java - 在 viewpager 中翻转图像

Question

我有一个用于水平滑动的全屏图像 slider 的 viewpager。我想做的是在 slider 上的每个图像后面放一个图像。也就是说，用户可以点击“翻转”按钮来显示另一张图片。

下面是我的代码，但是我有两个问题:

1. 我第一次点击翻转按钮时，它翻转了图像，但仅显示相同的图像。但是，当我第二次点击它时有用 :)。
2. 翻转按钮仅适用于第一张图片。当我滑动向右或向左翻动按钮不再起作用。有什么帮助吗？

注意:我使用的是 fullscreenActivity 主题，它会隐藏 UI 控件，直到用户单击图像。

FullscreenActivity.java

package me.zamaaan.wallpaper;

import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import me.zamaaan.wallpaper.util.SystemUiHider;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import static me.zamaaan.wallpaper.HeavyLifter.FAIL;
import static me.zamaaan.wallpaper.HeavyLifter.SUCCESS;
import android.view.View.OnClickListener;
import android.view.animation.Animation;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.AnimationUtils;


import java.util.ArrayList;
import java.util.List;

/** A helper class that will do the heavy work of decoding images and actually setting the wallpaper */


/**
 * An example full-screen activity that shows and hides the system UI (i.e.
 * status bar and navigation/system bar) with user interaction.
 * 
 * @see SystemUiHider
 */
public class FullscreenActivity extends Activity implements OnClickListener, AnimationListener{
    /**
     * Whether or not the system UI should be auto-hidden after
     * {@link #AUTO_HIDE_DELAY_MILLIS} milliseconds.
     */
    private static final boolean AUTO_HIDE = true;
    private HeavyLifter chuckNorris;
    private Animation animation1;
    private Animation animation2;
    private boolean isBackOfCardShowing = true;

    /*
    an array with the ids of the images for the viewpager

     */
    public Integer[] mImageIds = {
            R.drawable.background1, R.drawable.background2,
            R.drawable.background3, R.drawable.background4,
            R.drawable.background1, R.drawable.background2,
            R.drawable.background1, R.drawable.background2,
            R.drawable.background3, R.drawable.background4,
            R.drawable.background1, R.drawable.background2,
            R.drawable.background3
    };
    /*
    an array with the ids of the images for the back flip of each image in the viewpager
     */
    public Integer[] mBackIds = {
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash, R.drawable.splash,
            R.drawable.splash
    };

    /**
     * If {@link #AUTO_HIDE} is set, the number of milliseconds to wait after
     * user interaction before hiding the system UI.
     */
    private static final int AUTO_HIDE_DELAY_MILLIS = 3000;

    /**
     * If set, will toggle the system UI visibility upon interaction. Otherwise,
     * will show the system UI visibility upon interaction.
     */
    private static final boolean TOGGLE_ON_CLICK = true;

    /**
     * The flags to pass to {@link SystemUiHider#getInstance}.
     */
    private static final int HIDER_FLAGS = SystemUiHider.FLAG_HIDE_NAVIGATION;

    /**
     * The instance of the {@link SystemUiHider} for this activity.
     */
    private SystemUiHider mSystemUiHider;

    /**
     * The pager widget, which handles animation and allows swiping horizontally to access previous
     * and next wizard steps.
     */
    private ViewPager mPager;

    /**
     * The pager adapter, which provides the pages to the view pager widget.
     */
    private PagerAdapter mPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_fullscreen);
        animation1 = AnimationUtils.loadAnimation(this, R.anim.to_middle);
        animation1.setAnimationListener(this);
        animation2 = AnimationUtils.loadAnimation(this, R.anim.from_middle);
        animation2.setAnimationListener(this);
        findViewById(R.id.flip).setOnClickListener(this);

