Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * 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.actionbarsherlock.sample.hcgallery; import java.io.IOException; import java.util.List; import android.app.ActionBar; import android.app.Activity; 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.support.v4.app.Fragment; import android.support.v4.view.Menu; import android.util.Log; import android.view.LayoutInflater; import android.view.MenuInflater; import android.view.MenuItem; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.view.ViewGroup; public class CameraFragment extends Fragment { private Preview mPreview; Camera mCamera; int mNumberOfCameras; int mCameraCurrentlyLocked; // The first rear facing camera int mDefaultCameraId; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Create a RelativeLayout container that will hold a SurfaceView, // and set it as the content of our activity. mPreview = new Preview(this.getActivity()); // Find the total number of cameras available mNumberOfCameras = Camera.getNumberOfCameras(); // Find the ID of the default camera CameraInfo cameraInfo = new CameraInfo(); for (int i = 0; i < mNumberOfCameras; i++) { Camera.getCameraInfo(i, cameraInfo); if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) { 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(); // Open the default i.e. the first rear facing camera. mCamera = Camera.open(mDefaultCameraId); mCameraCurrentlyLocked = mDefaultCameraId; 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.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. mCamera = Camera.open((mCameraCurrentlyLocked + 1) % mNumberOfCameras); mCameraCurrentlyLocked = (mCameraCurrentlyLocked + 1) % mNumberOfCameras; 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); 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; 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(); requestLayout(); } } public void switchCamera(Camera camera) { setCamera(camera); try { camera.setPreviewDisplay(mHolder); } catch (IOException exception) { Log.e(TAG, "IOException caused by setPreviewDisplay()", exception); } Camera.Parameters parameters = camera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); camera.setParameters(parameters); } @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); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed && 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); } } 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(); } }