Android仿京東首頁畫軸效果

記得之前京東首頁有一個效果,有一個畫軸,然後可以滾動畫軸,去打開畫(不知道怎麼去形容這個效果,就叫做畫軸效果吧- -!),然後去做相關操作,剛開始看到這個效果,想法是動態的去改變一個ImageView的高度,基本效果也就出來了,不過滾動部分的內容,當時接觸的也不是很多,只是看過一些大牛的博客,略微了解了一點,當時也忙著寫項目,也就沒去多想,前些天忽然想到這個效果,就想著實現一下,不過京東新版本好像去掉這個東西了,只能憑著自己的記憶來大概搞一下,也是對滑動這部分內容的一個小練習吧.

先看一下效果圖:

一、需求分析

看到效果之後,先來分析一下:
首先是需要一個可以滑動的畫軸,並且這個畫軸需要一定的滑動空間,有滑動的效果,這個用Scroller幫助完成就可以了.
然後看一下畫軸點擊移動時候的背景圖,是跟隨畫軸移動,動態改變高度的.這個用一個ImageView來搞定,設置ImageView的scaleType就可以了,不過這個地方有一些小問題,下面會說.

二、具體實現

簡單分析完,來實現一下,先來做一下畫軸.創建一個ScrollPaintView繼承自RelativeLayout,因為需要一定的滑動空間,所以需要是一個ViewGroup.

ScrollPaintView的一些基本屬性:

public class ScrollPaintView extends RelativeLayout {
 /**
 * TAG
 */
 private static final String TAG = "ScrollPaintView";
 /**
 * 默認滾軸高度
 */
 private final int DEFAULT_PAINT_SCROLL_HEIGHT = 25;
 /**
 * 默認滾動的速度
 */
 private final int DEFAULT_SCROLL_SPEED = 1000;
 /**
 * 默認分割點高度
 */
 private final int DEFAULT_PARTITION_NODE = 150;
 /**
 * 默認畫軸文字大小
 */
 private final int DEFAULT_PAINT_SCROLL_TXT_SIZE = 16;
 /**
 * Scroller
 */
 private Scroller mScroller;
 /**
 * 滾軸Iv
 */
 private ImageView mPaintScrollImageView;
 /**
 * 滾軸Tv
 */
 private TextView mPaintScrollTextView;
 /**
 * 圖畫Iv
 */
 private ImageView mPaintView;
 /**
 * 畫軸圖
 */
 private Bitmap mPaintScrollBp;
 /**
 * 畫軸高度
 */
 private int mPaintIvHeight;
 /**
 * 畫軸文字
 */
 private String mPaintScrollTxt;
 /**
 * 畫軸文字大小
 */
 private float mPaintScrollTxtSize;
 /**
 * 畫軸文字顏色
 */
 private int mPaintScrollTxtColor;
 /**
 * 圖畫開始時的高度
 */
 private int mPaintStartHeight;
 /**
 * 上一次獲取的Y
 */
 private int mLastY;
 /**
 * 滾動速度
 */
 private int mScrollSpeed;
 /**
 * 分隔節點
 */
 private int partitionNode;
 /**
 * 是否是向上滾動
 */
 private boolean isScrllerTop = false;
 /**
 * 是否正在點擊
 */
 private boolean isClick = false;
 /**
 * 布局參數
 */
 private LayoutParams lpp;
 /**
 * 屏幕高度
 */
 private int screenHeight;
 /**
 * 屏幕寬度
 */
 private int screenWidth;
 /**
 * 回調監聽
 */
 private ScrollPaintCompleteListener listener;
 /**
 * 上一次滾動的Y值
 */
 private int lastScrollY;

 /**
 * 構造方法
 */
 public ScrollPaintView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 // 獲取屬性
 TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ScrollPaintView);
 mPaintIvHeight = (int) ta.getDimension(R.styleable.ScrollPaintView_paintScrollHeight, TypedValue.applyDimension(
  TypedValue.COMPLEX_UNIT_DIP, DEFAULT_PAINT_SCROLL_HEIGHT, getResources().getDisplayMetrics()));
 mScrollSpeed = ta.getInteger(R.styleable.ScrollPaintView_scrollSpeed, DEFAULT_SCROLL_SPEED);
 partitionNode = ta.getInteger(R.styleable.ScrollPaintView_scrollPartitionNode, DEFAULT_PARTITION_NODE);
 mPaintScrollBp = drawableToBitamp(ta.getDrawable(R.styleable.ScrollPaintView_paintScrollSrc));
 mPaintScrollTxt = ta.getString(R.styleable.ScrollPaintView_paintScrollTxt);
 mPaintScrollTxtColor = ta.getColor(R.styleable.ScrollPaintView_paintScrollTxtColor, Color.BLACK);
 mPaintScrollTxtSize = px2sp(ta.getDimensionPixelSize(R.styleable.ScrollPaintView_paintScrollTxtSize, DEFAULT_PAINT_SCROLL_TXT_SIZE));
 ta.recycle();
 }
}