        // Loop through the ids to create a list of full screen image views
        ImageAdapter imageAdapter = new ImageAdapter(this);
        List<ImageView> images = new ArrayList<ImageView>();

        for (int i = 0; i < imageAdapter.getCount(); i++) {
            ImageView imageView = new ImageView(this);
            imageView.setId(i);
            imageView.setImageResource(imageAdapter.mThumbIds[i]);
            imageView.setScaleType(ImageView.ScaleType.FIT_XY);
            images.add(imageView);
        }

        final View controlsView = findViewById(R.id.fullscreen_content_controls);
        final View contentView = findViewById(R.id.view_pager);

        // Set up an instance of SystemUiHider to control the system UI for
        // this activity.
        mSystemUiHider = SystemUiHider.getInstance(this, contentView, HIDER_FLAGS);
        mSystemUiHider.setup();
        mSystemUiHider.setOnVisibilityChangeListener(new SystemUiHider.OnVisibilityChangeListener() {
                    // Cached values.
                    int mControlsHeight;
                    int mShortAnimTime;

                    @Override
                    @TargetApi(Build.VERSION_CODES.HONEYCOMB_MR2)
                    public void onVisibilityChange(boolean visible) {
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
                            // If the ViewPropertyAnimator API is available
                            // (Honeycomb MR2 and later), use it to animate the
                            // in-layout UI controls at the bottom of the
                            // screen.
                            if (mControlsHeight == 0) {
                                mControlsHeight = controlsView.getHeight();
                            }
                            if (mShortAnimTime == 0) {
                                mShortAnimTime = getResources().getInteger(
                                        android.R.integer.config_shortAnimTime);
                            }
                            controlsView
                                    .animate()
                                    .translationY(visible ? 0 : mControlsHeight)
                                    .setDuration(mShortAnimTime);
                        } else {
                            // If the ViewPropertyAnimator APIs aren't
                            // available, simply show or hide the in-layout UI
                            // controls.
                            controlsView.setVisibility(visible ? View.VISIBLE
                                    : View.GONE);
                        }

                        if (visible && AUTO_HIDE) {
                            // Schedule a hide().
                            delayedHide(AUTO_HIDE_DELAY_MILLIS);
                        }
                    }
                });

        // Set up the user interaction to manually show or hide the system UI.
        contentView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (TOGGLE_ON_CLICK) {
                    mSystemUiHider.toggle();
                } else {
                    mSystemUiHider.show();
                }
            }
        });

        // Upon interacting with UI controls, delay any scheduled hide()
        // operations to prevent the jarring behavior of controls going away
        // while interacting with the UI.
        findViewById(R.id.btnSetAsWallpaper).setOnTouchListener(
                mDelayHideTouchListener);
        findViewById(R.id.btnSaveWallpaper).setOnTouchListener(
                mDelayHideTouchListener);



        // Finally create the adapter
        ImagePagerAdapter imagePagerAdapter = new ImagePagerAdapter(images);
        ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);
        viewPager.setAdapter(imagePagerAdapter);

        // Set the ViewPager to point to the selected image from the previous activity
        // Selected image id
        int position = getIntent().getExtras().getInt("id");
        viewPager.setCurrentItem(position);
        //set title of Image
        this.setTitle(imageAdapter.mThumbTitles[position]);
        // Load are heavy lifter (goes and does work on another thread), to get a response after the lifters thread
        // has finished we pass in a Handler that will be notified when it completes
        chuckNorris = new HeavyLifter(this, chuckFinishedHandler);

    }


    @Override
    public void onClick(View v) {
        v.setEnabled(false);
        ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).clearAnimation();
        ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).setAnimation(animation1);
        ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).startAnimation(animation1);
    }
    @Override
    public void onAnimationEnd(Animation animation) {
        int i = getIntent().getExtras().getInt("id");
        if (animation==animation1) {
            if (isBackOfCardShowing) {
                ((ImageView)findViewById(i)).setImageResource(mImageIds[i]);
            } else {
                ((ImageView)findViewById(i)).setImageResource(mBackIds[i]);
            }
            ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).clearAnimation();
            ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).setAnimation(animation2);
            ((ImageView)findViewById(getIntent().getExtras().getInt("id"))).startAnimation(animation2);
        } else {
            isBackOfCardShowing=!isBackOfCardShowing;
            findViewById(R.id.flip).setEnabled(true);
        }
    }

