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教程原文：Android自定义View——从零开始实现圆形进度条大家要是看到有错误的地方或者有啥好的建议，欢迎留言评论
源码已上传至github，要获取最新源码可点此传送
CircleBarView.java
public class CircleBarView extends View {
private Paint bgPaint;//绘制背景圆弧的画笔
private Paint progressPaint;//绘制圆弧的画笔
private RectF mRectF;//绘制圆弧的矩形区域
private CircleBarAnim anim;
private float progressNum;//可以更新的进度条数值
private float maxNum;//进度条最大值
private int progressColor;//进度条圆弧颜色
private int bgColor;//背景圆弧颜色
private float startAngle;//背景圆弧的起始角度
private float sweepAngle;//背景圆弧扫过的角度
private float barWidth;//圆弧进度条宽度
private int defaultSize;//自定义View默认的宽高
private float progressSweepAngle;//进度条圆弧扫过的角度
private TextView textView;
private OnAnimationListener onAnimationListener;
public CircleBarView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context,attrs);
}
private void init(Context context,AttributeSet attrs){
TypedArray typedArray = context.obtainStyledAttributes(attrs,R.styleable.CircleBarView);
progressColor = typedArray.getColor(R.styleable.CircleBarView_progress_color,Color.GREEN);
bgColor = typedArray.getColor(R.styleable.CircleBarView_bg_color,Color.GRAY);
startAngle = typedArray.getFloat(R.styleable.CircleBarView_start_angle,0);
sweepAngle = typedArray.getFloat(R.styleable.CircleBarView_sweep_angle,360);
barWidth = typedArray.getDimension(R.styleable.CircleBarView_bar_width,DpOrPxUtils.dip2px(context,10));
typedArray.recycle();//typedArray用完之后需要回收，防止内存泄漏
progressNum = 0;
maxNum = 100;
defaultSize = DpOrPxUtils.dip2px(context,100);
mRectF = new RectF();
anim = new CircleBarAnim();
progressPaint = new Paint();
progressPaint.setStyle(Paint.Style.STROKE);//只描边，不填充
progressPaint.setColor(progressColor);
progressPaint.setAntiAlias(true);//设置抗锯齿
progressPaint.setStrokeWidth(barWidth);
progressPaint.setStrokeCap(Paint.Cap.ROUND);//设置画笔为圆角
bgPaint = new Paint();
bgPaint.setStyle(Paint.Style.STROKE);//只描边，不填充
bgPaint.setColor(bgColor);
bgPaint.setAntiAlias(true);//设置抗锯齿
bgPaint.setStrokeWidth(barWidth);
bgPaint.setStrokeCap(Paint.Cap.ROUND);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int height = measureSize(defaultSize, heightMeasureSpec);
int width = measureSize(defaultSize, widthMeasureSpec);
int min = Math.min(width, height);// 获取View最短边的长度
setMeasuredDimension(min, min);// 强制改View为以最短边为长度的正方形
if(min >= barWidth*2){
mRectF.set(barWidth/2,barWidth/2,min-barWidth/2,min-barWidth/2);
}
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawArc(mRectF,startAngle,sweepAngle,false,bgPaint);
canvas.drawArc(mRectF,startAngle,progressSweepAngle,false, progressPaint);
}
public class CircleBarAnim extends Animation{
public CircleBarAnim(){
}
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
super.applyTransformation(interpolatedTime, t);
progressSweepAngle = interpolatedTime * sweepAngle * progressNum / maxNum;
if(textView !=null){
textView.setText(onAnimationListener.howToChangeText(interpolatedTime, progressNum,maxNum));
}
onAnimationListener.howTiChangeProgressColor(progressPaint,interpolatedTime, progressNum,maxNum);
postInvalidate();
}
}
private int measureSize(int defaultSize,int measureSpec) {
int result = defaultSize;
int specMode = View.MeasureSpec.getMode(measureSpec);
int specSize = View.MeasureSpec.getSize(measureSpec);
if (specMode == View.MeasureSpec.EXACTLY) {
result = specSize;
} else if (specMode == View.MeasureSpec.AT_MOST) {
result = Math.min(result, specSize);
}
return result;
}
/**
* 设置进度条最大值
* @param maxNum
*/
public void setMaxNum(float maxNum) {
this.maxNum = maxNum;
}
/**
* 设置进度条数值
* @param progressNum 进度条数值
* @param time 动画持续时间
