Learn more about GDI + [33]: tgppen-geometric transformation of the paint brush-settransform

Ry transformation is matrix transformation. The matrix of the paint brush ignores Dx and Dy translation parameters. It is better to select linecapround.
In this example:

Code File:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, comctrls, stdctrls, extctrls; Type tform1 = Class (tform) Panel1: tpanel; button1: tbutton; trackbar1: ttrackbar; trackbar2: ttrackbar; trackbar3: ttrackbar; trackbar4: ttrackbar; Procedure formcreate (Sender: tobject); Procedure upload (Sender: tobject ); procedure future (Sender: tobject); Procedure trackbar2change (Sender: tobject); Procedure trackbar3change (Sender: tobject); Procedure future (Sender: tobject); end; var form1: tform1; implementation {$ R *. DFM} uses gdipobj, gdipapi; Procedure plugin (Sender: tobject); const n = 40; begin trackbar1.min: =-N; trackbar1.max: = N; trackbar2.min: =-N; trackbar2.max: = N; trackbar3.min: =-N; trackbar3.max: = N; trackbar4.min: =-N; trackbar4.max: = N; trackbar1.position: = 10; trackbar2.position: = 0; trackbar3.position: = 0; trackbar4.position: = 10; button1.onclick: = formcreate; end; Procedure tform1.formpaint (Sender: tobject); var G: tgpgraphics; B: tgpbrush; P: tgppen; matrix: tgpmatrix; M11, m12, m21, m22: single; begin G: = tgpgraphics. create (canvas. handle); B: = tgphatchbrush. create (hatchstylelargegrid, aclforestgreen); P: = tgppen. create (B, 16); M11: = trackbar1.position/10; M12: = trackbar2.position/10; m21: = trackbar3.position/10; m22: = trackbar4.position/10; matrix: = tgpmatrix. create (M11, M12, m21, m22, 0, 0); p. settransform (matrix); p. setstartcap (linecapround); p. setendcap (linecapround); G. drawline (p, 30, 30, clientwidth-panel1.width-30, clientheight-30); matrix. free; B. free; p. free; G. free; end; Procedure tform1.trackbar1change (Sender: tobject); begin repaint; end; Procedure prepare (Sender: tobject); begin repaint; end; Procedure tform1.trackbar3change (Sender: tobject ); begin repaint; end; Procedure tform1.trackbar4change (Sender: tobject); begin repaint; end.
 
   
 

Form file:

Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 184 clientwidth = 327 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 = 228 Top = 0 width = 99 Height = 184 align = alright taborder = 0 explicitleft = 225 explicitheight = 170 object button1: tbutton left = 14 top = 8 width = 75 Height = 25 caption = #21021 #22987 #21270 taborder = 0 end object trackbar1: ttrackbar left = 0 Top = 39 width = 100 Height = 20 showselrange = false taborder = 1 onchange = trackbar1change end object trackbar2: ttrackbar left = 0 Top = 72 width = 100 Height = 20 showselrange = false taborder = 2 onchange = trackbar2change end object trackbar3: ttrackbar left = 0 Top = 106 width = 100 Height = 20 showselrange = false taborder = 3 onchange = trackbar3change end object trackbar4: ttrackbar left = 0 Top = 140 width = 100 Height = 20 showselrange = false taborder = 4 onchange = trackbar4change end endend