android 自定义View 滚动选择器PickerView
1:自定义View
package com.arch.datetimepicker;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;
public class PickerView extends View {
public static final String TAG = "PickerView";
/**
* Text spacing and minTextSize ratio
*/
//public static final float MARGIN_ALPHA = 2.0f;
/**
* Automatic rollback to intermediate speed
*/
public static final float SPEED = 20;
private List mDataList;
/**
* Selected location, this position is the center of mDataList, has been unchanged
*/
private int mCurrentSelected;
private Paint mPaint;
private float mMaxTextSize = 15;
private float mMinTextSize = 10;
private float mMaxTextAlpha = 255;
private float mMinTextAlpha = 255;
private int mColorText = 0x333333;
private int mViewHeight;
private int mViewWidth;
private float mLastDownY;
private int textSizeUp ;
private int textSizeDown;
private float MARGIN_ALPHA;
/**
* Sliding distance
*/
private float mMoveLen = 0;
private boolean isInit = false;
private onSelectListener mSelectListener;
private Timer timer;
private MyTimerTask mTask;
Handler updateHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
if (Math.abs(mMoveLen) < SPEED) {
mMoveLen = 0;
if (mTask != null) {
mTask.cancel();
mTask = null;
performSelect();
}
} else
// Here mMoveLen / Math.abs (mMoveLen) is to maintain the mMoveLen positive and negative numbers, in order to achieve roll or roll
mMoveLen = mMoveLen - mMoveLen / Math.abs(mMoveLen) * SPEED;
invalidate();
}
};
public void setPaintTextSizeDivide(int upSize ,int downSize,float divide){
textSizeUp = upSize;
textSizeDown = downSize;
MARGIN_ALPHA = divide;
}
public PickerView(Context context) {
super(context);
init();
}
public PickerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public void setOnSelectListener(onSelectListener listener) {
mSelectListener = listener;
}
private void performSelect() {
if (mSelectListener != null)
mSelectListener.onSelect(mDataList.get(mCurrentSelected));
}
public void setData(List datas) {
mDataList = datas;
mCurrentSelected = datas.size() / 2;
invalidate();
}
/**
* Select the selected item index
*
* @param selected
*/
public void setSelected(int selected) {
mCurrentSelected = selected;
int distance = mDataList.size() / 2 - mCurrentSelected;
if (distance < 0)
for (int i = 0; i < -distance; i++) {
moveHeadToTail();
mCurrentSelected--;
}
else if (distance > 0)
for (int i = 0; i < distance; i++) {
moveTailToHead();
mCurrentSelected++;
}
invalidate();
}
/**
* Select selected content
*
* @param mSelectItem
*/
public void setSelected(String mSelectItem) {
for (int i = 0; i < mDataList.size(); i++)
if (mDataList.get(i).equals(mSelectItem)) {
setSelected(i);
break;
}
}
private void moveHeadToTail() {
String head = mDataList.get(0);
mDataList.remove(0);
mDataList.add(head);
}
private void moveTailToHead() {
String tail = mDataList.get(mDataList.size() - 1);
mDataList.remove(mDataList.size() - 1);
mDataList.add(0, tail);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mViewHeight = getMeasuredHeight();
mViewWidth = getMeasuredWidth();
// Font size according to View height
mMaxTextSize = mViewHeight / 4.0f;
mMinTextSize = mMaxTextSize / 2f;
isInit = true;
invalidate();
}
private void init() {
timer = new Timer();
mDataList = new ArrayList();
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setTextAlign(Paint.Align.CENTER);
mPaint.setColor(mColorText);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// draw view according index
if (isInit)
drawData(canvas);
}
private void drawData(Canvas canvas) {
// First draw the selected text and then draw up the rest of the text
float scale = parabola(mViewHeight / 4.0f, mMoveLen);
float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
mPaint.setTextSize(textSizeUp);
mPaint.setColor(0xffea9566);
mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
// Text center draw, pay attention to the calculation of baseline to achieve the center, y value is text center coordinates
float x = (float) (mViewWidth / 2.0);
