頁面整個佈局大體上是ScrollView裡面包含了一個ImageView和RecyclerView，所以先得到ImageView的高度，當ScrollView向上滑動時，設定標題欄的背景色、文字顏色，當超過ImageView的高度時，設定其背景為白色，字型為黑色。

重寫ScrollView，獲取手勢滑動距離

ObservableScrollView

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ScrollView;

public class ObservableScrollView extends ScrollView {

    private OnScrollChangedListener mOnScrollChangedListener;

    public ObservableScrollView(Context context) {
        super(context);
    }

    public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public ObservableScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setOnScrollChangedListener(OnScrollChangedListener onScrollChangedListener) {
        this.mOnScrollChangedListener = onScrollChangedListener;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if (mOnScrollChangedListener != null) {
            mOnScrollChangedListener.onScrollChanged(this, x, y, oldx, oldy);
        }
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return false; // 此處為了演示，阻止ScrollView攔截Touch事件
    }

    interface OnScrollChangedListener {

        void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy);

    }
}
 

然後是計算滑動高度，設定顏色

int mAlpha = 0;

scrollview.setOnScrollChangedListener(new ObservableScrollView.OnScrollChangedListener() {
            @Override
            public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy) {
                int minHeight = 50;
                int maxHeight = rl_userhome_top.getMeasuredHeight();
                if (maxHeight == 0) {
                    maxHeight = 500;
                }
                if (scrollView.getScrollY() <= minHeight) {
                    mAlpha = 0;
                } else if (scrollView.getScrollY() > maxHeight) {
                    mAlpha = 255;
                } else {
                    mAlpha = (scrollView.getScrollY() - minHeight) * 255 / (maxHeight - minHeight);
                }

                if (mAlpha <= 0) {
                    tv_title.setTextColor(Color.rgb(255, 255, 255));
                    iconColorFilter(Color.parseColor("#ffffff"));
                    rl_userhome_title.setBackgroundColor(Color.argb(0, 255, 255, 255));
                } else if (mAlpha >= 255) {
                    tv_title.setTextColor(Color.rgb(0, 0, 0));
                    iconColorFilter(Color.parseColor("#000000"));
                    rl_userhome_title.setBackgroundColor(Color.argb(mAlpha, 255, 255, 255));
                } else {
                    tv_title.setTextColor(Color.rgb(255 - mAlpha, 255 - mAlpha, 255 - mAlpha));
                    iconColorFilter(Color.rgb(255 - mAlpha, 255 - mAlpha, 255 - mAlpha));
                    rl_userhome_title.setBackgroundColor(Color.argb(mAlpha, mAlpha, mAlpha, mAlpha));
                }
            }
        });
 

若導航欄有圖示，修改icon

   /**
     * 標題欄/導航欄icon 顏色改變
     *
     * @param color
     */
    private void iconColorFilter(int color) {
        PorterDuffColorFilter colorFilter = new PorterDuffColorFilter(color, PorterDuff.Mode.SRC_ATOP);
        iv_back.setColorFilter(colorFilter);
    }