OK, so I think there is no sufficient answer for general camera preview stretching problem. Or at least I didn't find one. My app also suffered this stretching syndrome and it took me a while to puzzle together a solution from all the user answers on this portal and internet.
I tried @Hesam's solution but it didn't work and left my camera preview majorly distorted.
First I show the code of my solution (the important parts of the code) and then I explain why I took those steps. There is room for performance modifications.
Main activity xml layout:
<RelativeLayout
android:id="@+id/main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="@+id/camera_preview"
android:layout_centerInParent="true"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
Camera Preview:
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder prHolder;
private Camera prCamera;
public List<Camera.Size> prSupportedPreviewSizes;
private Camera.Size prPreviewSize;
@SuppressWarnings("deprecation")
public YoCameraPreview(Context context, Camera camera) {
super(context);
prCamera = camera;
prSupportedPreviewSizes = prCamera.getParameters().getSupportedPreviewSizes();
prHolder = getHolder();
prHolder.addCallback(this);
prHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
try {
prCamera.setPreviewDisplay(holder);
prCamera.startPreview();
} catch (IOException e) {
Log.d("Yologram", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if (prHolder.getSurface() == null){
return;
}
try {
prCamera.stopPreview();
} catch (Exception e){
}
try {
Camera.Parameters parameters = prCamera.getParameters();
List<String> focusModes = parameters.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
}
parameters.setPreviewSize(prPreviewSize.width, prPreviewSize.height);
prCamera.setParameters(parameters);
prCamera.setPreviewDisplay(prHolder);
prCamera.startPreview();
} catch (Exception e){
Log.d("Yologram", "Error starting camera preview: " + e.getMessage());
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
setMeasuredDimension(width, height);
if (prSupportedPreviewSizes != null) {
prPreviewSize =
getOptimalPreviewSize(prSupportedPreviewSizes, width, height);
}
}
public Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) h / w;
if (sizes == null)
return null;
Camera.Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
for (Camera.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);
}
}
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Camera.Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
}
Main activity:
public class MainActivity extends Activity {
...
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
maCamera = getCameraInstance();
maLayoutPreview = (FrameLayout) findViewById(R.id.camera_preview);
maPreview = new CameraPreview(this, maCamera);
Point displayDim = getDisplayWH();
Point layoutPreviewDim = calcCamPrevDimensions(displayDim,
maPreview.getOptimalPreviewSize(maPreview.prSupportedPreviewSizes,
displayDim.x, displayDim.y));
if (layoutPreviewDim != null) {
RelativeLayout.LayoutParams layoutPreviewParams =
(RelativeLayout.LayoutParams) maLayoutPreview.getLayoutParams();
layoutPreviewParams.width = layoutPreviewDim.x;
layoutPreviewParams.height = layoutPreviewDim.y;
layoutPreviewParams.addRule(RelativeLayout.CENTER_IN_PARENT);
maLayoutPreview.setLayoutParams(layoutPreviewParams);
}
maLayoutPreview.addView(maPreview);
}
@SuppressLint("NewApi")
@SuppressWarnings("deprecation")
private Point getDisplayWH() {
Display display = this.getWindowManager().getDefaultDisplay();
Point displayWH = new Point();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
display.getSize(displayWH);
return displayWH;
}
displayWH.set(display.getWidth(), display.getHeight());
return displayWH;
}
private Point calcCamPrevDimensions(Point disDim, Camera.Size camDim) {
Point displayDim = disDim;
Camera.Size cameraDim = camDim;
double widthRatio = (double) displayDim.x / cameraDim.width;
double heightRatio = (double) displayDim.y / cameraDim.height;
// use ">" to zoom preview full screen
if (widthRatio < heightRatio) {
Point calcDimensions = new Point();
calcDimensions.x = displayDim.x;
calcDimensions.y = (displayDim.x * cameraDim.height) / cameraDim.width;
return calcDimensions;
}
// use "<" to zoom preview full screen
if (widthRatio > heightRatio) {
Point calcDimensions = new Point();
calcDimensions.x = (displayDim.y * cameraDim.width) / cameraDim.height;
calcDimensions.y = displayDim.y;
return calcDimensions;
}
return null;
}
}
My commentary:
The point of all this is, that although you calculate the optimal camera size in getOptimalPreviewSize()
you only pick the closest ratio to fit your screen. So unless the ratio is exactly the same the preview will stretch.
Why will it stretch? Because your FrameLayout camera preview is set in layout.xml to match_parent in width and height. So that is why the preview will stretch to full screen.
What needs to be done is to set camera preview layout width and height to match the chosen camera size ratio, so the preview keeps its aspect ratio and won't distort.
I tried to use the CameraPreview
class to do all the calculations and layout changes, but I couldn't figure it out. I tried to apply this solution, but SurfaceView
doesn't recognize getChildCount ()
or getChildAt (int index)
. I think, I got it working eventually with a reference to maLayoutPreview
, but it was misbehaving and applied the set ratio to my whole app and it did so after first picture was taken. So I let it go and moved the layout modifications to the MainActivity
.
In CameraPreview
I changed prSupportedPreviewSizes
and getOptimalPreviewSize()
to public so I can use it in MainActivity
. Then I needed the display dimensions (minus the navigation/status bar if there is one) and chosen optimal camera size. I tried to get the RelativeLayout (or FrameLayout) size instead of display size, but it was returning zero value. This solution didn't work for me. The layout got it's value after onWindowFocusChanged
(checked in the log).
So I have my methods for calculating the layout dimensions to match the aspect ratio of chosen camera size. Now you just need to set LayoutParams
of your camera preview layout. Change the width, height and center it in parent.
There are two choices how to calculate the preview dimensions. Either you want it to fit the screen with black bars (if windowBackground is set to null) on the sides or top/bottom. Or you want the preview zoomed to full screen. I left comment with more information in calcCamPrevDimensions()
.