float y = (float) (mViewHeight / 2.0 + mMoveLen);
Paint.FontMetricsInt fmi = mPaint.getFontMetricsInt();
float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
canvas.drawText(mDataList.get(mCurrentSelected), x, baseline, mPaint);
// Draw top data
for (int i = 1; (mCurrentSelected - i) >= 0; i++) {
drawOtherText(canvas, i, -1);
}
// Draw below data
for (int i = 1; (mCurrentSelected + i) < mDataList.size(); i++) {
drawOtherText(canvas, i, 1);
}
}
/**
* @param canvas
* @param position
* Distance mCurrentSelected difference
* @param type
* 1 represents down drawing, -1 means up drawing
*/
private void drawOtherText(Canvas canvas, int position, int type) {
float d = (float) (MARGIN_ALPHA * mMinTextSize * position + type
* mMoveLen);
float scale = parabola(mViewHeight / 4.0f, d);
float size = (mMaxTextSize - mMinTextSize) * scale + mMinTextSize;
mPaint.setTextSize(textSizeDown);
mPaint.setColor(0x333333);
mPaint.setAlpha((int) ((mMaxTextAlpha - mMinTextAlpha) * scale + mMinTextAlpha));
float y = (float) (mViewHeight / 2.0 + type * d);
Paint.FontMetricsInt fmi = mPaint.getFontMetricsInt();
float baseline = (float) (y - (fmi.bottom / 2.0 + fmi.top / 2.0));
canvas.drawText(mDataList.get(mCurrentSelected + type * position),
(float) (mViewWidth / 2.0), baseline, mPaint);
}
/**
* parabola
*
* @param zero
* Zero coordinates
* @param x
* Offset
* @return scale
*/
private float parabola(float zero, float x) {
float f = (float) (1 - Math.pow(x / zero, 2));
return f < 0 ? 0 : f;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
doDown(event);
break;
case MotionEvent.ACTION_MOVE:
doMove(event);
break;
case MotionEvent.ACTION_UP:
doUp(event);
break;
}
return true;
}
private void doDown(MotionEvent event) {
if (mTask != null) {
mTask.cancel();
mTask = null;
}
mLastDownY = event.getY();
}
private void doMove(MotionEvent event) {
mMoveLen += (event.getY() - mLastDownY);
if (mMoveLen > MARGIN_ALPHA * mMinTextSize / 2) {
// Slide down
moveTailToHead();
mMoveLen = mMoveLen - MARGIN_ALPHA * mMinTextSize;
} else if (mMoveLen < -MARGIN_ALPHA * mMinTextSize / 2) {
// Slide up
moveHeadToTail();
mMoveLen = mMoveLen + MARGIN_ALPHA * mMinTextSize;
}
mLastDownY = event.getY();
invalidate();
}
private void doUp(MotionEvent event) {
// Raise the position after mCurrentSelected from the current position to the middle of the selected position
if (Math.abs(mMoveLen) < 0.0001) {
mMoveLen = 0;
return;
}
if (mTask != null) {
mTask.cancel();
mTask = null;
}
mTask = new MyTimerTask(updateHandler);
timer.schedule(mTask, 0, 10);
}
class MyTimerTask extends TimerTask {
Handler handler;
public MyTimerTask(Handler handler) {
this.handler = handler;
}
@Override
public void run() {
handler.sendMessage(handler.obtainMessage());
}
}
public interface onSelectListener {
void onSelect(String text);
}
} package com.arch.datetimepicker;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import com.arch.datetimepicker.PickerView.onSelectListener;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private PickerView mHourPicker;
private PickerView mMinutePicker;
List hour = new ArrayList<>();
List minute = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHourPicker = (PickerView) findViewById(R.id.choose_hour);
mMinutePicker = (PickerView) findViewById(R.id.choose_minute);
mHourPicker.setPaintTextSizeDivide(140,140,2.8f);
mMinutePicker.setPaintTextSizeDivide(140,140,2.8f);
mHourPicker.setOnSelectListener(new onSelectListener() {
@Override
public void onSelect(String hour) {
android.util.Log.i("PickerView","hour "+hour);
}
});
mMinutePicker.setOnSelectListener(new onSelectListener() {
@Override
public void onSelect(String minute) {
android.util.Log.i("PickerView","minute "+minute);
}
});
for (int i = 0; i < 24; i++) {
hour.add(i < 10 ? "0" + i : "" + i);
}
mHourPicker.setData(hour);
for (int i = 0; i < 60; i++) {
minute.add(i < 10 ? "0" + i : "" + i);
}
mMinutePicker.setData(minute);
mHourPicker.setSelected(0);
mMinutePicker.setSelected(0);
}
}
3：布局