看一下創建畫軸:

 /**
 * 創建滾軸
 */
 private void makePaintScroll() {
 // 如果已經存在,則不再創建
 if (null != mPaintScrollImageView || null != mPaintScrollTextView) {
  return;
 }
 // 創建滾軸
 mPaintScrollImageView = new ImageView(getContext());
 LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
 lp.height = mPaintIvHeight;
 mPaintScrollImageView.setLayoutParams(lp);
 mPaintScrollImageView.setScaleType(ImageView.ScaleType.FIT_XY);
 mPaintScrollImageView.setImageBitmap(null == mPaintScrollBp ? makeDefaultScroll() : mPaintScrollBp);
 addView(mPaintScrollImageView);
 // 創建文字
 mPaintScrollTextView = new TextView(getContext());
 LayoutParams lpt = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
 lpt.height = mPaintIvHeight;
 mPaintScrollTextView.setLayoutParams(lpt);
 mPaintScrollTextView.setText(null == mPaintScrollTxt ? "" : mPaintScrollTxt);
 mPaintScrollTextView.setTextSize(mPaintScrollTxtSize);
 mPaintScrollTextView.setTextColor(mPaintScrollTxtColor);
 mPaintScrollTextView.setGravity(Gravity.CENTER);
 addView(mPaintScrollTextView);
 }

 /**
 * 設置默認的滾軸
 *
 * @return
 */
 private Bitmap makeDefaultScroll() {
 Bitmap defaultBp = Bitmap.createBitmap(screenWidth, mPaintIvHeight,
  Bitmap.Config.ARGB_8888);
 //填充顏色
 defaultBp.eraseColor(Color.parseColor("#FF0000"));
 return defaultBp;

 }

創建了一個畫軸ImageView和一個文字TextView作為初始的畫軸,如果沒有傳入畫軸的圖片,則默認去創建一個畫軸.不難理解,接著去配合Scroller,讓畫軸滾動起來.

簡單滾動:

 /**
 * 處理View
 */
 private void handleView() {
 // 初始化Scroller
 mScroller = new Scroller(getContext());
 // 畫軸點擊效果
 mPaintScrollImageView.setOnTouchListener(new OnTouchListener() {
  @Override
  public boolean onTouch(View view, MotionEvent event) {
  int x = (int) event.getRawX();
  int y = (int) event.getRawY();
  int action = event.getAction();
  switch (action) {
   case MotionEvent.ACTION_DOWN: 
   isClick = true;
   mLastY = y;
   if (!mScroller.isFinished()) { // 如果上次的調用沒有執行完就取消。
    mScroller.abortAnimation();
   }
   return true;
   case MotionEvent.ACTION_MOVE: 
   // 移動的距離
   int dy = y - mLastY;
   mLastY = y;
   // 滑動
   scrollBy(0, -dy);
   return true;
   case MotionEvent.ACTION_UP:
   mScroller.startScroll(getScrollX(), getScrollY(), -getScrollX(), -getScrollY(), 1000);
   invalidate();
   return true;
  }
  return false;
  }
 });
 }

 /**
 * 滑動處理
 */
 @Override
 public void computeScroll() {
 if (mScroller.computeScrollOffset()) { // 計算新位置，並判斷上一個滾動是否完成。 
  scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
  invalidate();
  }
 }

這樣滑動處理就做完了,在布局中引用一下,看一下效果

activity_main:

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:background="#eeeeee"
 tools:context="com.example.junweiliu.scrollpaintdemo.MainActivity">
  <!--畫軸控件-->
 <com.example.junweiliu.scrollpaintdemo.widget.ScrollPaintView
  android:id="@+id/spv_paint"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  app:paintScrollHeight="25dp"
  app:paintScrollSrc="@mipmap/paint_scroll_img"
  app:paintScrollTxt="拉我看看"
  app:paintScrollTxtColor="#FF000000"
  app:paintScrollTxtSize="16sp"
 >
 </com.example.junweiliu.scrollpaintdemo.widget.ScrollPaintView>
</RelativeLayout>

