如何使用内部带有ImageView的ViewPager OnTouchListener以及OnClickListener

Question

I have a ViewPager that have 4 pages, the pages will keep sliding using runable and handler....each page contains an ImageView, the ImageView onClickListener event is set in the Adapter

the ViewPager has OnTouchListener event set while initialization

I'm setting the ViewPager OnTouchListener event to stop sliding when the user touches the viewpager and continue sliding when user release his finger

here is how i set ViewPager OnTouchListener event:

    BandsViewPager.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    stopSliding = true;
                    bandsHandler.removeCallbacks(animateBandsViewPager);
                    break;

                case MotionEvent.ACTION_CANCEL:
                    break;

                case MotionEvent.ACTION_UP:
                    // calls when touch release on ViewPager
                    if (bands != null && bands.size() != 0) {
                        stopSliding = false;
                        bandsRunnable(bands.size());
                        bandsHandler.postDelayed(animateBandsViewPager, ANIM_VIEWPAGER_DELAY);
                    }

                    break;

                case MotionEvent.ACTION_MOVE:
                    // calls when ViewPager touch
                    if (bandsHandler != null && stopSliding == false) {
                        stopSliding = true;
                    }
                    break;
            }
            return false;
        }
    });

and Here is how I set ImageView OnClickListener inside the ViewPager adapter class:

    mImageView.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            switch(ClickActionType){
                case BAND_CLICK_ACTION_BRAND:
                    Categories_Fragment categoriesFrag= new Categories_Fragment();
                    Bundle categoriesArgs = new Bundle();
                    categoriesArgs.putInt("BrandId", ClickActionTypeId);
                    categoriesArgs.putInt("TabId", TabId);
                    if (UI.getAppLanguage() == 0)
                        categoriesArgs.putString("BrandName", TitleAr);
                    else
                        categoriesArgs.putString("BrandName", TitleEn);
                    categoriesFrag.setArguments(categoriesArgs);
                    FManager.beginTransaction()
                            .replace(R.id.main_content, categoriesFrag, Categories_Fragment.ARG_ITEM_ID)
                            .addToBackStack(Categories_Fragment.ARG_ITEM_ID)
                            .commit();
                    break;

                case BAND_CLICK_ACTION_ITEM:
                    Item_Details_Fragment itemDetailsFrag= new Item_Details_Fragment();
                    Bundle itemDetailsArgs = new Bundle();
                    itemDetailsArgs.putInt("ItemId", ClickActionTypeId);
                    itemDetailsFrag.setArguments(itemDetailsArgs);
                    FManager.beginTransaction()
                            .replace(R.id.main_content, itemDetailsFrag, Item_Details_Fragment.ARG_ITEM_ID)
                            .addToBackStack(Item_Details_Fragment.ARG_ITEM_ID)
                            .commit();
                    break;
                case BAND_CLICK_ACTION_CATEGORY:
                    Items_Fragment itemsFrag= new Items_Fragment();
                    Bundle itemsArgs = new Bundle();
                    itemsArgs.putInt("CategoryId", ClickActionTypeId);
                    if (UI.getAppLanguage() == 0)
                        itemsArgs.putString("CategoryName", TitleAr);
                    else
                        itemsArgs.putString("CategoryName", TitleEn);
                    itemsArgs.putInt("BrandId", 0);
                    itemsArgs.putInt("TabId", TabId);
                    itemsFrag.setArguments(itemsArgs);
                    FManager.beginTransaction()
                            .replace(R.id.main_content, itemsFrag, Items_Fragment.ARG_ITEM_ID)
                            .addToBackStack(Items_Fragment.ARG_ITEM_ID)
                            .commit();
                    break;
                default:
            }

        }
    });

If I remove the ImageView OnClickListener then the ViewPager will receive touch events.

Answer 1

The reason your ImageView is stealing the MotionEvent callbacks from your ViewPager is because the OnTouchListener.onTouch() method of your ViewPager always returns false . This means it will not capture any new MotionEvent callbacks after another View (your ImageView ) returns true in the onTouchEvent() method. Any View that is "clickable" returns true for any MotionEvent , and setting an OnClickListener for a View makes it clickable.

Now the immediate reaction might be to make the OnTouchListener.onTouch() method return true for some or all case statements. But this would either make the ViewPager intercept all MotionEvent callbacks, or not give you the functionality that you want.

The correct implementation would be to subclass ViewPager and override the onInterceptTouchEvent and onTouchEvent methods. The key is not to return true in the case of MotionEvent.ACTION_DOWN in onTouchEvent , as this will delegate every gesture to the ViewPager . Instead you should intercept the MotionEvent callbacks in the case of MotionEvent.ACTION_MOVE after a "slop" threshold has been exceeded. This will send all successive MotionEvent callbacks to the ViewPager.onTouchEvent() method, instead of any child views.

The Android documentation includes best practices on managing touch events . I also highly recommend watching Mastering the Android Touch System if you want to have a better understanding of how the Android framework handles touch events.