// val h = (img.width * 1.0f / img.drawable.intrinsicWidth * img.drawable.intrinsicHeight).toInt()

// val animator = ValueAnimator.ofInt(img.height,h)

public class LiveImageView extends AppCompatImageView {
    private int mDx;
    private int mMinDx;

    public LiveImageView(@NonNull Context context) {
        super(context);
    }

    public LiveImageView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public LiveImageView(@NonNull Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setDx(int dx) {
        if (getDrawable() == null) {
            return;
        }
        mDx = dx - mMinDx;
        if (mDx <= 0) {
            mDx = 0;
        }
        if (mDx > getDrawable().getBounds().height() - mMinDx) {
            mDx = getDrawable().getBounds().height() - mMinDx;
        }
        invalidate();
    }

    @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mMinDx = h;
    }

    public int getDx() {
        return mDx;
    }

    @Override protected void onDraw(Canvas canvas) {

        Drawable drawable = getDrawable();
        int w = getWidth();
        int h = (int) (getWidth() * 1.0f / drawable.getIntrinsicWidth() * drawable.getIntrinsicHeight());

        // 图片drawable的左上角和由下角
        /*
            ImageView w = mathParent,h = 100
            drawable.setBounds(0, 0, w, h / 2); 则最终图片显示将被压缩显示在 h / 2高度
            drawable.setBounds(0, 0, w, 2h); 则最终图片显示将在2h内显示，当然超出ImageView的h部分 drawble最终的图片展示不会完全展示 2h即 仅仅部分显示-截取
        */
        drawable.setBounds(0, 0, w, h);
        canvas.save();
        canvas.translate(0, -getDx());
        super.onDraw(canvas);
        canvas.restore();
    }

    private Bitmap drawableToBitmap(Drawable drawable) {
        if (drawable instanceof BitmapDrawable) {
            BitmapDrawable bd = (BitmapDrawable) drawable;
            return bd.getBitmap();
        }
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        drawable.draw(canvas);
        return bitmap;
    }
}

// bounds实现缩放
Drawable originalDrawable = context.getDrawable(R.drawable.my_image);

int width = originalDrawable.getIntrinsicWidth();
int height = originalDrawable.getIntrinsicHeight();

int newWidth = (int) (width * scale);
int newHeight = (int) (height * scale);

originalDrawable.setBounds(0, 0, newWidth, newHeight);

originalDrawable.draw(canvas);