本文主要是介绍自定义颜色、大小渐变的圆点指示器，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
源码 点击打开链接
首先看布局文件activity_main.xml
布局很简单只有装图片的ViewPager--以及自定义的圆点指示器
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"tools:context="com.example.pageindicator.MainActivity" ><android.support.v4.view.ViewPagerandroid:id="@+id/mViewpager"android:layout_width="match_parent"android:layout_height="300dp" ></android.support.v4.view.ViewPager><com.example.pageindicator.CustomPageIndicatorandroid:id="@+id/mPagerIndicator"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:layout_marginTop="50dp" ></com.example.pageindicator.CustomPageIndicator></LinearLayout>首先看主界面把MainActivity
package com.example.pageindicator; import java.util.ArrayList;import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;public class MainActivity extends Activity { private ViewPager mViewPager; CustomPageIndicator mPagerIndicator;MyAdapter mAdapter; private ArrayList<ImageView> imageViewList; private boolean isScrolling = false;@SuppressWarnings("deprecation") @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); imageViewList = new ArrayList<ImageView>(); int[] imagesInt = {R.drawable.p1,R.drawable.p2,R.drawable.p3}; for (int i = 0; i < imagesInt.length; i++) { ImageView imageView = new ImageView(MainActivity.this); imageView.setBackgroundResource(imagesInt[i]); imageViewList.add(imageView); } mPagerIndicator = (CustomPageIndicator) findViewById(R.id.mPagerIndicator);mViewPager = (ViewPager) findViewById(R.id.mViewpager); mAdapter = new MyAdapter(); mViewPager.setAdapter(mAdapter); mViewPager.setOnPageChangeListener(new OnPageChangeListener() { @Override public void onPageSelected(int position) { mPagerIndicator.setActivityCircle(position);} @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {float percent = positionOffset;if(isScrolling && percent > 0.0f && percent < 1.0f){mPagerIndicator.setScrollProgress(position,percent);}} @Override public void onPageScrollStateChanged(int arg0) {if(arg0 != 0){isScrolling = true;}else{isScrolling = false;}//下面判断不严谨
// if(arg0 == 1){
// isScrolling = true;
// }else{
// isScrolling = false;
// }} }); } class MyAdapter extends PagerAdapter{ @Override public int getCount() { return imageViewList.size(); } @Override public boolean isViewFromObject(View arg0, Object arg1) { return arg0 == arg1; } @Override public void destroyItem(ViewGroup container, int position, Object object) { container.removeView(imageViewList.get(position)); } @Override public Object instantiateItem(ViewGroup container, int position) { container.addView(imageViewList.get(position)); return imageViewList.get(position); } }
} 主界面是最简单的ViewPager页面切换效果--主要是看 mPagerIndicator.setScrollProgress(position,percent);、mPagerIndicator.setActivityCircle(position);的代码
接下来就看圆点指示器自定义类把CustomPageIndicator 先贴出代码来，然后在稍微讲解下
package com.example.pageindicator;import java.util.ArrayList;import android.R.color;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.provider.CalendarContract.Colors;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;public class CustomPageIndicator extends View {int[] imagesInt = { R.drawable.p1, R.drawable.p2, R.drawable.p3 };private int circleCount = imagesInt.length;private int activeCircleIndex = 0;private int circleRadius;// 半径4private int activeCircleRadius;// 当前小球半径6private int circleDivider;// 间距6private ArrayList<Circle> circles = null;Paint mPaint;private int normalCircleColor;private int acitiveCircleColor;public CustomPageIndicator(Context context, AttributeSet attrs) {this(context, attrs, 0);}public CustomPageIndicator(Context context) {this(context, null);}public