我正在开发一款获取屏幕当前像素颜色的Android应用
应用程序概念非常简单CameraPreview类实现SurfcaeHolder.Callback接口
并onSurfcaeChanged获得颜色
我的问题是代码在samsung6s上运行得很好但是它不能用于 nuxus6p 回调surfaceCreated和surfaceChanged从未调用过
这是我的代码示例
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder mHolder;
private Camera mCamera;
String TAG = "TAG";
Context context;
OnColorDetected onColorDetected;
ColorDetectionPresenter presenter;
Camera.Size previewSize;
int midPixxel;
public CameraPreview(Context context, Camera camera, ColorDetectionPresenter presenter) {
super(context);
mCamera = camera;
this.context = context;
this.presenter = presenter;
// 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);
}
public void setOnColorDetected(OnColorDetected onColorDetected) {
this.onColorDetected = onColorDetected;
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
Log.d("SURFACE_STATE","created");
mCamera.setPreviewDisplay(holder);
mCamera.setPreviewCallback(new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
int frameHeight = camera.getParameters().getPreviewSize().height;
int frameWidth = camera.getParameters().getPreviewSize().width;
// number of pixels//transforms NV21 pixel data into RGB pixels
int rgb[] = new int[frameWidth * frameHeight];
// convertion
int[] myPixels = decodeYUV420SP(rgb, data, frameWidth, frameHeight);
for (int i = 0; i < myPixels.length; i++) {
//Toast.makeText(context, MainActivity.getBestMatchingColorName(myPixels[i]), Toast.LENGTH_SHORT).show();
}
}
});
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
Log.d("SURFACE_STATE","changed");
if (mHolder.getSurface() == null) {
// preview surface does not exist
return;
}
// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e) {
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes here
// start preview with new settings
try {
Camera.Parameters parameters = mCamera.getParameters();
mCamera.setPreviewDisplay(mHolder);
List<Camera.Size> previewSizes = parameters.getSupportedPreviewSizes();
if (previewSizes == null)
previewSizes = parameters.getSupportedPictureSizes();
// You need to choose the most appropriate previewSize for your
previewSize = previewSizes.get(0);
for(int i=0;i<previewSizes.size();i++){
if(previewSizes.get(i).width>previewSize.width)
previewSize=previewSizes.get(i);
}
// .... select one of previewSizes here
cameraSetup(width, height);
parameters.setPictureSize(previewSize.width, previewSize.height);
mCamera.setParameters(parameters);
mCamera.setPreviewCallback(new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
int frameHeight = camera.getParameters().getPreviewSize().height;
int frameWidth = camera.getParameters().getPreviewSize().width;
// number of pixels//transforms NV21 pixel data into RGB pixels
int rgb[] = new int[frameWidth * frameHeight];
// convertion
int[] myPixels = decodeYUV420SP(rgb, data, frameWidth, frameHeight);
String colorName = presenter.getBestMatchingColorName(myPixels[myPixels.length / 2]);
onColorDetected.colorDetected(colorName);
}
});
mCamera.startPreview();
} catch (Exception e) {
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
int[] decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {
// Pulled directly from:
// http://ketai.googlecode.com/svn/trunk/ketai/src/edu/uic/ketai/inputService/KetaiCamera.java
final int frameSize = width * height;
for (int j = 0, yp = 0; j < height; j++) {
int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
for (int i = 0; i < width; i++, yp++) {
int y = (0xff & ((int) yuv420sp[yp])) - 16;
if (y < 0)
y = 0;
if ((i & 1) == 0) {
v = (0xff & yuv420sp[uvp++]) - 128;
u = (0xff & yuv420sp[uvp++]) - 128;
}
int y1192 = 1192 * y;
int r = (y1192 + 1634 * v);
int g = (y1192 - 833 * v - 400 * u);
int b = (y1192 + 2066 * u);
if (r < 0)
r = 0;
else if (r > 262143)
r = 262143;
if (g < 0)
g = 0;
else if (g > 262143)
g = 262143;
if (b < 0)
b = 0;
else if (b > 262143)
b = 262143;
rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
}
}
return rgb;
}
private void cameraSetup(int w, int h) {
// set the camera parameters, including the preview size
FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) getLayoutParams();
double cameraAspectRatio = ((double) previewSize.width) / previewSize.height;
if (((double) h) / w > cameraAspectRatio) {
lp.width = (int) (h / cameraAspectRatio + 0.5);
lp.height = h;
} else {
lp.height = (int) (w * cameraAspectRatio + 0.5);
lp.width = w;
lp.topMargin = (h - lp.height) / 2;
}
lp.gravity = Gravity.CENTER_HORIZONTAL | Gravity.TOP;
setLayoutParams(lp);
requestLayout();
}
}
这就是我称呼它的方式
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
colorDetectionPresenter = new ColorDetectionPresenter();
camera = Camera.open();
cameraPreview = new CameraPreview(getActivity(), camera, colorDetectionPresenter);
params = camera.getParameters();
params.setPreviewFormat(ImageFormat.NV21);
camera.setDisplayOrientation(90);
siz = params.getSupportedPreviewSizes().get(0);
params.setPreviewSize(siz.width, siz.height);
}
我尝试在onCreate，onCreateView和onResume无效的情况下初始化相机预览
有什么建议 ？
它只对我的nexus6p起作用