Android ListView实现下拉顶部图片变大效果

概述本文实例为大家分享了Android九宫格图片展示的具体代码，供大家参考，具体内容如下

本文实例为大家分享了AndroID九宫格图片展示的具体代码，供大家参考，具体内容如下

在git上查看牛人的代码，发现是反编译别人的代码，还没加注释，代码也没有完全编译完整，所以这里我做的简单的注释，仅供学习。

变量说明

这里变量包含了：自定义返回动画加速度、自定义动画线程、头部图片vIEw，最后的y坐标，做好的比例，做大的比例等。

private static final String TAG = "PullToZoomListVIEw";  private static final int INVALID_VALUE = -1;//重置值  //自定义加速度动画  private static final Interpolator sInterpolator = new Interpolator() {    public float getInterpolation(float interpolator) {      float f = interpolator - 1.0F;      return 1.0F + f * (f * (f * (f * f)));    }  };  private int mActivePointerID = INVALID_VALUE;//当前手指的ID  private FrameLayout mheaderContainer;//头部  private int mheaderHeight;//头部图片的高度  private ImageVIEw mheaderImage;//头部图片  float mLastMotionY = INVALID_VALUE;//最后y坐标  float mLastScale = INVALID_VALUE;//最后的比例  float mMaxScale = INVALID_VALUE;//最大的比例  private OnScrollListener mOnScrollListener;//滑动监听  private ScalingRunnalable mScalingRunnalable;//动画线程  private int mScreenHeight;//屏幕高度  private ImageVIEw mShadow;//阴影遮罩

自定义view初始化：设置了头部的头部和遮罩并且设置了监听。

/**   * 初始化   * @param paramContext   */  private voID init(Context paramContext) {    displayMetrics metrics = new displayMetrics();    ((Activity) paramContext).getwindowManager().getDefaultdisplay().getMetrics(metrics);    this.mScreenHeight = metrics.heightPixels;//屏幕高度赋值    this.mheaderContainer = new FrameLayout(paramContext);//头部    this.mheaderImage = new ImageVIEw(paramContext);//头部图片    int screenWIDth = metrics.wIDthPixels;//屏幕宽度    //设置头部VIEw的样式 设置屏幕宽度，最大样式高度为屏幕高度的9/16    setheaderVIEwSize(screenWIDth,(int) (9.0F * (screenWIDth / 16.0F)));    this.mShadow = new ImageVIEw(paramContext);//遮罩    FrameLayout.LayoutParams layoutParams =        new FrameLayout.LayoutParams(VIEwGroup.LayoutParams.MATCH_PARENT,VIEwGroup.LayoutParams.MATCH_PARENT);    layoutParams.gravity = Gravity.CENTER;    this.mShadow.setLayoutParams(layoutParams);//设置遮罩样式    //头部添加VIEw    this.mheaderContainer.addVIEw(this.mheaderImage);    this.mheaderContainer.addVIEw(this.mShadow);    //添加头部    addheaderVIEw(this.mheaderContainer);    //初始化返回动画    this.mScalingRunnalable = new ScalingRunnalable();    //设置监听    super.setonScrollListener(this);  }

开启动画：判断当前的头部布局底部的位置C是否大于图片的初始化高度。

/**   * 开启动画   */  private voID endScraling() {    if (this.mheaderContainer.getBottom() >= this.mheaderHeight) {      Log.d(TAG,"this.mScalingRunnalable.startAnimation(200L)");      this.mScalingRunnalable.startAnimation(200L);    }  }

多指触碰时将第0个手指赋值。

/**   * 多点触碰的时候按下,当第0个有手指抬起，再次有手指按下后，将按下的事件的手指指针作为当前手指指针   *   * @param motionEvent   */  private voID onSecondaryPointerUp(MotionEvent motionEvent) {    Log.d(TAG,"onSecondaryPointerUp motionEvent.getPointerID(0) = " + motionEvent.getPointerID(0));    Log.d(TAG,"onSecondaryPointerUp this.mActivePointerID = " + this.mActivePointerID);    if (motionEvent.getPointerID(0) == this.mActivePointerID) {      this.mLastMotionY = motionEvent.getY(0);      this.mActivePointerID = motionEvent.getPointerID(0);    }    Log.d(TAG,"onSecondaryPointerUp mLastMotionY = " + mLastMotionY);    Log.d(TAG,"onSecondaryPointerUp mActivePointerID = " + mActivePointerID);  }

