Gallery自动循环滚动以及手动滚动的平滑切换（二）

第三，实现自动滚动

由于我们还要手动滚动，所以自动滚动用单独一个进程来实现

private void startAutoScroll() {
        new Thread() {
            @Override
            public void run() {
                int count = 0;
                while (mAutoScroll) {
                    count = 0;
                    while (count < 30) {
                        count++;
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        if (mOnTouch) {// 用戶手动滑动时，停止自动滚动
                            count = 0;
                        }
                    }
                    mPosition++;
                    Message msg = mHandler.obtainMessage(SCROLL, mPosition, 0);
                    mHandler.sendMessage(msg);
                }
            }

        }.start();
    }

    private Handler mHandler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case SCROLL:
                mGallery.setSelection(msg.arg1);
                break;
            }
        }

   };

 

第四 实现手动滚动

手动滚动时，要停止自动滚动，监听gallery的onTouch事件，DOWN时mOnTouch置为true,UP时mOnTouch置为false即可

mGallery.setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                int action = event.getAction();
                if (action == MotionEvent.ACTION_DOWN) {
                    mOnTouch = true;
                } else if (action == MotionEvent.ACTION_UP) {
                    mOnTouch = false;
                }
                return false;
            }

        });

 

到现在我们已经可以自动滚动，手动滚动时自动滚动也会停止。

我们也许还需要加上dot提示图片滚动的位置

LinearLayout layout = (LinearLayout) findViewById(R.id.dot);
        if (mDots == null) {
            mDots = new ImageView[ids.length];
            for (int i = 0; i < ids.length; i++) {
                if (mDots[i] == null)
                    mDots[i] = new ImageView(this);

                mDots[i].setBackgroundResource(R.drawable.banner_tab_unselected);
                layout.addView(mDots[i], new LinearLayout.LayoutParams(mWidth
                        / ids.length + 1, LayoutParams.WRAP_CONTENT));
            }
            mDots[0].setBackgroundResource(R.drawable.banner_tab_selected);
        }

 

mGallery.setOnItemSelectedListener(new OnItemSelectedListener() {

            @Override
            public void onItemSelected(AdapterView arg0, View view,
                    int position, long arg3) {
                mDotPosition = position % ids.length;
                mDots[mDotPosition]
                        .setBackgroundResource(R.drawable.banner_tab_selected);
                if (mDotPosition != mPreDotPosition)
                    mDots[mPreDotPosition]
                            .setBackgroundResource(R.drawable.banner_tab_unselected);
                mPreDotPosition = mDotPosition;
            }

            @Override
            public void onNothingSelected(AdapterView arg0) {

            }

        });