Android Camera Check findBestPreviewSizeValue( Camera.Parameters parameters, Point screenResolution)

Description

find Best Preview Size Value

License

Apache License

Declaration

public static Point findBestPreviewSizeValue(
            Camera.Parameters parameters, Point screenResolution) 

Method Source Code

//package com.java2s;
/*/*  w w  w.  j  av a2 s . com*/
 * Copyright (C) 2014 ZXing authors
 *
 * 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.
 */

import android.graphics.Point;

import android.hardware.Camera;

import android.util.Log;
import java.util.ArrayList;

import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

public class Main {
    private static final String TAG = "CameraConfiguration";
    private static final int MIN_PREVIEW_PIXELS = 480 * 320;
    private static final double MAX_ASPECT_DISTORTION = 0.15;

    public static Point findBestPreviewSizeValue(
            Camera.Parameters parameters, Point screenResolution) {

        List<Camera.Size> rawSupportedSizes = parameters
                .getSupportedPreviewSizes();
        if (rawSupportedSizes == null) {
            Log.w(TAG,
                    "Device returned no supported preview sizes; using default");
            Camera.Size defaultSize = parameters.getPreviewSize();
            if (defaultSize == null) {
                throw new IllegalStateException(
                        "Parameters contained no preview size!");
            }
            return new Point(defaultSize.width, defaultSize.height);
        }

        // Sort by size, descending
        List<Camera.Size> supportedPreviewSizes = new ArrayList<>(
                rawSupportedSizes);
        Collections.sort(supportedPreviewSizes,
                new Comparator<Camera.Size>() {
                    @Override
                    public int compare(Camera.Size a, Camera.Size b) {
                        int aPixels = a.height * a.width;
                        int bPixels = b.height * b.width;
                        if (bPixels < aPixels) {
                            return -1;
                        }
                        if (bPixels > aPixels) {
                            return 1;
                        }
                        return 0;
                    }
                });

        if (Log.isLoggable(TAG, Log.INFO)) {
            StringBuilder previewSizesString = new StringBuilder();
            for (Camera.Size supportedPreviewSize : supportedPreviewSizes) {
                previewSizesString.append(supportedPreviewSize.width)
                        .append('x').append(supportedPreviewSize.height)
                        .append(' ');
            }
            Log.i(TAG, "Supported preview sizes: " + previewSizesString);
        }

        double screenAspectRatio = (double) screenResolution.x
                / (double) screenResolution.y;

        // Remove sizes that are unsuitable
        Iterator<Camera.Size> it = supportedPreviewSizes.iterator();
        while (it.hasNext()) {
            Camera.Size supportedPreviewSize = it.next();
            int realWidth = supportedPreviewSize.width;
            int realHeight = supportedPreviewSize.height;
            if (realWidth * realHeight < MIN_PREVIEW_PIXELS) {
                it.remove();
                continue;
            }

            boolean isCandidatePortrait = realWidth < realHeight;
            int maybeFlippedWidth = isCandidatePortrait ? realHeight
                    : realWidth;
            int maybeFlippedHeight = isCandidatePortrait ? realWidth
                    : realHeight;
            double aspectRatio = (double) maybeFlippedWidth
                    / (double) maybeFlippedHeight;
            double distortion = Math.abs(aspectRatio - screenAspectRatio);
            if (distortion > MAX_ASPECT_DISTORTION) {
                it.remove();
                continue;
            }

            if (maybeFlippedWidth == screenResolution.x
                    && maybeFlippedHeight == screenResolution.y) {
                Point exactPoint = new Point(realWidth, realHeight);
                Log.i(TAG,
                        "Found preview size exactly matching screen size: "
                                + exactPoint);
                return exactPoint;
            }
        }

        // If no exact match, use largest preview size. This was not a great idea on older devices because
        // of the additional computation needed. We're likely to get here on newer Android 4+ devices, where
        // the CPU is much more powerful.
        if (!supportedPreviewSizes.isEmpty()) {
            Camera.Size largestPreview = supportedPreviewSizes.get(0);
            Point largestSize = new Point(largestPreview.width,
                    largestPreview.height);
            Log.i(TAG, "Using largest suitable preview size: "
                    + largestSize);
            return largestSize;
        }

        // If there is nothing at all suitable, return current preview size
        Camera.Size defaultPreview = parameters.getPreviewSize();
        if (defaultPreview == null) {
            throw new IllegalStateException(
                    "Parameters contained no preview size!");
        }
        Point defaultSize = new Point(defaultPreview.width,
                defaultPreview.height);
        Log.i(TAG, "No suitable preview sizes, using default: "
                + defaultSize);
        return defaultSize;
    }
}

Related

1. checkCameraHardware(Context context)
2. checkFrontCamera(Context context)
3. deviceHasCamera(Context context)
4. sizeSupported(Camera.Parameters cp, CamcorderProfile profile)
5. hasFlash(Camera mCamera)