Android 绘制聊天气泡

三角形

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <rotate
            android:fromDegrees="45"
            android:pivotX="-40%"
            android:pivotY="80%">
            <shape android:shape="rectangle">
                <size
                    android:width="@dimen/px_20"
                    android:height="@dimen/px_20" />
                <solid android:color="@color/app_line_background" />
            </shape>
        </rotate>
    </item>
</layer-list>

气泡区

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <layer-list>
            <item>
                <shape>
                    <corners android:bottomLeftRadius="@dimen/px_8" android:bottomRightRadius="@dimen/px_8" android:topRightRadius="@dimen/px_8" />
                    <solid android:color="@color/app_line_background" />
                </shape>
            </item>
        </layer-list>
    </item>
</selector>