Tutorial 3: Creating Forms & Supporting Multiple Languages

Go through tutorial 2 first.

In this tutorial, we look into more complex dialogs. For our application, we use the form dialog. A form displays a set of data fields in the form of a list, with each data field in the list consisting of a label and a control. The label can be on the same line as the control, or it can be on a separate line, with the control below it. In addition, a form dialog is automatically associated with a standard menu that supplies the options:
Add field, Edit label, Delete field, Save and, optionally, Edit.

Selecting one of the first four of these options results in a call to the appropriate one of the CAknForm functions: AddItemL(), EditCurrentLabel(), DeleteCurrentItem() and SaveFormDataL(). In our application, we use only the save option which in turn calls the SaveFormDataL() function.
An S60 form has two modes: in ‘view’ mode it acts as an application view that displays a list of data items, and in ‘edit’ mode it can be used to modify the data items displayed. By default, it starts up in ‘view’ mode and you can switch to ‘edit’ mode by selecting the Edit menu option. When you have finished editing the data, you press the right softkey (temporarily labeled Done)to return to the ‘view’ mode. A form is actually more powerful than a dialog. If, for example, the data items it is displaying are the fields of a database record, you can implement the commands described above to add, delete, or modify entire records.
You can specify that the form should be edit-only (via a fiag in the FORM resource), so that the form is always in ‘edit’ mode, and in this case, the Edit menu option does not appear.

You can also override its DynInitMenuPaneL() to disable some or all of the other menu options. You specify a form in the resource file by creating a FORM resource and assigning it to the form attribute of a DIALOG resource (or a PAGE resource for multipage dialogs). The FORM resource contains the list of DLG LINES that specify the label and control for each field in the form’s list.

We can also provide support for multiple languages in the application through the rls file. While you can put text strings directly within the resource file, this is not recommended if you need your application to support different languages. Symbian recommends that you put all your strings into a RLS file, and then include this string file using #includein your RSS file. There should be a separate RLS file for each language you support.
Each string in the RLS file is defined using the rls string keyword. For example:

rls_string STRING_r_gui_start "Start";  

As you can see, the DIALOG resource defines the flags and softkeys, and the form attribute points to a FORM resource. This resource specifies the dialog’s content which, in this case, consists of one dialog line: a S60-specific control, known as a pop-up field (type EAknCtPopupFieldText and control structure POPUP FIELD), which is used to select the city. The FORM resource has an additional flags attribute, which is used here to set each control and its prompt to be displayed on separate lines, and to set the ‘edit only’ mode that was mentioned earlier. We also define the list of cities to appear in the popup field using a RESOURCE ARRAY r_city_list.

PreLayoutDynInit() is overridden to set the initial values of the controls in the form. We also override the SaveFormDataL() method to perform the save operations. For our application, we obtain the index of the selected city from the popup menu using the CurrentValueIndex() method in popupFieldText. we then print a dialog similar to the one printed in the second app to display the selected city index. The descriptor method Format() does this. The format string supplied to Format() is very similar to the format string in C, supporting %d, %s, %f, etc.

This wont display the form on the screen. To make the form appear on the screen once we select the start menu item, we need to handle the command in HandleCommand() method in Application Ui Class. We create a new form object and execute R_THIRDAPP_DIALOG which was defined in the resource file.

Download Source code for this tutorial here.
Go through tutorial 4 now.


3 responses to “Tutorial 3: Creating Forms & Supporting Multiple Languages

  1. Pingback: Tutorial 2 : First Dialog « Pulkit Goyal

  2. Pingback: Step by step tutorial for your first Symbian Application « Pulkit Goyal

  3. Pingback: Tutorial 4: Building the Yellow Pages Application « Pulkit Goyal

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