Designing Forms
A window provided for easy data entry and presentation on the computer screen.
Database table or query providing data displayed in the form. The data source is needed because forms itself are only tools for displaying and entering data, while tables and queries are the source of data. New, empty forms have no data source assigned, so they are not displaying any data from your database unless you assign a data source to them.
Direct equivalent of a column in a table or query. Most frequently used are fields for displaying text and numbers. Entering a new value or changing the existing value of such a field causes a change in the bound table or query column (after accepting the change).
Tasks you are performing to define the appearance and functions of the form. To do this, you need to provide data source, insert form fields of various types and place them at the appropriate location.
Form's element. Main widget types are:
Widgets displaying information, e.g. a text box or an image box. Each widget of this type can be bound to a data source field (a table or a query column). Therefore, such widgets are called in short form fields.
Widgets able to perform a specified action, e.g. a push button that can close the current form. Within other applications this widget type is sometimes called form control because it can perform previously defined action of controlling your database application's behavior.
Other widgets allowing to enrich a form's appearance, e.g. a “line widget” can visually separate two form areas.
A widget that can contain other widgets within its area. For example, frame widget or tab widget are containers. The form's surface itself is a container as well. A command button cannot be called as container because it is not possible to insert a widget inside it. In more complex cases, container widgets can be inserted inside a container, so nesting is possible.
In chapter 5.2 you learned about how to enter data directly into tables using their data sheet view. However, in many cases forms are better suited for data entry:
A table can contain too many columns to display them on your screen. A form can display such a data using multiple rows.
A form allows to visually split data fields into logical groups, thus increasing readability. Labels with additional information can be inserted to give users more hints on how to use the form or what given data fields mean.
Command buttons can be used within forms for commonly used commands so users can use forms in a similar way as a standalone applications they know.
In data sheet view displaying multi-row data text fields or images is as easy as within forms.
As with table or query design, you are able to use Data View and Design View. Form designing is performed in Design View. We will often refer to the form design window as to Form Designer.
To create a new empty form, select -> from the Menubar. Optionally, you can use command from drop-down button on the Project Navigator's toolbar or command from the context menu.
A new frame will appear, you can resize the form by moving the borders. The form is covered with a grid which simplifies accurate positioning of the widgets.
As with table design, Form Designer provides Property pane. To save some space on the screen, the pane has three tabs related to the currently selected form:
Contains a list of properties for the currently selected widget.
Contains properties related specifically to the data source of the currently selected widget or the form itself.
Contains a hierarchy of all widgets of the form. The list simplifies widgets lookup by name and navigation between them.
There is information about currently selected widget's name and type displayed on the first and second tab.
Additional toolbars are also available:
The Widgets toolbar used for inserting new widgets into the form
The Format toolbar used to format form's elements (e.g. adjusting widget's size, grouping). Formatting commands are also available in the menu. More about these commands can be found in the section called “The Menu”.
The Widgets tab in the Property pane provides a list of form widgets and their hierarchy. Each widget is presented within the hierarchy beside other widgets being on the same level (the same parent container). Child widgets (inside containers) are presented using indented names.
Each widget has displayed its name and type. The type has also an icon displayed - the same as the one displayed on the toolbar used while form designing is performed.
Changing the current selection on the list causes appropriate selection on the designed form. This allows for easier widget lookup by name and easier navigation. For example, it is possible to select a widget by name, and then switch to the Properties tab to change the widget's properties.
Keeping the Ctrl key pressed while an item on the widgets list is being selected allows to select multiple widgets at a time. Keeping the Shift key pressed allows to select entire lists of widgets.
Giving widgets reasonable names can be useful but is not mandatory. Note
that widget's name is a property that is not visible to the user of your form.
Users will only see a widget text, provided by Text property
or similar.
Let's create a form providing information about persons, i.e. a form connected
it with Persons table.
If the form being designed should present data obtained from the database, you need to place appropriate fields on it. To do this, use the buttons on the Widgets toolbar. Each button corresponds to a single widget type.
Click button on the Widgets toolbar.