效果圖:

滾動條基本能用了,接著來設置一個ImageView來配合使用下,先獲取到一個ImageView,然後拖動畫軸時,來動態改變ImageView的高度,在做這部分內容前,先來考慮下,因為需求需要的是圖畫整體不會變形,是一點一點拉開的感覺,就像是打開一幅畫一樣,那麼用哪種scaleType能滿足呢.試了好多種,來分別看一下:

相關代碼:

提供一個設置ImageView的方法
在MotionEvent.ACTION_MOVE:中動態改變ImageView的高度
滑動時動態改變ImageView的高度

 /**
 * 設置paintView
 *
 * @param paintView
 */
 public void setPaintView(ImageView paintView) {
 if (null == paintView) {
  Log.e(TAG, "設置的View為空");
  return;
 }
 mPaintView = paintView;
 }

MotionEvent.ACTION_MOVE:

 // 滑動處理 
 case MotionEvent.ACTION_MOVE: 
 ...
 // 動態改變高度
 if (Math.abs(getScrollY()) > 0) {
    lpp.height = mPaintStartHeight + Math.abs(getScrollY());
    mPaintView.setLayoutParams(lpp);
   }

滑動處理:

 /**
 * 滑動處理
 */
 @Override
 public void computeScroll() {
 if (mScroller.computeScrollOffset()) { // 計算新位置，並判斷上一個滾動是否完成。
  // 請求處理點擊事件,防止父控件滑動
  requestDisallowInterceptTouchEvent(true);
  scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
  // 重新設置顯示的控件高度
  if (0 < Math.abs(mScroller.getCurrY())) {
  if (!isScrllerTop) {
   lpp.height = mPaintStartHeight + Math.abs(mScroller.getCurrY()) + mPaintIvHeight / 2;
  } else {
   lpp.height = mPaintStartHeight + Math.abs(mScroller.getCurrY()) - mPaintIvHeight / 2;
  }
  } else {
  lpp.height = mPaintStartHeight;
  }
  mPaintView.setLayoutParams(lpp);
  invalidate();
 }
}

設置不同scaleType效果,簡單試幾個效果:

fitXY:

centerCrop:

matrix:

觀察一下,好像那個效果都不是很好,不過matrix拉開的效果和預期需要的是一樣的,不過用matrix之後,就沒有辦法設置其他scaleType了,沒辦法把圖片進行縮放了,這腫麼辦呢,其實很簡單,只需要把顯示的圖片提前進行一下縮放就可以了.

處理圖片相關:

 /**
 * 設置paintView
 *
 * @param paintView
 */
 public void setPaintView(ImageView paintView) {
 if (null == paintView) {
  Log.e(TAG, "設置的View為空");
  return;
 }
 // 處理圖片,對圖片按照屏幕寬高比進行縮放
 Bitmap bp = drawableToBitamp(paintView.getDrawable());
 paintView.setImageBitmap(scaleBitmal(bp));
 // 設置縮放形式
 paintView.setScaleType(ImageView.ScaleType.MATRIX);
 mPaintView = paintView;
 }
 /**
 * drawable轉bitmap
 *
 * @param drawable
 * @return
 */
 private Bitmap drawableToBitamp(Drawable drawable) {
 if (null == drawable) {
  return null;
 }
 if (drawable instanceof BitmapDrawable) {
  BitmapDrawable bd = (BitmapDrawable) drawable;
  return bd.getBitmap();
 }
 int w = drawable.getIntrinsicWidth();
 int h = drawable.getIntrinsicHeight();
 Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
 Canvas canvas = new Canvas(bitmap);
 drawable.setBounds(0, 0, w, h);
 drawable.draw(canvas);
 return bitmap;
 }


 /**
 * 按照屏幕寬高縮放圖片
 *
 * @param bp
 * @return
 */
 private Bitmap scaleBitmal(Bitmap bp) {
 // 寬度比例
 float scaleW = (float) screenWidth / (float) bp.getWidth();
 // 高度比例
 float scaleH = (float) screenHeight / (float) bp.getHeight();
 // 矩陣,用於縮放圖片
 Matrix matrix = new Matrix();
 matrix.postScale(scaleW, scaleH);
 // 縮放後的圖片
 Bitmap scaleBp = Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), matrix, true);
 return scaleBp;
 }

看一下效果:

效果還不錯,接下來就是做一下細節上的處理,設置一個臨界點,讓畫軸向上或者向下滾動,設置邊界點,讓畫軸不越界等等.還有一般都是在ScrollView中使用到這個效果,所以要去處理一下事件沖突,當然還有去重寫一下onMeasure方法,不然會出現不顯示的情況.(相信大家也遇到過ScrollView裡邊嵌套ListView導致ListView顯示不全)這裡就不再詳細介紹了.直接貼下代碼.

