Android项目中如何实现自定义相机预览界面

public static void setCameraDisplayOrientation(Activity activity,int cameraIo, Camera camera){

Camera.CameraInfo info=new Camera.CameraInfo();
Camera.getCameraInfo(cameraIo,info);
int rotation=activity.getWindowManager().getDefaultDisplay().getRotation();
int degress=0;
switch(rotation){
case Surface.ROTATION_0:
 degress=0;
 break;
case Surface.ROTATION_90:
 degress=90;
 break;
 case Surface.ROTATION_180:
 degress=180;
 break;
case Surface.ROTATION_270:
 degress=270;
 break;
}
int result;
if(info.facing=Camera.CameraInfo.CAMERA_FACING_FRONT){
 result = (info.orientation + degrees) % 360;
 > 就是摄像头需要顺时针转过多少度才能恢复自然方向
 result = (360 - result) % 360;
 } else { // back-facing
 result = (info.orientation - degrees + 360) % 360;
 }
 camera.setDisplayOrientation(result);
switch (result) {
 case 0:
 case 180:
 setCameraSize(camera.getParameters(),   getScreenWidth(), getScreenHeight());
 break;
 case 90:
 case 270:
 setCameraSize(camera.getParameters(),   getScreenHeight(), getScreenWidth());
  break;
}
}

public static void setCameraSize(Camera.Parameters parameters, int width, int height) {
 Map<String, List<Size>> allSizes = new HashMap<>();
 String typePreview = "typePreview";
 String typePicture = "typePicture";
 allSizes.put(typePreview, parameters.getSupportedPreviewSizes());
 allSizes.put(typePicture, parameters.getSupportedPictureSizes());
 Iterator iterator = allSizes.entrySet().iterator();
 while (iterator.hasNext()) {
  Map.Entry<String, List<Size>> entry = (Map.Entry<String, List<Size>>) iterator.next();
  List<Size> sizes = entry.getValue();
  if (sizes == null || sizes.isEmpty()) continue;
  ArrayList<WrapCameraSize> wrapCameraSizes = new ArrayList<>(sizes.size());
  for (Size size : sizes) {
  WrapCameraSize wrapCameraSize = new WrapCameraSize();
  wrapCameraSize.setWidth(size.width);
  wrapCameraSize.setHeight(size.height);
  wrapCameraSize.setD(Math.abs((size.width - width)) + Math.abs((size.height - height)));
  if (size.width == width && size.height == height) {
   if (typePreview.equals(entry.getKey())) {
   parameters.setPreviewSize(size.width, size.height);
   } else if (typePicture.equals(entry.getKey())) {
   parameters.setPictureSize(size.width, size.height);
   }
   Log.d(TAG, "best size: width=" + size.width + ";height=" + size.height);
   break;
  }
  wrapCameraSizes.add(wrapCameraSize);
  }
  Log.d(TAG, "wrapCameraSizes.size()=" + wrapCameraSizes.size());
  Size resultSize = null;
  if (typePreview.equals(entry.getKey())) {
  resultSize = parameters.getPreviewSize();
  } else if (typePicture.equals(entry.getKey())) {
  resultSize = parameters.getPictureSize();
  }
  if (resultSize == null || (resultSize.width != width && resultSize.height != height)) {
  //找到相机Preview Size 和 Picture Size中最适合的大小
  if(wrapCameraSizes.isEmpty()) continue;
  WrapCameraSize minCameraSize = Collections.min(wrapCameraSizes);
  while (!(minCameraSize.getWidth() >= width && minCameraSize.getHeight() >= height)) {
   wrapCameraSizes.remove(minCameraSize);
   if(wrapCameraSizes.isEmpty()) break;
   minCameraSize = null;
   minCameraSize = Collections.min(wrapCameraSizes);
  }
  Log.d(TAG, "best min size: width=" + minCameraSize.getWidth() + ";height=" + minCameraSize.getHeight());
  if (typePreview.equals(entry.getKey())) {
   parameters.setPreviewSize(minCameraSize.getWidth(), minCameraSize.getHeight());
  } else if (typePicture.equals(entry.getKey())) {
   parameters.setPictureSize(minCameraSize.getWidth(), minCameraSize.getHeight());
  }
  }
  iterator.remove();
 }
 }