Canonical layouts are proven, versatile layouts that provide an optimal user experience on a variety of form factors.
The canonical layouts support small screen phones as well as tablets, foldables, and ChromeOS devices. Derived from Material Design guidance, the layouts are aesthetic as well as functional.
The Android framework includes specialized components that make implementation of the layouts straightforward and reliable.
The canonical layouts create engaging, productivity‑enhancing UIs that form the foundation of great apps.
List-detail
The list-detail layout enables users to explore lists of items that have descriptive, explanatory, or other supplementary information—the item detail.
The layout divides the app window into two side-by-side panes: one for the list, one for the detail. Users select items from the list to display the item detail. Deep links in the detail reveal additional content in the detail pane.
Expanded-width displays (see Use window size classes) accommodate both the list and detail at the same time. Selection of a list item updates the detail pane to show the related content for the selected item.
Medium- and compact-width displays show either the list or the detail, depending on user interaction with the app. When just the list is visible, selection of a list item displays the detail in place of the list. When just the detail is visible, pressing the back button redisplays the list.
Configuration changes such as device orientation changes or app window size changes can change the display's window size class. A list‑detail layout responds accordingly, preserving app state:
- If an expanded-width display showing both the list and detail panes narrows to medium or compact, the detail pane remains visible and the list pane is hidden
- If a medium- or compact-width display has just the detail pane visible and the window size class widens to expanded, the list and detail are shown together, and the list indicates that the item corresponding to the content in the detail pane is selected
- If a medium- or compact-width display has just the list pane visible and widens to expanded, the list and a placeholder detail pane are shown together
List-detail is ideal for messaging apps, contact managers, file browsers, or any app where the content can be organized as a list of items that reveal additional information.
Implementation
O paradigma declarativo do Compose oferece suporte para a lógica da classe de tamanho de janela, que determina se os painéis de lista e de detalhes vão aparecer simultaneamente (quando a classe de tamanho da janela de largura for expandida) ou não (quando a classe de tamanho da janela de largura for média ou compacta).
Para garantir o fluxo de dados unidirecional, eleve todo o estado, incluindo a classe de tamanho da janela atual e os detalhes do item de lista selecionado (se houver algum). Assim, todos os elementos combináveis vão ter acesso aos dados e poderão ser renderizados corretamente.
Ao mostrar apenas o painel de detalhes em tamanhos de janela pequenos, adicione um BackHandler
para remover o painel de detalhes e mostrar apenas o painel da lista. O BackHandler não
faz parte da navegação geral do app, já que o gerenciador depende da
classe de tamanho da janela e do estado de detalhes selecionado.
Para conferir um exemplo de implementação, consulte Detalhes da lista com o Compose.
Feed
A feed layout arranges equivalent content elements in a configurable grid for quick, convenient viewing of a large amount of content.
Size and position establish relationships among the content elements.
Content groups are created by making elements the same size and positioning them together. Attention is drawn to elements by making them larger than nearby elements.
Cards and lists are common components of feed layouts.
A feed layout supports displays of almost any size because the grid can adapt from a single, scrolling column to a multi‑column scrolling feed of content.
Feeds are especially well suited for news and social media apps.
Implementation
Um feed consiste em um grande número de elementos de conteúdo em um contêiner de rolagem vertical disposto em uma grade. As listas lentas renderizam um grande número de itens de maneira eficiente em colunas ou linhas. As grades lentas renderizam itens em grades, com suporte à configuração de tamanhos e comprimentos deles.
Configure as colunas do layout de grade com base na área de exibição disponível para definir a largura mínima permitida para itens da grade. Ao definir itens de grade, ajuste o tamanho das colunas para enfatizar alguns itens em detrimento de outros.
Para cabeçalhos de seção, divisores ou outros itens criados para ocupar a largura total
do feed, use maxLineSpan para ocupar a largura total do layout.
Em telas de largura compacta que não têm espaço suficiente para mostrar mais de uma
coluna, o LazyVerticalGrid se comporta como uma LazyColumn.
Para conferir um exemplo de implementação, consulte o exemplo Feed com Compose.
Supporting pane
Supporting pane layout organizes app content into primary and secondary display areas.
The primary display area occupies the majority of the app window (typically about two thirds) and contains the main content. The secondary display area is a pane that takes up the remainder of the app window and presents content that supports the main content.
Supporting pane layouts work well on expanded-width displays (see Use window size classes) in landscape orientation. Medium- or compact‑width displays support showing both the primary and secondary display areas if the content is adaptable to narrower display spaces, or if the additional content can be initially hidden in a bottom or side sheet accessible by means of a control such as a menu or button.
A supporting pane layout differs from a list‑detail layout in the relationship of the primary and secondary content. Secondary pane content is meaningful only in relation to the primary content; for example, a supporting pane tool window is irrelevant by itself. The supplementary content in the detail pane of a list‑detail layout, however, is meaningful even without the primary content, for example, the description of a product from a product listing.
Use cases for supporting pane include:
- Productivity apps: A document or spreadsheet accompanied by reviewer comments in a supporting pane
- Media apps: A streaming video complemented by a list of related videos in a supporting pane, or the depiction of an album of music supplemented with a playlist
- Search and reference apps: A query input form with results in a supporting pane
Implementation
O Compose oferece suporte para a lógica de classe de tamanho de janela, o que permite determinar se o conteúdo principal e o de suporte vão aparecer ao mesmo tempo ou se o conteúdo de suporte vai ser colocado em um local alternativo.
Eleve todo o estado, incluindo a classe de tamanho de janela atual e informações relacionadas aos dados no conteúdo principal e de suporte.
Para telas de largura compacta, coloque o conteúdo de suporte abaixo do conteúdo principal ou dentro de uma página inferior. Para larguras médias e expandidas, posicione o conteúdo de apoio ao lado do conteúdo principal, dimensionado de acordo com o conteúdo e o espaço disponível. Para largura média, divida o espaço de exibição igualmente entre o conteúdo principal e o de suporte. Para largura expandida, forneça 70% do espaço para o conteúdo principal, 30% para o conteúdo de suporte.
Para conferir um exemplo de implementação, consulte o exemplo Painel de suporte com o Compose.
Additional resources
- Material Design — Canonical layouts