三、完整代碼

MainActivity:

package com.example.junweiliu.scrollpaintdemo;

import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import com.example.junweiliu.scrollpaintdemo.widget.ScrollPaintView;

public class MainActivity extends AppCompatActivity {
  private static final String TAG = "MainActivity";
  /**
   * 需要顯示的IV
   */
  private ImageView mPaintIv;
  /**
   * 畫軸
   */
  private ScrollPaintView mScrollPaintView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initView();

  }

  /**
   * 初始化控件
   */
  private void initView() {
    mPaintIv = (ImageView) findViewById(R.id.iv_paint);
    mScrollPaintView = (ScrollPaintView) findViewById(R.id.spv_paint);
    mScrollPaintView.setPaintView(mPaintIv);
    mPaintIv.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View view) {
        Toast.makeText(MainActivity.this, "功夫!", Toast.LENGTH_SHORT).show();
      }
    });
    mScrollPaintView.setScrollPaintCompleteListener(new ScrollPaintView.ScrollPaintCompleteListener() {
      @Override
      public void onScrollTouch(TextView tv) {
        mPaintIv.setVisibility(View.VISIBLE);
      }

      @Override
      public void onScrollTop(TextView tv) {
//        Log.e(TAG, "收縮了");
        tv.setText("拉我看看");
        if (View.VISIBLE == mPaintIv.getVisibility()) {
          mPaintIv.setVisibility(View.GONE);
        }
      }

      @Override
      public void onScrollBottom(TextView tv) {
//        Log.e(TAG, "展開了");
        tv.setText("到底了");
        Intent intent = new Intent(MainActivity.this, DetailActivity.class);
        startActivity(intent);
        // 延遲800毫秒重置位置
        new Handler(new Handler.Callback() {
          @Override
          public boolean handleMessage(Message message) {
            mScrollPaintView.replaceScroll();
            return false;
          }
        }).sendEmptyMessageDelayed(0, 600);
      }

      @Override
      public void onScrollMove(TextView tv) {
//        Log.e(TAG, "移動了");
        tv.setText("請上下拖動");
      }
    });
  }
}

ScrollPaintView:

package com.example.junweiliu.scrollpaintdemo.widget;

import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.Scroller;
import android.widget.TextView;

import com.example.junweiliu.scrollpaintdemo.R;

/**
 * Created by junweiliu on 16/12/10.
 */
public class ScrollPaintView extends RelativeLayout {
  /**
   * TAG
   */
  private static final String TAG = "ScrollPaintView";
  /**
   * 默認滾軸高度
   */
  private final int DEFAULT_PAINT_SCROLL_HEIGHT = 25;
  /**
   * 默認滾動的速度
   */
  private final int DEFAULT_SCROLL_SPEED = 1000;
  /**
   * 默認分割點高度
   */
  private final int DEFAULT_PARTITION_NODE = 150;
  /**
   * 默認畫軸文字大小
   */
  private final int DEFAULT_PAINT_SCROLL_TXT_SIZE = 16;
  /**
   * Scroller
   */
  private Scroller mScroller;
  /**
   * 滾軸Iv
   */
  private ImageView mPaintScrollImageView;
  /**
   * 滾軸Tv
   */
  private TextView mPaintScrollTextView;
  /**
   * 圖畫Iv
   */
  private ImageView mPaintView;
  /**
   * 畫軸圖
   */
  private Bitmap mPaintScrollBp;
  /**
   * 畫軸高度
   */
  private int mPaintIvHeight;
  /**
   * 畫軸文字
   */
  private String mPaintScrollTxt;
  /**
   * 畫軸文字大小
   */
  private float mPaintScrollTxtSize;
  /**
   * 畫軸文字顏色
   */
  private int mPaintScrollTxtColor;
  /**
   * 圖畫開始時的高度
   */
  private int mPaintStartHeight;
  /**
   * 上一次獲取的Y
   */
  private int mLastY;
  /**
   * 滾動速度
   */
  private int mScrollSpeed;
  /**
   * 分隔節點
   */
  private int partitionNode;
  /**
   * 是否是向上滾動
   */
  private boolean isScrllerTop = false;
  /**
   * 是否正在點擊
   */
  private boolean isClick = false;
  /**
   * 布局參數
   */
  private LayoutParams lpp;
  /**
   * 屏幕高度
   */
  private int screenHeight;
  /**
   * 屏幕寬度
   */
  private int screenWidth;
  /**
   * 回調監聽
   */
  private ScrollPaintCompleteListener listener;
  /**
   * 上一次滾動的Y值
   */
  private int lastScrollY;

