Question

如何使用ViewPager等最新工具实现与GitHub中的用户界面和代码相同的功能。创建的代码还没有使用最新的工具开发。对我来说，它似乎有点困难。

有什么建议吗？

Answer 1

试试这个

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.example.pagercontainer.PagerContainer
        android:id="@+id/pager_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#CCC">
        <android.support.v4.view.ViewPager
            android:layout_width="150dp"
            android:layout_height="100dp"
            android:layout_gravity="center_horizontal" />
    </com.example.pagercontainer.PagerContainer>

</RelativeLayout>

PagerActivity.java

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * PagerActivity: A Sample Activity for PagerContainer
 */
public class PagerActivity extends Activity {

    PagerContainer mContainer;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mContainer = (PagerContainer) findViewById(R.id.pager_container);

        ViewPager pager = mContainer.getViewPager();
        PagerAdapter adapter = new MyPagerAdapter();
        pager.setAdapter(adapter);
        //Necessary or the pager will only have one extra page to show
        // make this at least however many pages you can see
        pager.setOffscreenPageLimit(adapter.getCount());
        //A little space between pages
        pager.setPageMargin(15);

        //If hardware acceleration is enabled, you should also remove
        // clipping on the pager for its children.
        pager.setClipChildren(false);
    }

    //Nothing special about this adapter, just throwing up colored views for demo
    private class MyPagerAdapter extends PagerAdapter {

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            TextView view = new TextView(PagerActivity.this);
            view.setText("Item "+position);
            view.setGravity(Gravity.CENTER);
            view.setBackgroundColor(Color.argb(255, position * 50, position * 10, position * 50));

            container.addView(view);
            return view;
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View)object);
        }

        @Override
        public int getCount() {
            return 5;
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return (view == object);
        }
    }
}

PagerContainer .java

import android.content.Context;
import android.graphics.Point;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.FrameLayout;

/**
 * PagerContainer: A layout that displays a ViewPager with its children that are outside
 * the typical pager bounds.
 */
public class PagerContainer extends FrameLayout implements ViewPager.OnPageChangeListener {

    private ViewPager mPager;
    boolean mNeedsRedraw = false;

    public PagerContainer(Context context) {
        super(context);
        init();
    }

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

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

    private void init() {
        //Disable clipping of children so non-selected pages are visible
        setClipChildren(false);

        //Child clipping doesn't work with hardware acceleration in Android 3.x/4.x
        //You need to set this value here if using hardware acceleration in an
        // application targeted at these releases.
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);
    }

    @Override
    protected void onFinishInflate() {
        try {
            mPager = (ViewPager) getChildAt(0);
            mPager.setOnPageChangeListener(this);
        } catch (Exception e) {
            throw new IllegalStateException("The root child of PagerContainer must be a ViewPager");
        }
    }

    public ViewPager getViewPager() {
        return mPager;
    }

    private Point mCenter = new Point();
    private Point mInitialTouch = new Point();

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        mCenter.x = w / 2;
        mCenter.y = h / 2;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        //We capture any touches not already handled by the ViewPager
        // to implement scrolling from a touch outside the pager bounds.
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                mInitialTouch.x = (int)ev.getX();
                mInitialTouch.y = (int)ev.getY();
            default:
                ev.offsetLocation(mCenter.x - mInitialTouch.x, mCenter.y - mInitialTouch.y);
                break;
        }

        return mPager.dispatchTouchEvent(ev);
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        //Force the container to redraw on scrolling.
        //Without this the outer pages render initially and then stay static
        if (mNeedsRedraw) invalidate();
    }

    @Override
    public void onPageSelected(int position) { }

    @Override
    public void onPageScrollStateChanged(int state) {
        mNeedsRedraw = (state != ViewPager.SCROLL_STATE_IDLE);
    }
}

请参阅this

使用ViewPager进行卡片翻转的相册？

1 个答案: