Android實現漸變圓環、圓形進度條效果

發布時間：2020-09-13 15:32:13 來源：腳本之家閱讀：1119 作者：再見孫悟空_ 欄目：移動開發

最近做了一個功能，里面涉及到了漸變圓形的需求。就是一個顏色可以漸變的圓環，最后實現的效果如下圖：

左圖是帶漸變效果，右圖是不帶漸變效果。原理還是繪圖，Canvas可以繪制的對象有：弧線(arcs)、填充顏色(argb和color)、 Bitmap、圓(circle和oval)、點(point)、線(line)、矩形(Rect)、圖片(Picture)、圓角矩形 (RoundRect)、文本(text)、頂點(Vertices)、路徑(path)。通過組合這些對象我們可以畫出一些簡單有趣的界面出來，但是光有這些功能還是不夠的，如果我要畫一個儀表盤(數字圍繞顯示在一個圓圈中)呢？幸好Android還提供了一些對Canvas位置轉換的方法：rorate、scale、translate、skew(扭曲)等，而且它允許你通過獲得它的轉換矩陣對象(getMatrix方法，不知道什么是轉換矩陣？) 直接操作它。這些操作就像是雖然你的筆還是原來的地方畫，但是畫紙旋轉或者移動了，所以你畫的東西的方位就產生變化。為了方便一些轉換操作，Canvas 還提供了保存和回滾屬性的方法(save和restore)，比如你可以先保存目前畫紙的位置(save)，然后旋轉90度，向下移動100像素后畫一些圖形，畫完后調用restore方法返回到剛才保存的位置。

話不多說，上代碼

核心類：

自定義控件 CircleProgressBar

package com.jky.mobile_xmxt.view;
 
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.SweepGradient;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Transformation;
 
import com.jky.mobile_xmxt.R;
 
import java.text.DecimalFormat;
 
/**
 * 圓盤計步圖表
 */
public class CircleProgressBar extends View {
 
 private RectF mWheelRect = new RectF();
 private Paint mDefaultWheelPaint;
 private Paint mFinishWheelPaint;
 private Paint mCenterWheelPaint;
 private Paint mTitlePaint, mStepPaint, mTargetPaint;
 private float mCircleStrokeWidth;
 private float mSweepAnglePer;
 private float mPercent;
 private int mStepNum, mCurrStepNum;
 private float pressExtraStrokeWidth;
 private BarAnimation mAnim;
 private int mMaxStepNum;// 默認最大步數
 private float mTitleY, mStepY, mTargetY;
 private DecimalFormat mDecimalFormat = new DecimalFormat("#.0");// 格式為保留小數點后一位
 public static String GOAL_STEP;
 public static String PERCENT;
 
 public CircleProgressBar(Context context) {
 super(context);
 init(null, 0);
 }
 
 public CircleProgressBar(Context context, AttributeSet attrs) {
 super(context, attrs);
 init(attrs, 0);
 }
 
 public CircleProgressBar(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 init(attrs, defStyle);
 }
 
 private void init(AttributeSet attrs, int defStyle) {
 
 mFinishWheelPaint = new Paint();
 mFinishWheelPaint.setColor(Color.rgb(100, 113, 205));
 mFinishWheelPaint.setStyle(Paint.Style.STROKE);// 空心
 mFinishWheelPaint.setStrokeCap(Paint.Cap.ROUND);// 圓角畫筆
 mFinishWheelPaint.setAntiAlias(true);// 去鋸齒
 
 mCenterWheelPaint = new Paint();
 mCenterWheelPaint.setColor(Color.rgb(243, 243, 243));
 mCenterWheelPaint.setStyle(Paint.Style.STROKE);
 mCenterWheelPaint.setStrokeCap(Paint.Cap.ROUND);
 mCenterWheelPaint.setAntiAlias(true);
 
 mDefaultWheelPaint = new Paint();
 mDefaultWheelPaint.setColor(Color.rgb(127, 127, 127));
 mDefaultWheelPaint.setStyle(Paint.Style.STROKE);
 mDefaultWheelPaint.setStrokeCap(Paint.Cap.ROUND);
 mDefaultWheelPaint.setAntiAlias(true);
 
 mTitlePaint = new Paint();
 mTitlePaint.setAntiAlias(true);
 mTitlePaint.setColor(Color.WHITE);
 
 mStepPaint = new Paint();
 mStepPaint.setAntiAlias(true);
 mStepPaint.setColor(Color.WHITE);
 
 mTargetPaint = new Paint();
 mTargetPaint.setAntiAlias(true);
 mTargetPaint.setColor(Color.WHITE);
 mAnim = new BarAnimation();
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
 canvas.drawArc(mWheelRect, 0, 359, false, mDefaultWheelPaint);
 canvas.drawArc(mWheelRect, 0, 359, false, mCenterWheelPaint);
 canvas.drawArc(mWheelRect, 90, mSweepAnglePer, false, mFinishWheelPaint);
// canvas.drawText("步數", mWheelRect.centerX() - (mTitlePaint.measureText("步數") / 2), mTitleY,
// mTitlePaint);
 canvas.drawText(mCurrStepNum + "",
  mWheelRect.centerX() - (mStepPaint.measureText(String.valueOf(mCurrStepNum)) / 2), mStepY,
  mStepPaint);
 String description = "";
 float percent = getPercent();
 if(percent > 0.5){
  description ="嚴重污染";
 }else if(percent<0.5){
  description ="中等污染";
 }else{
  description ="普通污染";
 }
 
