如何将进度条居中显示,就像在相对布局的父元素中居中显示Android中一样,并且如何删除警告消息。如何更改ProgressBar的可见性(不可见或已消失或可见)。
MyScreen
var ProgressBar = require('ProgressBarAndroid');
<View style={{ flex: 1, backgroundColor: 'steelblue', padding: 10, justifyContent: 'center' }}>
<Text style={{
backgroundColor: 'steelblue', justifyContent: 'center', alignItems: 'center', fontSize: 40, textAlign: 'center',
color: 'white', marginBottom: 30
}}>LOGIN</Text>
<ProgressBar style={{justifyContent:'center',alignItems:'center',styleAttr:'LargeInverse', color:'white'}} />
<View style={{ justifyContent: 'center' }}>
<TextInput
style={{ height: 50, marginLeft: 30, marginRight: 30, marginBottom: 20, color: 'white', fontSize: 20 }}
placeholder='Username' placeholderTextColor='white'
autoFocus={true}
returnKeyType='next'
keyboardType='email-address'
onChangeText={(valUsername) => _values.username = valUsername}
/>
<TextInput
secureTextEntry={true}
style={{ height: 50, marginLeft: 30, marginRight: 30, marginBottom: 20, color: 'white', fontSize: 20 }}
placeholder='Password' placeholderTextColor='white'
onChangeText={(valPassword) => _values.password = valPassword}
/>
</View>
<Button onPress={() => { _handlePress() } } label='Login' />
<View>
<Text style={{ color: 'white', justifyContent: 'center', textAlign: 'center', alignItems: 'center', fontSize: 20, textDecorationLine: 'underline', textDecorationStyle: 'solid' }}>
Forgot Password
</Text>
<Text style={{ color: 'white', marginTop: 10, justifyContent: 'center', textAlign: 'center', alignItems: 'center', fontSize: 20, textDecorationLine: 'underline', textDecorationStyle: 'solid' }}>
SignUp
</Text>
</View>
</View>