重置所有的数据

/** * 重置所有数据*/  private voID reset() {    this.mActivePointerID = INVALID_VALUE;    this.mLastMotionY = INVALID_VALUE;    this.mMaxScale = INVALID_VALUE;    this.mLastScale = INVALID_VALUE;  }

向上滚动时修改布局样式

@OverrIDe  public voID onScroll(AbsListVIEw vIEw,int firstVisibleItem,int visibleItemCount,int totalitemCount) {    Log.d(TAG,"onScroll");    float bottomSpacing = this.mheaderHeight - this.mheaderContainer.getBottom();    Log.d(TAG,"onScroll bottomSpacing = " + bottomSpacing);    if ((bottomSpacing > 0.0F) && (bottomSpacing < this.mheaderHeight)) {//如果是向上滑动      int toUpScroll = (int) (0.65D * bottomSpacing);      this.mheaderImage.scrollTo(0,-toUpScroll);      Log.d(TAG,"onScroll 向上滑动 toUpScroll = " + toUpScroll);    } else if (this.mheaderImage.getScrollY() != 0) {      Log.d(TAG,"onScroll this.mheaderImage.getScrollY() = " + this.mheaderImage.getScrollY());      this.mheaderImage.scrollTo(0,0);    }    if (this.mOnScrollListener != null) {      this.mOnScrollListener.onScroll(vIEw,firstVisibleItem,visibleItemCount,totalitemCount);    }  }

不同事件处理，修改布局样式

@OverrIDe  public boolean ontouchEvent(MotionEvent motionEvent) {    switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {      case MotionEvent.ACTION_OUTSIDE:      case MotionEvent.ACTION_DOWN:        if (!this.mScalingRunnalable.mIsFinished) {          this.mScalingRunnalable.abortAnimation();        }        this.mLastMotionY = motionEvent.getY();        //获取第一个手指指针的ID        this.mActivePointerID = motionEvent.getPointerID(0);        this.mMaxScale = (this.mScreenHeight / this.mheaderHeight);        this.mLastScale = (this.mheaderContainer.getBottom() / this.mheaderHeight);        Log.d(TAG,"ontouchEvent ACTION_DOWN mLastMotionY = " + mLastMotionY);        Log.d(TAG,"ontouchEvent ACTION_DOWN mActivePointerID = " + mActivePointerID);        Log.d(TAG,"ontouchEvent ACTION_DOWN mMaxScale = " + mMaxScale);        Log.d(TAG,"ontouchEvent ACTION_DOWN mLastScale = " + mLastScale);        break;      case MotionEvent.ACTION_MOVE:        Log.d(TAG,"ontouchEvent ACTION_MOVE mActivePointerID" + mActivePointerID);        //获取当前ID的手机指针        int pointer = motionEvent.findPointerIndex(this.mActivePointerID);        //判断指针不为空        if (pointer == INVALID_VALUE) {          Log.e(TAG,"InvalID pointerID=" + this.mActivePointerID + " in ontouchEvent");        } else {          //如果开始没有赋值，则需要赋值          if (this.mLastMotionY == INVALID_VALUE) {            this.mLastMotionY = motionEvent.getY(pointer);          }          if (this.mheaderContainer.getBottom() >= this.mheaderHeight) {            //获取头部样式            VIEwGroup.LayoutParams headerParams = this.mheaderContainer.getLayoutParams();            float currentScale = ((motionEvent.getY(pointer) - this.mLastMotionY + this.mheaderContainer.getBottom())                / this.mheaderHeight - this.mLastScale)                / 2.0F + this.mLastScale;            if ((this.mLastScale <= 1.0D) && (currentScale < this.mLastScale)) {              //最后比例小于默认并且当前的比例要小于上次的比例，则修改头部的高度              headerParams.height = this.mheaderHeight;              this.mheaderContainer.setLayoutParams(headerParams);              return super.ontouchEvent(motionEvent);            } else {              //否则，将当前的比例赋值为最后一次的比例              this.mLastScale = Math.min(Math.max(currentScale,1.0F),this.mMaxScale);              headerParams.height = ((int) (this.mheaderHeight * this.mLastScale));              //判断修改后的高度小于屏幕的高度              if (headerParams.height < this.mScreenHeight) {                this.mheaderContainer.setLayoutParams(headerParams);              }              //记录最后的y坐标              this.mLastMotionY = motionEvent.getY(pointer);              return true;            }          }          this.mLastMotionY = motionEvent.getY(pointer);        }        break;      case MotionEvent.ACTION_UP:        Log.d(TAG,"ontouchEvent ACTION_UP 重置");        //重置        reset();        //当手指起来的时候，结算拉伸，判断是否开启动画        endScraling();        break;      case MotionEvent.ACTION_CANCEL:        int actionIndex = motionEvent.getActionIndex();//获取当前最上层的指针        this.mLastMotionY = motionEvent.getY(actionIndex);//获取最后的y坐标        this.mActivePointerID = motionEvent.getPointerID(actionIndex);//获取最上层指针的手指        Log.d(TAG,"ontouchEvent ACTION_CANCEL actionIndex = " + actionIndex + " mLastMotionY = " + mLastMotionY + " mActivePointerID = " + mActivePointerID);        break;      case MotionEvent.ACTION_POINTER_DOWN:        //当第二个手指按下或者放开触发这个事件        onSecondaryPointerUp(motionEvent);        this.mLastMotionY = motionEvent.getY(motionEvent.findPointerIndex(this.mActivePointerID));        Log.d(TAG,"ontouchEvent_Po ACTION_POINTER_DOWN mLastMotionY = " + mLastMotionY);        break;      case MotionEvent.ACTION_POINTER_UP:        //当第二个手指按下或者放开        Log.d(TAG,"ontouchEvent_Po ACTION_POINTER_UP ");        break;    }    return super.ontouchEvent(motionEvent);  }

