一直想知道微信那个全屏相机是怎么实现的，网上我也搜了很多博客，都不能准确的还原，主要是在全面屏上，会拉伸变形。那全屏实现不了，那就实现伪全屏吧。什么是伪全屏？就是寻找最合适的比例显示相机画面。
先看看效果，在普通的手机上，小米6
可以看到是没有问题的，因为小米6的相机支持的预览尺寸有16：9，而他的屏幕也是16：9 ，所以是刚好可以全屏显示。
下面再来看看小米9，全面屏手机
可以看到，相机的画面没有变形，但是底部却留了一部分黑色。为什么呢？因为小米9支持的预览尺寸是16：9，但屏幕却是18：9，背景设置为黑色，底部就会留有一块黑色，但貌似影响不是很大，因为平时原生的相机，也是有一块黑色的，也是不会全屏。
然后，在三星S9上面，相机是支持18：9的尺寸的，所以，在三星上会完美全屏显示。
实现原理
1、自定义一个view，继承SurfaceView，获取这个view的宽高比
float widthSize = getMeasuredWidth();
float heightSize = getMeasuredHeight();
float screenProp = heightSize / widthSize;
2、然后获取相机支持的预览尺寸previewSize和拍摄尺寸pictureSize，先进行尺寸的排序，从小到大排列。然后循环进行比较，如果宽度大于设置的最小宽度（建议1000以上，不然图片尺寸过小会模糊），并且宽高比和view的宽高比最接近的，那我们就拿这个尺寸来显示。
private Camera.Size getBestSize(List list, int th, float rate) {
Collections.sort(list, sizeComparator);
float previewDisparity = 100;
int index = 0;
for (int i = 0; i < list.size(); i++) {
Camera.Size cur = list.get(i);
float prop = (float) cur.width / (float) cur.height;
if (Math.abs(rate - prop) < previewDisparity && cur.height > th) {
previewDisparity = Math.abs(rate - prop);
index = i;
}
}
Log.i("---", "MakeSure Picture and preview :w = " + list.get(index).width + " h = " + list.get(index).height);
return list.get(index);
}
3、设置完尺寸，接下来，就是改变这个view的高度
float prevewProp = (float) previewSize.width / (float) previewSize.height;
final ViewGroup.LayoutParams params = getLayoutParams();
params.height = (int) (widthSize * prevewProp);
post(new Runnable() {
@Override
public void run() {
setLayoutParams(params);
}
});
4、主要就是以上步骤，其他的拍照，看看下面全部代码吧。
package com.linghit.aicamera.lib;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import static android.graphics.Bitmap.createBitmap;
/**
* DATE : 2019-06-24
* NAME : 景天
* 伪全屏相机
*/
public class FullCameraView extends SurfaceView {
private Camera camera;
//默认开启后置摄像头
private boolean isBackCamera = true;
private CameraSizeComparator sizeComparator = new CameraSizeComparator();
public FullCameraView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
SurfaceHolder mSurfaceHolder = getHolder();
mSurfaceHolder.setFormat(PixelFormat.TRANSPARENT);
mSurfaceHolder.setKeepScreenOn(true);
mSurfaceHolder.addCallback(mSurfaceCallback);
}
public void takePhoto(final TakePhotoCallback takePhotoCallback) {
camera.takePicture(null, null, new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
//进行拍照操作
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
Matrix matrix = new Matrix();
if (isBackCamera) {
matrix.setRotate(90);
} else {
matrix.setRotate(270);
//前置摄像头，镜像水平翻转
matrix.postScale(-1, 1);
}
bitmap = createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
if (takePhotoCallback != null) {
takePhotoCallback.onFinish(bitmap);
}
}
});
}
public void onDestroy() {
if (camera != null) {
camera.release();
}
}
/**
* 切换前后摄像头
*/
public void changeCamera() {
int cameraCount = 0;
//得到摄像头的个数，大于1才能切换
cameraCount = Camera.getNumberOfCameras();
if (cameraCount > 1) {
camera.setPreviewCallback(null);
camera.stopPreview();
camera.release();
camera = null;
isBackCamera = !isBackCamera;
openCamera(getHolder());
}
}
public interface TakePhotoCallback {
void onFinish(Bitmap bitmap);
}
private SurfaceHolder.Callback mSurfaceCallback = new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
openCamera(surfaceHolder);
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
if (camera != null) {
camera.stopPreview();
camera.release();
}
}
};
private void openCamera(SurfaceHolder surfaceHolder) {
try {
if (isBackCamera) {
camera = Camera.open(0);
} else {
camera = Camera.open(1);
}
final Camera.Parameters parameters = camera.getParameters();
parameters.setJpegQuality(100);
float widthSize = getMeasuredWidth();
float heightSize = getMeasuredHeight();
float screenProp = heightSize / widthSize;
//设置尺寸，第二个参数为最小尺寸，为了图片清晰度，所以要给一个最小的尺寸
Camera.Size previewSize = getBestSize(parameters.getSupportedPreviewSizes(), 1000, screenProp);
Camera.Size pictureSize = getBestSize(parameters.getSupportedPictureSizes(), 1400, screenProp);
parameters.setPreviewSize(previewSize.width, previewSize.height);
parameters.setPictureSize(pictureSize.width, pictureSize.height);
List focusModes = parameters.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);
}
camera.setParameters(parameters);
camera.setDisplayOrientation(90);
camera.setPreviewDisplay(surfaceHolder);
camera.startPreview();
float prevewProp = (float) previewSize.width / (float) previewSize.height;
final ViewGroup.LayoutParams params = getLayoutParams();
params.height = (int) (widthSize * prevewProp);
post(new Runnable() {
@Override
public void run() {
setLayoutParams(params);
}
});
} catch (Exception e) {
Log.e("surfaceCreated", e.toString());
}
}
private Camera.Size getBestSize(List list, int th, float rate) {
Collections.sort(list, sizeComparator);
float previewDisparity = 100;
int index = 0;
for (int i = 0; i < list.size(); i++) {
Camera.Size cur = list.get(i);
float prop = (float) cur.width / (float) cur.height;
if (Math.abs(rate - prop) < previewDisparity && cur.height > th) {
previewDisparity = Math.abs(rate - prop);
index = i;
}
}
Log.i("---", "MakeSure Picture and preview :w = " + list.get(index).width + " h = " + list.get(index).height);
return list.get(index);
}
private class CameraSizeComparator implements Comparator {
public int compare(Camera.Size lhs, Camera.Size rhs) {
if (lhs.width == rhs.width) {
return 0;
} else if (lhs.width > rhs.width) {
return 1;
} else {
return -1;
}
}
}
}