Click on the form surface with the mouse button. A new text box widget will be placed in the point where you clicked. Before you release you can drag your mouse to specify a desired size for the widget.
If needed, move the inserted widget using drag & drop to a desired position. You can resize the widget afterwards by dragging one of the small boxes appearing near its corners. Note that the boxes are only visible when the widget is selected. If you select another widget or the form surface, the boxes disappear.
Click the toolbar button again and click on the form surface to insert another widget. Repeat this action once again until you get three text boxes inserted in your form. For sake of simplicity we will limit ourselves to three data fields.
There is a context menu available in form's design mode, activated by a mouse button click the desired widget or the form's surface. The menu offers commands like , , , and other, more complex. Many of the commands are also provided in the Menubar, usually . Keyboard shortcuts are also available for these commands. Some of the commands are only available for certain types of widgets.
The commands , and makes it possible to move or copy widgets between forms, even between separate database projects.
Holding the Ctrl key down while clicking a widget allows to select multiple widgets.
Instead of using and commands, to duplicate a widget within the same form you can hold down the Ctrl key while moving the widget. After the Ctrl key is released, the dragged widget will not be moved but copied in the new location.
The fields you inserted have no data source assigned yet, so these are not able to display information from the database. To assign data source, use the Data Source tab of the Property pane.
The very first step is to specify the form's data source,
i.e. a place the displayed data will be fetched from. As mentioned above, you
will use table persons as a
data source
for your new form.
Click on the form's surface, as you will alter its properties.
Switch to the
Data Source tab and enter persons
table name in the Form's data source drop down list.
Alternatively, you can select this name from the drop down list.
You have assigned form's data source. Now you need to do specify widget's data source.
Click the first text field widget at the top of the form.
In the Data Source
tab of the property pane enter field name name in the
Widget's data source drop down list. Alternatively, you can select
this name from the drop down list.
Click on next text field widget and enter surname as the data source.
Enter data sources for street, house_number
and city text fields
in a similar way.
You can now save the form's design (this is not mandatory to test the
form in action). To save, click the
Save object changes toolbar button or use the
-> (Ctrl+S)
menu command. Upon saving you will be asked for entering the form's name. Enter
Persons as caption and click the
button. The form's name will be filled automatically.
This is the right moment for testing your form. Click the
toolbar button. Unless you made a
mistake while entering data sources, you should see
form's fields filled
with data from the persons table.
If you want to remove widget's data source assignment for a form widget, you can use button near the Widet's data source drop down list. Similarly, you can use the button near the Form's data source drop down list.
Use the button to select appropriate table or query in the Project Navigator, so you can quickly open a table or query being the data source of the form.
To make it easier for the form's user to identify the meaning of every field
widget, these should have added text labels with appropriate titles. To
create text labels the
Label widget is used.
Insert three text label widgets onto the form, placing them on the left
side of the text fields (or on the right hand if your operating system
uses right-to-left layout). On inserting a new label, a text cursor
appears at the location where you can enter the desired title. Enter consecutively:
Name, Surname and Street. Additionally,
on the top of the form insert another label displaying name of the form,
i.e. Persons. Enlarge this label's size and and increase the font size using
->
menu command.
An Action is a single activity isolated in the application,
available for the user to execute. It can also be executed automatically as a
reaction for a given event (e.g. after opening a form).
Many actions can be assigned to form button. The assigned action is executed after button is clicked.
To assign action:
Switch to form's Design view if you have not done yet.
Select the existing button widget by clicking on it or put a new button widget onto the form. If you inserted a new button, enter its title and press Enter key.
Click the button widget with the mouse button to display the context menu.
From the context menu select command.
An Assigning Action to Command Button dialog window will appear presenting a list of available actions. One of the actions is selected if the widget already has action assigned. Otherwise the Action type drop down list has the No type item selected.
From the Action type drop down list select Application item. Available application-wide actions will be listed.
Select one of the actions on the list (e.g. Delete Row).
Click the button or press the Enter key to accept your selection.
After switching to the form's data view you can try whether the action works. For example, if you assigned Delete Row action, clicking the button, the current database row will be deleted, similarly to executing -> (Ctrl+Delete) menu command (depending on your settings you may be asked to confirm the removal).
