问题
I'm facing to a problem with a Samsung Galaxy Tab. I want to use the camera flash as torch.
Does anyone know how to enable it ?
Hereby a code that works to enable/disable the camera flash on a HTC Desire but fails on Samsung Galaxy Tab.
FlashLight.java :
package com.example.FlashLight;
import android.app.Activity;
import android.hardware.Camera;
import android.hardware.Camera.Parameters;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class FlashLight extends Activity {
private final static String LOG_TAG = "FlashLight";
private Button mOnBtn;
private Button mOffBtn;
private Camera mCamera;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mOnBtn = (Button) findViewById(R.id.on_btn);
mOnBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
processOnClick();
}
});
mOffBtn = (Button) findViewById(R.id.off_btn);
mOffBtn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
processOffClick();
}
});
}
@Override
protected void onResume() {
super.onResume();
try{
mCamera = Camera.open();
} catch( Exception e ){
Log.e(LOG_TAG, "Impossible d'ouvrir la camera");
}
}
@Override
protected void onPause() {
if( mCamera != null ){
mCamera.release();
mCamera = null;
}
super.onPause();
}
private void processOffClick(){
if( mCamera != null ){
Parameters params = mCamera.getParameters();
params.setFlashMode( Parameters.FLASH_MODE_OFF );
mCamera.setParameters( params );
}
}
private void processOnClick(){
if( mCamera != null ){
Parameters params = mCamera.getParameters();
params.setFlashMode( Parameters.FLASH_MODE_TORCH );
mCamera.setParameters( params );
}
}
}
AndroidManifest.xml :
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".FlashLight"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
</manifest>
layout/main.xml :
<?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"
>
<Button
android:id="@+id/on_btn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Flash ON" />
<Button
android:id="@+id/off_btn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Flash OFF" />
</LinearLayout>
Thanks !
回答1:
You aren't doing anything wrong. In fact, you are doing everything correct. You are encountering a Device-Specific issue that is very prevalent in the Android world. I have found the following behavioral patterns for FLASH_MODE_TORCH:
- Works fine in all cases
- Works fine, but not with autofocus on
- Doesn't work at all
Frustratingly, getSupportedFlashModes() will return FLASH_MODE_TORCH on nearly every device when only a handful actually support it.
Also, some device implementations swizzle the supported flash modes. If you go through Camera.Parameters you can try setting the flash mode to FLASH_MODE_ON, FLASH_MODE_AUTO or FLASH_MODE_RED_EYE and see whether any of them work. Note - this is a device-specific hack.
I have filed these types of bugs with Google regarding the DroidX and Nexus S. They closed it as a device-specific issue. I would say to report this to Samsung in hopes for a driver or firmware fix, but their Android support channels do not exist.
回答2:
Took me a while but I think you're missing a startPreview()
there.
After you do your Camera.open()
and after you set the parametrs, do a mCamera.startPreview()
. That should do the trick.
回答3:
This is how I made it work.
if (Build.MODEL.equals("GT-P1000")) {
Log.d(FlashlightActivity.TAG, "This is Samsung Galaxy Tab.");
params.setFlashMode(Parameters.FLASH_MODE_ON);
camera.setParameters(params);
camera.startPreview();
camera.autoFocus(new AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
}
});
isLEDturnedOn = true;
Log.d(FlashlightActivity.TAG, "LED turned ON.");
}
回答4:
This is how I turn on and of the torch in LG Nexus 4 and Samsung Galaxy Ace 2.
public void changeTorch() {
try {
camera = Camera.open();
// try to open the camera to turn on the torch
Camera.Parameters param = camera.getParameters();
param.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
camera.setParameters(param);
camera.startPreview(); // needed for some devices
Log.v("BSW torch", "Torch ON");
} catch (Exception e) {
// if open camera fails, try to release camera
Log.w("BSW torch", "Camera is being used trying to turn Torch OFF");
try {
camera.release();
} catch (Exception ex) {
Log.e("BSF torch", "Error releasing camera");
}
}
}
来源:https://stackoverflow.com/questions/5017455/how-to-use-camera-flash-led-as-torch-on-a-samsung-galaxy-tab