Android最省内存的ViewPager添加小圆点指示器

这个你可以用View叠加来实现，但是这个效果不太理想，1占内存，而移植起来不方便，需要找各种资源，所以采用自己绘制更好，方便，而且效率高。

  
import java.util.ArrayList;  
import java.util.List;  
import java.util.Map;  
  
import android.content.Context;  
import android.graphics.Canvas;  
import android.graphics.Paint;  
import android.graphics.Paint.Style;  
import android.support.v4.view.ViewPager;  
import android.util.AttributeSet;  
import android.view.View;  
  
public class ADView extends ViewPager {  
  
    AdAdapter mAdAdapter;  
    Context context;  
    Paint paint;  
    List<Map<String, String>> urls;  
  
    public ADView(Context context, AttributeSet attrs) {  
        super(context, attrs);  
        this.context = context;  
        paint = new Paint();  
        InitAdapter();  
    }  
  
    private void InitAdapter() {  
        urls = new ArrayList<Map<String, String>>();  
        mAdAdapter = new AdAdapter(context, urls);  
        this.setAdapter(mAdAdapter);  
    }  
  
    public void setData(List<Map<String, String>> data) {  
        urls.clear();  
        for (int i = 0; i < data.size(); i++) {  
            urls.add(data.get(i));  
        }  
        if(urls.size()>0){  
            this.setVisibility(View.VISIBLE);  
        }else{  
            this.setVisibility(View.GONE);  
        }  
        mAdAdapter.notifyDataSetChanged();  
    }  
  
    @Override  
    public void draw(Canvas canvas) {  
        super.draw(canvas);  
        drawCycle(canvas);  
    }  
  
    private void drawCycle(Canvas canvas) {  
        canvas.save();  
        canvas.translate(getScrollX(), getScrollY());  
        int count = 0;  
        if (this.getAdapter() != null) {  
            count = this.getAdapter().getCount();  
        }  
        int select = getCurrentItem();  
        float density = getContext().getResources().getDisplayMetrics().density;  
        int itemWidth = (int) (11 * density);  
        int itemHeight = itemWidth / 2;  
        int x = (getWidth() - count * itemWidth)/2;  
        int y = getHeight() - itemWidth;  
        int minItemHeight = (int) ((float) itemHeight * 0.8F);  
        paint.setAntiAlias(true);  
  
        paint.setStyle(Style.FILL);  
        for (int i = 0; i < count; i++) {  
            if (select == i) {  
                paint.setColor(0xFFbdbdbd);  
                canvas.drawCircle(x + itemWidth * i + itemWidth / 2, y, minItemHeight, paint);  
            } else {  
                paint.setColor(0xFFe6e6e6);  
                canvas.drawCircle(x + itemWidth * i + itemWidth / 2, y, minItemHeight, paint);  
            }  
        }  
        canvas.restore();  
    }  
  
}  

标签： isp

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