 10; spinedit2.increment: = 10; spinedit1.onchange: = formpaint; spinedit2.onchange: = formpaint; end; procedure tform1.formpaint (Sender: tobject); var G: tgpgraphics; P: tgppen; x, y, W, H: integer; begin G: = tgpgraphics. create (canvas. handle); P: = tgppen. create (aclred, 2); G. clear (aclwhite); X: = clientwidth Div 6; Y: = clientheight Div 6; W: = x * 4; H: = y * 3; A1: = strtointdef (spinedit1.text, 0); A2: = strtointdef (spinedit2.text, 360); G. drawarc (p, X, Y, W, H, a1, a2); G. free; p. free; end.
 
   
 

Form file:

Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 184 clientwidth = 258 color = clbtnface font. charset = default_charset font. color = clwindowtext font. height =-11 font. name = 'tahoma 'font. style = [] oldcreateorder = false position = pow.topcenter oncreate = formcreate onpaint = formpaint pixelsperinch = 96 textheight = 13 object Panel1: tpanel left = 0 Top = 151 width = 258 Height = 33 align = Albottom bevelouter = bvnone taborder = 0 explicitleft = 8 explicittop = 96 explicitwidth = 257 object label2: tlabel left = 136 Top = 8 width = 52 Height = 13 caption = #26059 #36716 #35282 #24230 ': 'End object label1: tlabel left = 8 Top = 8 width = 52 Height = 13 caption = #36215 #22987 #35282 #24230 ': 'End object spinedit2: tspinedit left = 194 Top = 3 width = 55 Height = 22 maxvalue = 0 minvalue = 0 taborder = 0 value = 0 end object spinedit1: tspinedit left = 66 Top = 3 width = 55 Height = 22 maxvalue = 0 minvalue = 0 taborder = 1 value = 0 end endend