CustomPageIndicator(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);initCircle();}private void initCircle() {normalCircleColor = Color.parseColor("#000000");acitiveCircleColor = Color.parseColor("#EE3B3B");// 填充、抗锯齿--颜色、大小mPaint = new Paint();mPaint.setStyle(Paint.Style.FILL);mPaint.setAntiAlias(true);circleRadius = PhoneUtils.dp2px(getContext(), 4);activeCircleRadius = PhoneUtils.dp2px(getContext(), 6);circleDivider = PhoneUtils.dp2px(getContext(), 6);circles = new ArrayList<CustomPageIndicator.Circle>();// 创建3个原点集合for (int i = 0; i < circleCount; i++) {Circle circle = new Circle();if (activeCircleIndex == i) {// 当前的点位circle.color = acitiveCircleColor;circle.radius = activeCircleRadius;circle.centerX = activeCircleRadius;circle.centerY = activeCircleRadius;} else {// 其他点位circle.color = normalCircleColor;circle.radius = circleRadius;circle.centerX = activeCircleRadius + i* PhoneUtils.dp2px(getContext(), 14);circle.centerY = activeCircleRadius;}circles.add(circle);}}/*** 设置目前活动的小球* 第一部分根据startValue求出其中A,R,G,B中各个色彩的初始值；第二部分根据endValue求出其中A,R,G,B中各个色彩的结束值* ，最后是根据当前动画的百分比进度求出对应的数值*/public void setActivityCircle(int index) {lastCircle = circles.get(activeCircleIndex);lastCircle.color = ColorHelper.evaluate(0.1f, normalCircleColor,acitiveCircleColor);lastCircle.radius = circleRadius;activeCircleIndex = index;currentActivedCircele = circles.get(activeCircleIndex);currentActivedCircele.color = ColorHelper.evaluate(0.1f,acitiveCircleColor, normalCircleColor);currentActivedCircele.radius = activeCircleRadius;invalidate();}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {int resultWidth = 0;int resultHeight = 0;resultWidth = circleCount * circleRadius * 2 + (circleCount - 1)* circleDivider + 2 * (activeCircleRadius - circleRadius);resultHeight = 2 * activeCircleRadius;setMeasuredDimension(resultWidth, resultHeight);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);for (int i = 0; i < circleCount; i++) {Circle circle = circles.get(i);mPaint.setColor(circle.color);canvas.drawCircle(circle.centerX, circle.centerY, circle.radius,mPaint);}}/*** 圆心xy坐标，半径，颜色*/private class Circle {float centerX;float centerY;float radius;int color;}private float lastPercent = -1;private Circle lastCircle;private Circle currentActivedCircele;private Circle right;private Circle left;public void setScrollProgress(int leftPosition, float percent) {right = circles.get(leftPosition + 1);left = circles.get(leftPosition);// 手指右滑-递减if (lastPercent > percent) {left.radius = circleRadius + (1 - percent)* PhoneUtils.dp2px(getContext(), 2);right.radius = circleRadius + percent* PhoneUtils.dp2px(getContext(), 2);if (left.color == normalCircleColor) {left.color = ColorHelper.evaluate(percent, normalCircleColor,acitiveCircleColor);} else {left.color = ColorHelper.evaluate(percent, acitiveCircleColor,normalCircleColor);}if (right.color == normalCircleColor) {right.color = ColorHelper.evaluate(1 - percent,normalCircleColor, acitiveCircleColor);} else {right.color = ColorHelper.evaluate(1 - percent,acitiveCircleColor, normalCircleColor);}}// 手指左滑-递增if (lastPercent < percent) {left.radius = circleRadius + (1 - percent)* PhoneUtils.dp2px(getContext(), 2);right.radius = circleRadius + percent* PhoneUtils.dp2px(getContext(), 2);if (right.color == normalCircleColor) {right.color = ColorHelper.evaluate(1 - percent,normalCircleColor, acitiveCircleColor);} else {right.color = ColorHelper.evaluate(1 - percent,acitiveCircleColor, normalCircleColor);}if (left.color == normalCircleColor) {left.color = ColorHelper.evaluate(percent, normalCircleColor,acitiveCircleColor);} else {left.color = ColorHelper.evaluate(percent, acitiveCircleColor,normalCircleColor);}}invalidate();lastPercent = percent;}}
