Delphi's drawing function [3]-rectangular graphics

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) button1: tbutton; button2: tbutton; button3: tbutton; button4: tbutton; button5: tbutton; Procedure upload (Sender: tobject); Procedure button1click (Sender: tobject); Procedure button2click (Sender: tobject ); procedure button3click (Sender: tobject); Procedure button4click (Sender: tobject); Procedure button5click (Sender: tobject); end; var form1: tform1; implementation {$ R *. DFM} var BTN: tbutton; const Y1 = 10; y2 = 80; {set paint brush first} procedure tform1.formcreate (Sender: tobject); begin canvas. pen. width: = 4; canvas. pen. color: = clred; canvas. brush. color: = clwhite; end; {the rectangle can be drawn using the coordinates in the upper left and lower right corner.} procedure tform1.button1click (Sender: tobject); begin BTN: = tbutton (sender); canvas. rectangle (BTN. left, Y1, BTN. left + Btn. width, Y2); end; {a rectangle structure can be drawn as a parameter} procedure tform1.button2click (Sender: tobject); var R: trect; {define a rectangle structure} begin BTN: = tbutton (sender); R: = rect (BTN. left, Y1, BTN. left + Btn. width, Y2); canvas. rectangle (r); end; {draw the rounded corner rectangle; the last two parameters are set to the rounded corner} procedure tform1.button3click (Sender: tobject); begin BTN: = tbutton (sender); canvas. roundrect (BTN. left, Y1, BTN. left + Btn. width, Y2, 20, 20); end; {draw the focus rectangle; it is not affected by the paint brush; its color is calculated according to the color of the paint brush} procedure tform1.button4click (Sender: tobject); var R: trect; begin BTN: = tbutton (sender); R: = rect (BTN. left, Y1, BTN. left + Btn. width, Y2); canvas. drawfocusrect (r); end; {rectangular stroke, not a paint brush} procedure tform1.button5click (Sender: tobject); var R: trect; begin BTN: = tbutton (sender); R: = rect (BTN. left, Y1, BTN. left + Btn. width, Y2); canvas. framerect (r); end.
 
   
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