Android Reverse Camera Matrix

CalculateTextureMatrix.Java

public Matrix calculateTextureMatrix(TextureView textureView, View previewView) {
        Matrix matrix = new Matrix();
        Camera.Size previewSize = mICamera.mCamera.getParameters().getPreviewSize();
        float actualPreviewWidth = previewSize.width;
        float actualPreviewHeight = previewSize.height;

        float previewWidth = previewView.getWidth();
        float previewHeight = previewView.getHeight();

        int deviceAndCameraAngleDiff = mICamera.getCameraAngle(this);

        float scaleX, scaleY;
        if (deviceAndCameraAngleDiff % 180 == 0) {
            scaleX = previewWidth / actualPreviewWidth;
            scaleY = previewHeight / actualPreviewHeight;
        } else {
            scaleX = previewWidth / actualPreviewHeight;
            scaleY = previewHeight / actualPreviewWidth;
        }

        float scale = Math.max(scaleX, scaleY);

        matrix.postScale(
                1 / scaleX * scale,
                1 / scaleY * scale,
                textureView.getWidth() / 2f,
                textureView.getHeight() / 2f
        );


        return matrix;
    }