android - 在启动 CustomViewPager 时启动动画

Question

我成功地在我的 CustomViewPager 开始时创建了一个动画，它的作用类似于轮播。所以在这里，我的元素在 3 秒内从左边来到右边。问题是它只是一个翻译我想知道是否有可能让我的 viewpager 从远处滚动到他的最终位置。

你有办法做到这一点吗？问候。

编辑:因此，我尝试了其他方法，并创建了我的自定义 ScrollToAnimation。我成功地创造了我想要的东西，但运动并不顺利，你能帮帮我吗？我的新代码:

import android.support.v4.view.ViewPager;
import android.view.animation.Animation;
import android.view.animation.Transformation;

import java.util.Calendar;

public class ScrollToAnimation extends Animation {
    private int currentIndex = 0, nbChilds = -1, deltaT = 0;
    private float fromX, toX;
    private long animationStart;
    private ViewPager viewpager;

    public ScrollToAnimation(ViewPager viewpager, float fromX, float toX, int duration) {
        this.viewpager = viewpager;
        this.fromX = fromX;
        this.toX = toX;

        nbChilds = viewpager.getChildCount();
        deltaT = duration / nbChilds;

        setDuration(duration);
        animationStart = Calendar.getInstance().getTimeInMillis();
    }

    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        super.applyTransformation(interpolatedTime, t);
        int offset = (int) (-fromX * interpolatedTime + fromX);
        viewpager.scrollTo(offset, 0);

        long animationProgression = Calendar.getInstance().getTimeInMillis() - animationStart;
        currentIndex = (int) (animationProgression/deltaT);
        if(viewpager.getCurrentItem() != currentIndex) {
            viewpager.setCurrentItem(nbChilds-currentIndex, false);
        }
    }
}

ViewPager:

import android.content.Context;
import android.graphics.Canvas;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.animation.Animation;
import android.view.animation.Interpolator;

import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class CarouselViewPager extends ViewPager {
    private DisplayMetrics metrics;
    private Animation animation;
    private SpeedScroller mScroller = null;
    private boolean animationNotStarted = true, leftToRight;

    public CarouselViewPager(Context context) {
        super(context);
        postInitViewPager();
        metrics = getContext().getResources().getDisplayMetrics();
    }

    public CarouselViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
        postInitViewPager();
        metrics = getContext().getResources().getDisplayMetrics();
    }

    private void postInitViewPager() {
        try {
            Class<?> viewpager = ViewPager.class;
            Field scroller = viewpager.getDeclaredField("mScroller");
            scroller.setAccessible(true);
            Field interpolator = viewpager.getDeclaredField("sInterpolator");
            interpolator.setAccessible(true);

            mScroller = new SpeedScroller(getContext(), (Interpolator) interpolator.get(null));
            scroller.set(this, mScroller);
        } catch (Exception e) {
            Log.e("postInitViewPager", e.getMessage());
        }
    }

    public void setScrollDurationFactor(double scrollFactor) {
        mScroller.setScrollDurationFactor(scrollFactor);
    }

    @Override
    public void setCurrentItem(int item, boolean smoothScroll) {
        try {
            Method method = ViewPager.class.getDeclaredMethod("setCurrentItemInternal", int.class, boolean.class, boolean.class, int.class);
            method.setAccessible(true);
            method.invoke(this, item, true, false, 1500);
        } catch (Exception e) {
            e.printStackTrace();
            super.setCurrentItem(item, smoothScroll);
        }
    }

    public void startAnimation(boolean leftToRight) {
        animation = new ScrollToAnimation(this, ((metrics.widthPixels/2)+200)*2, 0, 2000);
        animationNotStarted = false;
        this.leftToRight = leftToRight;
    }

    private Canvas enterAnimation(final Canvas c) {
        animationNotStarted = true;
        startAnimation(animation);
        scrollTo(0, 0);
        return c;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (!animationNotStarted) {
            canvas = enterAnimation(canvas);
        }
        super.onDraw(canvas);
    }
}

编辑2:

这里有一个屏幕截图可以帮助您了解我想要什么。实际上我有一个像这样的自定义 viewpager :

我想要的动画如下:

• 当我启动动画时，项目在很远的地方。
• 之后，它们从左到右(或相反)并停在所选项目上，但我希望在项目滚动时具有缩放效果。
• 借助自定义适配器，我成功创建了缩放效果

我的问题，这里是当我设置当前项目时它不流畅，你有什么想法吗？这是代码适配器

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;

public class CarouselAdapter extends FragmentPagerAdapter implements ViewPager.OnPageChangeListener {
    private float scale;
    private MainActivity context;

    private FragmentManager fragmentManager;
    private ArrayList<Entity> entities = new ArrayList<>();
    private ScaledFrameLayout cur = null, next = null;

    public CarouselAdapter(MainActivity context, FragmentManager fragmentManager, ArrayList<Entity> mData) {
        super(fragmentManager);
        this.fragmentManager = fragmentManager;
        this.context = context;
        this.entities = mData;
    }

    @Override
    public Fragment getItem(int position) {
        if (position == MainActivity.FIRST_PAGE) {
            scale = MainActivity.BIG_SCALE;
        } else {
            scale = MainActivity.SMALL_SCALE;
        }
        Fragment fragment = CarouselFragment.newInstance(context, entities.get(position), position, scale);
        return fragment;
    }