*/
public void setProgressNum(float progressNum, int time) {
this.progressNum = progressNum;
anim.setDuration(time);
this.startAnimation(anim);
}
/**
* 设置显示文字的TextView
* @param textView
*/
public void setTextView(TextView textView) {
this.textView = textView;
}
public interface OnAnimationListener {
/**
* 如何处理要显示的文字内容
* @param interpolatedTime 从0渐变成1,到1时结束动画
* @param updateNum 进度条数值
* @param maxNum 进度条最大值
* @return
*/
String howToChangeText(float interpolatedTime, float updateNum, float maxNum);
/**
* 如何处理进度条的颜色
* @param paint 进度条画笔
* @param interpolatedTime 从0渐变成1,到1时结束动画
* @param updateNum 进度条数值
* @param maxNum 进度条最大值
*/
void howTiChangeProgressColor(Paint paint, float interpolatedTime, float updateNum, float maxNum);
}
public void setOnAnimationListener(OnAnimationListener onAnimationListener) {
this.onAnimationListener = onAnimationListener;
}
}
DpOrPxUtils.java
public class DpOrPxUtils {
public static int dip2px(Context context, float dpValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (dpValue * scale + 0.5f);
}
public static int px2dip(Context context, float pxValue) {
final float scale = context.getResources().getDisplayMetrics().density;
return (int) (pxValue / scale + 0.5f);
}
}
ShowActivity.java
public class ShowActivity extends AppCompatActivity {
private Button btnRestart;
private CircleBarView circleBarView;
private TextView textProgress;
private CircleBarView circleBarView2;
private TextView textProgress2;
private int num;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_show);
textProgress = (TextView) findViewById(R.id.text_progress);
circleBarView = (CircleBarView)findViewById(R.id.circle_view);
circleBarView.setTextView(textProgress);
circleBarView.setOnAnimationListener(new CircleBarView.OnAnimationListener() {
@Override
public String howToChangeText(float interpolatedTime, float updateNum, float maxNum) {
DecimalFormat decimalFormat=new DecimalFormat("0.00");
String s = decimalFormat.format(interpolatedTime * updateNum / maxNum * 100)+"%";
return s;
}
@Override
public void howTiChangeProgressColor(Paint paint, float interpolatedTime, float updateNum, float maxNum) {
LinearGradientUtil linearGradientUtil = new LinearGradientUtil(Color.YELLOW,Color.RED);
paint.setColor(linearGradientUtil.getColor(interpolatedTime));
}
});
circleBarView.setProgressNum(80,1000);
textProgress2 = (TextView) findViewById(R.id.text_progress2);
circleBarView2 = (CircleBarView)findViewById(R.id.circle_view2);
circleBarView2.setTextView(textProgress2);
circleBarView2.setOnAnimationListener(new CircleBarView.OnAnimationListener() {
@Override
public String howToChangeText(float interpolatedTime, float updateNum, float maxNum) {
DecimalFormat decimalFormat=new DecimalFormat("0.00");
String s = decimalFormat.format(interpolatedTime * updateNum / maxNum * 100)+"%";
return s;
}
@Override
public void howTiChangeProgressColor(Paint paint, float interpolatedTime, float updateNum, float maxNum) {
}
});
num = 0;
setProgressNumInThread();
btnRestart = (Button) findViewById(R.id.btn_restart);
btnRestart.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
circleBarView.setProgressNum(80,1000);
setProgressNumInThread();
}
});
}
private Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what){
case 0:
circleBarView2.setProgressNum(num,0);
break;
}
}
};
private void setProgressNumInThread(){
new Thread(new Runnable() {
@Override
public void run() {
try {
for (int i=1;i<=100;i++){
num = i;
handler.obtainMessage(0).sendToTarget();
Thread.sleep(50);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
}
}
activity_show.xml