Set Y location of the pivot point around which the view will rotate and scale. How the elements of the vertical chain will be positioned. The vertical bias attribute of the child will then affect the positioning of the packed elements. Content and code samples on this page are subject to the licenses described in the Content License. Android API Reference. Constraint Layout. Android Developers. ConstraintSet public class ConstraintSet extends Object java.
ConstraintSet This class allows you to define programmatically a set of constraints to be used with ConstraintLayout. Constraint getParameters int mId int[] getReferencedIds int id get the reference id's of a helper. Inherited methods From class java. END The right side of a view in right to left languages. GONE This view is gone, and will not take any space for layout purposes.
LEFT The left side of a view. See the Issue Tracker documentation for more information. For more information, see the GitHub article What's New in 1. This release is the second beta. This release is the first beta. For more information, see the GitHub article What's New in 2. This is the release candidate for 2. Get started with instant games. Integrate with Firebase. Play Install Referrer. Play Install Referrer Library. Application Licensing. Android GPU Inspector.
System profiling. Analyze a system profile. Frame profiling. Analyze a frame profile. Frame Profiler UI. Customize or port game engines. Process input events. Support game controllers. Achieve proper frame pacing. Frame pacing in Vulkan. Integrate Android Performance Tuner. Output audio. Manage memory. Use prebuilt or turnkey game engines. Develop with Defold. Develop with Godot. Develop with Unity. Use Android Performance Tuner. Game best practices. Maximize device availability.
Art assets. OpenGL and Vulkan. Game Mode. Best practices. Building effective unit tests. Automating UI tests. Testing app component integrations. Android Vitals. Optimizing for Battery Life. System tracing. Build and test apps for accessibility. Advanced topics. Protecting against security threats with SafetyNet. Build for Billions. Margin values appear on all four sides. Change a margin by clicking the value and choosing a different value. Inner lines indicate the constrained width and length.
Use sliders to change the horizontal and vertical constraint bias for elements with opposing constraints. Position elements with constraint bias In the previous exercise you constrained an ImageView to all four sides of the layout. Wrap Content : Expand the element as needed to fit its content. Create constraints between elements In this exercise you will add two Button elements and add a constraint from one to the other to position them together.
Drag a Button from the Palette to the lower right corner of the parent layout. Constrain the button to the right side and to the bottom of the parent layout. Constrain one element to another To create a constraint between UI elements within a layout, click on one element's constraint handle and drag it to the other element's constraint handle.
Drag a second Button to any location in the layout. Drag a constraint from the right side of the second Button to the left side of the first, as shown in the following animated figure.
Drag another constraint from the second Button to the bottom of the layout, as shown in the following animated figure.
The Layout Editor automatically adds an 8dp margin, and as a result, the Buttons are aligned vertically. Use the Attributes pane to add the text for each Button. As you enter the character s into the text attribute field, a popup menu shows the string resources in the project so that you can select one.
After selecting an element, such as the Upload Button, enter the ID into the ID field at the top of the Attributes pane: Use a baseline constraint By using a baseline constraint, you can vertically align elements that have text, such as a TextView, EditText, or Button, so that the text baselines are aligned.
Drag a TextView from the Palette to the layout. Note that the Plain Text element uses a larger text size which makes it wider and taller than the TextView. Right click the TextView "Camera" element and select "Show baseline": Then click and drag from the TextView's baseline, which is blinking in green, to the baseline of the Plain Text element, as shown in the following animated figure: You can now add a constraint to bring the two elements closer to each other, and move them in the layout to another location—the elements move together and stay aligned: You can also use a baseline constraint to align the Button elements.
Select the Discard button right click on it and choose "Show baseline", as shown in the following animated figure: After adding the baseline constraint, the bottom constraint of the Discard button is automatically removed. You can now change the margin for the Upload button, and the Discard button will still be aligned with it.
Select the Upload button, and change the right and bottom margins to 16dp in the Attributes pane, as shown in the animated figure below. Pack elements and infer constraints In this exercise you learn how to expand an element horizontally and vertically using the Pack tool, and how to use the Infer Constraints tool. Note the following: The layout includes the header ImageView for the image of Singapore, the favorite ImageView for a star, and the Upload and Discard buttons.
To see the vertical bias, select the element and look at the view inspector's vertical slider shown in the figure below. The bottom handle of header is constrained to the bottom handle of favorite , with a margin of 16dp. The Pack tool In this exercise, you'll add a TextView for the description of the image, and expand it to fill available space. Drag a new TextView from the Palette and place it below the other text elements.
With the new TextView selected, click the Expand Horizontally tool in the Pack tool to expand the view horizontally to fill available space, as shown in the following figure: The result of expanding the text element horizontally: With the TextView selected, click the Expand Vertically tool to expand vertically to fill available vertical space.
The result of expanding the text element vertically: The TextView now fills the available space in the layout.
The Infer Constraints tool The Infer Constraints tool infers , or figures out, the constraints you need to match a rough layout of elements. The resulting layout should look like the following: Use ratios to size elements You can quickly resize elements by aspect ratio if at least one of the element's dimensions is set to match constraints. Select the ImageView and add constraints and dimensions, as shown in the figure below with the following callouts: Bottom constraint connected to the bottom of the layout with a 0 margin.
Side constraint connected to the left side of the layout with a 0 margin. Top constraint connected to the top of the layout with a 0 margin. Side constraint connected to the right side of the layout with a 0 margin. The ratio entry box appears below the bottom right corner of the square: To enable aspect ratio constraints and set your ImageView to have a aspect ratio, enter in the ratio field: You can see the entire action and result in the following animated figure: By using ratios you can ensure your designs stay perfect while allowing images to be resized on different device screens.
Use barriers to align elements that dynamically vary in size Barriers allow you to specify a constraint based on multiple UI elements. Choose German from the Language menu if it has not already been chosen, so that the app's layout appears in German. Right click on ConstraintLayout in the blueprint or the Component Tree. You will see the Add Vertical barrier and Add Horizontal barrier options.
To create a vertical line for the two TextView elements, select Add Vertical barrier to add a barrier. Create a new layout. To start a new constraint layout file, follow these steps. Caused by: www. Reason: The given artifact contains a string literal with a package reference 'www. Libraries using reflection such as annotation processors need to be updated manually to add.
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