    @Override
    public int getItemPosition(Object object) {
        return super.getItemPosition(object);
    }

    @Override
    public int getCount() {
        return entities.size();
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        if (positionOffset >= 0f && positionOffset <= 1f) {
            cur = getRootView(position);
            cur.setScaleBoth(MainActivity.BIG_SCALE - MainActivity.DIFF_SCALE * positionOffset);

            if (position < entities.size()-1) {
                next = getRootView(position + 1);
                next.setScaleBoth(MainActivity.SMALL_SCALE + MainActivity.DIFF_SCALE * positionOffset);
            }
        }
    }

    @Override
    public void onPageSelected(int position) { }

    @Override
    public void onPageScrollStateChanged(int state) {}

    private ScaledFrameLayout getRootView(int position) {
        return (ScaledFrameLayout) fragmentManager.findFragmentByTag(this.getFragmentTag(position)).getView().findViewById(R.id.rootItem);
    }

    private String getFragmentTag(int position) {
        return "android:switcher:" + context.carousel.getId() + ":" + position;
    }
}

更简单的方法是改变当前项目的当前位置而不刷新所有内容，这可能吗？我的意思是不进行任何转换，因为如您所见，我已经有了翻译，当我设置当前项目时，结果与我的带有偏移量的 scrollto 发生冲突。

Answer 1

我认为您必须使 imageSlider 中的一个具有平滑滚动和图像随动画变化。

github 中提供的 Android Image Slider 库现在请参阅以下步骤以使用它。

• 第 1 步:在 lib 下编译 Gradle。

  dependencies {
  compile "com.android.support:support-v4:+"
  compile 'com.squareup.picasso:picasso:2.3.2'
  compile 'com.nineoldandroids:library:2.4.0'
  compile 'com.daimajia.slider:library:1.1.5@aar'
  }
  

• 第 2 步:向您的 AndroidManifest.xml 添加权限(如有必要)

   <!-- if you want to load images from the internet -->
   <uses-permission android:name="android.permission.INTERNET" /> 
  
   <!-- if you want to load images from a file OR from the internet -->
   <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
  

• 第 3 步:将 slider 添加到您的布局:

  <com.daimajia.slider.library.SliderLayout
  android:id="@+id/slider"
  android:layout_width="match_parent"
  android:layout_height="200dp"
  />
  

  现在在您的 Activity 中编写代码，在此处 SlideShow.class 中管理代码。

   public class SlideShow extends Activity {
       ImageView mIVmenu;
       SliderLayout sliderLayout;
       ListView menu_list;
       ArrayList<String> imgList = new ArrayList<String>();
       int position;
       Button btnBack;
       static int adapter_position = 0;
       String animation_name;
  
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           setContentView(R.layout.slideshow);
           sliderLayout = (SliderLayout) findViewById(R.id.sliderlayout);
           menu_list = (ListView) findViewById(R.id.menu_list);
           btnBack = (Button) findViewById(R.id.btn_back_slideshow);
           menu_list.setAdapter(adapter);
           // get Data from Intent array list and set on array list
           imgList = getIntent().getStringArrayListExtra("arrayList");
           position = getIntent().getExtras().getInt("position");
          animation_name = SliderLayout.Transformer.Default.toString();
       }
  
      // call method for set images in slideshow and configure slideshow..
     addImagesToSlider();
  
     btnBack.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
          Intent i = new Intent(SlideShow.this, MainActivity.class);
          startActivity(i);
          finish();
      }
  });
  
  }
  
   private void addImagesToSlider() {
      for (int i = 0; i < imgList.size(); i++) {
      TextSliderView textSliderView = new TextSliderView(this);
      textSliderView.description("").image(new File(imgList.get(i))).setScaleType(BaseSliderView.ScaleType.CenterInside).setOnSliderClickListener(new BaseSliderView.OnSliderClickListener() {
          @Override
          public void onSliderClick(BaseSliderView slider) {
          }
      });
      sliderLayout.addSlider(textSliderView);
     }
  
  sliderLayout.setPresetTransformer(animation_name);
  sliderLayout.setCustomAnimation(new DescriptionAnimation());
  sliderLayout.stopAutoCycle();
  sliderLayout.setCurrentPosition(position);
  }
  
  BaseAdapter adapter = new BaseAdapter() {
  @Override
  public int getCount() {
      return SliderLayout.Transformer.values().length;
  }
  
  @Override
  public Object getItem(int position) {
      return null;
  }
  
  @Override
  public long getItemId(int position) {
      return 0;
  }
  
  @Override
  public View getView(final int position, View convertView, ViewGroup parent) {
  
      View view;
      view = LayoutInflater.from(parent.getContext()).inflate(R.layout.slidemenu_item, parent, false);
      TextView tv = (TextView) view.findViewById(R.id.txtslideTitle);
      final String str = SliderLayout.Transformer.values()[position].toString();
      tv.setText(str);
  
      view.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
  
              sliderLayout.setPresetTransformer(str);
              animation_name = str;
              notifyDataSetChanged();
  
          }
      });
      if (str.equals(animation_name)) {
          adapter_position = position;                        
  tv.setBackgroundColor(getResources().getColor(R.color.colorAccent));
      } else {  tv.setBackgroundColor(getResources().getColor(R.color.colorPrimaryDark));
      }
      return view;
  }
      };
  }
  

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