This sample shows how to draw a rounded corner background on text. It supports the following cases:
Depending on the position of the text, we need to draw four different drawables as text backgrounds:
The four drawables that need to be drawn depending on the position of the text:
To position the background, we need to:
All of these can be computed based on the text Layout. To render the background behind the text we need access to the Canvas. A custom TextView has access to all of the information necessary to position the drawables and render them.
Our solution involves splitting our problem into 4 parts and creating classes dealing with them individually:
TextRoundedBgHelper
TextRoundedBgAttributeReader
TextRoundedBgHelper
interface and its implementations: SingleLineRenderer
and MultiLineRenderer
RoundedBgTextView
, a class that extends AppCompatTextView
, reads the attributes with the help of TextRoundedBgAttributeReader
, overrides onDraw
where it uses TextRoundedBgHelper
to draw the background.Clone this repository, enter the top level directory and run ./gradlew tasks
to get an overview of all the tasks available for this project.
Some important tasks are:
assembleDebug - Assembles all Debug builds.
installDebug - Installs the Debug build.
connectedAndroidTest - Installs and runs the tests for Debug build on connected
devices.
test - Run all unit tests.
If you've found an error in this sample, please file an issue: https://github.com/googlesamples/android-text/issues
Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub.
Copyright 2018 The Android Open Source Project
Licensed to the Apache Software Foundation (ASF) under one or more contributor
license agreements. See the NOTICE file distributed with this work for
additional information regarding copyright ownership. The ASF licenses this
file to you under the Apache License, Version 2.0 (the "License"); you may not
use this file except in compliance with the License. You may obtain a copy of
the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations under
the License.