  /**
   * 回調接口
   */
  public interface ScrollPaintCompleteListener {
    /**
     * 點擊時的回調
     */
    public void onScrollTouch(TextView tv);

    /**
     * 收縮時的回調
     */
    public void onScrollTop(TextView tv);

    /**
     * 展開時的回調
     */
    public void onScrollBottom(TextView tv);

    /**
     * 滾動中的回調
     */
    public void onScrollMove(TextView tv);

  }


  public ScrollPaintView(Context context) {
    this(context, null);
  }

  public ScrollPaintView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public ScrollPaintView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    // 獲取屬性
    TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.ScrollPaintView);
    mPaintIvHeight = (int) ta.getDimension(R.styleable.ScrollPaintView_paintScrollHeight, TypedValue.applyDimension(
        TypedValue.COMPLEX_UNIT_DIP, DEFAULT_PAINT_SCROLL_HEIGHT, getResources().getDisplayMetrics()));
    mScrollSpeed = ta.getInteger(R.styleable.ScrollPaintView_scrollSpeed, DEFAULT_SCROLL_SPEED);
    partitionNode = ta.getInteger(R.styleable.ScrollPaintView_scrollPartitionNode, DEFAULT_PARTITION_NODE);
    mPaintScrollBp = drawableToBitamp(ta.getDrawable(R.styleable.ScrollPaintView_paintScrollSrc));
    mPaintScrollTxt = ta.getString(R.styleable.ScrollPaintView_paintScrollTxt);
    mPaintScrollTxtColor = ta.getColor(R.styleable.ScrollPaintView_paintScrollTxtColor, Color.BLACK);
    mPaintScrollTxtSize = px2sp(ta.getDimensionPixelSize(R.styleable.ScrollPaintView_paintScrollTxtSize, DEFAULT_PAINT_SCROLL_TXT_SIZE));
    ta.recycle();
    init();
    makePaintScroll();
    handleView();
  }

  /**
   * 設置paintView
   *
   * @param paintView
   */
  public void setPaintView(ImageView paintView) {
    if (null == paintView) {
      Log.e(TAG, "設置的View為空");
      return;
    }
    // 處理圖片,對圖片按照屏幕寬高比進行縮放
    Bitmap bp = drawableToBitamp(paintView.getDrawable());
    paintView.setImageBitmap(scaleBitmal(bp));
    // 設置縮放形式
    paintView.setScaleType(ImageView.ScaleType.MATRIX);
    mPaintView = paintView;
  }

  /**
   * 設置回調
   */
  public void setScrollPaintCompleteListener(ScrollPaintCompleteListener listener) {
    if (null != listener) {
      this.listener = listener;
    }
  }

  /**
   * 初始化
   */
  private void init() {
    mScroller = new Scroller(getContext());
    lpp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
    // 獲取屏幕信息
    DisplayMetrics displayMetrics = new DisplayMetrics();
    ((Activity) getContext()).getWindowManager().getDefaultDisplay()
        .getMetrics(displayMetrics);
    // 屏幕高度
    screenHeight = displayMetrics.heightPixels;
    // 屏幕寬度
    screenWidth = displayMetrics.widthPixels;
  }


  /**
   * 創建滾軸
   */
  private void makePaintScroll() {
    // 如果已經存在,則不再創建
    if (null != mPaintScrollImageView || null != mPaintScrollTextView) {
      return;
    }
    // 創建滾軸
    mPaintScrollImageView = new ImageView(getContext());
    LayoutParams lp = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
    lp.height = mPaintIvHeight;
    mPaintScrollImageView.setLayoutParams(lp);
    mPaintScrollImageView.setScaleType(ImageView.ScaleType.FIT_XY);
    mPaintScrollImageView.setImageBitmap(null == mPaintScrollBp ? makeDefaultScroll() : mPaintScrollBp);
    addView(mPaintScrollImageView);
    // 創建文字
    mPaintScrollTextView = new TextView(getContext());
    LayoutParams lpt = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
    lpt.height = mPaintIvHeight;
    mPaintScrollTextView.setLayoutParams(lpt);
    mPaintScrollTextView.setText(null == mPaintScrollTxt ? "" : mPaintScrollTxt);
    mPaintScrollTextView.setTextSize(mPaintScrollTxtSize);
    mPaintScrollTextView.setTextColor(mPaintScrollTxtColor);
    mPaintScrollTextView.setGravity(Gravity.CENTER);
    addView(mPaintScrollTextView);
  }


