Loading of widgets from DML markup and DML Editor in DlangUI

[Vadim Lopatin via Digitalmars-d-announce]

Hello,

Useful feature is added to DlangUI.

You can write UI layout as QML-like code, and load it in runtime 
from file, resource, or just string constant.


Instead of manual creation of widgets in code, you may write like 
this:

==================================================
     module app;

     import dlangui;

     mixin APP_ENTRY_POINT;

     /// entry point for dlangui based application
     extern (C) int UIAppMain(string[] args) {
         // create window
         Window window = Platform.instance.createWindow("DlangUI 
example - HelloWorld", null);

         // create some widget to show in window
         window.mainWidget = parseML(q{
             VerticalLayout {
                 margins: 10
                 padding: 10
                 backgroundColor: "#C0E0E070" // semitransparent 
yellow background
                 // red bold text with size = 150% of base style 
size and font face Arial
                 TextWidget { text: "Hello World example for 
DlangUI"; textColor: "red"; fontSize: 150%; fontWeight: 800; 
fontFace: "Arial" }
                 // arrange controls as form - table with two 
columns
                 TableLayout {
                     colCount: 2
                     TextWidget { text: "param 1" }
                     EditLine { id: edit1; text: "some text" }
                     TextWidget { text: "param 2" }
                     EditLine { id: edit2; text: "some text for 
param2" }
                     TextWidget { text: "some radio buttons" }
                     // arrange some radio buttons vertically
                     VerticalLayout {
                         RadioButton { id: rb1; text: "Item 1" }
                         RadioButton { id: rb2; text: "Item 2" }
                         RadioButton { id: rb3; text: "Item 3" }
                     }
                     TextWidget { text: "and checkboxes" }
                     // arrange some checkboxes horizontally
                     HorizontalLayout {
                         CheckBox { id: cb1; text: "checkbox 1" }
                         CheckBox { id: cb2; text: "checkbox 2" }
                     }
                 }
                 HorizontalLayout {
                     Button { id: btnOk; text: "Ok" }
                     Button { id: btnCancel; text: "Cancel" }
                 }
             }
         });
         // you can access loaded items by id - e.g. to assign 
signal listeners
         auto edit1 = 
window.mainWidget.childById!EditLine("edit1");
         auto edit2 = 
window.mainWidget.childById!EditLine("edit2");
         // close window on Cancel button click
         
window.mainWidget.childById!Button("btnCancel").onClickListener = 
delegate(Widget w) {
             window.close();
             return true;
         };
         // show message box with content of editors
         
window.mainWidget.childById!Button("btnOk").onClickListener = 
delegate(Widget w) {
             window.showMessageBox(UIString("Ok button pressed"d),
                                   UIString("Editors 
content\nEdit1: "d ~ edit1.text ~ "\nEdit2: "d ~ edit2.text));
             return true;
         };

         // show window
         window.show();

         // run message loop
         return Platform.instance.enterMessageLoop();
     }
==================================================

Function parseML loads widgets from code written in DML language.


There is DMLEdit sample app in DlangUI/examples directory.

You can run it with dub:


         dub run dlangui:dmledit


It allows to edit QML text and see how it will look like when 
loaded into app (F5 refreshes view).

Syntax highlight, bracket matching, go to error and other useful 
features are implemented.

TODOs:
* automatic mapping of loaded widgets to member variables (e.g. 
by matching of widget id and variable names)
* automatic assignment of signal listeners to member functions, 
according to DML or just based on signal name and widget id (e.g. 
onButton1Click method may be connected to widget with 
id="Button1" signal click )


I hope this enhancement will be useful.


Best regards,
     Vadim