Introduction to Delphi xe2 firemonkey (28)-Data Binding: tbindingslist: Expression Function Test: selectedtext (), checkedstate ()

Example concept: Use label1 to display the listbox1 option, and use label2 to display the checkbox1 status.

1. place controls: label1, label2, listbox1, checkbox1, bindingslist1, and bindscope1;
2. Activate the onclick event of listbox1 and the default event of the form.

Unit unit1; interfaceuses system. sysutils, system. types, system. uitypes, system. classes, system. variants, FMX. types, FMX. controls, FMX. forms, FMX. dialogs, Data. BIND. engext, FMX. BIND. dbengext, Data. BIND. components, FMX. layouts, FMX. listBox; Type tform1 = Class (tform) label1: tlabel; label2: tlabel; listbox1: tlistbox; checkbox1: tcheckbox; bindingslist1: success; identifier: tbindscope; Procedure formcreate (Sender: tobject); Procedure listbox1click (Sender: tobject); end; var form1: tform1; implementation {$ R *. FMX} uses FMX. BIND. editors; // when expression functions are used for selectedtext, selecteditem, and checkedstate, the supported units are procedure tform1.formcreate (Sender: tobject); var I: integer; begin for I: = 1 to 9 do listbox1.items. add ('item _ '+ inttostr (I); with tbindexpression. create (bindingslist1) Do begin controlcomponent: = label1; controlexpression: = 'text'; sourcecomponent: = bindscope1; sourceexpression: = 'selectedtext (listbox1 )'; // same as the next line // sourceexpression: = 'listbox1. selected. text'; active: = true; end; with tbindexpression. create (bindingslist1) Do begin controlcomponent: = label2; controlexpression: = 'text'; sourcecomponent: = bindscope1; sourceexpression: = 'checkedstate (checkbox1) '; // checked: 'true'; unchecked: 'false'; grayed: ''// sourceexpression: = 'checkbox1. ischecked '; // in this example, this is equivalent to the previous line Active: = true; end; checkbox1.onclick: = listbox1.onclick; end; Procedure tform1.listbox1click (Sender: tobject ); begin bindingslist1.y y (sender, ''); end.