Windows API function (6) in VCL: begindeferwindowpos

Begindeferwindowpos, deferwindowpos, and enddeferwindowpos are functions used together to adjust the position, size, and Z sequence of a set of windows. They are useful in extctrls units.

Next, adjust a group of buttons in Panel1 using the conventional method, and then implement them again using the above three functions.

In this example:

Code File:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls, extctrls; Type tform1 = Class (tform) Panel1: tpanel; button1: tbutton; button2: tbutton; button3: tbutton; button4: tbutton; identifier: identifier; identifier: tradiobutton; Procedure identifier (Sender: tobject); end; vaR form1: tform1; implementation {$ R *. DFM} procedure tform1.radiobutton1click (Sender: tobject); var num, I: integer; BTN: tbutton; L, t, W, H: integer; begin num: = panel1.controlcount; l: = 10; T: = 10; W: = (panel1.clientwidth-L * (Num + 1) Div num; H: = (panel1.clientheight-T * (Num + 1 )) div num; for I: = 0 to num-1 do begin if panel1.controls [I] Is tbutton then begin BTN: = tbutton (panel1.controls [I]); BTN. left: = L; BTN. top: = (H + T) * I + T; BTN. width: = W; BTN. height: = H; end; Procedure tform1.radiobutton2click (Sender: tobject); var num, I: integer; BTN: tbutton; L, t, W, H: integer; begin num: = panel1.controlcount; L: = 10; T: = 10; W: = (panel1.clientwidth-L * (Num + 1) Div num; h: = (panel1.clientheight-T * (Num + 1) Div num; for I: = 0 to num-1 do begin if panel1.controls [I] Is tbutton then begin BTN: = tbutton (panel1.controls [I]); BTN. left: = (W + l) * I + L; BTN. top: = T; BTN. width: = W; BTN. height: = H; end.
 
   
 

Form file:

Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 220 clientwidth = 307 color = clbtnface font. charset = default_charset font. color = clwindowtext font. height =-11 font. name = 'tahoma 'font. style = [] oldcreateorder = false pixelsperinch = 96 textheight = 13 object Panel1: tpanel left = 8 Top = 8 width = 289 Height = 161 caption = 'panel1' taborder = 0 object button1: tbutton left = 152 Top = 72 width = 75 Height = 25 caption = 'button1' taborder = 0 end object button2: tbutton left = 160 Top = 80 width = 75 Height = 25 caption = 'button2' taborder = 1 end object button3: tbutton left = 168 Top = 88 width = 75 Height = 25 caption = 'button3' taborder = 2 end object button4: tbutton left = 176 Top = 96 width = 75 Height = 25 caption = 'button4' taborder = 3 end object radiobutton1: tradiobutton left = 50 top = 183 width = 113 Height = 17 caption = 'radiobutton1' taborder = 1 onclick = radiobutton1click end object radiobutton2: tradiobutton left = 184 Top = 183 width = 113 Height = 17 caption = 'radiobutton2' taborder = 2 onclick = radiobutton2click endend
 
   
 

Code re-implemented with begindeferwindowpos, deferwindowpos, and enddeferwindowpos (the form and running effect are the same ):

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls, extctrls; Type tform1 = Class (tform) Panel1: tpanel; button1: tbutton; button2: tbutton; button3: tbutton; button4: tbutton; identifier: identifier; identifier: tradiobutton; Procedure identifier (Sender: tobject); end; vaR form1: tform1; implementation {$ R *. DFM} procedure tform1.radiobutton1click (Sender: tobject); var num, I: integer; BTN: tbutton; L, t, W, H: integer; deferhandle: thandle; begin num: = panel1.controlcount; L: = 10; T: = 10; W: = (panel1.clientwidth-L * (Num + 1) Div num; h: = (panel1.clientheight-T * (Num + 1) Div num; deferhandle: = begindeferwindowpos (Num); {prepare to adjust a set of Windows} For I: = 0 to num-1 do begin if panel1.controls [I] Is tbutton then begin BTN: = tbutton (panel1.controls [I]); deferhandle: = deferwindowpos (deferhandle, BTN. handle, hwnd_top, {This parameter determines the Z order} l, (H + T) * I + T, W, H, {new position and size} swp_nozorder {more control, currently, the Z sequence is not changed}); end; enddeferwindowpos (deferhandle); {implementation adjustment} end; Procedure tform1.radiobutton2click (Sender: tobject); var num, I: integer; BTN: tbutton; L, t, W, H: integer; deferhandle: thandle; begin num: = panel1.controlcount; L: = 10; T: = 10; W: = (panel1.clientwidth-L * (Num + 1) Div num; H: = (panel1.clientheight-T * (Num + 1) Div num; deferhandle: = begindeferwindowpos (Num ); for I: = 0 to num-1 do begin if panel1.controls [I] Is tbutton then begin BTN: = tbutton (panel1.controls [I]); deferhandle: = deferwindowpos (deferhandle, BTN. handle, hwnd_top, (W + l) * I + L, t, W, H, swp_nozorder); end; enddeferwindowpos (deferhandle); end.