Chapter 15 Notes

Title: The Interactive Interface

Summary

So much ado about Labels and the text in them.

Programming Concepts Summary

Eight Views for this chapter.

Additional views covered later

• WebView

• Picker

• ListView

• TableView

Not covered:

• Map

• OpenGLView

Programs

Program SliderDemo

Page 372.

Concepts:

1. Three public properties
   1. Minimum
   2. Maximum
   3. Value

2. fires ValueChanged

3. ValueChangedEventArgs has two values named OldValue and NewValue.

4. recommend you add some padding at the left and right.

Pitfalls: Set the Maximum first, setting minimum greater than the default maximum causes an error. I.e. maximum > minimum == true.

Also:

Classes:

1. Slider

Program RgbSliders

Page 377.

Concepts:

1. Demo's slider with Color classes.

Program TextFade

Page 380.

1. Another slider demo on the alpha channel.

Program StepperDemo

Page 383.

Concepts:

• Adds an Increment property to allow an incremental value other than 1.

Program SwitchDemo

Page 385.

Concepts:

Introduces the Switch

1. Property: IsToggled of type bool.

2. Event: Toggled

Classes:

1. Switch

Program CheckBoxDemo

Page 387.

Concepts:

1. Properties:

   1. Text

   2. FontSize

   3. IsChecked

2. Event: IsCheckedChanged

Classes:

1. CheckBox is similar to the the switch, but the text identifier is par to of the visual.

Typing Text

• Entry (Horizontal scrolling)
• Editor ((Default wrapping and vertical scrolling)

• SearchBar (Horizontal scrolling)

Methods/Properties:

• Focus --> returns true if element receives focus

• UnFocus --> removes input focus from element

• IsFocused --> read only, true if visual element currently has input focus

• Focused --> Event is fired when a visual element acquires input focus.

• Unfocused --> Event is fired when a visual element loses input focus.

• Property --> Keyboard, tells about the type of

There exists different keyboards

• Default
• Text
• Chat
• Url
• Email
• Telephone
• Numeric (positive numbers only)

Program EntryKeyboards

Page 395.

Concepts:

1. You don’t want to set HorizontalOptions on an Entry to Left, Cen-ter, or Right unless you

also set the WidthRequest property

1. Hence, always put data entry views in a scroll view!

Properties:

1. Text - the string that appears in the Entry

2. TextColor - a Color value

3. IsPassword - a Boolean that causes characters to be masked right after they’re typed

4. Placeholder - light-colored text that appears in the Entry but disappears as soon as the user begins typing.

Events:

1. TextChanged

2. Completed

Classes: Entry

Program QuadraticEquations

Page 397.

Notice the platform-specific WidthRequest setting in the implicit Style for the Entry. This gives each Entry a one-inch width.

Concepts:

1. Demo of Entry.

Program JustNotes

Page 404.

This is the most basic program that Android starts with on their site...

Another simple demo of the Entry. Introduces Keyboard configuration.

Program SearchBar

Page 406.

Concepts:

1. Demos a search bar for searching a text document.

Classes:

1. SearchBar

Program DaysBetweenDates

Page 411.

Concepts:

1. Demos DatePicker.

2. Calculates days between dates.

Classes:

1. DatePicker

Program SetTimer

Page 415.

Concepts:

1. How to display an alert.

2. How to use the TimePicker

Classes:

1. DisplayAlert page 416.