|
前面几篇文章介绍了Camera1，Camera2，CameraView和CameraX的使用，对各个API的使用，应该问题不大，不过在真正开发过程当中，也会遇到各类不一样的问题，本篇文章继续介绍相机开发过程当中遇到的问题，主要是相机预览、拍照尺寸，方向，以及图像数据的处理。php 尺寸这里的尺寸，主要是预览尺寸、拍照尺寸和显示预览画面的View大小。html 预览尺寸如何获取预览尺寸?咱们能够从cameraview的源码中获取到，分为了Camera1和Camera2。java Camera1mCameraParameters = mCamera.getParameters();
// Supported preview sizes
mPreviewSizes.clear();
for (Camera.Size size : mCameraParameters.getSupportedPreviewSizes()) {
Log.d("DEBUG", "###### SupportedPreviewSizes: width=" + size.width + ", height="
+ size.height);
mPreviewSizes.add(new Size(size.width, size.height));
}
复制代码
Camera2mPreviewSizes.clear();
for (android.util.Size size : map.getOutputSizes(mPreview.getOutputClass())) {
int width = size.getWidth();
int height = size.getHeight();
if (width <= MAX_PREVIEW_WIDTH && height <= MAX_PREVIEW_HEIGHT) {
mPreviewSizes.add(new Size(width, height));
}
}
复制代码
不一样的厂商和系统所支持的预览尺寸是不同，下面是红米Note 5A手机上支持的全部预览尺寸：android SupportedPreviewSizes: width=1280, height=720 SupportedPreviewSizes: width=960, height=720 SupportedPreviewSizes: width=864, height=480 SupportedPreviewSizes: width=800, height=480 SupportedPreviewSizes: width=768, height=432 SupportedPreviewSizes: width=720, height=480 SupportedPreviewSizes: width=640, height=640 SupportedPreviewSizes: width=640, height=480 SupportedPreviewSizes: width=480, height=640 SupportedPreviewSizes: width=640, height=360 SupportedPreviewSizes: width=576, height=432 SupportedPreviewSizes: width=480, height=360 SupportedPreviewSizes: width=480, height=320 SupportedPreviewSizes: width=384, height=288 SupportedPreviewSizes: width=352, height=288 SupportedPreviewSizes: width=320, height=240 SupportedPreviewSizes: width=240, height=320 SupportedPreviewSizes: width=240, height=160 SupportedPreviewSizes: width=176, height=144 SupportedPreviewSizes: width=144, height=176 SupportedPreviewSizes: width=160, height=120 复制代码 这里尺寸的比例通常都是4:三、16:9，其余比例是在此基础上裁剪出来的git 选取预览尺寸在相同宽高比下，选择最接近View的宽高，避免过大的预览尺寸, 形成性能损耗, 引发预览卡顿。 Camera1private Size chooseOptimalSize(SortedSet<Size> sizes) {
if (!mPreview.isReady()) { // Not yet laid out
return sizes.first(); // Return the smallest size
}
int desiredWidth;
int desiredHeight;
final int surfaceWidth = mPreview.getWidth();
final int surfaceHeight = mPreview.getHeight();
if (isLandscape(mDisplayOrientation)) {
desiredWidth = surfaceHeight;
desiredHeight = surfaceWidth;
} else {
desiredWidth = surfaceWidth;
desiredHeight = surfaceHeight;
}
Size result = null;
for (Size size : sizes) { // Iterate from small to large
if (desiredWidth <= size.getWidth() && desiredHeight <= size.getHeight()) {
return size;
}
result = size;
}
return result;
}
复制代码
区分了横竖屏，而后获得尺寸中宽和高等于或者大于View的宽高的尺寸。app Camera2private Size chooseOptimalSize() {
int surfaceLonger, surfaceShorter;
final int surfaceWidth = mPreview.getWidth();
final int surfaceHeight = mPreview.getHeight();
if (surfaceWidth < surfaceHeight) {
surfaceLonger = surfaceHeight;
surfaceShorter = surfaceWidth;
} else {
surfaceLonger = surfaceWidth;
surfaceShorter = surfaceHeight;
}
SortedSet<Size> candidates = mPreviewSizes.sizes(mAspectRatio);
// Pick the smallest of those big enough
for (Size size : candidates) {
if (size.getWidth() >= surfaceLonger && size.getHeight() >= surfaceShorter) {
return size;
}
}
// If no size is big enough, pick the largest one.