上面的initCircle方法中是进行原点初始化操作，定义了圆点的默认色normalCircleColor，选中色acitiveCircleColor，以及圆点之间的距离circleDivider，
默认圆点的半径circleRadius，选中原点的半径activeCircleRadius，然后根据ViewPager的图片数量进行分装圆点对象集合
然后看onMeasure去测量View的整体大小--不解释了
最后看onDraw就是去绘制圆点，这些方法比较简单
mPagerIndicator.setActivityCircle(position);这个就是滚动到某一页面进行的逻辑处理
/*** 设置目前活动的小球* 第一部分根据startValue求出其中A,R,G,B中各个色彩的初始值；第二部分根据endValue求出其中A,R,G,B中各个色彩的结束值* ，最后是根据当前动画的百分比进度求出对应的数值*/public void setActivityCircle(int index) {lastCircle = circles.get(activeCircleIndex);lastCircle.color = ColorHelper.evaluate(0.1f, normalCircleColor,acitiveCircleColor);lastCircle.radius = circleRadius;activeCircleIndex = index;currentActivedCircele = circles.get(activeCircleIndex);currentActivedCircele.color = ColorHelper.evaluate(0.1f,acitiveCircleColor, normalCircleColor);currentActivedCircele.radius = activeCircleRadius;invalidate();}逻辑比较简单，就是判断上一个原点，和目前选中的圆点，然后进行颜色和半径的设置修改，在进行重绘操作
最后看比较复杂的mPagerIndicator.setScrollProgress(position,percent);逻辑处理
public void setScrollProgress(int leftPosition, float percent) {right = circles.get(leftPosition + 1);left = circles.get(leftPosition);// 手指右滑-递减if (lastPercent > percent) {left.radius = circleRadius + (1 - percent)* PhoneUtils.dp2px(getContext(), 2);right.radius = circleRadius + percent* PhoneUtils.dp2px(getContext(), 2);if (left.color == normalCircleColor) {left.color = ColorHelper.evaluate(percent, normalCircleColor,acitiveCircleColor);} else {left.color = ColorHelper.evaluate(percent, acitiveCircleColor,normalCircleColor);}if (right.color == normalCircleColor) {right.color = ColorHelper.evaluate(1 - percent,normalCircleColor, acitiveCircleColor);} else {right.color = ColorHelper.evaluate(1 - percent,acitiveCircleColor, normalCircleColor);}}// 手指左滑-递增if (lastPercent < percent) {left.radius = circleRadius + (1 - percent)* PhoneUtils.dp2px(getContext(), 2);right.radius = circleRadius + percent* PhoneUtils.dp2px(getContext(), 2);if (right.color == normalCircleColor) {right.color = ColorHelper.evaluate(1 - percent,normalCircleColor, acitiveCircleColor);} else {right.color = ColorHelper.evaluate(1 - percent,acitiveCircleColor, normalCircleColor);}if (left.color == normalCircleColor) {left.color = ColorHelper.evaluate(percent, normalCircleColor,acitiveCircleColor);} else {left.color = ColorHelper.evaluate(percent, acitiveCircleColor,normalCircleColor);}}invalidate();lastPercent = percent;}以上的代码，我感觉还有bug，不过效果基本上出来了，就是判断左右滑动的方向，进行颜色的变化修改
另外还有一下工具类
MeasureUtil
package com.example.pageindicator; import android.app.Activity;
import android.util.DisplayMetrics; /** * 测绘工具�? */
public final class MeasureUtil { /** * 获取屏幕尺寸 * * @param activity * Activity * @return 屏幕尺寸像素值，下标�?的�?为宽，下标为1的�?为高 */ public static float[] getScreenSize(Activity activity) { DisplayMetrics metrics = new DisplayMetrics(); activity.getWindowManager().getDefaultDisplay().getMetrics(metrics); return new float[] { metrics.widthPixels, metrics.heightPixels }; }
} PhoneUtils
package com.example.pageindicator; import android.content.Context; public class PhoneUtils { public static int dp2px(Context context,float dpValue){ float scale = context.getResources().getDisplayMetrics().density; return (int)(dpValue * scale +0.5f); }
} ColorHelper
package com.example.pageindicator;import android.animation.ArgbEvaluator;
import android.graphics.Color;public class ColorHelper {private static final String TAG = "ColorHelper";private static ArgbEvaluator colorEvaluator = new ArgbEvaluator();public static Integer evaluate(float fraction,int start,int end ){return (Integer) colorEvaluator.evaluate(fraction, start, end);}}
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