 canvas.drawText(description , mWheelRect.centerX() -
  (mTargetPaint.measureText(description) / 2), mTargetY, mTargetPaint);
 SweepGradient sweepGradient = new SweepGradient(mWheelRect.centerX(), mWheelRect.centerY(),
  new int[]{getResources().getColor(R.color.color_environment_severe), getResources().getColor(R.color.color_environment_serious),
   getResources().getColor(R.color.color_environment_excellent),
   getResources().getColor(R.color.color_environment_good), getResources().getColor(R.color.color_environment_mild),
   getResources().getColor(R.color.color_environment_moderate)}, null);
 mFinishWheelPaint.setShader(sweepGradient);
 }
 
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 int height = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
 int width = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
 int min = Math.min(width, height);// 獲取View最短邊的長度
 setMeasuredDimension(min, min);// 強制改View為以最短邊為長度的正方形
 mCircleStrokeWidth = getTextScale(15, min);// 圓弧的寬度
 pressExtraStrokeWidth = getTextScale(10, min);// 圓弧離矩形的距離
 mWheelRect.set(mCircleStrokeWidth + pressExtraStrokeWidth, mCircleStrokeWidth + pressExtraStrokeWidth,
  min - mCircleStrokeWidth - pressExtraStrokeWidth, min - mCircleStrokeWidth - pressExtraStrokeWidth);// 設置矩形
 mTitlePaint.setTextSize(getTextScale(60, min));
 mStepPaint.setTextSize(getTextScale(120, min));
 mTargetPaint.setTextSize(getTextScale(40, min));
 mTitleY = getTextScale(170, min);
 mStepY = getTextScale(300, min);
 mTargetY = getTextScale(380, min);
 mFinishWheelPaint.setStrokeWidth(mCircleStrokeWidth);
 mCenterWheelPaint.setStrokeWidth(mCircleStrokeWidth);
 mDefaultWheelPaint.setStrokeWidth(mCircleStrokeWidth - getTextScale(2, min));
 mDefaultWheelPaint.setShadowLayer(getTextScale(10, min), 0, 0, Color.rgb(127, 127, 127));// 設置陰影
 }
 
 /**
 * 進度條動畫
 *
 * @author Administrator
 */
 public class BarAnimation extends Animation {
 
 /**
  * 每次系統調用這個方法時， 改變mSweepAnglePer，mPercent，stepnumbernow的值，
  * 然后調用postInvalidate()不停的繪制view。
  */
 @Override
 protected void applyTransformation(float interpolatedTime, Transformation t) {
// if (interpolatedTime < 1.0f) {
// mPercent = Float.parseFloat(mDecimalFormat.format(interpolatedTime * mStepNum * 100f / mMaxStepNum));// 將浮點值四舍五入保留一位小數
// mSweepAnglePer = interpolatedTime * mStepNum * 360 / mMaxStepNum;
// mCurrStepNum = (int) (interpolatedTime * mStepNum);
// } else {
  mPercent = Float.parseFloat(mDecimalFormat.format(mStepNum * 100f / mMaxStepNum));// 將浮點值四舍五入保留一位小數
  if (mPercent > 100.0f) {
  mPercent = 100.0f;
  }
  PERCENT = String.valueOf(mPercent);
  mSweepAnglePer = mStepNum * 360 / mMaxStepNum;
  mCurrStepNum = mStepNum;
// }
 
  requestLayout();
 }
 }
 
 public float getPercent() {
 return mPercent;
 }
 
 /**
 * 根據控件的大小改變絕對位置的比例
 *
 * @param n
 * @param m
 * @return
 */
 public float getTextScale(float n, float m) {
 return n / 500 * m;
 }
 
 /**
 * 更新步數和設置一圈動畫時間
 *
 * @param stepCount
 * @param time
 */
 public void update(int stepCount, int time) {
 this.mStepNum = stepCount;
 mAnim.setDuration(time);
 // setAnimationTime(time);
 this.startAnimation(mAnim);
 }
 
 /**
 * @param stepNum
 */
 public void setMaxStepNum(int stepNum) {
 mMaxStepNum = stepNum;
 GOAL_STEP = String.valueOf(mMaxStepNum);
 }
 
 public void setColor(int color) {
 mFinishWheelPaint.setColor(color);
 mStepPaint.setColor(color);
 }
 
 /**
 * 設置動畫時間
 *
 * @param time
 */
 public void setAnimationTime(int time) {
 mAnim.setDuration(time * mStepNum / mMaxStepNum);// 按照比例設置動畫執行時間
 }
 
}

xml引用

<com.jky.mobile_xmxt.view.CircleProgressBar
 android:id="@+id/color_progress_view"
 android:layout_width="match_parent"
 android:layout_height="0dp"
 android:layout_weight="6"
 />

Activity調用方法

color_progress_view = (CircleProgressBar)view.findViewById(R.id.color_progress_view);
color_progress_view.setMaxStepNum(500);
color_progress_view.update(470,1000);

由于和調用其他控件方法類似，姑且省去了很多其他業務邏輯代碼，代碼不是特別復雜，修改起來也很方便（修改顏色，總量及比例等），所以只粘貼核心相關的代碼，希望可以幫助到大家。

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持億速云。

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