Android中怎么实现圆形渐变加载进度条，相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
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package com.view;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.RectF;import android.graphics.SweepGradient;import android.util.AttributeSet;import android.view.View;import com.fx.R;public class CompletedView extends View { // 画实心圆的画笔 private Paint mCirclePaint; // 画圆环的画笔 private Paint mRingPaint; // 画圆环的画笔背景色 private Paint mRingPaintBg; // 画字体的画笔 private Paint mTextPaint; // 圆形颜色 private int mCircleColor; // 圆环颜色 private int mRingColor; // 圆环背景颜色 private int mRingBgColor; // 半径 private float mRadius; // 圆环半径 private float mRingRadius; // 圆环宽度 private float mStrokeWidth; // 圆心x坐标 private int mXCenter; // 圆心y坐标 private int mYCenter; // 字的长度 private float mTxtWidth; // 字的高度 private float mTxtHeight; // 总进度 private int mTotalProgress = 100; // 当前进度 private int mProgress; private String string; public CompletedView(Context context, AttributeSet attrs) { super(context, attrs); // 获取自定义的属性 initAttrs(context, attrs); initVariable(); } //属性 private void initAttrs(Context context, AttributeSet attrs) { TypedArray typeArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.TasksCompletedView, 0, 0); mRadius = typeArray.getDimension(R.styleable.TasksCompletedView_radius, 80); mStrokeWidth = typeArray.getDimension(R.styleable.TasksCompletedView_strokeWidth, 10); mCircleColor = typeArray.getColor(R.styleable.TasksCompletedView_circleColor, 0xFFFFFFFF); mRingColor = typeArray.getColor(R.styleable.TasksCompletedView_ringColor, 0xFFFFFFFF); mRingBgColor = typeArray.getColor(R.styleable.TasksCompletedView_ringBgColor, 0xFFFFFFFF); mRingRadius = mRadius + mStrokeWidth / 2; } RectF oval; //初始化画笔 private void initVariable() { oval = new RectF(); //内圆 mCirclePaint = new Paint(); mCirclePaint.setAntiAlias(true); mCirclePaint.setColor(mCircleColor); mCirclePaint.setStyle(Paint.Style.FILL); mCirclePaint.setStrokeCap(Paint.Cap.ROUND); //外圆弧背景 mRingPaintBg = new Paint(); mRingPaintBg.setAntiAlias(true); mRingPaintBg.setColor(mRingBgColor); mRingPaintBg.setStyle(Paint.Style.STROKE); mRingPaintBg.setStrokeWidth(mStrokeWidth); //外圆弧 mRingPaint = new Paint(); mRingPaint.setAntiAlias(true);// mRingPaint.setColor(mRingColor); mRingPaint.setStyle(Paint.Style.STROKE); mRingPaint.setStrokeWidth(mStrokeWidth); mRingPaint.setStrokeCap(Paint.Cap.ROUND);//设置线冒样式，有圆 有方 //中间字 mTextPaint = new Paint(); mTextPaint.setAntiAlias(true); mTextPaint.setStyle(Paint.Style.FILL); mTextPaint.setColor(mRingColor); mTextPaint.setTextSize(mRadius / 2); Paint.FontMetrics fm = mTextPaint.getFontMetrics(); mTxtHeight = (int) Math.ceil(fm.descent - fm.ascent); } SweepGradient sweepGradient; //画图 @Override protected void onDraw(Canvas canvas) { mXCenter = getWidth() / 2; mYCenter = getHeight() / 2; //内圆 canvas.drawCircle(mXCenter, mYCenter, mRadius, mCirclePaint); //外圆弧背景 RectF oval1 = new RectF(); oval1.left = (mXCenter - mRingRadius); oval1.top = (mYCenter - mRingRadius); oval1.right = mRingRadius * 2 + (mXCenter - mRingRadius); oval1.bottom = mRingRadius * 2 + (mYCenter - mRingRadius); canvas.drawArc(oval1, 0, 360, false, mRingPaintBg); //圆弧所在的椭圆对象、圆弧的起始角度、圆弧的角度、是否显示半径连线 //外圆弧 if (mProgress > 0 ) { oval.left = (mXCenter - mRingRadius); oval.top = (mYCenter - mRingRadius); oval.right = mRingRadius * 2 + (mXCenter - mRingRadius); oval.bottom = mRingRadius * 2 + (mYCenter - mRingRadius); if (sweepGradient==null) { int[] arcColors= new int[]{mRingColor,Color.parseColor("#b05e39"),mRingColor}; float[] arcPostion=new float[]{0.0f,0.5f,0.95f};// sweepGradient = new SweepGradient(mXCenter, mYCenter, mRingColor,Color.parseColor("#b05e39")); sweepGradient = new SweepGradient(mXCenter, mYCenter, arcColors,arcPostion); Matrix matrix = new Matrix(); matrix.setRotate(-90,mXCenter,mYCenter); sweepGradient.setLocalMatrix(matrix); mRingPaint.setShader(sweepGradient); } canvas.drawArc(oval, -90, ((float)mProgress / mTotalProgress) * 360, false, mRingPaint); // //字体 String txt = mProgress + "%"; mTxtWidth = mTextPaint.measureText(txt, 0, txt.length()); canvas.drawText(txt, mXCenter - mTxtWidth / 2, mYCenter + mTxtHeight / 4, mTextPaint); } } public void setText(String string){ } //设置进度 public void setProgress(int progress) { mProgress = progress; postInvalidate();//重绘 }}
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