android自訂相機黑屏問題

對於一些手機，像HTC，當自訂Camera時，調用Camera.Parameters的parameters.setPreviewSize(width,height)方法時，如果width和height為奇數情況下，則會出現黑屏現象，解決辦法可參考SDK提供的ApiDemos中關於Camera的例子：

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

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

同時，在HTC手機中，設定parameters.setPictureSize(width,height)屬性，也會導致黑屏，而在三星手機上則沒有問題。還有如果設定setPreviewSize屬性的寬高錯誤的話，拍出的照片也會存在失真等Bug，所以遇到適配問題時，最好的辦法就是不設定PreviewSize和PictureSize屬性。

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; }