由于android系统提供的SeekBar是直线型的。但是有些时候我们需要用到其他形状的SeekBar，那么就需要自定义View来实现。这里只是实现了一个环形的，其他形状的类似。
效果图如下
package com.lee.circleseekbar.view;
import com.lee.circleseekbar.R;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
/**
*
* CircleSeekBar
*
* @author lee
*
*/
public class CircleSeekBar extends View {
private final boolean DEBUG = true;
private final String TAG = "CircleSeekBar";
private Context mContext = null;
private AttributeSet mAttrs = null;
private Drawable mThumbDrawable = null;
private int mThumbHeight = 0;
private int mThumbWidth = 0;
private int[] mThumbNormal = null;
private int[] mThumbPressed = null;
private int mSeekBarMax = 0;
private Paint mSeekBarBackgroundPaint = null;
private Paint mSeekbarProgressPaint = null;
private RectF mArcRectF = null;
private boolean mIsShowProgressText = false;
private Paint mProgressTextPaint = null;
private int mProgressTextSize = 0;
private int mViewHeight = 0;
private int mViewWidth = 0;
private int mSeekBarSize = 0;
private int mSeekBarRadius = 0;
private int mSeekBarCenterX = 0;
private int mSeekBarCenterY = 0;
private float mThumbLeft = 0;
private float mThumbTop = 0;
private float mSeekBarDegree = 0;
private int mCurrentProgress = 0;
public CircleSeekBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mContext = context;
mAttrs = attrs;
initView();
}
public CircleSeekBar(Context context, AttributeSet attrs) {
super(context, attrs);
mContext = context;
mAttrs = attrs;
initView();
}
public CircleSeekBar(Context context) {
super(context);
mContext = context;
initView();
}
private void initView(){
if(DEBUG) Log.d(TAG, "initView");
TypedArray localTypedArray = mContext.obtainStyledAttributes(mAttrs, R.styleable.CircleSeekBar);
//thumb的属性是使用android:thumb属性进行设置的
//返回的Drawable为一个StateListDrawable类型，即可以实现选中效果的drawable list
//mThumbNormal和mThumbPressed则是用于设置不同状态的效果，当点击thumb时设置mThumbPressed，否则设置mThumbNormal
mThumbDrawable = localTypedArray.getDrawable(R.styleable.CircleSeekBar_android_thumb);
mThumbWidth = this.mThumbDrawable.getIntrinsicWidth();
mThumbHeight = this.mThumbDrawable.getIntrinsicHeight();
mThumbNormal = new int[]{-android.R.attr.state_focused, -android.R.attr.state_pressed,
-android.R.attr.state_selected, -android.R.attr.state_checked};
mThumbPressed = new int[]{android.R.attr.state_focused, android.R.attr.state_pressed,
android.R.attr.state_selected, android.R.attr.state_checked};
float progressWidth = localTypedArray.getDimension(R.styleable.CircleSeekBar_progress_width, 5);
int progressBackgroundColor = localTypedArray.getColor(R.styleable.CircleSeekBar_progress_background, Color.GRAY);
int progressFrontColor = localTypedArray.getColor(R.styleable.CircleSeekBar_progress_front, Color.BLUE);
mSeekBarMax = localTypedArray.getInteger(R.styleable.CircleSeekBar_progress_max, 100);
mSeekbarProgressPaint = new Paint();
mSeekBarBackgroundPaint = new Paint();
mSeekbarProgressPaint.setColor(progressFrontColor);
mSeekBarBackgroundPaint.setColor(progressBackgroundColor);
mSeekbarProgressPaint.setAntiAlias(true);
mSeekBarBackgroundPaint.setAntiAlias(true);
mSeekbarProgressPaint.setStyle(Paint.Style.STROKE);
mSeekBarBackgroundPaint.setStyle(Paint.Style.STROKE);
mSeekbarProgressPaint.setStrokeWidth(progressWidth);
mSeekBarBackgroundPaint.setStrokeWidth(progressWidth);
mArcRectF = new RectF();
mIsShowProgressText = localTypedArray.getBoolean(R.styleable.CircleSeekBar_show_progress_text, false);
