Task 3 - Explore the Layout Editor

Introduction to Layout Editor

The layout editor in Android Studio is a powerful tool that allows you to design and build your app's UI visually. It provides a user-friendly interface to work with layouts without writing XML code manually, although you can still write or edit the XML directly if you prefer.

Understanding Fragments and Layouts

• Fragments: A fragment represents a portion of the user interface or behavior in an activity. You can combine multiple fragments in a single activity to build a multi-pane UI and reuse a fragment in multiple activities.
• Layouts: Each fragment has an associated layout file in XML that defines the structure of the UI. Layout files contain elements called views (like buttons, text fields, etc.), which are the building blocks for your user interface.

Using the Layout Editor

• Open Layout Editor:
  • In Android Studio, find the Project panel on the left.
  • Navigate to the res > layout folder, and double-click on the layout file you wish to edit (e.g., fragment_first.xml).

• Layout Editor Views:
  • The layout editor will open, showing both the design and the code editor. You can switch between the 'Design' view, 'Split' view (both code and design), and the 'Code' view using the tabs at the bottom of the editor window.
• Design and Blueprint:
  • The 'Design' view shows a visual representation of your layout.
  • The 'Blueprint' view, available as a toggle button on the toolbar of the layout editor, shows the structural outline of your layout without the visual details. It can be useful for seeing the underlying structure of complex layouts.
• Palette and Component Tree:
  • The Palette contains all the different views and view groups that you can add to your layout.
  • The Component Tree shows the hierarchy of views in your current layout, allowing you to easily select and organize UI components.

Modifying View Properties

• Selecting a View:
  • Click on a view in the 'Design' editor or select it from the 'Component Tree'.
  • The 'Attributes' panel on the right side will show the properties of the selected view.
• Changing Properties:
  • You can modify properties such as layout width, height, constraints (if using ConstraintLayout), margins, padding, text, and more in the 'Attributes' panel.
  • To change a property, click on the value next to the property name and enter a new value or choose from a dropdown list.

Adding Resources

• String Resources:
  • To add a new string resource, find the text property in the 'Attributes' panel.
  • Click on the '...' button to open the 'Resources' dialog, then click on the '+' button to add a new string value.
• Color Resources:
  • Similarly, for color properties, you can use the 'Resources' dialog to add a new color value or select an existing one.
  • This helps in maintaining a consistent color theme across your app and simplifies changes in the future.

Step 1: Open the Layout Editor in Android Studio

Opening the Layout Editor

• Locate the Layout File:
  • In the Project panel on the left-hand side of Android Studio, navigate to the app > res > layout directory.
  • Here, you should see your layout files, including fragment_first.xml.
• Open fragment_first.xml:
  • Double-click on fragment_first.xml to open it in the Layout Editor.
  • If you can't find the fragment_first.xml file, ensure you're using Android Studio 3.6 or higher, as required for this tutorial.

Familiarizing Yourself with the Layout Editor Panels

• The Layout Editor includes several panels, which might be arranged differently depending on the version of Android Studio you are using. Their functionality, however, remains consistent.
• Palette (1):
  • On the left side, you'll find the Palette containing various UI components like Buttons, TextViews, EditTexts, etc. You can drag these elements onto your design surface.
• Component Tree (2):
  • Below the Palette is the Component Tree, which outlines the structure of your layout. It shows the hierarchy of views and how they are nested within each other.
• Design Editor (3):
  • In the center, the Design Editor offers a visual representation of your layout. It's where you can see what your app's UI will look like on a device after it's compiled.

Exploring Design and Code Views

• In the upper right corner of the Design Editor, you'll find three icons representing different views: Code (<>), Split (<>|), and Design (no brackets).
• Code View: Shows only the XML code.
• Split View: Displays both the visual design and XML code.
• Design View: Shows only the visual design.

Adjusting the View

• Utilize the + and - zoom buttons in the lower right of the Design Editor to zoom in and out of the design surface.
• The "zoom-to-fit" button allows you to adjust the view so both panels fit on your screen.

Using Design and Blueprint Layouts

• The Design layout on the left-hand side visually represents how your app will look in reality.
• The Blueprint layout on the right provides a schematic view of your layout, which can be useful for examining the structure and constraints without the distraction of colors and other styling details.

Orientation and Device Testing

• Use the orientation icon at the top of the design toolbar to switch between portrait and landscape orientations.
• The device menu allows you to preview your layout on different devices, which is crucial for ensuring your app looks great on all screen sizes.

Up Next: Attributes Panel

• On the right side of the Layout Editor, you'll see the Attributes panel, which you'll explore in the next steps of this codelab. This panel lets you adjust the properties of selected UI components within your layout.

