Converting a view to Bitmap without displaying it in Android?

Question

I will try to explain what exactly I need to do.

I have 3 separate screens say A,B,C. There is another screen called say HomeScreen where all the 3 screens bitmap sh

Answer 1

There is a great Kotlin extension function in Android KTX: View.drawToBitmap(Bitmap.Config)

Answer 2

Layout or view to bitmap:

 private Bitmap createBitmapFromLayout(View tv) {      
    int spec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    tv.measure(spec, spec);
    tv.layout(0, 0, tv.getMeasuredWidth(), tv.getMeasuredHeight());
    Bitmap b = Bitmap.createBitmap(tv.getMeasuredWidth(), tv.getMeasuredWidth(),
            Bitmap.Config.ARGB_8888);
    Canvas c = new Canvas(b);
    c.translate((-tv.getScrollX()), (-tv.getScrollY()));
    tv.draw(c);
    return b;
}

Calling Method:

Bitmap src = createBitmapFromLayout(View.inflate(this, R.layout.sample, null)/* or pass your view object*/);

Answer 3

I think this is a bit better :

/**
 * draws the view's content to a bitmap. code initially based on :
 * http://nadavfima.com/android-snippet-inflate-a-layout-draw-to-a-bitmap/
 */
@Nullable
public static Bitmap drawToBitmap(final View viewToDrawFrom, int width, int height) {
    boolean wasDrawingCacheEnabled = viewToDrawFrom.isDrawingCacheEnabled();
    if (!wasDrawingCacheEnabled)
        viewToDrawFrom.setDrawingCacheEnabled(true);
    if (width <= 0 || height <= 0) {
        if (viewToDrawFrom.getWidth() <= 0 || viewToDrawFrom.getHeight() <= 0) {
            viewToDrawFrom.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            width = viewToDrawFrom.getMeasuredWidth();
            height = viewToDrawFrom.getMeasuredHeight();
        }
        if (width <= 0 || height <= 0) {
            final Bitmap bmp = viewToDrawFrom.getDrawingCache();
            final Bitmap result = bmp == null ? null : Bitmap.createBitmap(bmp);
            if (!wasDrawingCacheEnabled)
                viewToDrawFrom.setDrawingCacheEnabled(false);
            return result;
        }
        viewToDrawFrom.layout(0, 0, width, height);
    } else {
        viewToDrawFrom.measure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
        viewToDrawFrom.layout(0, 0, viewToDrawFrom.getMeasuredWidth(), viewToDrawFrom.getMeasuredHeight());
    }
    final Bitmap drawingCache = viewToDrawFrom.getDrawingCache();
    final Bitmap bmp = ThumbnailUtils.extractThumbnail(drawingCache, width, height);
    final Bitmap result = bmp == null || bmp != drawingCache ? bmp : Bitmap.createBitmap(bmp);
    if (!wasDrawingCacheEnabled)
        viewToDrawFrom.setDrawingCacheEnabled(false);
    return result;
}

Using the above code, you don't have to specify the size of the bitmap (use 0 for width&height) if you want to use the one of the view itself.

Also, if you wish to convert special views (SurfaceView, Surface or Window, for example) to a bitmap, you should consider using PixelCopy class instead. It requires API 24 and above though. I don't know how to do it before.