int progressTextStroke = (int) localTypedArray.getDimension(R.styleable.CircleSeekBar_progress_text_stroke_width, 5);
int progressTextColor = localTypedArray.getColor(R.styleable.CircleSeekBar_progress_text_color, Color.GREEN);
mProgressTextSize = (int) localTypedArray.getDimension(R.styleable.CircleSeekBar_progress_text_size, 50);
mProgressTextPaint = new Paint();
mProgressTextPaint.setColor(progressTextColor);
mProgressTextPaint.setAntiAlias(true);
mProgressTextPaint.setStrokeWidth(progressTextStroke);
mProgressTextPaint.setTextSize(mProgressTextSize);
localTypedArray.recycle();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if(DEBUG) Log.d(TAG, "onMeasure");
mViewWidth = getWidth();
mViewHeight = getHeight();
mSeekBarSize = mViewWidth > mViewHeight ? mViewHeight : mViewWidth;
mSeekBarCenterX = mViewWidth / 2;
mSeekBarCenterY = mViewHeight / 2;
mSeekBarRadius = mSeekBarSize / 2 - mThumbWidth / 2;
int left = mSeekBarCenterX - mSeekBarRadius;
int right = mSeekBarCenterX + mSeekBarRadius;
int top = mSeekBarCenterY - mSeekBarRadius;
int bottom = mSeekBarCenterY + mSeekBarRadius;
mArcRectF.set(left, top, right, bottom);
// 起始位置，三点钟方向
setThumbPosition(Math.toRadians(mSeekBarDegree));
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawCircle(mSeekBarCenterX, mSeekBarCenterY, mSeekBarRadius,
mSeekBarBackgroundPaint);
canvas.drawArc(this.mArcRectF, 0.0F, mSeekBarDegree, false, mSeekbarProgressPaint);
drawThumbBitmap(canvas);
drawProgressText(canvas);
super.onDraw(canvas);
}
private void drawThumbBitmap(Canvas canvas) {
this.mThumbDrawable.setBounds((int) mThumbLeft, (int) mThumbTop,
(int) (mThumbLeft + mThumbWidth), (int) (mThumbTop + mThumbHeight));
this.mThumbDrawable.draw(canvas);
}
private void drawProgressText(Canvas canvas) {
if (true == mIsShowProgressText){
float textWidth = mProgressTextPaint.measureText("" + mCurrentProgress);
canvas.drawText("" + mCurrentProgress, mSeekBarCenterX - textWidth / 2, mSeekBarCenterY
+ mProgressTextSize / 2, mProgressTextPaint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
seekTo(eventX, eventY, false);
break ;
case MotionEvent.ACTION_MOVE:
seekTo(eventX, eventY, false);
break ;
case MotionEvent.ACTION_UP:
seekTo(eventX, eventY, true);
break ;
}
return true;
}
private void seekTo(float eventX, float eventY, boolean isUp) {
if (true == isPointOnThumb(eventX, eventY) && false == isUp) {
mThumbDrawable.setState(mThumbPressed);
double radian = Math.atan2(eventY - mSeekBarCenterY, eventX - mSeekBarCenterX);
/*
* 由于atan2返回的值为[-pi,pi]
* 因此需要将弧度值转换一下，使得区间为[0,2*pi]
*/
if (radian < 0){
radian = radian + 2*Math.PI;
}
if(DEBUG) Log.e(TAG, "seekTo radian = " + radian);
setThumbPosition(radian);
mSeekBarDegree = (float) Math.round(Math.toDegrees(radian));
mCurrentProgress = (int) (mSeekBarMax * mSeekBarDegree / 360);
invalidate();
}else{
mThumbDrawable.setState(mThumbNormal);
invalidate();
}
}
private boolean isPointOnThumb(float eventX, float eventY) {
boolean result = false;
double distance = Math.sqrt(Math.pow(eventX - mSeekBarCenterX, 2)
+ Math.pow(eventY - mSeekBarCenterY, 2));
if (distance < mSeekBarSize && distance > (mSeekBarSize / 2 - mThumbWidth)){
result = true;
}
return result;
}
private void setThumbPosition(double radian) {
if(DEBUG) Log.v(TAG, "setThumbPosition radian = " + radian);
double x = mSeekBarCenterX + mSeekBarRadius * Math.cos(radian);
double y = mSeekBarCenterY + mSeekBarRadius * Math.sin(radian);
mThumbLeft = (float) (x - mThumbWidth / 2);
mThumbTop = (float) (y - mThumbHeight / 2);