    @Override
    public void onAnimationRepeat(Animation animation) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onAnimationStart(Animation animation) {
        // TODO Auto-generated method stub

    }
    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);

        // Trigger the initial hide() shortly after the activity has been
        // created, to briefly hint to the user that UI controls
        // are available.
        delayedHide(100);
    }

    /**
     * Touch listener to use for in-layout UI controls to delay hiding the
     * system UI. This is to prevent the jarring behavior of controls going away
     * while interacting with activity UI.
     */
    View.OnTouchListener mDelayHideTouchListener = new View.OnTouchListener() {
        @Override
        public boolean onTouch(View view, MotionEvent motionEvent) {
            if (AUTO_HIDE) {
                delayedHide(AUTO_HIDE_DELAY_MILLIS);
            }
            return false;
        }
    };

    Handler mHideHandler = new Handler();
    Runnable mHideRunnable = new Runnable() {
        @Override
        public void run() {
            mSystemUiHider.hide();
        }
    };

    /**
     * Schedules a call to hide() in [delay] milliseconds, canceling any
     * previously scheduled calls.
     */
    private void delayedHide(int delayMillis) {
        mHideHandler.removeCallbacks(mHideRunnable);
        mHideHandler.postDelayed(mHideRunnable, delayMillis);
    }

    /**
     * Called from XML when the save wallpaper button is pressed
     * Thie retrieves the id of the current image from our list
     * It then asks chuck to save it as a wallpaper!
     * The chuckHandler will be called when this operation is complete
     * @param v
     */

    public void saveWallpaper(View v) {
         // get intent data
        Intent i = getIntent();

        // Selected image id
        int position = i.getExtras().getInt("id");
        ImageAdapter imageAdapter = new ImageAdapter(this);


     // Show a toast message on successful save
        if(chuckNorris.saveResourceAsWallpaper(imageAdapter.mThumbIds[position])){
            Toast.makeText(FullscreenActivity.this, "Image Saved to ZamaaanWallpaper folder", Toast.LENGTH_SHORT).show();
        }
        else{
            Toast.makeText(FullscreenActivity.this, "Image couldn't be saved, try again", Toast.LENGTH_SHORT).show();
        }

    }

    /**
     * Called from XML when the set wallpaper button is pressed
     * Thie retrieves the id of the current image from our list
     * It then asks chuck to set it as a wallpaper!
     * The chuckHandler will be called when this operation is complete
     * @param v
     */
    public void setAsWallpaper(View v) {
         // get intent data
        Intent i = getIntent();

        // Selected image id
        int position = i.getExtras().getInt("id");
        ImageAdapter imageAdapter = new ImageAdapter(this);

        chuckNorris.setResourceAsWallpaper(imageAdapter.mThumbIds[position]);
    }

    /**
     * This is the handler that is notified when are HeavyLifter is finished doing an operation
     */
    private Handler chuckFinishedHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch(msg.what){
            case SUCCESS:
                Toast.makeText(FullscreenActivity.this, "Wallpaper set", Toast.LENGTH_SHORT).show();
                break;
            case FAIL:
                Toast.makeText(FullscreenActivity.this, "Wallper NOT set, try again", Toast.LENGTH_SHORT).show();
                break;
            default:
                super.handleMessage(msg);
            }
        }
    };



    }

Answer 1

我解决了我的问题。我只需要:

1. 将每个页面的 boolean isBackOfCardShowing 更改为 boolean 数组并将其初始化为 false。
2. 使用 viewpager.getCurrentItem() 获取当前页面的位置，而不是我正在做的。