Camera黑屏问题

对于一些手机，像HTC，当自定义Camera时，调用Camera.Parameters的 parameters.setPreviewSize(width, height)方法时，如果width和height为奇数情况下，则会出现黑屏现象，解决办法可参考SDK提供的ApiDemos中关于Camera的 例子：

List<Size> sizes = parameters.getSupportedPreviewSizes();

Size optimalSize = getOptimalPreviewSize(sizes, w, h); parameters.setPreviewSize(optimalSize.width, optimalSize.height);

同时，在HTC手机中，设置parameters.setPictureSize(width,height)属性，也会导致黑屏，而在三星手机上则没有问题。还有如果设置setPreviewSize属性的宽高错误的话，拍出的照片也会存在失真等Bug，所以遇到适配问题时，最好的办法就是不设置PreviewSize和PictureSize属性。

getOptimalPreviewSize方法

private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {   final double ASPECT_TOLERANCE = 0.05;   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; }