public class CameraPreview extends Activity { private Preview mPreview; Camera mCamera; int numberOfCameras; int cameraCurrentlyLocked; // The first rear facing camera int defaultCameraId; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Hide the window title. requestWindowFeature(Window.FEATURE_NO_TITLE); getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); // Create a RelativeLayout container that will hold a SurfaceView, // and set it as the content of our activity. mPreview = new Preview(this); setContentView(mPreview); // Find the total number of cameras available numberOfCameras = Camera.getNumberOfCameras(); // Find the ID of the default camera CameraInfo cameraInfo = new CameraInfo(); for (int i = 0; i < numberOfCameras; i++) { Camera.getCameraInfo(i, cameraInfo); if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {//h后面的摄像头 defaultCameraId = i; } } } @Override protected void onResume() { super.onResume(); // Open the default i.e. the first rear facing camera. mCamera = Camera.open(); cameraCurrentlyLocked = defaultCameraId; mPreview.setCamera(mCamera); } @Override protected void onPause() { super.onPause(); // Because the Camera object is a shared resource, it's very // important to release it when the activity is paused. if (mCamera != null) { mPreview.setCamera(null); mCamera.release(); mCamera = null; } } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate our menu which can gather user input for switching camera MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.camera_menu, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle item selection switch (item.getItemId()) { case R.id.switch_cam: // check for availability of multiple cameras if (numberOfCameras == 1) { AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(this.getString(R.string.camera_alert)) .setNeutralButton("Close", null); AlertDialog alert = builder.create(); alert.show(); return true; } // OK, we have multiple cameras. // Release this camera -> cameraCurrentlyLocked if (mCamera != null) { mCamera.stopPreview(); mPreview.setCamera(null); mCamera.release(); mCamera = null; } // Acquire the next camera and request Preview to reconfigure // parameters. mCamera = Camera .open((cameraCurrentlyLocked + 1) % numberOfCameras); cameraCurrentlyLocked = (cameraCurrentlyLocked + 1) % numberOfCameras; mPreview.switchCamera(mCamera); // Start the preview mCamera.startPreview(); return true; default: return super.onOptionsItemSelected(item); } }}// ----------------------------------------------------------------------/** * A simple wrapper around a Camera and a SurfaceView that renders a centered preview of the Camera * to the surface. We need to center the SurfaceView because not all devices have cameras that * support preview sizes at the same aspect ratio as the device's display. */class Preview extends ViewGroup implements SurfaceHolder.Callback { private final String TAG = "Preview"; SurfaceView mSurfaceView; SurfaceHolder mHolder; Size mPreviewSize; List<Size> mSupportedPreviewSizes; Camera mCamera; Preview(Context context) { super(context); mSurfaceView = new SurfaceView(context); addView(mSurfaceView); // Install a SurfaceHolder.Callback so we get notified when the // underlying surface is created and destroyed. mHolder = mSurfaceView.getHolder(); mHolder.addCallback(this); mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void setCamera(Camera camera) { mCamera = camera; if (mCamera != null) { //照相机支持的 大小 可能有不同的相机 mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes(); requestLayout(); } }//切换 camera public void switchCamera(Camera camera) { setCamera(camera); try { camera.setPreviewDisplay(mHolder); } catch (IOException exception) { Log.e(TAG, "IOException caused by setPreviewDisplay()", exception); } Camera.Parameters parameters = camera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); camera.setParameters(parameters); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // We purposely disregard child measurements because act as a // wrapper to a SurfaceView that centers the camera preview instead // of stretching it. final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec); final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec); setMeasuredDimension(width, height); if (mSupportedPreviewSizes != null) { mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed && getChildCount() > 0) { final View child = getChildAt(0); final int width = r - l; final int height = b - t; int previewWidth = width; int previewHeight = height; if (mPreviewSize != null) { previewWidth = mPreviewSize.width; previewHeight = mPreviewSize.height; } // Center the child SurfaceView within the parent. //让surface居中 还要判断是横屏还是竖屏 if (width * previewHeight > height * previewWidth) { final int scaledChildWidth = previewWidth * height / previewHeight; child.layout((width - scaledChildWidth) / 2, 0, (width + scaledChildWidth) / 2, height); } else { final int scaledChildHeight = previewHeight * width / previewWidth; child.layout(0, (height - scaledChildHeight) / 2, width, (height + scaledChildHeight) / 2); } } } public void surfaceCreated(SurfaceHolder holder) { // The Surface has been created, acquire the camera and tell it where // to draw. try { if (mCamera != null) { mCamera.setPreviewDisplay(holder); } } catch (IOException exception) { Log.e(TAG, "IOException caused by setPreviewDisplay()", exception); } } public void surfaceDestroyed(SurfaceHolder holder) { // Surface will be destroyed when we return, so stop the preview. if (mCamera != null) { mCamera.stopPreview(); } } //设置 camera的 高度和宽度为 屏幕 private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) { final double ASPECT_TOLERANCE = 0.1; 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; } //开始设置camera的图像 public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { // Now that the size is known, set up the camera parameters and begin // the preview. Camera.Parameters parameters = mCamera.getParameters(); parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height); requestLayout(); mCamera.setParameters(parameters); mCamera.startPreview(); }}
import android.graphics.*;import android.os.Bundle;import android.view.View;//图形的拼接public class Clipping extends GraphicsActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new SampleView(this)); } private static class SampleView extends View { private Paint mPaint; private Path mPath; public SampleView(Context context) { super(context); setFocusable(true); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setStrokeWidth(6); mPaint.setTextSize(16); mPaint.setTextAlign(Paint.Align.RIGHT); //设置paint 绘制文字从右边开始写 mPath = new Path(); } private void drawScene(Canvas canvas) { canvas.clipRect(0, 0, 100, 100); //在背景上 "抠一个方形的洞",填充为白色 canvas.drawColor(Color.WHITE); mPaint.setColor(Color.RED); canvas.drawLine(0, 0, 100, 100, mPaint); mPaint.setColor(Color.GREEN); canvas.drawCircle(30, 70, 30, mPaint); mPaint.setColor(Color.BLUE); canvas.drawText("Clipping", 100, 30, mPaint); } @Override protected void onDraw(Canvas canvas) { canvas.drawColor(Color.GRAY); canvas.save(); canvas.translate(10, 10); //移动到10,10 绘制第一个图案 drawScene(canvas); canvas.restore(); canvas.save(); //开始一个新的图案绘制 canvas.translate(160, 10); canvas.clipRect(10, 10, 90, 90); //抠出外部的矩形 canvas.clipRect(30, 30, 70, 70, Region.Op.DIFFERENCE);//两个矩形的不同的地方 如果是INTERSECT(交叉)就可以显示中心的矩形,两个矩形的相交 drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(10, 160); mPath.reset(); canvas.clipPath(mPath); // makes the clip empty mPath.addCircle(50, 50, 50, Path.Direction.CCW);//矩形圆形的交集 canvas.clipPath(mPath, Region.Op.REPLACE); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(160, 160); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.UNION); // 两个矩形的联合集 drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(10, 310); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.XOR); //两个矩形的联合 但是去除他们的交集 drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(160, 310); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.REVERSE_DIFFERENCE);//下面矩形没有的那一部分 drawScene(canvas); canvas.restore(); } }}
