Android 简单定制OptionMenu外观

《Android内核剖析》第8章笔记

1. 分析

1.1 主要类

1.2 主要流程

1.3 关键代码

 

    private void openPanel(PanelFeatureState st, KeyEvent event) {
        // System.out.println("Open panel: isOpen=" + st.isOpen);

        // Already open, return
        if (st.isOpen) {
            return;
        }

        Callback cb = getCallback();
        if ((cb != null) && (!cb.onMenuOpened(st.featureId, st.menu))) {
            // Callback doesn't want the menu to open, reset any state
            closePanel(st, true);
            return;
        }

        final WindowManager wm = getWindowManager();
        if (wm == null) {
            return;
        }

        // Prepare panel (should have been done before, but just in case)
        if (!preparePanel(st, event)) {
            return;
        }
        ....

 

 

    public final boolean preparePanel(PanelFeatureState st, KeyEvent event) {
        // Already prepared (isPrepared will be reset to false later)
        if (st.isPrepared)
            return true;

        if ((mPreparedPanel != null) && (mPreparedPanel != st)) {
            // Another Panel is prepared and possibly open, so close it
            closePanel(mPreparedPanel, false);
        }

        final Callback cb = getCallback();

        if (cb != null) {
            st.createdPanelView = cb.onCreatePanelView(st.featureId);
        }

        if (st.createdPanelView == null) {
            // Init the panel state's menu--return false if init failed
            if (st.menu == null) {
                if (!initializePanelMenu(st) || (st.menu == null)) {
                    return false;
                }
                // Call callback, and return if it doesn't want to display menu
                if ((cb == null) || !cb.onCreatePanelMenu(st.featureId, st.menu)) {
                    // Ditch the menu created above
                    st.menu = null;

                    return false;
                }
            }

            // Callback and return if the callback does not want to show the menu
            if (!cb.onPreparePanel(st.featureId, st.createdPanelView, st.menu)) {
                return false;
            }

            // Set the proper keymap
            KeyCharacterMap kmap = KeyCharacterMap.load(event != null ? event.getDeviceId() : 0);
            st.qwertyMode = kmap.getKeyboardType() != KeyCharacterMap.NUMERIC;
            st.menu.setQwertyMode(st.qwertyMode);
        }

        // Set other state
        st.isPrepared = true;
        st.isHandled = false;
        mPreparedPanel = st;

        return true;
    }

 根据Callback 也即Activity的onCreatePanelView()方法的返回结果， 导致preparePanel返回不同的布尔值， 最终影响openPanel()方法的执行路径 。若返回false， 表示使用完全自定义的OptionMenu视图，openPanel()直接退出；否则使用系统的OptionMenu视图。

 

所以， 可以重写Activity的onCreatePanelView()方法提供一个完全自定义的OptionMenu视图

2. 示例

1. Java代码。 重写Activity的onCreatePanelView()方法。 

 

 

public class CustomOptionMenuActivity extends Activity {

	@Override
	public View onCreatePanelView(int featureId) {
		// return super.onCreatePanelView(featureId);

		View v = getLayoutInflater().inflate(
				R.layout.activity_custom_option_menu, null);

		v.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				MyLog.i("");
				Toast.makeText(CustomOptionMenuActivity.this, "text",
						Toast.LENGTH_SHORT).show();
				CustomOptionMenuActivity.this.finish();
			}
		});
		return v;
	}
}

 

2. 布局文件

 

 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:orientation="vertical" android:layout_width="fill_parent"
	android:layout_height="fill_parent">
	<TextView android:text="TextView" android:id="@+id/textView1"
		android:layout_width="wrap_content" android:layout_height="wrap_content"
		android:paddingBottom="10dip"></TextView>
</LinearLayout>

 

3. 截图

 

 

如上图， 点击Menu键后， 出现一个自定义OptionMenu。