}
/*
* 增加set方法，用于在java代码中调用
*/
public void setProgress(int progress) {
if(DEBUG) Log.v(TAG, "setProgress progress = " + progress);
if (progress > mSeekBarMax){
progress = mSeekBarMax;
}
if (progress < 0){
progress = 0;
}
mCurrentProgress = progress;
mSeekBarDegree = (progress * 360 / mSeekBarMax);
if(DEBUG) Log.d(TAG, "setProgress mSeekBarDegree = " + mSeekBarDegree);
setThumbPosition(Math.toRadians(mSeekBarDegree));
invalidate();
}
public int getProgress(){
return mCurrentProgress;
}
public void setProgressMax(int max){
if(DEBUG) Log.v(TAG, "setProgressMax max = " + max);
mSeekBarMax = max;
}
public int getProgressMax(){
return mSeekBarMax;
}
public void setProgressThumb(int thumbId){
mThumbDrawable = mContext.getResources().getDrawable(thumbId);
}
public void setProgressWidth(int width){
if(DEBUG) Log.v(TAG, "setProgressWidth width = " + width);
mSeekbarProgressPaint.setStrokeWidth(width);
mSeekBarBackgroundPaint.setStrokeWidth(width);
}
public void setProgressBackgroundColor(int color){
mSeekBarBackgroundPaint.setColor(color);
}
public void setProgressFrontColor(int color){
mSeekbarProgressPaint.setColor(color);
}
public void setProgressTextColor(int color){
mProgressTextPaint.setColor(color);
}
public void setProgressTextSize(int size){
if(DEBUG) Log.v(TAG, "setProgressTextSize size = " + size);
mProgressTextPaint.setTextSize(size);
}
public void setProgressTextStrokeWidth(int width){
if(DEBUG) Log.v(TAG, "setProgressTextStrokeWidth width = " + width);
mProgressTextPaint.setStrokeWidth(width);
}
public void setIsShowProgressText(boolean isShow){
mIsShowProgressText = isShow;
}
}
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:circle_seekbar="http://schemas.android.com/apk/res/com.lee.circleseekbar"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<com.lee.circleseekbar.view.CircleSeekBar
android:id="@+id/circle_seekbar"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_centerInParent="true"
android:thumb="@drawable/thumb"
circle_seekbar:progress_background="@android:color/darker_gray"
circle_seekbar:progress_front="@android:color/holo_blue_light"
circle_seekbar:progress_max="1000"
circle_seekbar:progress_text_color="@android:color/holo_green_light"
circle_seekbar:progress_text_size="30dp"
circle_seekbar:progress_text_stroke_width="4dp"
circle_seekbar:progress_width="2dp"
circle_seekbar:show_progress_text="true" />
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="CircleSeekBar">
<attr name="android:thumb" />
<attr name="progress_width" format="dimension" />
<attr name="progress_background" format="color" />
<attr name="progress_front" format="color" />
<attr name="progress_max" format="integer" />
<attr name="show_progress_text" format="boolean" />
<attr name="progress_text_stroke_width" format="dimension" />
<attr name="progress_text_color" format="color" />
<attr name="progress_text_size" format="dimension" />
</declare-styleable>
</resources>package com.lee.circleseekbar;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import com.lee.circleseekbar.view.CircleSeekBar;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
CircleSeekBar circleSeekBar = (CircleSeekBar) findViewById(R.id.circle_seekbar);
circleSeekBar.setProgress(100);
circleSeekBar.setProgressFrontColor(Color.RED);
//circleSeekBar.setProgressWidth(20);
}
}
Demo下载地址
http://download.csdn.net/detail/ly0904010214/8370879
原文地址：http://blog.csdn.net/ly0904010214/article/details/42805363
