【Android Camera1】Camera1 Parameters参数详解(一)—— Size (previewpicturethumbnail)

本篇文章将对Camera1和Size相关的参数，逐个进行详细解析。在Camera1源码分析文章里、已阐述过相关源码。并提供了读取和更新Parameters的2个方法如下：
读取Parameters

  public static @Nullable Camera.Parameters getCameraParameters(@NonNull Camera camera) {
        try {
            return camera.getParameters();
        }catch (Exception e){
            return null;
        }
    }	

更新Parameters

    public static boolean setCameraParameters(@NonNull Camera camera, @NonNull Camera.Parameters parameters) {
        try {
            camera.setParameters(parameters);
            return true;
        }catch (Exception e){
            return false;
        }
    }

本篇文章涉及的具体参数如下：

Sets the image format for preview pictures.
If this is never called, the default format will be ImageFormat.NV21, which uses the NV21 encoding format.
Use getSupportedPreviewFormats to get a list of the available preview formats.
It is strongly recommended that either ImageFormat.NV21 or ImageFormat.YV12 is used, since they are supported by all camera devices.
For YV12, the image buffer that is received is not necessarily tightly packed, as there may be padding at the end of each row of pixel data, as described in ImageFormat.YV12. For camera callback data, it can be assumed that the stride of the Y and UV data is the smallest possible that meets the alignment requirements. That is, if the preview size is width x height, then the following equations describe the buffer index for the beginning of row y for the Y plane and row c for the U and V planes:
 
 yStride   = (int) ceil(width / 16.0) * 16;
 uvStride  = (int) ceil( (yStride / 2) / 16.0) * 16;
 ySize     = yStride * height;
 uvSize    = uvStride * height / 2;
 yRowIndex = yStride * y;
 uRowIndex = ySize + uvSize + uvStride * c;
 vRowIndex = ySize + uvStride * c;
 size      = ySize + uvSize * 2;
 
          
Params:
pixel_format – the desired preview picture format, defined by one of the ImageFormat constants. (E.g., ImageFormat.NV21 (default), or ImageFormat.YV12)
See Also:
ImageFormat, getSupportedPreviewFormats

默认为ImageFormat.NV21

        // Formats for setPreviewFormat and setPictureFormat.
        private static final String PIXEL_FORMAT_YUV422SP = "yuv422sp";
        private static final String PIXEL_FORMAT_YUV420SP = "yuv420sp";
        private static final String PIXEL_FORMAT_YUV422I = "yuv422i-yuyv";
        private static final String PIXEL_FORMAT_YUV420P = "yuv420p";
        private static final String PIXEL_FORMAT_RGB565 = "rgb565";
        private static final String PIXEL_FORMAT_JPEG = "jpeg";
        private static final String PIXEL_FORMAT_BAYER_RGGB = "bayer-rggb";

        private String cameraFormatForPixelFormat(int pixel_format) {
            switch(pixel_format) {
            case ImageFormat.NV16:      return PIXEL_FORMAT_YUV422SP;
            case ImageFormat.NV21:      return PIXEL_FORMAT_YUV420SP;
            case ImageFormat.YUY2:      return PIXEL_FORMAT_YUV422I;
            case ImageFormat.YV12:      return PIXEL_FORMAT_YUV420P;
            case ImageFormat.RGB_565:   return PIXEL_FORMAT_RGB565;
            case ImageFormat.JPEG:      return PIXEL_FORMAT_JPEG;
            default:                    return null;
            }
        }

        private int pixelFormatForCameraFormat(String format) {
            if (format == null)
                return ImageFormat.UNKNOWN;

            if (format.equals(PIXEL_FORMAT_YUV422SP))
                return ImageFormat.NV16;

            if (format.equals(PIXEL_FORMAT_YUV420SP))
                return ImageFormat.NV21;

            if (format.equals(PIXEL_FORMAT_YUV422I))
                return ImageFormat.YUY2;

            if (format.equals(PIXEL_FORMAT_YUV420P))
                return ImageFormat.YV12;

            if (format.equals(PIXEL_FORMAT_RGB565))
                return ImageFormat.RGB_565;

            if (format.equals(PIXEL_FORMAT_JPEG))
                return ImageFormat.JPEG;

            return ImageFormat.UNKNOWN;
        }

这里面出现了很多的格式：
YV12 YUY2 NV16 YUV422SP YUV420SP 等等；详细解释请参看：Camera理论知识和基本原理【7】图像表示方式和存储格式。

已废弃，参考【5. preview-fps-range】

 
 public void setPreviewFpsRange(int min, int max) {
     set(KEY_PREVIEW_FPS_RANGE, "" + min + "," + max);
 }

int[] previewRange = new int[2];
mCameraParameters.getPreviewFpsRange(previewRange);

public List getSupportedPreviewFpsRange() {
    String str = get(KEY_PREVIEW_FPS_RANGE + SUPPORTED_VALUES_SUFFIX);
    return splitRange(str);
}