我创建了一个打开相机的演示应用程序。现在我想在用户触摸实时相机预览时获取像素的颜色。
我已经尝试过覆盖onTouchEvent
并且我在 x,y 中成功getting the position of pixel
,but
但我没有得到 it.it 总是显示0,0,0
的RGB color value
欢迎所有建议,包括实现相同功能的任何替代方法。[ Excluding OpenCv because it requires to install OpenCvManager apk also to support my application
]
法典:
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback, PreviewCallback {
private Camera camera;
private SurfaceHolder holder;
int[] myPixels;
public CameraPreview(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public CameraPreview(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CameraPreview(Context context) {
super(context);
}
public void init(Camera camera) {
this.camera = camera;
initSurfaceHolder();
}
@SuppressWarnings("deprecation") // needed for < 3.0
private void initSurfaceHolder() {
holder = getHolder();
holder.addCallback(this);
holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
initCamera(holder);
}
private void initCamera(SurfaceHolder holder) {
try {
camera.setPreviewDisplay(holder);
camera.getParameters().setPreviewFormat(ImageFormat.NV21);
camera.setPreviewCallback(this);
camera.startPreview();
} catch (Exception e) {
Log.d("Error setting camera preview", e);
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if(event.getAction() == MotionEvent.ACTION_DOWN)
{
android.util.Log.d("touched", "called");
/* int x = (int)event.getX();
int y = (int)event.getY();
android.util.Log.d("touched pixel :", x+" "+y);
setDrawingCacheEnabled(true);
buildDrawingCache();
Bitmap mBmp = getDrawingCache();
int pixel = mBmp.getPixel(x, y);
int redValue = Color.red(pixel);
int blueValue = Color.blue(pixel);
int greenValue = Color.green(pixel);
android.util.Log.d("touched pixel color :", redValue+" "+greenValue+" "+blueValue);
android.util.Log.d("touched pixel color from preview:", redValue+" "+greenValue+" "+blueValue);
*/
//how to get particular pixel from myPixels[]
}
return false;
}
@Override
public void onPreviewFrame(byte[] data, Camera camera) {
android.util.Log.d("onPreviewFrame", "called");
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
myPixels = decodeYUV420SP(rgb, data, frameWidth, frameHeight);
}
public int[] decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {
// here we're using our own internal PImage attributes
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;
// use interal buffer instead of pixels for UX reasons
rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000)
| ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
}
}
return rgb;
}
}
我采用了不同的方法来解决这个问题。我会在有空后立即发布代码。
Algorithm :
- 在实时摄像机上创建叠加层
- 当用户触摸时,使用从实时摄像机获取的最新YUV缓冲流的RGB数据更新叠加层
- 从叠加图像中选择 RGB 颜色
看起来myPixel是2D数据(宽x高)的一维表示。
这意味着myPixel的长度为(宽度*高度)。
假设像素是(x,y),那么
int idx = ( height * y ) + x;
int color = myPixels[idx];
使用上述信息,您可以修改decodeYUV420SP
方法以仅输出特定像素的颜色。