我没有找到任何方法来裁剪相机预览，然后在Surface View上显示它。
Android - 可以裁剪相机预览吗？
以编程方式滚动图像的代码将是这样的：
public void setCameraOrientationOnOpen()
{
mCamera.stopPreview();
int rotation = getRotation();
Camera.Parameters currentCameraParameters = mCamera.getParameters();
List<Camera.Size> previewSizes = currentCameraParameters.getSupportedPreviewSizes();
mOptimalCameraSize = getOptimaPreviewCameraSize(previewSizes, (double)9/16);
currentCameraParameters.setPreviewSize(mOptimalCameraSize.width, mOptimalCameraSize.height);
mCamera.setParameters(currentCameraParameters);
float ratio = 100;
int ratio1 = (mSurfaceView.getLayoutParams().height * 100) / mOptimalCameraSize.width; //height
int ratio2 = (mSurfaceView.getLayoutParams().width * 100) / mOptimalCameraSize.height; //width
ratio = Math.max(ratio1, ratio2);
mSurfaceView.getLayoutParams().height = (int) ((mOptimalCameraSize.width * ratio) / 100);
mSurfaceView.getLayoutParams().width = (int) ((mOptimalCameraSize.height * ratio) / 100);
if(ratio > 100)
{
int offset = (mSurfaceView.getLayoutParams().height - mBoxHeight)/2;
mScrollView.scrollTo(0, offset); //center the image
}
mCamera.setDisplayOrientation(rotation);
mOptimalCameraSize = mCamera.getParameters().getPreviewSize();
}
我从相机为我的相机内容框（比例16：9）计算最佳预览尺寸，然后将计算出的比率应用于图像以保持相同的比例并最终计算所需的滚动（图像将在中间）
创建一个居中的Frame Layout，它将存储Camera Preview并用Views覆盖它以“裁剪”它。创建视图时，动态拉伸也居中的透明视图。
XML：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000" >
<FrameLayout
android:id="@+id/camera_preview_frame"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_centerVertical="true" />
<View
android:id="@+id/transparent_window"
android:layout_width="fill_parent"
android:layout_height="50dip"
android:layout_centerVertical="true"
android:background="@android:color/transparent" />
<View
android:id="@+id/black_top_box"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_above="@id/transparent_window"
android:background="#000"/>
<View
android:id="@+id/black_bottom_box"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="@id/transparent_window"
android:background="#000"/>
</RelativeLayout>
然后在活动类的OnCreate（）方法中，可以像这样拉伸透明视图。
camera activity.Java
final View transView = findViewById(R.id.transparent_window);
transView.post(new Runnable() {
@Override
public void run() {
RelativeLayout.LayoutParams params;
params = (RelativeLayout.LayoutParams) transView.getLayoutParams();
params.height = transView.getWidth();
transView.setLayoutParams(params);
transView.postInvalidate();
}
});
这是我手机上的screenshot。中间的灰色斑点是通过透明视图的相机对地板的视图
这是一个面向orientation = landscape的解决方案，可以完成@drees的优秀答案。
只需在res文件夹中添加layout-land文件夹，复制整个布局xml并将@drees代码的布局部分更改为：
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/background_dark" >
<FrameLayout
android:id="@+id/frameSurface"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:background="@android:color/background_light"/>
<View
android:id="@+id/transparent_window"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_centerInParent="true"
android:background="@android:color/transparent" />
<View
android:id="@+id/black_top_box"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toLeftOf="@id/transparent_window"
android:background="@android:color/background_dark"/>
<View
android:id="@+id/black_bottom_box"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_toRightOf="@id/transparent_window"
android:background="@android:color/background_dark"/>
</RelativeLayout>
这种解决方案是针对您的情况的更多解决方案之一。有些代码已被弃用，不建议在企业项目中使用，但如果您只是需要显示相机预览而不会挤压它就足够了。 如果你在预览之前需要处理图像，那么你应该看看SurfaceTexture
public class CameraPreview
extends SurfaceView
implements SurfaceHolder.Callback, Camera.PreviewCallback {
public static final String TAG = CameraPreview.class.getSimpleName();
private static final int PICTURE_SIZE_MAX_WIDTH = 1280;
private static final int PREVIEW_SIZE_MAX_WIDTH = 640;
private static final double ASPECT_RATIO = 3.0 / 4.0;
private Camera mCamera;
private SurfaceHolder mHolder;
private boolean mIsLive;
private boolean mIsPreviewing;
public CameraPreview(Context context) {
super(context);
init(context);
}
public CameraPreview(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public CameraPreview(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = (int) (width / ASPECT_RATIO + 0.5);
setMeasuredDimension(width, height);
}
@Override
protected void onVisibilityChanged(@NonNull View changedView, int visibility) {