return candidates.last();
}
复制代码
先判断View宽高，区分其中较大值和较小值，而后再获得尺寸中宽和高大于或者等于View的较大值和较小值的尺寸。post 拍照尺寸代码也是从cameraview中截取出来的性能 Camera1mPictureSizes.clear();
for (Camera.Size size : mCameraParameters.getSupportedPictureSizes()) {
Log.d("DEBUG", "###### SupportedPictureSizes: width=" + size.width + ", height="
+ size.height);
mPictureSizes.add(new Size(size.width, size.height));
}
复制代码
Camera2protected void collectPictureSizes(SizeMap sizes, StreamConfigurationMap map) {
for (android.util.Size size : map.getOutputSizes(ImageFormat.JPEG)) {
mPictureSizes.add(new Size(size.getWidth(), size.getHeight()));
}
}
复制代码
在红米Note 5A手机支持的拍照尺寸：ui SupportedPictureSizes: width=4160, height=3120 SupportedPictureSizes: width=4160, height=2340 SupportedPictureSizes: width=4096, height=3072 SupportedPictureSizes: width=4096, height=2304 SupportedPictureSizes: width=4000, height=3000 SupportedPictureSizes: width=3840, height=2160 SupportedPictureSizes: width=3264, height=2448 SupportedPictureSizes: width=3200, height=2400 SupportedPictureSizes: width=2976, height=2976 SupportedPictureSizes: width=2592, height=1944 SupportedPictureSizes: width=2592, height=1458 SupportedPictureSizes: width=2688, height=1512 SupportedPictureSizes: width=2304, height=1728 SupportedPictureSizes: width=2048, height=1536 SupportedPictureSizes: width=2336, height=1314 SupportedPictureSizes: width=1920, height=1080 SupportedPictureSizes: width=1600, height=1200 SupportedPictureSizes: width=1440, height=1080 SupportedPictureSizes: width=1280, height=960 SupportedPictureSizes: width=1280, height=768 SupportedPictureSizes: width=1280, height=720 SupportedPictureSizes: width=1200, height=1200 SupportedPictureSizes: width=1024, height=768 SupportedPictureSizes: width=800, height=600 SupportedPictureSizes: width=864, height=480 SupportedPictureSizes: width=800, height=480 SupportedPictureSizes: width=720, height=480 SupportedPictureSizes: width=640, height=480 SupportedPictureSizes: width=640, height=360 SupportedPictureSizes: width=480, height=640 SupportedPictureSizes: width=480, height=360 SupportedPictureSizes: width=480, height=320 SupportedPictureSizes: width=352, height=288 SupportedPictureSizes: width=320, height=240 SupportedPictureSizes: width=240, height=320 复制代码 这里尺寸的比例通常也是4:三、16:9 选取拍照尺寸Camaer1和Camera2都是同样的逻辑，选取固定宽高比例中的最大尺寸，这样拍摄的图片最清晰。 Size largest = mPictureSizes.sizes(mAspectRatio).last(); 复制代码 方向这里的设置方向有两种：图像预览方向和拍照方向。在这以前，须要先介绍几个概念：
屏幕坐标方向在Android系统中，以屏幕左上角为坐标系统的原点(0,0)坐标，该坐标系是固定不变的，不会由于设备方向的变化而改变。 屏幕天然方向每一个设备都有一个天然方向，手机和平板天然方向不同，如图所示，这里盗个图： OrientationEventListener监听设备方向，回调方法：
abstract public void onOrientationChanged(int orientation); 复制代码
摄像头传感器方向相机预览方向将摄像头传感器捕获的图像，显示在屏幕上的方向，就是相机预览方向。默认状况下，和摄像头传感器方向一致，能够经过Camera API进行改变。 后置对竖屏来讲，看到的图像逆时针旋转了90度，所以预览方向须要顺时针旋转90度，才能与屏幕的天然方向保持一致。 前置前置的 Camera1 private int calcDisplayOrientation(int screenOrientationDegrees) {
if (mCameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
return (360 - (mCameraInfo.orientation + screenOrientationDegrees) % 360) % 360; // compensate the mirror
} else { // back-facing
return (mCameraInfo.orientation - screenOrientationDegrees + 360) % 360;
}
}
复制代码
代码中区分了前置和后置摄像头。
Camera2 使用的TextureView的setTransform进行旋转，并有区分横竖屏。 /** * Configures the transform matrix for TextureView based on {@link #mDisplayOrientation} and * the surface size. */
void configureTransform() {
Matrix matrix = new Matrix();
if (mDisplayOrientation % 180 == 90) {
final int width = getWidth();
final int height = getHeight();
// Rotate the camera preview when the screen is landscape.
matrix.setPolyToPoly(
new float[]{
0.f, 0.f, // top left
width, 0.f, // top right
0.f, height, // bottom left
width, height, // bottom right
}, 0,
mDisplayOrientation == 90 ?
