我的解决方案更像是构建一个方形蒙版，然后将其放置在预览表面上。
您主要需要三样东西，首先是一个方形框架组件。我制作了一个自定义组件：
package com.example.squaredviewer;
import android.content.Context;
import android.util.AttributeSet;
import android.view.Display;
import android.view.WindowManager;
import android.widget.RelativeLayout;
/**
* Created by yadirhb on 14-08-2015.
*/
public class SquaredFrame extends RelativeLayout{
public SquaredFrame(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int size = Math.min(getMeasuredWidth(), getMeasuredHeight());
setMeasuredDimension(size, size);
}
}
根据您正在开发的 Android API 版本，您可能需要添加另一个构造函数重载。对于 Kitkat 来说，这很好。
第二步是构建布局：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:visibility="visible">
<RelativeLayout
android:id="@+id/camera_preview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="false"
android:layout_alignParentTop="false"
android:layout_centerInParent="true"
android:background="#ffffff">
</RelativeLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="#131008">
</LinearLayout>
<com.example.squaredviewer.SquaredFrame
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"></com.example.squaredviewer.SquaredFrame>
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="#131008" />
</LinearLayout>
</RelativeLayout>
请注意，RelativeLayout“camera_preview”是用于渲染预览的，它居中并且有一个包含平方组件的 LinearLayout。这实际上是“蒙版”，它覆盖了相机预览。另请注意，除了透明的 SquaredFrame 之外，其他两个都是黑色的背景色。
现在是表面视图，用于根据纵横比调整表面大小的相机预览。
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private final String TAG = "PIC-FRAME";
private SurfaceHolder mHolder;
private Camera mCamera;
private Display display;
public CameraPreview(Activity context, Camera camera) {
super(context);
mCamera = camera;
display = ((WindowManager) context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = getHolder();
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
setKeepScreenOn(true);
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
this.getHolder().removeCallback(this);
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (mHolder.getSurface() == null) {
// preview surface does not exist
return;
}
try {
// stop preview before making changes
mCamera.stopPreview();
// set preview size and make any resize, rotate or
// reformatting changes here
// Now that the size is known, set up the camera parameters and begin
// the preview.
Camera.Parameters parameters = mCamera.getParameters();
// You need to choose the most appropriate previewSize for your app
Camera.Size previewSize = parametes.getSupportedPreviewSizes().get(0);
parameters.setPreviewSize(previewSize.width, previewSize.height);
// start preview with new settings
mCamera.setParameters(parameters);
// Set the holder size based on the aspect ratio
int size = Math.min(display.getWidth(), display.getHeight());
double ratio = (double) previewSize.width / previewSize.height;
mHolder.setFixedSize((int)(size * ratio), size);
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (Exception e) {
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
}
现在一切都必须绑定在活动类中
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_picture_taker);
mDecorView = getWindow().getDecorView();
//mCamera = a camera instance;
// Create our Preview view and set it as the content of our activity.
mPreview = new CameraPreview(this, mCamera);
//Layout where camera preview is shown.
RelativeLayout preview = (RelativeLayout) findViewById(R.id.camera_preview);
//FrameLayout stack controllers inside and superpose them.
preview.addView(mPreview, 0);
// TODO
}
有点长，但我希望它对不止一个人有帮助。:-)
