Android侧边栏滑动切换的view效果

时间：2022-06-25 23:23:47 编辑：袖梨来源：一聚教程网

代码如下复制代码

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Paint;

import android.graphics.drawable.BitmapDrawable;

import android.util.AttributeSet;

import android.view.MotionEvent;

import android.view.View;

public class SideBar extends View {

private static final int MARGIN_BOTTOM = 2;

private int mItemHeight = 18;

private OnLetterTouchListener mOnLetterTouchListener;

private Paint mPaint;

private float mWidthCenter;

private int backgroundColor = 0x00F0F0F0;

private char[] chars = AppCommon.INDEXER_CHARS;

public interface OnLetterTouchListener {

public abstract void onPressedDown(int index, char ch);

public abstract void onPressedUp(int index, char ch);

}

public SideBar(Context context) {

this(context, null);

}

public SideBar(Context context, AttributeSet attrs) {

this(context, attrs, -1);

}

public SideBar(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

init();

}

private int startY = 0;//其实位置的y轴坐标

public SideBar setChars(char[] chars) {

this.chars = chars;

// for(int i = 0 ; i < (26 - chars.length) / 2 ; i++){

// startY += i * mItemHeight;

// }

init();

postInvalidate();

return this;

}

private void init() {

mPaint = new Paint();

mPaint.setColor(0xFFCFCFD0);

mPaint.setAntiAlias(true);

mPaint.setFakeBoldText(true);

mPaint.setTextSize(32);

mPaint.setColor(getResources().getColor(R.color.blue));

mPaint.setSubpixelText(true);

mPaint.setTextAlign(Paint.Align.CENTER);

setBackgroundColor(backgroundColor);

}

public boolean onTouchEvent(MotionEvent event) {

super.onTouchEvent(event);

int idx = (int) event.getY() / mItemHeight;

if (idx >= chars.length) {

idx = chars.length - 1;

} else if (idx < 0) {

idx = 0;

}

if (event.getAction() == MotionEvent.ACTION_DOWN || event.getAction() == MotionEvent.ACTION_MOVE) {

setBackgroundResource(R.color.sidebar_select_background);

if (mOnLetterTouchListener != null) {

mOnLetterTouchListener.onPressedDown(idx, chars[idx]);

}

} else if (event.getAction() == MotionEvent.ACTION_UP) {

setBackgroundDrawable(new BitmapDrawable());

setBackgroundColor(backgroundColor);

if (mOnLetterTouchListener != null) {

mOnLetterTouchListener.onPressedUp(idx, chars[idx]);

}

return true;

}

@Override

protected void onSizeChanged(int w, int h, int oldw, int oldh) {

mItemHeight = (h - MARGIN_BOTTOM) / 26;

mWidthCenter = getMeasuredWidth() / 2;

super.onSizeChanged(w, h, oldw, oldh);

}

protected void onDraw(Canvas canvas) {

for (int i = 0; i < chars.length; i++) {

canvas.drawText(String.valueOf(chars[i]), mWidthCenter,startY + mItemHeight + (i * mItemHeight), mPaint);

}

super.onDraw(canvas);

}

public void setOnLetterTouchListener(OnLetterTouchListener listener) {

mOnLetterTouchListener = listener;

}

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