// Clockwise
new float[]{
0.f, height, // top left
0.f, 0.f, // top right
width, height, // bottom left
width, 0.f, // bottom right
} : // mDisplayOrientation == 270
// Counter-clockwise
new float[]{
width, 0.f, // top left
width, height, // top right
0.f, 0.f, // bottom left
0.f, height, // bottom right
}, 0,
4);
} else if (mDisplayOrientation == 180) {
matrix.postRotate(180, getWidth() / 2, getHeight() / 2);
}
mTextureView.setTransform(matrix);
}
复制代码
拍照方向设置预览方向并不会改变拍出照片的方向。 Camera1使用 mCameraParameters.setRotation(calcCameraRotation(displayOrientation));
......
/** * Calculate camera rotation * * This calculation is applied to the output JPEG either via Exif Orientation tag * or by actually transforming the bitmap. (Determined by vendor camera API implementation) * * Note: This is not the same calculation as the display orientation * * @param screenOrientationDegrees Screen orientation in degrees * @return Number of degrees to rotate image in order for it to view correctly. */
private int calcCameraRotation(int screenOrientationDegrees) {
if (mCameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
return (mCameraInfo.orientation + screenOrientationDegrees) % 360;
} else { // back-facing
final int landscapeFlip = isLandscape(screenOrientationDegrees) ? 180 : 0;
return (mCameraInfo.orientation + screenOrientationDegrees + landscapeFlip) % 360;
}
}
复制代码
相机采集到的图像，只须要旋转相机orientation度。 Camera2根据 // Calculate JPEG orientation.
@SuppressWarnings("ConstantConditions")
int sensorOrientation = mCameraCharacteristics.get(
CameraCharacteristics.SENSOR_ORIENTATION);
captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION,
(sensorOrientation +
mDisplayOrientation * (mFacing == Constants.FACING_FRONT ? 1 : -1) +
360) % 360);
复制代码
图像数据Android Camera默认返回的数据格式是NV21。Camera1经过 YUVYUV是一种颜色编码方法，和它相似的还有RGB颜色编码方法，主要应用于电视系统和模拟视频领域。其中YUV表明三个份量，Y 表明明亮度，U 和 V 表示的是色度，色度又定义了颜色的两个方面：色调和饱和度。将Y与UV分离，没有UV信息同样能够显示完整的图像，可是只能显示灰度图。 YUV采样格式YUV 图像的主流采样方式有以下三种：
盗个图说明比较清晰，黑点表示采样该像素点的Y份量，空心圆圈表示采用该像素点的UV份量 YUV存储格式有两种存储格式，planar和packed。
YUV格式信息能够参考：YUV pixel formats
YUVY格式YUVY格式属于packed存储格式，相邻的两个Y共用其相邻的两个U、V Y0 UO Y1 V0 Y2 U2 Y3 V2 复制代码 Y0、Y1共用 U0、V0 UYVY格式UYVY格式也属于packed存储格式，与YUYV格式不一样的是UV的排列顺序不同而已 YUV422P格式YUV422P格式属于planar存储格式，先连续存储全部像素点的Y，紧接着存储全部像素点的U，随后是全部像素点的V YV十二、YU12格式YU12和YV12格式都属于YUV420P格式，YUV420P是planar存储格式。先存储全部Y，而后在存储U、V。 NV十二、NV21格式NV十二、NV21格式YUV420SP格式，YUV420SP也是planar存储格式。先存储全部Y，而后按照UV或者VU的交替顺序进行存储。 YV21: YYYYYYYY UU VV => YUV420P YV12: YYYYYYYY VV UU => YUV420P NV12: YYYYYYYY UV UV => YUV420SP NV21: YYYYYYYY VU VU => YUV420SP 复制代码 Android Camera 默认数据格式是 NV21，Camera1直接设置 if (format == ImageFormat.NV21) {
throw new IllegalArgumentException(
"NV21 format is not supported");
}
复制代码
在最新的 YCrCb format used for images, which uses the NV21 encoding format. This is the default format for android.hardware.Camera preview images, when not otherwise set with android.hardware.Camera.Parameters.setPreviewFormat(int). For the android.hardware.camera2 API, the YUV_420_888 format is recommended for YUV output instead. 复制代码 Camera2建议使用 参考 |
|
|
