hi, im trying to make a simple camera app, by extending the
CameraPreview class in the api demos, anyway im trying to cast the
preview onto a surfaceview that i have defined in my layout xml file.
but everytime i do this i get a null pointer exception, and i cant for
the life of me figure out how to make this work.
if anyone has any info or sample code i would be very gratefull.
this is what i have so far, the Preview class is what i took from the
CameraPreview.java
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package bob.CameraAlbum;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.hardware.CameraDevice;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.widget.TabHost;
import android.widget.TabHost.TabSpec;
public class Camera extends Activity {
private TabHost myTabHost;
private Preview mPreview;
@Override
protected void onCreate(Bundle icicle) {
super.onCreate(icicle);
//SurfaceHolder mHolder;
// Hide the window title.
// requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.tabs);
mPreview = new Preview(this);
this.myTabHost = (TabHost)this.findViewById(R.id.tabhost);
this.myTabHost.setup();
TabSpec ts1 = myTabHost.newTabSpec("TAB1");
ts1.setIndicator("Take Photo",
getResources().getDrawable(R.drawable.cameraphoto));
ts1.setContent(R.id.grid_set_menu_page1);
this.myTabHost.addTab(ts1);
TabSpec ts2 = myTabHost.newTabSpec("TAB2");
ts2.setIndicator("Album",
getResources().getDrawable(R.drawable.driveharddisk));
ts2.setContent(R.id.grid_set_menu_page2);
this.myTabHost.addTab(ts2);
TabSpec ts3 = myTabHost.newTabSpec("TAB3");
ts3.setIndicator("Upload",
getResources().getDrawable(R.drawable.networkwireless));
ts3.setContent(R.id.grid_set_menu_page3);
this.myTabHost.addTab(ts3);
this.myTabHost.setCurrentTab(0);
//mPreview = (Preview) findViewById(R.id.photo_surface);
}
@Override
protected void onResume() {
// Because the CameraDevice object is not a shared resource,
// it's very important to release it when the activity is paused.
super.onResume();
mPreview.resume();
}
@Override
protected void onPause() {
// Start Preview again when we resume.
super.onPause();
mPreview.pause();
}
}
class Preview extends SurfaceView implements SurfaceHolder.Callback {
SurfaceHolder mHolder;
private PreviewThread mPreviewThread;
private boolean mHasSurface;
SurfaceView Sview;
Preview(Context context) {
super(context);
// Install a SurfaceHolder.Callback so we get notified when
the
// underlying surface is created and destroyed.
Sview=(SurfaceView) findViewById(R.id.photo_surface);
mHolder = Sview.getHolder();
mHolder.addCallback(this);
mHasSurface = false;
// In this example, we hardcode the size of the preview. In a
real
// application this should be more dynamic. This guarantees
that
// the uderlying surface will never change size.
mHolder.setFixedSize(320, 240);
}
public void resume() {
// We do the actual acquisition in a separate thread. Create
it now.
if (mPreviewThread == null) {
mPreviewThread = new PreviewThread();
// If we already have a surface, just start the thread now
too.
if (mHasSurface == true) {
mPreviewThread.start();
}
}
}
public void pause() {
// Stop Preview.
if (mPreviewThread != null) {
mPreviewThread.requestExitAndWait();
mPreviewThread = null;
}
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, start our main acquisition
thread.
mHasSurface = true;
if (mPreviewThread != null) {
mPreviewThread.start();
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return. Stop the preview.
mHasSurface = false;
pause();
}
public void surfaceChanged(SurfaceHolder holder, int format, int
w, int h) {
// Surface size or format has changed. This should not happen
in this
// example.
}
//
----------------------------------------------------------------------
class PreviewThread extends Thread {
private boolean mDone;
PreviewThread() {
super();
mDone = false;
}
@Override
public void run() {
// We first open the CameraDevice and configure it.
CameraDevice camera = CameraDevice.open();
if (camera != null) {
CameraDevice.CaptureParams param = new
CameraDevice.CaptureParams();
param.type = 1; // preview
param.srcWidth = 1280;
param.srcHeight = 960;
param.leftPixel = 0;
param.topPixel = 0;
param.outputWidth = 320;
param.outputHeight = 240;
param.dataFormat = 2; // RGB_565
camera.setCaptureParams(param);
}
// This is our main acquisition thread's loop, we go until
// asked to quit.
SurfaceHolder holder = mHolder;
while (!mDone) {
// Lock the surface, this returns a Canvas that can
// be used to render into.
Canvas canvas = holder.lockCanvas();
// Capture directly into the Surface
if (camera != null) {
camera.capture(canvas);
}
// And finally unlock and post the surface.
holder.unlockCanvasAndPost(canvas);
}
// Make sure to release the CameraDevice
if (camera != null) {
camera.close();
}
}
public void requestExitAndWait() {
// don't call this from PreviewThread thread or it a
guaranteed
// deadlock!
mDone = true;
try {
join();
} catch (InterruptedException ex) { }
}
}
}
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