  /**
   * 測量方法
   *
   * @param widthMeasureSpec
   * @param heightMeasureSpec
   */
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    if (null != mPaintView && getTop() + mPaintIvHeight != mPaintView.getHeight()) {
      // 重新設置圖畫高度
      mPaintStartHeight = getTop() + mPaintIvHeight / 2;
      lpp.height = mPaintStartHeight;
      mPaintView.setLayoutParams(lpp);
    }
    // 測量狀態欄高度
    Rect frame = new Rect();
    ((Activity) getContext()).getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
    int statusBarHeight = frame.top;
    // 高度為屏幕高度減去狀態欄高度和top的高度
    setMeasuredDimension(screenWidth, screenHeight - getTop() - statusBarHeight);
  }

  /**
   * 處理View
   */
  private void handleView() {
    mPaintScrollImageView.setOnTouchListener(new OnTouchListener() {
      @Override
      public boolean onTouch(View view, MotionEvent event) {
        if (null == mPaintView) {
          Log.e(TAG, "設置的View為空");
          return true;
        }
        // 獲取點擊的XY坐標
        int x = (int) event.getRawX();
        int y = (int) event.getRawY();
        int action = event.getAction();
        switch (action) {
          case MotionEvent.ACTION_DOWN: {
            // 請求處理點擊事件
            requestDisallowInterceptTouchEvent(true);
            isClick = true;
            mLastY = y;
            if (!mScroller.isFinished()) { // 如果上次的調用沒有執行完就取消。
              mScroller.abortAnimation();
            }
            if (null != listener) {
              listener.onScrollTouch(mPaintScrollTextView);
            }
            return true;
          }
          case MotionEvent.ACTION_MOVE: {
            // 移動的距離
            int dy = y - mLastY;
            mLastY = y;
            // 滑動
            scrollBy(0, -dy);
            // 如果是向上滑動並且是在初始位置,則不去做處理
            if (getScrollY() >= 0 && dy <= 0) {
              lpp.height = mPaintStartHeight;
              mPaintView.setLayoutParams(lpp);
              scrollTo(0, 0);
              return true;
            }
            // 如果是向下滑動並且超過屏幕高度,則不去處理
            if (Math.abs(getScrollY()) >= getHeight() - mPaintIvHeight && dy >= 0) {
              lpp.height = mPaintStartHeight + getHeight() - mPaintIvHeight;
              mPaintView.setLayoutParams(lpp);
              scrollTo(0, -(getHeight() - mPaintIvHeight));
              return true;
            }
            // 滾動回調
            if (null != listener) {
              listener.onScrollMove(mPaintScrollTextView);
            }
            // 重新設置顯示的控件高度
            if (Math.abs(getScrollY()) > 0) {
              lpp.height = mPaintStartHeight + Math.abs(getScrollY());
              mPaintView.setLayoutParams(lpp);
            }
            return true;
          }
          case MotionEvent.ACTION_UP:
            // 恢復事件處理
            requestDisallowInterceptTouchEvent(false);
            isClick = false;
            // 沒有發生移動
            if (getScrollY() >= 0) {
              if (null != listener) {
                listener.onScrollTop(mPaintScrollTextView);
              }
              return true;
            }
            if (-getScrollY() < partitionNode) {  // 如果小於臨界值,則返回起始坐標
              // XY都從滑動的距離回去，最後一個參數是多少毫秒內執行完這個動作。
              isScrllerTop = true;
              mScroller.startScroll(getScrollX(), getScrollY(), -getScrollX(), -getScrollY(), mScrollSpeed);
            } else {  // 如果大於臨界值,則展開
              isScrllerTop = false;
              mScroller.startScroll(getScrollX(), getScrollY(), -getScrollX(), -(getHeight() - (-getScrollY()) - mPaintIvHeight), mScrollSpeed);
            }
            invalidate();
            return true;
        }
        return false;
      }
    });
  }


