Android custom View imitation of WeChat LetterView effect

Updated: March 3, 2017 13:56:26 Author: VittaWinnie

This article mainly introduces the effect of Android custom View imitating WeChat LetterView. The code is simple and easy to understand, very good, and has the value of reference. Friends who need it can refer to it.

I won't say much nonsense, the specific code is as follows:

 public class LetterView extends View {
  private String TAG = ();
  //A,B,C....Z,#
  public List&lt;String&gt; letters;
  private Paint mPaint;
  private int selectPosition = -1;
  private TextView mLetter;
  public void setmLetter(TextView mLetter) {
     = mLetter;
  }
  public LetterView(Context context) {
    this(context,null);
  }
  public LetterView(Context context, AttributeSet attrs) {
    this(context, attrs,0);
  }
  public LetterView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    //Produce letters    letters = new ArrayList&lt;&gt;();
    for (int i = 65; i &lt; 91; i++) {
      ((,"%c",i));
      (TAG, "LetterView: "+ (,"%c",i));
    }
    ("#");//Add a # //Initialize the brush    mPaint = new Paint();
    (true);
    ();
    (30);
  }
  @Override
  protected void onDraw(Canvas canvas) {
    (canvas);
    /**
      * Get the width of the View
      * Get the height of the View
      */
    int width = getMeasuredWidth();
    int height = getMeasuredHeight();
    //Measure the width of the word    int size = ();
    for (int i = 0; i &lt; size; i++) {
      float textWidth = ((i));
      int singleHeight = height / size;
      if (selectPosition == i){//Selected        ();
      }else{
        ();
      }
      ((i),(width - textWidth)/2, singleHeight * (i + 1),mPaint);
      /**
        * drawText() x y \_ is the baseline
        */
    invalidate();
    }
  }
  /**
    * Android encapsulates touch events, wraps actions and location information; onClick is also a motionEvent
    * onClick event is actually onTouchEvent event
    * @param event
    * @return
    */
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    //Packed action, location information// ();//Coordinate value relative to the View itself// ();//Return is the coordinate value relative to the screen    float y = ();
    (TAG, "onTouchEvent: Y:"+ y);
//    (TAG, "onTouchEvent: RawY:"+() );
    int measuredHeight = getMeasuredHeight();
    int singleHeight = measuredHeight / ();
    int position = (int) (y / singleHeight);
    (TAG, "onTouchEvent: " + position );
    switch (()) {
      case MotionEvent.ACTION_MOVE:
        (TAG, "onTouchEvent: ACTION_MOVE" );
      case MotionEvent.ACTION_DOWN:
        (TAG, "onTouchEvent: ACTION_DOWN" );
        selectPosition = position;
        if (mLetter != null) {
          ();
          //The limit situation may be out of bounds, so you need to judge          if (position &lt; () &amp;&amp; position &gt;= 0){
            ((position));
          }
        }
        break;
      case MotionEvent.ACTION_UP:
        (TAG, "onTouchEvent: ACTION_UP" );
        selectPosition = -1;
        if (mLetter != null) {
          ();
        }
        break;
    }
    //Return true means the event has been processed    return true;
  }
}

android
view
WeChat

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Android custom View imitation of WeChat LetterView effect

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