本文實例為大家分享了Android自定義圓點指示器的具體代碼，供大家參考，具體內容如下

先上效果圖

大概思路就是自定義View 從左至右繪制圓點 然后在ViewPager的OnPageChangeListener中設置當前頁面的圓點

下面是代碼

先定義屬性

<resources> <attr name='selectedColor' format='color'/> <attr name='unselectedColor' format='color'/> <declare-styleable name='Indicator'><attr name='selectedColor'/><attr name='unselectedColor'/> </declare-styleable></resources>

接下來是自定義的View

public class Indicator extends View{ private static final int DEFAULT_TOTAL_INDEX = 5; private static final int DEFAULT_CURRENT_INDEX = 0; private static final int DEFAULT_CIRCLE_DISTANCE = 40; private static final int DEFAULT_CIRCLE_RADIUS = 8; private static final int DEFAULT_CIRCLE_SELECTED_RADIUS = 11; private int selectedColor; private int unselectedColor; private int currentIndex; private int totalIndex; private Paint paint; private int startX; private int startSelectedY; private int startY; private int centreX; public Indicator(Context context) {this(context,null); } public Indicator(Context context, AttributeSet attrs) {this(context, attrs,0); } public Indicator(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs,R.styleable.Indicator,defStyleAttr,0);selectedColor = typedArray.getColor(R.styleable.Indicator_selectedColor, Color.LTGRAY);unselectedColor = typedArray.getColor(R.styleable.Indicator_unselectedColor,Color.WHITE);typedArray.recycle();totalIndex = DEFAULT_TOTAL_INDEX;currentIndex = DEFAULT_CURRENT_INDEX;paint = new Paint(); }

從TypedArray中獲取自定義的屬性，totalIndex是總的圓點個數，currentIndex是當前頁面的圓點接下來是重寫的OnDraw()方法

@Override protected void onDraw(Canvas canvas) {super.onDraw(canvas);centreX = getWidth() / 2;startSelectedY = getHeight() / 2 - DEFAULT_CIRCLE_SELECTED_RADIUS;startY = getHeight() / 2 - DEFAULT_CIRCLE_RADIUS;if (totalIndex % 2 == 0){ startX = centreX - (int)(1.0 * (totalIndex - 1)/2 * DEFAULT_CIRCLE_DISTANCE);}else{ startX = centreX - totalIndex / 2 * DEFAULT_CIRCLE_DISTANCE;}paint.setAntiAlias(true);paint.setColor(unselectedColor);int tempX = startX;for(int i = 0 ; i < totalIndex ; i++ ){ RectF rectF = new RectF(tempX - DEFAULT_CIRCLE_RADIUS,startY, tempX + DEFAULT_CIRCLE_RADIUS,startY + 2 * DEFAULT_CIRCLE_RADIUS); if (i == currentIndex) {paint.setColor(selectedColor);rectF = new RectF(tempX - DEFAULT_CIRCLE_SELECTED_RADIUS,startSelectedY,tempX + DEFAULT_CIRCLE_SELECTED_RADIUS,startSelectedY + 2 * DEFAULT_CIRCLE_SELECTED_RADIUS); } canvas.drawOval(rectF,paint); if (paint.getColor() == selectedColor)paint.setColor(unselectedColor); tempX += DEFAULT_CIRCLE_DISTANCE;} }

因為當前頁面的圓點和未選中頁面的圓點要設置不同的大小 所以分別設置每個圓點的坐標 然后用for循環(huán)繪制圓點這里有一點要注意 new RectF() 的四個參數分別是圓點外面的矩形的左上角的X,Y和右下角的X,Y

接下來是設置當前頁面的圓點的方法

public void setCurrentIndex(int currentIndex){//if (currentIndex < 0)// currentIndex += totalIndex ;//if (currentIndex > totalIndex - 1)// currentIndex %= totalIndex;this.currentIndex = currentIndex;invalidate(); }

