03.自定义View(AlphabetView字母索引View)
感谢红橙Darren博主 package com.rzm.commonlibrary.views; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.support.annotation.Nullable; import android.util.AttributeSet; import android.util.TypedValue; import android.view.MotionEvent; import android.view.View; import com.rzm.commonlibrary.R; /** * Created by renzhenming on 2018/3/24. * 实现根据字母分类排序的列表，多用于地址选择或者手机通讯录 */ public class AlphabetView extends View{ //普通模式绘制的画笔 private final Paint mPaint; //触摸时绘制用的画笔 private final Paint mTouchPaint; //默认字母大小 private int mTextSize = 16; //默认字母颜色 private int mTextColor = Color.BLACK; //触摸时字母颜色 private int mTouchTextColor = Color.RED; //控件的高度 private int mViewHeight; //26个字母 private String mLetters[] = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N" ,"O","P","Q","R","S","T","U","V","W","X","Y","Z"}; private int mItemHeight; //当前触摸的字母 private String mCurrentTouchLetter; //当前是否在触摸 private boolean mCurrentIsTouch = false; //抬起之后是否清除当前选中的高亮颜色 private boolean mClearAfterUp = true; public AlphabetView(Context context) { this(context,null); } public AlphabetView(Context context, @Nullable AttributeSet attrs) { this(context, attrs,-1); } public AlphabetView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); //获取自定义属性 TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.AlphabetView); mTextColor = typedArray.getColor(R.styleable.AlphabetView_textColor, mTextColor); mTouchTextColor = typedArray.getColor(R.styleable.AlphabetView_touchTextColor, mTouchTextColor); mTextSize = typedArray.getDimensionPixelSize(R.styleable.AlphabetView_textSize, mTextSize); typedArray.recycle(); //设置画笔用于绘制字母 /** * 为什么使用两个画笔而不是单独的使用一个然后切换颜色的设置，因为paint是有一个 * 设置颜色的方法的setColor,我们看一下setColor的源码，发现是native方法实现的， * private static native void nSetColor(long paintPtr, @ColorInt int color); * 如果在onDraw中频繁的切换颜色性能会降低，所以这就是通常使用几种颜色定义几个画笔 * 的原因 */ mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setDither(true); mPaint.setColor(mTextColor); mPaint.setTextSize(sp2px(mTextSize)); mTouchPaint = new Paint(); mTouchPaint.setAntiAlias(true); mTouchPaint.setDither(true); mTouchPaint.setColor(mTouchTextColor); mTouchPaint.setTextSize(sp2px(mTextSize)); } private float sp2px(int sp){ return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,sp,getResources().getDisplayMetrics()); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //根据布局中设置的宽度模式确定宽度 int width =0; int mode = MeasureSpec.getMode(widthMeasureSpec); if (mode == MeasureSpec.EXACTLY){ width = MeasureSpec.getSize(widthMeasureSpec); } if (mode == MeasureSpec.AT_MOST){ //计算宽度,两边的padding加上文字宽度，这个文字随意，不过最好是26个字母中最宽的 float textWidth = mPaint.measureText(""); width = (int) (getPaddingLeft() + getPaddingRight()+textWidth); } //获取设置的高度 mViewHeight = MeasureSpec.getSize(heightMeasureSpec); setMeasuredDimension(width, mViewHeight); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //获取每个字母占的高度 mItemHeight = (getHeight()-getPaddingTop() - getPaddingBottom())/mLetters.length; //绘制26个字母 for (int i = 0; i < mLetters.length; i++) { //得到每个字母的中心位置,防止给布局设置了paddingTop，所以这里+上 int letterCenterY = i* mItemHeight + mItemHeight /2+getPaddingTop(); //得到每个字母的中心位置 Paint.FontMetrics fontMetrics = mPaint.getFontMetrics(); int dy = (int) ((fontMetrics.bottom - fontMetrics.top)/2 - fontMetrics.bottom); //根据字母中心位置求字母的基线 //baseline = center + (FontMetrics.bottom - FontMetrics.top)/2 - FontMetrics.bottom; int baseLine = letterCenterY+dy; //获取每一个字母绘制的x坐标 float letterWidth = mPaint.measureText(mLetters[i]); //确保每一个字母都在中间位置 int x = (int) (getWidth()/2 - letterWidth/2); //开始绘制 /** * text 需要绘制的文字 x 绘制文字原点X坐标 y 绘制文字原点Y坐标 xy指的时文字左下角的坐标，也就是基线和文字最左边下方的交点 paint 画笔 */ if (mLetters[i].equals(mCurrentTouchLetter)){ canvas.drawText(mLetters[i],x,baseLine,mTouchPaint); }else{ canvas.drawText(mLetters[i],x,baseLine,mPaint); } } } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()){ case MotionEvent.ACTION_DOWN: case MotionEvent.ACTION_MOVE: //当前触摸的位置,相对与控件的位置而不是相对于屏幕 float startY = event.getY(); //计算当前字母的位置 int position = (int)startY/mItemHeight; //防止当触摸超出控件范围的时候，设定position值，防止数组越界 if (position <0){ position = 0; } if (position > mLetters.length - 1){ position = mLetters.length - 1; } //滑动过程中如果滑动的位置和上一次相同，就不再处理，减少invalidate的次数 if (mLetters[position].equals(mCurrentTouchLetter)){ return true; } //记录当前触摸的弥足 mCurrentTouchLetter = mLetters[position]; mCurrentIsTouch = true; if (mTouchListener != null){ mTouchListener.onTouch(mCurrentTouchLetter,mCurrentIsTouch); } break; case MotionEvent.ACTION_UP: //抬起时设置为false mCurrentIsTouch = false; if (mTouchListener != null){ mTouchListener.onTouch(mCurrentTouchLetter,mCurrentIsTouch); } if (mClearAfterUp){ //将当前触摸的字母设置为null,up之后重绘界面，清除高亮状态 mCurrentTouchLetter = null; } break; } invalidate(); return true; } /** * 设置手指触摸抬起之后，是否恢复高亮状态为正常状态，默认为true * @param mClearAfterUp */ public void setClearAfterUp(boolean mClearAfterUp) { this.mClearAfterUp = mClearAfterUp; } // 设置触摸监听 private OnAlphabetTouchListener mTouchListener; public void setOnAlphabetTouchListener(OnAlphabetTouchListener touchListener) { this.mTouchListener = touchListener; } public interface OnAlphabetTouchListener { void onTouch(String letter, boolean isTouch); } }