To remove an action assignment, select No type item from the Action type drop down list of the Assigning Action to Command Button dialog window.
Actions only work in the form's data view. Not every action's assignment is reasonable. For example, the action is available in data view, but only if you have a widget selected in the Design view. If you make changes to the font settings the changes are applied to the text of that selected widget.
In most cases form widgets should be conveniently arranged and aligned. Positioning, aligning and resizing widgets by hand is not easy and these parameters are not adjusted when the user resizes the form. In fact the situation is even worse because you cannot assume a given form requires a given space because users have different font sizes and display resolutions.
Using special tool called widget layouts can help to automatically lay out the form widgets. Widget layout is an action of grouping two or more widgets so these are well positioned and have appropriate sizes.
Using layout in a form improves alignment. Moreover, its space is better used. Text fields are closer to each other, spacing is constant.
There are two methods to create widget layout.
Select two or more widgets that should be placed in a common layout, and select one of the layout types from the context menu item Layout Widgets .
Click a container widget (or a form surface itself), where widgets are inserted and select one of the layout types from the context menu item Layout Widgets . All widgets existing within the container or within the form, being on the same level will be put into a single common layout.
In each of these cases you can also use -> menu.
Widget layout is presented in the design view using a blue, green or red box drawn with a broken line. This line is displayed only in the form's design view.
Besides the grid type, there are other widget layout types.
Vertical widget layout
Horizontal widget layout
A spring in widget layouts is a special, invisible element allowing to adjust widget's position and size within layouts. Such a spring stretches or squeezes a widget on the right, top, bottom or left hand, so it can have desired size and position.
To use a spring:
Select spring icon on the Widgets toolbar.
Click on a selected point of the form to insert the spring.
To make springs work you need to create a global widget layout, i.e. a layout for the form itself. Then, springs can use edges of the form as a boundary for expanding.
To remove widget layout without removing widgets, perform one of these actions:
Click with the mouse button on the layout's border and select command from the context menu.
Click with the mouse button on the layout's border and select -> menu command.
Removing widget layout using the command will not remove widgets contained in the layout. If you want to remove the widgets as well, just select the layout by clicking on its border and press Delete key or use -> menu command or context menu command.
Instead of setting a fixed size for your widgets, in Kexi you can choose between various widget's size policies. A size policy is a flexible strategy for controlling how a widget is stretched (or shrunk) depending on other neighbouring widgets and space available within the form.
After putting widgets into a layout, typically each widget gets a proportional (Preferred) size policy. These widgets will be automatically resized with preferred settings, depending on their type and size of the entire layout itself. For example, three buttons put into the horizontal layout will be resized to fit their visible text.
For each widget inserted into the form, there are settings for size policy available in the Property Editor. The settings are presented as a group of properties called Size Policy.
This group of properties contains:
defining horizontal size of the widget,
defining vertical size of the widget,
defining strength of activity of the Horizontal Size Policy,
defining strength of activity of the Vertical Size Policy
The following values are available in the drop down list for Horizontal Size Policy and Vertical Size Policy properties visible in the Property Editor:
this value means that the widget cannot be automatically resized; it should maintain the constant size defined at design time (width or height),
this value means that the original size of the widget is set as minimal allowed, it is sufficient and there is no need for expanding the widget, but the widget will be expanded if needed. This type of policy can be used to force the widget to be expanded to the whole width or height, especially if you set a stretch value greater than 0.
this value means that the original size of the widget is set as maximum allowed and can be decreased without breaking the widget's usability and readability if other widgets need more space,
this value means that the original size of the widget is the best and preferred; the widget can be shrunk or expanded however and it will stay readable,
this value means that the original size of the widget is reasonable but the widget can be also shrunk; it can be expanded as well to take as much space as possible,
this value means that the original size of the widget is allowed; it can be expanded to take as much space as possible,
this value means that the original size of the widget is ignored; the widget can be expanded to take as much space as possible but other widgets usually will not allow for that
Different widget types have various default size policies; for example, button widgets have default size policy set to Minimum (in both directions), while text field widgets have vertical size policy set to Fixed.