注釋里的代碼是當頁面可以循環(huán)的時候設置的接下來是設置總的圓點個數的方法

public void setTotalIndex(int totalIndex){int oldTotalIndex = this.totalIndex;if (totalIndex < 1) return;if (totalIndex < oldTotalIndex){ if (currentIndex == totalIndex )currentIndex = totalIndex - 1;}this.totalIndex = totalIndex;invalidate(); }

當刪除圓點的時候 如果currentIndex是最后一個 讓currentIndex向前移動接下來是重寫的OnMeasure()方法

@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {setMeasuredDimension(measureWidth(widthMeasureSpec),measureHeight(heightMeasureSpec)); } private int measureHeight(int measureSpec){int result;int specMode = MeasureSpec.getMode(measureSpec);int specSize = MeasureSpec.getSize(measureSpec);int desired = DEFAULT_CIRCLE_SELECTED_RADIUS * 2 + getPaddingBottom() + getPaddingTop();if(specMode == MeasureSpec.EXACTLY) { result = Math.max(desired,specSize);}else{ if(specMode == MeasureSpec.AT_MOST){result = Math.min(desired,specSize); } else result = desired;}return result; } private int measureWidth(int measureSpec){int result;int specMode = MeasureSpec.getMode(measureSpec);int specSize = MeasureSpec.getSize(measureSpec);int desired = (totalIndex - 1) * DEFAULT_CIRCLE_DISTANCE + DEFAULT_CIRCLE_SELECTED_RADIUS * 2 + getPaddingLeft() + getPaddingRight();if(specMode == MeasureSpec.EXACTLY) { result = Math.max(desired,specSize);}else{ if(specMode == MeasureSpec.AT_MOST){result = Math.min(desired,specSize); }else result = desired;}return result; }

下面是MainActivity的布局代碼，很簡單

<RelativeLayout xmlns:android='http://schemas.android.com/apk/res/android' xmlns:tools='http://schemas.android.com/tools' xmlns:app='http://schemas.android.com/apk/res-auto' android:layout_width='match_parent' android:layout_height='match_parent' tools:context='com.example.lzh123.learnviewpager.MainActivity'> <android.support.v4.view.ViewPagerandroid: android:layout_width='match_parent'android:layout_height='match_parent'/> <com.example.lzh123.learnviewpager.Indicatorapp:selectedColor='#FFFFFF'app:unselectedColor='#C7C7C7'android: android:layout_centerInParent='true'android:layout_width='wrap_content'android:layout_height='wrap_content' /> </RelativeLayout>

下面是MainActivity的代碼

public class MainActivity extends AppCompatActivity { View layout1,layout2,layout3; ViewPager viewPager; Indicator indicator; List<View> viewList; @Override protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main); viewPager = (ViewPager) findViewById(R.id.viewPager);LayoutInflater inflater = getLayoutInflater();layout1 = inflater.inflate(R.layout.layout1,null);layout2 = inflater.inflate(R.layout.layout2,null);layout3 = inflater.inflate(R.layout.layout3,null); viewList = new ArrayList<>();viewList.add(layout1);viewList.add(layout2);viewList.add(layout3); indicator = (Indicator) findViewById(R.id.indicator);indicator.setTotalIndex(viewList.size());PagerAdapter pagerAdapter = new PagerAdapter() { @Override public int getCount() {return viewList.size(); } @Override public void destroyItem(ViewGroup container, int position, Object object) {container.removeView(viewList.get(position)); } @Override public Object instantiateItem(ViewGroup container, int position) {container.addView(viewList.get(position)); return position; } @Override public boolean isViewFromObject(View view, Object object) {return view == viewList.get(Integer.parseInt(object.toString())); }}; viewPager.setAdapter(pagerAdapter);viewPager.setOnPageChangeListener(new PageChangeListener()); } public class PageChangeListener implements ViewPager.OnPageChangeListener{ @Overridepublic void onPageSelected(int position) { indicator.setCurrentIndex(position);} @Overridepublic void onPageScrollStateChanged(int state) { } @Overridepublic void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } }

ViewPager里添加了三個空頁面 然后設置指示器的圓點個數，最后在ViewPager的OnPageChangeListener中設置當前的 頁面的圓點。

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好吧啦網。