SeekBar是用来调节参数值的，系统默认的一般都不太适合我们，需要我们自定义，
里面也有一个RxJava背压的具体应用
废话不多说，看图
package com.example.helang.seekbar;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import java.util.concurrent.TimeUnit;
import io.reactivex.Observable;
import io.reactivex.ObservableEmitter;
import io.reactivex.ObservableOnSubscribe;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.functions.Consumer;
/**
* 自定义拖动seekBar
*/
public class CustomSeekBar extends View {
private static final String TAG = "CustomSeekBar";
private static final int radius = 65;//中间圆形进度条的半径
private static final int thumbSize = 200;
private int backgroundLineSize = 10;//背景线的宽度
private int foregroundLineSize = 18;//进度的宽度
private int lineSize;//整条背景线的长度
private float touchY;
private Bitmap thumbBitmap;
private Paint paint;
private Paint circlePaint;//绘制进度条的paint
private RectF backgroundLineRect = new RectF();//背景矩形
private RectF foregroundLineRect = new RectF();//进度矩形
private float currentDegrees = 0;//当前的进度，百分比例，不带百分号
private OnProgressListener onProgressListener;
public void setOnProgressListener(OnProgressListener onProgressListener) {
this.onProgressListener = onProgressListener;
}
public CustomSeekBar(Context context) {
this(context,null);
}
public CustomSeekBar(Context context, @Nullable AttributeSet attrs) {
this(context, attrs,0);
}
public CustomSeekBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initBitmap();
initPaint();
}
/**
* init bitmap
*/
private void initBitmap(){
thumbBitmap = drawableToBitmap(thumbSize,getResources().getDrawable(R.drawable.circle));
}
/**
* init paint
*/
private void initPaint() {
paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setTextSize(10);
//初始化圆形进度条的Paint
circlePaint = new Paint();
circlePaint.setAntiAlias(true); // 抗锯齿
circlePaint.setDither(true); // 防抖动
circlePaint.setStrokeWidth(10);
circlePaint.setShader(null); // 清除上一次的shader
circlePaint.setStyle(Paint.Style.STROKE); // 设置绘制的圆为空心
circlePaint.setShadowLayer(10, 10, 10, Color.RED);
circlePaint.setColor(Color.BLUE); // 设置圆弧的颜色
circlePaint.setStrokeCap(Paint.Cap.ROUND); // 把每段圆弧改成圆角的
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
drawLine(canvas);
drawThumb(canvas);
drawCircleProgress(canvas);
}
/**
* draw circle
* @param canvas
*/
private void drawCircleProgress(Canvas canvas){
RectF oval = new RectF(thumbSize/2-radius, thumbSize/2-radius,
thumbSize/2+radius, thumbSize/2+radius); // 圆的外接正方形
float alphaAngle = currentDegrees * 360.0f / 100 * 1.0f; // 计算每次画圆弧时扫过的角度，这里计算要注意分母要转为float类型，否则alphaAngle永远为0
canvas.drawArc(oval, -90, alphaAngle, false, circlePaint);
}
/**
* draw thumb
* @param canvas
*/
private void drawThumb(Canvas canvas){
//添加旋转,Matrix是Bitmap旋转的关键，用于bitmap一些补间动画的操作
canvas.translate((getWidth()-thumbSize)/2,(100-currentDegrees)/100*lineSize);
Matrix matrix = new Matrix();
matrix.setRotate(currentDegrees*10,thumbSize/2,thumbSize/2);
canvas.drawBitmap(thumbBitmap,matrix,null);//旋转背景
}
/**
* draw lines
* @param canvas
*/
private void drawLine(Canvas canvas){
//绘制背景线
backgroundLineRect.set((getWidth()-backgroundLineSize)/2,thumbSize/2,
(getWidth()+backgroundLineSize)/2, getParentHeight()-thumbSize/2);
lineSize = getParentHeight() - thumbSize;//去掉被thumb挡住的一部分长度
paint.setColor(Color.rgb(61,82,89));
canvas.drawRoundRect(backgroundLineRect, backgroundLineSize/2, backgroundLineSize/2, paint);
//绘制进度线
paint.setColor(Color.rgb(90,189,220));//进度线的颜色
foregroundLineRect.set((getWidth()-foregroundLineSize)/2,
(getParentHeight()-thumbSize)*(100-currentDegrees)/100+thumbSize/2,
(getWidth()+foregroundLineSize)/2,getParentHeight()-thumbSize/2);
canvas.drawRoundRect(foregroundLineRect,foregroundLineSize/2,foregroundLineSize/2,paint);
}
/**
* get ParentHeight
* @return
*/
private int getParentHeight(){
return getHeight();
}
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
return super.dispatchTouchEvent(event);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (!isEnabled())
return true;
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touchY = event.getRawY();//记录开始的Y值
break;
case MotionEvent.ACTION_MOVE:
currentDegrees += (touchY-event.getRawY())*1f/(getParentHeight())*100.0f;//当前进度值（100为满）
if (currentDegrees > 100){//超出去的不计算，默认为100
currentDegrees = 100;
}
if (currentDegrees<0){//超出去的不计算，默认为0
currentDegrees = 0;
}
if (observableEmitter != null){//使用背压发送
observableEmitter.onNext(1);
}else {//直接发送
sendProgress();
}
touchY = event.getRawY();
invalidate();
break;
case MotionEvent.ACTION_CANCEL:
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
private ObservableEmitter<Integer> observableEmitter;
/**
*增加背压，防止发射拖动的事件过快,导致内存溢出
*/
public void addBackPressure(){
Observable.create(new ObservableOnSubscribe<Integer>() {
@Override
public void subscribe(ObservableEmitter<Integer> emitter) throws Exception {
observableEmitter = emitter;
}
}).sample(500, TimeUnit.MILLISECONDS)
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Consumer<Integer>() {
@Override
public void accept(Integer integer) throws Exception {
sendProgress();
}
});
}
/**
* 发送进度
*/
private void sendProgress(){
if (onProgressListener != null){
onProgressListener.onProgress(currentDegrees);
}
}
/**
* 设置当前进度
* @param currentDegrees
*/
public void setCurrentDegrees(float currentDegrees){
this.currentDegrees = currentDegrees;
invalidate();
}
public interface OnProgressListener{
void onProgress(float progress);
}
/**
* make a drawable to a bitmap
* @param drawable drawable you want convert
* @return converted bitmap
*/
private Bitmap drawableToBitmap(int size, Drawable drawable) {
Bitmap bitmap = null;
if (drawable instanceof BitmapDrawable) {
BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
bitmap = bitmapDrawable.getBitmap();
if (bitmap != null && bitmap.getHeight() > 0) {
Matrix matrix = new Matrix();
float scaleHeight = size * 1.0f / bitmapDrawable.getIntrinsicHeight();
matrix.postScale(scaleHeight, scaleHeight);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
return bitmap;
}
}
bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
drawable.draw(canvas);
return bitmap;
}
}
Demo地址：https://github.com/helang1991/SeekBar
喜欢的就加个Star,谢谢