編輯:關於android開發
(四)實現設備硬件交互與媒體交互
4.6自定義攝像頭覆蓋層
1.將Camera中的內容實時的繪制到SurfaceView中
若要自定義拍攝界面,只要重新定義surface的界面即可
以下展示全部代碼
public class PreviewActivity extends AppCompatActivity implements SurfaceHolder.Callback { Camera mCamera; SurfaceView mPreview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_preview); mPreview= (SurfaceView) findViewById(R.id.preview); assert mPreview != null; mPreview.getHolder().addCallback(this); mPreview.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); mCamera=Camera.open(); } @Override protected void onPause() { super.onPause(); mCamera.stopPreview(); } @Override protected void onDestroy() { super.onDestroy(); mCamera.release(); } @Override public void surfaceCreated(SurfaceHolder holder) { try { mCamera.setPreviewDisplay(mPreview.getHolder()); } catch (IOException e) { e.printStackTrace(); } } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { Camera.Parameters params=mCamera.getParameters(); List<Camera.Size> sizes=params.getSupportedPreviewSizes(); Camera.Size selected=sizes.get(0); params.setPreviewSize(selected.width,selected.height); mCamera.setParameters(params); mCamera.setDisplayOrientation(90); mCamera.startPreview(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { } }
2.改變拍攝方向,調用setDisplayOrientation(90)後,拍攝方向方向才會垂直顯示
mCamera.setDisplayOrientation(90);
4.12創建傾斜監聽器
1.獲取系統的SensorManager服務
mSensorManager= (SensorManager) getSystemService(SENSOR_SERVICE);
2.獲取加速度感知器
mAccelerometer=mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
3.主方法中的監聽,實時改變顏色
public void onSensorChanged(SensorEvent event) { float[] values = event.values; float x = values[0] / 10; float y = values[1] / 10; int scaleFactor; if (x > 0) { scaleFactor = (int) Math.min(x * 255, 255); mRight.setBackgroundColor(Color.TRANSPARENT); mLeft.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); } else { scaleFactor = (int) Math.min(Math.abs(x) * 255, 255); mRight.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); mLeft.setBackgroundColor(Color.TRANSPARENT); } if (y > 0) { scaleFactor = (int) Math.min(y * 255, 255); mTop.setBackgroundColor(Color.TRANSPARENT); mBottom.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); } else { scaleFactor = (int) Math.min(Math.abs(y) * 255, 255); mTop.setBackgroundColor(Color.argb(scaleFactor, 255, 0, 0)); mBottom.setBackgroundColor(Color.TRANSPARENT); } valueView.setText(String.format("X:%1$1.2f,Y:%2$1.2f,Z:%3$1.2f", values[0], values[1], values[2]));
4.分別在resume和pause中注冊和注銷
@Override protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_UI); }
@Override protected void onPause() { super.onPause(); mSensorManager.unregisterListener(this); }
5.傳感器這塊水很深,真要學的話我發現一本書叫《Android傳感器高級編程》,哪天想不開了就去看看吧。
(五)數據持久化
5.1制作首選項界面
1.以前這種用戶信息或者系統配置的界面都是自己用組件慢慢實現,原來還有個叫PreferenceActivity的東西
2.首先,樣式還是通過XML定義,在res下新建目錄xml
以下是res/xml/settings.xml的完整代碼
<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <EditTextPreference android:defaultValue="Joshua" android:key="namePref" android:summary="Tell us your name" android:title="Name" /> <CheckBoxPreference android:defaultValue="false" android:key="morePref" android:title="Enable More Settings" /> <PreferenceScreen android:dependency="morePref" android:key="moreScreen" android:title="More Settings"> <ListPreference android:defaultValue="GRN" android:entries="@array/color_names" android:entryValues="@array/color_values" android:key="colorPref" android:summary="Choose your favorite color" android:title="Favorite Color" /> <PreferenceCategory android:title="LOCATION SETTINGS"> <CheckBoxPreference android:defaultValue="true" android:key="gpsPref" android:summary="use gps to find you" android:title="Use GPS Location" /> <CheckBoxPreference android:defaultValue="true" android:key="networkPref" android:summary="use NetWork to find you" android:title="Use NetWork Location" /> </PreferenceCategory> </PreferenceScreen> </PreferenceScreen>
3.接著,讓當前activity繼承PreferenceActivity
public class SettingsActivity extends AppCompatActivity
4.最後,將xml資源與當前activity綁定
addPreferencesFromResource(R.xml.color_setting);
5.此外,還可以加載默認的首選項內容,與SharedPreferences結合起來十分完美
PreferenceManager.setDefaultValues(SettingsActivity.this, R.xml.color_setting, false);
@Override protected void onResume() { super.onResume(); SharedPreferences settings=PreferenceManager.getDefaultSharedPreferences(this); String name=settings.getString("namePref",""); boolean isMoreEnabled=settings.getBoolean("morePref",false); }
6.不過,PreferenceActivity已經完成了其歷史使命,現在Google推薦使用PreferenceFragment
很簡單,直接上源碼
@Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_settings); PreferenceManager.setDefaultValues(SettingsActivity.this, R.xml.settings, false); getFragmentManager().beginTransaction().replace(R.id.preference, new PrefsFragment()).commit(); } public static class PrefsFragment extends PreferenceFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.settings); } }
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