Step 2: Explore and Resize the Component Tree

Understanding the Component Tree

The Component Tree panel in Android Studio's Layout Editor provides a visual representation of the UI components hierarchy. It shows how views, like TextViews and Buttons, are nested within a layout.

Interacting with the Component Tree

• Open fragment_first.xml: Ensure you're in the Design view of the Layout Editor, where the Component Tree is visible.
  • If the Component Tree is not visible, switch to the Design mode from Split or Code mode by clicking the appropriate icon at the top right of the editor.

• Resize the Component Tree: If the strings in the Component Tree are not fully visible, you can resize the panel by dragging its edges to make it larger or smaller, ensuring that you can read the component names and properties.
• Hide/Show the Component Tree:
  • To hide the Component Tree, click the 'Hide' icon (usually a small triangle) at the top right of the Component Tree panel.
  • To show it again, click on the vertical label "Component Tree" on the left side of the Layout Editor.

Step 3: Explore View Hierarchies

Viewing the Hierarchy

• Identify the Root View: In the Component Tree, the root of your layout is the ConstraintLayout. This root view contains all other views in the layout.
  • The ConstraintLayout is a type of ViewGroup, which allows for flexible positioning and sizing of child views.
• Child Views: Look for a TextView and a Button within the ConstraintLayout in the Component Tree.
  • These views are defined as children of the ConstraintLayout.

Examine the XML Code

• Switch to Code or Split View: If you want to see the XML markup for your layout, use the icons in the upper right corner to switch to Code or Split view.
• The XML code shows the ConstraintLayout as the root element with a TextView and a Button as its children.

Step 4: Change Property Values

Modify TextView Properties

• TextView Properties: In the XML code, locate the TextView element and its properties.

• It will have properties like android:layout_width, android:layout_height, and android:text.

• String Resource: The android:text property references a string resource named hello_first_fragment.

• To navigate to this string's declaration, right-click on the android:text property and select Go To > Declaration or Usages.
• Edit String Value: In the values/strings.xml file, change the text value to "Hello World!".

Update TextView in Layout Editor

• Select the TextView: Back in fragment_first.xml, select textview_first in the Component Tree to view its attributes in the Attributes panel.
• If the Attributes panel is not visible, click the vertical "Attributes" label at the top right of the Layout Editor.

• Observe Resource Reference: In the Attributes panel, you'll see the text attribute still references @string/hello_first_fragment.
  • This illustrates the advantage of using string resources: changing the string's value in strings.xml automatically updates all references to it.
• Search for a Property: To quickly find a specific property in the Attributes panel, use the search feature by clicking the magnifying glass icon.

Run the App

• Launch Your App: Run your app by clicking the green 'Run' button in the toolbar.
• Your app should now display "Hello World!" on the device or emulator, reflecting the change made in strings.xml.

Step 5: Change Text Display Properties

Adjusting Text Appearance

• Select textview_first: Make sure textview_first is selected in the Component Tree to modify its attributes in the layout editor.
• Find Text Appearance Attributes:
  • In the Attributes panel on the right, scroll down to find the textAppearance section under Common Attributes.
  • You may need to click to expand this section if it's not already open.

• Modify Text Appearance:
  • Change properties such as fontFamily, textSize, and textStyle.
  • To change the font family, click on the dropdown menu and select a font like "sans-serif-condensed."
  • For text size, click on the size field and type a new value, such as "30sp" (sp stands for scale-independent pixels, recommended for font sizes).
  • To make the text bold, find the textStyle property and select "bold" from the dropdown menu.
• Change Text Color:
  • Click in the textColor field to open the color selection menu. Start typing "g" to filter the list to colors containing the letter "g."
  • Choose a predefined color like @android:color/darker_gray from the list and press Enter to apply it.
• Review XML Changes:
  • Switch to the XML view to see that the changes you made in the visual editor have been reflected in the XML code.
  • The new properties will be listed within the <TextView> element.

• Run the App:
  • Run your app to see the changes. The text within textview_first should now display with the new font, size, style, and color you set.

Step 6: Display All Attributes

Exploring All Available Attributes

• Find All Attributes:
  • In the Attributes panel, continue scrolling past the common attributes until you find the section titled "All Attributes."
  • If the Attributes panel doesn't show any properties, ensure that textview_first is still highlighted in the Component Tree.
• Scroll Through Attributes:
  • Take some time to scroll through the list of all available attributes for a TextView. This will give you an idea of the vast number of properties you can modify.
  • Attributes range from alignment, padding, and margin settings to more advanced features like text filters and movement methods.

By completing these steps, you've learned how to customize the appearance of text in a TextView using the layout editor, how to apply changes directly through the Attributes panel, and how to verify those changes in the XML code. Additionally, you've gained insight into the extensive range of attributes available for UI components in Android, allowing you to further refine the look and feel of your app's UI.