The file containing the source code shown below is located in the corresponding directory in <sdk>/samples/android-<version>/...
/*
* Copyright (C) 2011 The Android开源工程
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.hcgallery;
import android.app.ActionBar;
import android.app.Activity;
import android.app.Fragment;
import android.content.Context;
import android.content.Intent;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import java.io.IOException;
import java.util.List;
public class CameraFragment extends Fragment {
private Preview mPreview;
Camera mCamera;
int mNumberOfCameras;
int mCurrentCamera; // Camera ID currently chosen
int mCameraCurrentlyLocked; // Camera ID that's actually acquired
// The first rear facing camera
int mDefaultCameraId;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Create a container that will hold a SurfaceView for camera previews
mPreview = new Preview(this.getActivity());
// Find the total number of cameras available
mNumberOfCameras = Camera.getNumberOfCameras();
// Find the ID of the rear-facing ("default") camera
CameraInfo cameraInfo = new CameraInfo();
for (int i = 0; i < mNumberOfCameras; i++) {
Camera.getCameraInfo(i, cameraInfo);
if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
mCurrentCamera = mDefaultCameraId = i;
}
}
setHasOptionsMenu(mNumberOfCameras > 1);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Add an up arrow to the "home" button, indicating that the button will go "up"
// one activity in the app's Activity heirarchy.
// Calls to getActionBar() aren't guaranteed to return the ActionBar when called
// from within the Fragment's onCreate method, because the Window's decor hasn't been
// initialized yet. Either call for the ActionBar reference in Activity.onCreate()
// (after the setContentView(...) call), or in the Fragment's onActivityCreated method.
Activity activity = this.getActivity();
ActionBar actionBar = activity.getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return mPreview;
}
@Override
public void onResume() {
super.onResume();
// Use mCurrentCamera to select the camera desired to safely restore
// the fragment after the camera has been changed
mCamera = Camera.open(mCurrentCamera);
mCameraCurrentlyLocked = mCurrentCamera;
mPreview.setCamera(mCamera);
}
@Override
public void onPause() {
super.onPause();
// Because the Camera object is a shared resource, it's very
// important to release it when the activity is paused.
if (mCamera != null) {
mPreview.setCamera(null);
mCamera.release();
mCamera = null;
}
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
if (mNumberOfCameras > 1) {
// Inflate our menu which can gather user input for switching camera
inflater.inflate(R.menu.camera_menu, menu);
} else {
super.onCreateOptionsMenu(menu, inflater);
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.menu_switch_cam:
// Release this camera -> mCameraCurrentlyLocked
if (mCamera != null) {
mCamera.stopPreview();
mPreview.setCamera(null);
mCamera.release();
mCamera = null;
}
// Acquire the next camera and request Preview to reconfigure
// parameters.
mCurrentCamera = (mCameraCurrentlyLocked + 1) % mNumberOfCameras;
mCamera = Camera.open(mCurrentCamera);
mCameraCurrentlyLocked = mCurrentCamera;
mPreview.switchCamera(mCamera);
// Start the preview
mCamera.startPreview();
return true;
case android.R.id.home:
Intent intent = new Intent(this.getActivity(), MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP|Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
// ----------------------------------------------------------------------
/**
* A simple wrapper around a Camera and a SurfaceView that renders a centered
* preview of the Camera to the surface. We need to center the SurfaceView
* because not all devices have cameras that support preview sizes at the same
* aspect ratio as the device's display.
*/
class Preview extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "Preview";
SurfaceView mSurfaceView;
SurfaceHolder mHolder;
Size mPreviewSize;
List<Size> mSupportedPreviewSizes;
Camera mCamera;
boolean mSurfaceCreated = false;
Preview(Context context) {
super(context);
mSurfaceView = new SurfaceView(context);
addView(mSurfaceView);
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void setCamera(Camera camera) {
mCamera = camera;
if (mCamera != null) {
mSupportedPreviewSizes = mCamera.getParameters()
.getSupportedPreviewSizes();
if (mSurfaceCreated) requestLayout();
}
}
public void switchCamera(Camera camera) {
setCamera(camera);
try {
camera.setPreviewDisplay(mHolder);
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// We purposely disregard child measurements because act as a
// wrapper to a SurfaceView that centers the camera preview instead
// of stretching it.
final int width = resolveSize(getSuggestedMinimumWidth(),
widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(),
heightMeasureSpec);
setMeasuredDimension(width, height);
if (mSupportedPreviewSizes != null) {
mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width,
height);
}
if (mCamera != null) {
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
mCamera.setParameters(parameters);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (getChildCount() > 0) {
final View child = getChildAt(0);
final int width = r - l;
final int height = b - t;
int previewWidth = width;
int previewHeight = height;
if (mPreviewSize != null) {
previewWidth = mPreviewSize.width;
previewHeight = mPreviewSize.height;
}
// Center the child SurfaceView within the parent.
if (width * previewHeight > height * previewWidth) {
final int scaledChildWidth = previewWidth * height
/ previewHeight;
child.layout((width - scaledChildWidth) / 2, 0,
(width + scaledChildWidth) / 2, height);
} else {
final int scaledChildHeight = previewHeight * width
/ previewWidth;
child.layout(0, (height - scaledChildHeight) / 2, width,
(height + scaledChildHeight) / 2);
}
}
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
try {
if (mCamera != null) {
mCamera.setPreviewDisplay(holder);
}
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
if (mPreviewSize == null) requestLayout();
mSurfaceCreated = true;
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
if (mCamera != null) {
mCamera.stopPreview();
}
}
private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) w / h;
if (sizes == null)
return null;
Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
// Try to find an size match aspect ratio and size
for (Size size : sizes) {
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
continue;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
// Cannot find the one match the aspect ratio, ignore the requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
requestLayout();
mCamera.setParameters(parameters);
mCamera.startPreview();
}
}