API Demos 2.2 研读笔记(5)——Window Feature

Android允许对手机屏幕的特征进行客户化,例如,客户化标题栏。如果我们想要对某一特征进行客户化,首先就要通过Window.requestFeature (int featureId) 方法进行申请。一旦申请了就不能去掉这个特征了。

Android事先为可能被客户化的特征定义了常量。

intDEFAULT_FEATURESThe default features enabled
intFEATURE_CONTEXT_MENUFlag for the context menu.
intFEATURE_CUSTOM_TITLEFlag for custom title.
intFEATURE_INDETERMINATE_PROGRESSFlag for indeterminate progress
intFEATURE_LEFT_ICONFlag for having an icon on the left side of the title bar
intFEATURE_NO_TITLEFlag for the "no title" feature, turning off the title at the top of the screen.
intFEATURE_OPTIONS_PANELFlag for the "options panel" feature.
intFEATURE_PROGRESSFlag for the progress indicator feature
intFEATURE_RIGHT_ICONFlag for having an icon on the right side of the title bar

下面以API Demo中Custom Title为例加以说明。

1. 首先创建客户化的title。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/screen"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView android:id="@+id/left_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:text="@string/custom_title_left" />
    <TextView android:id="@+id/right_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:text="@string/custom_title_right" />
</RelativeLayout>

2. 在CustomTitle.java中将客户化的title应用到activity中。

package com.example.android.apis.app;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import com.example.android.apis.R;

public class CustomTitle extends Activity {
    @Override
	protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
        setContentView(R.layout.custom_title);
        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title_1);
        
        final TextView leftText = (TextView) findViewById(R.id.left_text);
        final TextView rightText = (TextView) findViewById(R.id.right_text);
        final EditText leftTextEdit = (EditText) findViewById(R.id.left_text_edit);
        final EditText rightTextEdit = (EditText) findViewById(R.id.right_text_edit);
        Button leftButton = (Button) findViewById(R.id.left_text_button);
        Button rightButton = (Button) findViewById(R.id.right_text_button);
        
        leftButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                leftText.setText(leftTextEdit.getText());
            }
        });
        rightButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                rightText.setText(rightTextEdit.getText());
            }
        });
    }
}

 先在setContentView之前调用requestWindowFeature(Window.FEATURE_CUSTOM_TITLE),申请对标题进行客户化。然后调用getWindow().setFeatureInt将新的title应用到activity上。

客户化window feature时需要注意:

1. 要在setContentView之前调用requestFeature。由于requestWindowFeature = getWindow().requestFeature,所以调用requestWindowFeature 也可。

2. 不能将其他title相关feature与FEATURE_CUSTOM_TITLE一起使用。

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