  /**
   * 滑動處理
   */
  @Override
  public void computeScroll() {
    if (mScroller.computeScrollOffset()) { // 計算新位置，並判斷上一個滾動是否完成。
      // 請求處理點擊事件,防止父控件滑動
      requestDisallowInterceptTouchEvent(true);
      scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
      // 重新設置顯示的控件高度
      if (0 < Math.abs(mScroller.getCurrY())) {
        if (!isScrllerTop) {
          lpp.height = mPaintStartHeight + Math.abs(mScroller.getCurrY()) + mPaintIvHeight / 2;
        } else {
          lpp.height = mPaintStartHeight + Math.abs(mScroller.getCurrY()) - mPaintIvHeight / 2;
        }
      } else {
        lpp.height = mPaintStartHeight;
      }
      mPaintView.setLayoutParams(lpp);
      invalidate();
    } else {
      // 重新設置畫圖高度,防止高度異常
      if (mPaintView.getHeight() > mPaintStartHeight + Math.abs(mScroller.getCurrY()) && !isScrllerTop && mScroller.getStartY() > 0) {
        lpp.height = mPaintStartHeight + Math.abs(mScroller.getCurrY());
        mPaintView.setLayoutParams(lpp);
      }
    }
    // 防止多次調用
    if (lastScrollY != mScroller.getCurrY()) {
      // 收縮完成
      if (mScroller.getCurrY() >= 0 && !isClick) {
        if (null != listener) {
          listener.onScrollTop(mPaintScrollTextView);
        }
      }
      // 展開完成
      if (-mScroller.getCurrY() >= getHeight() - mPaintIvHeight && !isClick) {
        if (null != listener) {
          listener.onScrollBottom(mPaintScrollTextView);
        }
      }
      lastScrollY = mScroller.getCurrY();
    }
  }

  /**
   * 重置滾動
   */
  public void replaceScroll() {
    // 重置信息
    scrollTo(0, 0);
    mScroller.setFinalY(0);
    lastScrollY = 0;
    lpp.height = mPaintStartHeight;
    mPaintView.setLayoutParams(lpp);
    if (null != listener) {
      listener.onScrollTop(mPaintScrollTextView);
    }
  }

  /**
   * drawable轉bitmap
   *
   * @param drawable
   * @return
   */
  private Bitmap drawableToBitamp(Drawable drawable) {
    if (null == drawable) {
      return null;
    }
    if (drawable instanceof BitmapDrawable) {
      BitmapDrawable bd = (BitmapDrawable) drawable;
      return bd.getBitmap();
    }
    int w = drawable.getIntrinsicWidth();
    int h = drawable.getIntrinsicHeight();
    Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    drawable.setBounds(0, 0, w, h);
    drawable.draw(canvas);
    return bitmap;
  }


  /**
   * 按照屏幕寬高縮放圖片
   *
   * @param bp
   * @return
   */
  private Bitmap scaleBitmal(Bitmap bp) {
    // 寬度比例
    float scaleW = (float) screenWidth / (float) bp.getWidth();
    // 高度比例
    float scaleH = (float) screenHeight / (float) bp.getHeight();
    // 矩陣,用於縮放圖片
    Matrix matrix = new Matrix();
    matrix.postScale(scaleW, scaleH);
    // 縮放後的圖片
    Bitmap scaleBp = Bitmap.createBitmap(bp, 0, 0, bp.getWidth(), bp.getHeight(), matrix, true);
    return scaleBp;
  }

  /**
   * 設置默認的滾軸
   *
   * @return
   */
  private Bitmap makeDefaultScroll() {
    Bitmap defaultBp = Bitmap.createBitmap(screenWidth, mPaintIvHeight,
        Bitmap.Config.ARGB_8888);
    //填充顏色
    defaultBp.eraseColor(Color.parseColor("#FF0000"));
    return defaultBp;

  }


  /**
   * 將px值轉換為sp值，保證文字大小不變
   */
  public int px2sp(float pxValue) {
    final float fontScale = getContext().getResources().getDisplayMetrics().scaledDensity;
    return (int) (pxValue / fontScale + 0.5f);
  }

