![]() ![]() ![]() When GridLayout’s orientation property is horizontal and a columnCount has been set (to 8 in this example) the high-water mark (shown above in red) is maintained as a separate height value for each column. Automatic Index AllocationĪs children are added to a GridLayout, it maintains a cursor position and a “high-water mark” that it uses to place widgets in cells that don’t yet have anything in them. Each widget’s layout parameters have row and column indices that together define where the widget should be placed but when either or both of these values are not specified, GridLayout supplies default values rather than throwing an exception. The second thing you may notice in the XML resources is that widgets don’t always explicitly define which cells they are to be placed in. You don’t normally need to use these with GridLayout, for reasons that are described in the API doc for GridLayout.LayoutParams. The first difference you’ll notice in these examples is the absence of the WRAP_CONTENT and MATCH_PARENT constants that normally adorn Android layout resources. Here’s a slightly simpler version of the above XML layout. Samples/ApiDemos/res/layout/grid_layout_1.xml Samples/ApiDemos/src/com/example/android/apis/view/GridLayout0.java ![]() Two examples in the samples area of the Android 4.0 SDK show typical use of the programmatic and XML APIs respectively: When it doesn’t, you’ll still generally end up with a good starting point for a two-dimensional layout. In fact, the APIs are so similar that changing a tag name from LinearLayout to GridLayout in an XML file that uses LinearLayout will often produce a similar UI without requiring any other changes. Wherever possible, GridLayout uses the same conventions as LinearLayout for all its XML API - so it should be easy to start using GridLayout if you’ve already used LinearLayout. We’ll use the words row, column, and cell in the text below as shorthand for row group, column group and cell group respectively, where groups have one or more contiguous elements. It supports both row and column spanning, which together allow a widget to occupy a rectangular range of cells that are next to each other. GridLayout uses a grid of infinitely-thin lines to separate its drawing area into: rows, columns, and cells. Now the “Email address” label can belong both to a row that is baseline-aligned, and a column that is right-aligned. To provide better support for layouts like these we have added a new layout to the Android framework: GridLayout, which can be used to solve the above problems by dividing the container’s real estate into rows and columns: These problems aren’t new to Android, or UI toolkits in general, but we’ve used them to drive our work in enriching platform support for flatter hierarchies. It’s not possible to do this with nested LinearLayouts because the label needs to be aligned with other components both horizontally and vertically. Unsuitability for design tools that support free-form editingĪ simple example of the first problem is the following form:Īs the font and the text of the “Email address” label change, we want the label to remain aligned with the baseline of the component to its right, and aligned with the right edge of the label below it. ![]() Performance problems in hierarchies that are too deep Inability to control alignment along both axes simultaneously Android Layout Tricks #1, Flattening The Stack) have highlighted drawbacks of nested layouts which fall into three basic categories: It’s often possible to take a complicated layout and break it down into a set of nested linear layouts and, provided this nesting doesn’t get too deep, this is still a good choice for many simple layouts.Ī number of posts and articles (e.g. The most commonly used class for layout in Android is LinearLayout, which allows its children to be aligned in the usual ways: along either the horizontal or vertical axes. Ice Cream Sandwich (ICS) sports two new widgets that have been designed to support the richer user interfaces made possible by larger displays: Space and GridLayout. ![]()
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