The most frequently used size policies are Preferred, Minimum and Maximum.
The Vertical Stretch and Horizontal Stretch properties accept integer values greater than or equal to 0. These properties allow to fine-tune the behavior of size policies. The default value for the properties is 0. A higher value of the stretch means that the widget will be expanded more than widgets for which a lower stretch value is set.
In case when your form has no main layout set for auto-positioning and auto-resizing its widgets, you will probably want to modify the position and size of widgets so the form can look cleaner and be easier to use. The Kexi form designer simplifies this task by offering the following groups of commands:
Adjusting sizes of selected widgets. The commands are available in the -> submenu of the menubar and in the submenu of the context menu. The toolbar's drop down button is also available.
The size of the selected widgets will be altered so each widget will be resized to its preferred size and its contents; for example, a text label's size will be changed to fit its text. The position of the widgets will not be changed.
The size of the selected widgets will be altered so each widget's corner will be placed on the form's (or other container's) grid point. The widget's position can be slightly altered.
The height of the selected widgets will be altered so that each of them will have the same height as the shortest one. The position of the widgets will not be changed.
The height of the selected widgets will be altered so that each of them will have the same height as the tallest one. The position of the widgets will not be changed.
The width of the selected widgets will be altered so that each of them will have the same height as the narrowest one. The position of the widgets will not be changed.
The width of the selected widgets will be altered so that each of them will have the same height as the widest one. The position of the widgets will not be changed.
Aligning positions of the selected widgets. The commands are available in the -> submenu of the menubar and in the submenu of the context menu. The toolbar's drop down button is also available.
All the selected widgets' left positions will be moved to the position of the leftmost widget's left edge.
All the selected widgets' right positions will be moved to the position of the rightmost widget's right edge.
All the selected widgets' top positions will be moved to the position of the uppermost widget's upper edge.
All the selected widgets' bottom positions will be moved to the position of the bottommost widget's bottom edge.
All the selected widgets' top-left corners will be moved so that they are positioned in the nearest grid point.
None of the above commands resizes the widgets.
There are also additional commands available: (i.e. above all other widgets) and (i.e. below all other widgets). These two commands are rarely used, as it is not common to place one widget on top of an other (except when a container widget contains other widget inside). Also note that clicking a widget with a mouse button is enough to bring the widget to front.
A widget's focus determines that widget's activity available using keyboard. Focus is related to widgets displayed in the form's data view. Exactly one form widget can have focus at the same time. The most frequent use of focus is text entry (when a given text field is active, i.e. it is focused). An other example is a button widget - when focused, it is possible to “press” it using the Enter or Space key instead of a mouse button.
There are a few methods of making the widgets active (moving the focus to the widget): clicking with a mouse button, rotating the mouse wheel over the widget, or using the Tab key. The latter method is often used because of its speed and convenience for users. Availability of the focusing methods is controlled by Focus Policy property of a given widget.
There is a relationship between focusing (activating) widgets using Tab key and tab order setting of a form. After pressing the Tab key, the next widget should be focused, so the form should know about the tab order.
To alter tab order for a form's widget:
Switch to design view of the form.
Execute -> menu command. The Edit Tab Order dialog will appear with settings for this form.
The window contains a list with two columns: the first column displays widget names, the second - types of the widgets. To make it easier to recognize meaning of the names and types for the user, icons related to the types are also displayed. The list contains only widgets having focus policy allowing to use the Tab key. The window allows you to change the tab order or set the automatic tab order.
To change tab order, either:
Click a selected widget name in the widgets list and drag it to a desired position (up or down) using the mouse.
Click a selected widget name on the widgets list and use or buttons, to move the widgets to a desired position.
Click the Handle tab order automatically check box to set the automatic tab order for the form. If this option has been switched on, any changes made to the list of widgets by hand are not taken into account - Kexi will be handling the tab orders on its own. The automatic ordering means that the top-left widget will be focused first (or the top-right if your operating system uses right-to-left layout), and the order comes from the left to right (from the right to left, respectively) and from the top to bottom.
Click the button to accept the changes or button to dismiss the changes.
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