image.png
public class SideBar extends View {
/** 字母更新的监听器 */
private OnLetterUpdateListener onLetterUpdateListener;
/** 当前的字母指示的位置 */
private int currentIndex = -100;
/** 是否松手 */
private boolean isUp = true;
/** 字母测量的尺寸 */
private float measureText;
/** 数字模拟器 */
private Scroller scroller;
/** 触摸临界值 */
private float touchSlop;
/** 起始位置 */
private int startX = 100;
/** 变化比率 */
private float mX = 100;
//up事件的接口
public interface OnUpListener {
void up();
}
private OnUpListener onUpListener;
public interface OnLetterUpdateListener {
void onLetterUpdate(String letter);
}
public OnUpListener getOnUpListener() {
return onUpListener;
}
public void setOnUpListener(OnUpListener onUpListener) {
this.onUpListener = onUpListener;
}
public void setOnLetterUpdateListener(OnLetterUpdateListener onLetterUpdateListener) {
this.onLetterUpdateListener = onLetterUpdateListener;
}
private static final String[] LETTERS = new String[]{"#", "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 Paint paint;
// 单元格宽度
private int cellWidth;
// 单元格高度
private float cellHeight;
public SideBar(Context context) {
this(context, null);
}
public SideBar(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SideBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
/**
* 初始化数字模拟器
*/
private void init() {
scroller = new Scroller(getContext());
touchSlop = ViewConfiguration.get(getContext()).getTouchSlop();
// 创建一个抗锯齿的画笔
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
// 画笔文本加粗
paint.setTypeface(Typeface.DEFAULT_BOLD);
// 颜色
paint.setColor(getResources().getColor(R.color.text_blue_search));
setTextSize(26);
measureText = paint.measureText("M");
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int mHeight = getMeasuredHeight();
cellWidth = getMeasuredWidth();
cellHeight = mHeight * 1.0f / LETTERS.length;
if (!isUp) {
setMeasuredDimension(widthMeasureSpec * 3, heightMeasureSpec);
} else {
setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
}
}
@Override
protected void onDraw(Canvas canvas) {
// 遍历26个英文字母, 计算坐标, 进行绘制
for (int i = 0; i < LETTERS.length; i++) {
String letter = LETTERS[i];
// 计算x坐标
float dx = 0;
//float x = cellWidth * 0.5f - paint.measureText(letter) * 0.5f + 80;
// float x = cellWidth - paint.measureText(letter);
float x = cellWidth - measureText * 1.5f;
if (!isUp) {
mX = 1.0f;
}
switch (currentIndex - i) {
case -4:
dx = measureText * 1.5f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_4));
setTextSize(27);
break;
case -3:
dx = measureText * 2.5f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_3));
setTextSize(33);
break;
case -2:
dx = measureText * 4.0f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_2));
setTextSize(38);
break;
case -1:
dx = measureText * 5.0f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_1));
setTextSize(42);
break;
case 0:
paint.setColor(getResources().getColor(R.color.text_blue_search));
dx = measureText * 6.0f * mX;
setTextSize(50);
break;
case 1:
dx = measureText * 5.0f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_1));
setTextSize(42);
break;
case 2:
dx = measureText * 4.0f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_2));
setTextSize(38);
break;
case 3:
dx = measureText * 2.5f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_2));
setTextSize(33);
break;
case 4:
dx = measureText * 1.5f * mX;
paint.setColor(getResources().getColor(R.color.text_blue_search_3));
setTextSize(28);
break;
default:
dx = 0;
paint.setColor(getResources().getColor(R.color.text_blue_search_4));
setTextSize(26);
break;
}
if (!isUp) { //触摸状态
x -= dx;
} else { //松手状态
x -= dx;
paint.setColor(getResources().getColor(R.color.text_blue_search));
setTextSize(26);
}
// 计算y坐标
Rect bounds = new Rect();
// 获取文本的矩形区域
paint.getTextBounds(letter, 0, letter.length(), bounds);
float y = cellHeight * 0.5f + bounds.height() * 0.5f + i * cellHeight;
// 绘制文本
if (letter.equals("I")) {
x += measureText * 0.2f;
}
canvas.drawText(letter, x, y, paint);
}
}
private int lastIndex = -1;
@Override
public boolean onTouchEvent(MotionEvent event) {
float y;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
scroller.forceFinished(true);
isUp = false;
setPadding(500, 0, 0, 0);
// 获取被点击到的字母索引
y = event.getY();
// 根据y值, 计算当前按下的字母位置
currentIndex = (int) (y / cellHeight);
if (currentIndex != lastIndex) {
if (currentIndex >= 0 && currentIndex < LETTERS.length) {
String letter = LETTERS[currentIndex];
if (onLetterUpdateListener != null) {
onLetterUpdateListener.onLetterUpdate(letter);
}
// 记录上一次触摸的字母
lastIndex = currentIndex;
}
}
break;
case MotionEvent.ACTION_MOVE:
// 获取被点击到的字母索引
y = event.getY();
// 根据y值, 计算当前按下的字母位置
currentIndex = (int) (y / cellHeight);
if (currentIndex != lastIndex) {
if (currentIndex >= 0 && currentIndex < LETTERS.length) {
String letter = LETTERS[currentIndex];
if (onLetterUpdateListener != null) {
onLetterUpdateListener.onLetterUpdate(letter);
}
// 记录上一次触摸的字母
lastIndex = currentIndex;
}
}
break;
case MotionEvent.ACTION_UP:
isUp = true;
lastIndex = -1;
//调用回调里面的方法
if (null != onUpListener) {
onUpListener.up();
}
smaooth();
break;
default:
break;
}
invalidate();
return true;
}
/**
* 开启数字模拟器
*/
private void smaooth() {
scroller.startScroll(startX, 0,
-99, 0, 550);
}
@Override
public void computeScroll() {
// 当scroller数据模拟完毕时, 不应该继续进行递归
// 反之, 如果正在模拟数据才进行递归的操作
if (scroller.computeScrollOffset()) {// 当前还是正在模拟数据中
// 把当前scroller正在模拟的数据取出来, 使用scrollTo方法切换屏幕
mX = ((float) scroller.getCurrX()) / 100f;
// scrollTo(currX, 0);
if (mX == 0.01f) {
setPadding(0, 0, 0, 0);
}
invalidate(); // 在触发当前方法, 相当于递归.
}
}
private void setTextSize(int size) {
paint.setTextSize(size+10);
}
}
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