}

activity_main:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#eeeeee"
    tools:context="com.example.junweiliu.scrollpaintdemo.MainActivity">
  <ScrollView
      android:layout_width="match_parent"
      android:layout_height="match_parent">
    <RelativeLayout android:layout_width="match_parent"
            android:layout_height="match_parent">
      <!--頭部圖片部分-->
      <ImageView
          android:id="@+id/iv_banner"
          android:layout_width="match_parent"
          android:layout_height="200dp"
          android:scaleType="fitXY"
          android:src="@mipmap/show_banner"/>
      <!--中間內容部分-->
      <LinearLayout
          android:id="@+id/ll_first"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_below="@+id/iv_banner"
          android:layout_marginTop="20dp"
          android:orientation="horizontal"
          android:padding="16dp">
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_a"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="藝術片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_b"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="懷舊片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_c"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="科幻片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_d"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="動畫片"
              android:textColor="#666666"/>
        </LinearLayout>
      </LinearLayout>
      <LinearLayout
          android:id="@+id/ll_sencond"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_below="@+id/ll_first"
          android:layout_marginTop="20dp"
          android:orientation="horizontal"
          android:padding="16dp">
        <LinearLayout

            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_a"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="藝術片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_b"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="懷舊片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_c"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="科幻片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_d"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="動畫片"
              android:textColor="#666666"/>
        </LinearLayout>
      </LinearLayout>
      <LinearLayout
          android:id="@+id/ll_threeth"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_below="@+id/ll_sencond"
          android:layout_marginTop="20dp"
          android:orientation="horizontal"
          android:padding="16dp">
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_a"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="藝術片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_b"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="懷舊片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_c"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="科幻片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_d"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="動畫片"
              android:textColor="#666666"/>
        </LinearLayout>
      </LinearLayout>
      <LinearLayout
          android:id="@+id/ll_fourth"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_below="@+id/ll_threeth"
          android:layout_marginTop="20dp"
          android:orientation="horizontal"
          android:padding="16dp">
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_a"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="藝術片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_b"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="懷舊片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_marginRight="16dp"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_c"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="科幻片"
              android:textColor="#666666"/>
        </LinearLayout>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:gravity="center_horizontal"
            android:orientation="vertical">
          <ImageView
              android:layout_width="80dp"
              android:layout_height="120dp"
              android:scaleType="fitXY"
              android:src="@mipmap/movie_playbill_d"/>
          <TextView
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_marginTop="10dp"
              android:gravity="center"
              android:text="動畫片"
              android:textColor="#666666"/>
        </LinearLayout>
      </LinearLayout>

      <!--需要顯示的圖-->
      <ImageView
          android:id="@+id/iv_paint"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:scaleType="matrix"
          android:src="@mipmap/show_img"
          android:visibility="gone"/>
      <!--畫軸控件-->
      <com.example.junweiliu.scrollpaintdemo.widget.ScrollPaintView
          android:id="@+id/spv_paint"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:layout_below="@+id/iv_banner"
          app:paintScrollHeight="25dp"
          app:paintScrollSrc="@mipmap/paint_scroll_img"
          app:paintScrollTxt="拉我看看"
          app:paintScrollTxtColor="#FF000000"
          app:paintScrollTxtSize="16sp"
      >
      </com.example.junweiliu.scrollpaintdemo.widget.ScrollPaintView>
    </RelativeLayout>
  </ScrollView>
</RelativeLayout>

attr:

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <!--畫軸的高度-->
  <attr name="paintScrollHeight" format="dimension"/>
  <!--畫軸的圖片-->
  <attr name="paintScrollSrc" format="reference"/>
  <!--畫軸文字-->
  <attr name="paintScrollTxt" format="string"/>
  <!--畫軸文字顏色-->
  <attr name="paintScrollTxtColor" format="color"/>
  <!--畫軸文字大小-->
  <attr name="paintScrollTxtSize" format="dimension"/>
  <!--滾動速度-->
  <attr name="scrollSpeed" format="integer"/>
  <!--分割節點-->
  <attr name="scrollPartitionNode" format="integer"/>
  <declare-styleable name="ScrollPaintView">
    <attr name="paintScrollHeight"/>
    <attr name="paintScrollSrc"/>
    <attr name="paintScrollTxt"/>
    <attr name="paintScrollTxtColor"/>
    <attr name="paintScrollTxtSize"/>
    <attr name="scrollSpeed"/>
    <attr name="scrollPartitionNode"/>
  </declare-styleable>
</resources>

四、問題

滾動的時間不宜設置太短,因為動態設置ImageView高度時可能出現繪制速度趕不上滾動的速度,會出現錯位,當然時間設置太短,也看不到這種滑動的效果了.暫時想到的做法就是這樣,應該還會有更好的方法.

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持本站。