向上返回时的动画

/**   * 向上返回的动画   */  class ScalingRunnalable implements Runnable {    long mDuration;//持续时间    boolean mIsFinished = true;//是否结束    float mScale;//比例    long mStartTime;//开始时间    ScalingRunnalable() {    }    /**     * 中止动画     */    public voID abortAnimation() {      this.mIsFinished = true;    }    /**     * 是否中止     *     * @return     */    public boolean isFinished() {      return this.mIsFinished;    }    public voID run() {      Log.d(TAG,"ScalingRunnalable mIsFinished = " + this.mIsFinished + " this.mScale = " + this.mScale);      float currentScale;      VIEwGroup.LayoutParams mheaderContainerParams;//头部样式      //判断是否中止和已经滑动超过的默认大小      if ((!this.mIsFinished) && (this.mScale > 1.0D)) {        float currentTime = ((float) SystemClock.currentThreadTimeMillis() - (float) this.mStartTime) / (float) this.mDuration;        currentScale = this.mScale - (this.mScale - 1.0F) * PullToZoomListVIEw.sInterpolator.getInterpolation(currentTime);        Log.d(TAG,"ScalingRunnalable currentTime = " + currentTime + " currentScale = " + currentScale);        mheaderContainerParams = PullToZoomListVIEw.this.mheaderContainer.getLayoutParams();        if (currentScale > 1.0F) {          Log.d(TAG,"ScalingRunnalable currentScale > 1.0 -- 修改头部高度");          mheaderContainerParams.height = PullToZoomListVIEw.this.mheaderHeight;          mheaderContainerParams.height = ((int) (currentScale * PullToZoomListVIEw.this.mheaderHeight));          PullToZoomListVIEw.this.mheaderContainer.setLayoutParams(mheaderContainerParams);          PullToZoomListVIEw.this.post(this);//循环执行        } else {          Log.d(TAG,"ScalingRunnalable currentScale < 1.0 -- 中止");          this.mIsFinished = true;        }      }    }    public voID startAnimation(long paramLong) {      Log.d(TAG,"ScalingRunnalable 开始执行动画");      this.mStartTime = SystemClock.currentThreadTimeMillis();      this.mDuration = paramLong;      this.mScale = ((float) (PullToZoomListVIEw.this.mheaderContainer.getBottom()) / PullToZoomListVIEw.this.mheaderHeight);      this.mIsFinished = false;      Log.d(TAG,"ScalingRunnalable this.mStartTime = " + this.mStartTime);      Log.d(TAG,"ScalingRunnalable this.mDuration = " + this.mDuration);      Log.d(TAG,"ScalingRunnalable this.mScale = " + this.mScale);      Log.d(TAG,"ScalingRunnalable this.mIsFinished = " + this.mIsFinished);      PullToZoomListVIEw.this.post(this);    }  }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程小技巧。

总结

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