super.onVisibilityChanged(changedView, visibility);
//L.g().d(TAG, "onVisibilityChanged: visibility=" + visibility);
if (mIsLive) {
if (visibility == VISIBLE && !mIsPreviewing) {
startCameraPreview();
} else {
stopCameraPreview();
}
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
startCamera();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
stopCamera();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
//L.g().d(TAG, "surfaceChanged: format=" + format + ", width=" + w + ", height=" + h);
if (mHolder.getSurface() == null || mCamera == null) return;
mHolder = holder;
try {
mCamera.stopPreview();
} catch (Exception ignored) {}
try {
mCamera.setPreviewDisplay(mHolder);
if (mIsLive && mIsPreviewing) mCamera.startPreview();
} catch (Exception ignored) {}
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
//work with camera preview
if (mIsPreviewing) camera.setOneShotPreviewCallback(this);
}
private Camera.Size determineBestPreviewSize(Camera.Parameters parameters) {
return determineBestSize(parameters.getSupportedPreviewSizes(), PREVIEW_SIZE_MAX_WIDTH);
}
private Camera.Size determineBestPictureSize(Camera.Parameters parameters) {
return determineBestSize(parameters.getSupportedPictureSizes(), PICTURE_SIZE_MAX_WIDTH);
}
/**
* This code I found in this repository
* https://github.com/boxme/SquareCamera/blob/master/squarecamera/src/main/java/com/desmond/squarecamera/CameraFragment.java#L368
*/
private Camera.Size determineBestSize(List<Camera.Size> sizes, int widthThreshold) {
Camera.Size bestSize = null;
Camera.Size size;
int numOfSizes = sizes.size();
for (int i = 0; i < numOfSizes; i++) {
size = sizes.get(i);
boolean isDesireRatio = (size.width / 4) == (size.height / 3);
boolean isBetterSize = (bestSize == null) || size.width > bestSize.width;
if (isDesireRatio && isBetterSize) {
bestSize = size;
}
}
if (bestSize == null) {
return sizes.get(sizes.size() - 1);
}
return bestSize;
}
private void init(Context context) {
mHolder = getHolder();
mHolder.addCallback(this);
}
public void startCamera() {
if (!mIsLive) {
//L.g().d(TAG, "startCamera");
mIsPreviewing = false;
mCamera = Camera.open();
if (mCamera != null) {
try {
Camera.Parameters param = mCamera.getParameters();
Camera.Size bestPreviewSize = determineBestPreviewSize(param);
Camera.Size bestPictureSize = determineBestPictureSize(param);
param.setPreviewSize(bestPreviewSize.width, bestPreviewSize.height);
param.setPictureSize(bestPictureSize.width, bestPictureSize.height);
mCamera.setParameters(param);
} catch (RuntimeException ignored) {}
try {
mCamera.setDisplayOrientation(90);
mCamera.setPreviewCallback(this);
mCamera.setPreviewDisplay(mHolder);
mIsLive = true;
} catch (Exception ignored) {}
}
//else L.g().d(TAG, "startCamera: error launching the camera");
}
}
public void stopCamera() {
if (mCamera != null && mIsLive) {
//L.g().d(TAG, "stopCamera");
mCamera.stopPreview();
mCamera.release();
mCamera = null;
mIsPreviewing = false;
mIsLive = false;
}
}
public void startCameraPreview() {
if (mCamera != null && mIsLive && !mIsPreviewing) {
//L.g().d(TAG, "startCameraPreview");
mCamera.setPreviewCallback(this);
mCamera.startPreview();
mIsPreviewing = true;
}
}
public void stopCameraPreview() {
if (mCamera != null && mIsLive && mIsPreviewing) {
//L.g().d("stopCameraPreview");
mCamera.stopPreview();
mIsPreviewing = false;
}
}
}
经过大量的关注，我相信我需要在这里发布我的解决方案。
我唯一能做到的，它运作良好的是增加一个规模。
我想用相机输出的一部分创建一个纹理视图，但是如果不让预览得到破坏，我就无法做到这一点。
所以在我决定相机/屏幕比率开始捕捉的最佳分辨率后，我得到相机捕捉高度和我想要显示的高度之间的比例。
mPreviewSize = chooseOptimalSize(...);
int viewHeight = getDP(this, R.dimen.videoCaptureHeight);
float scaleY = mPreviewSize.getHeight() / viewHeight;
setScaleY(scaleY);
假设你的Rect或RecF在这里是你的计算
float imageWidth = bitmap.Width;
float imageHeight = bitmap.Height;
float width = yourscreenWidth;
float heigth = yourscreenHeight ;
var W= width / heigth / (imageWidth / imageHeight);
var W2 = rect.Width() / widt * W;
var H = rect.Height() / heigth;
var cropImageWidth = imageWidth * W2 ;
var cropImageHeight = imageHeight * H ;
var cropImageX = (imageWidth - cropImageWidth) / 2;
var cropImageY = (imageHeight - cropImageHeight) / 2;
Bitmap imageCropped = Bitmap.CreateBitmap(bitmap, (int)cropImageX, (int)cropImageY, (int)cropImageWidth, (int)cropImageHeight);