Preview.java

package com.zzx.factorytest.view;

import java.io.IOException;
import java.util.List;

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;

/**
 * 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.
 */
public 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;

	public Preview(Context context, AttributeSet attrs) {
		super(context, attrs);

		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.
		int widthPixels = getResources().getDisplayMetrics().widthPixels;
		int heightPixels = getResources().getDisplayMetrics().heightPixels;
		if (widthMeasureSpec >= heightMeasureSpec) {

		} else {

		}
		int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
		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;
			}
			child.layout(l, t, r, b);
			// 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);
			// }
		}
	}

	@Override
	public void surfaceCreated(SurfaceHolder holder) {
		Log.d("com.zzx.factorytest.activitys", "surfaceCreated");
		// 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;
	}

	@Override
	public void surfaceDestroyed(SurfaceHolder holder) {
		Log.d("com.zzx.factorytest.activitys", "surfaceDestroyed");
		// 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;
	}

	@Override
	public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
		Log.d("com.zzx.factorytest.activitys", "surfaceChanged");
		// Now that the size is known, set up the camera parameters and begin
		// the preview.
		try {

			Camera.Parameters parameters = mCamera.getParameters();
			parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
			requestLayout();

			mCamera.setParameters(parameters);
			mCamera.startPreview();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}