Android开发

api学习开发

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CircleImageView">
        <attr name="Radius" format="dimension"/>
        <attr name="type">
            <enum name="circle" value="0"/>
            <enum name="round" value="1"/>
        </attr>
    </declare-styleable>
</resources>

接着是自定义ImageView：CircleImageView.java：

/**
 * Created by Jay on 2015/10/25 0025.
 */
public class CircleImageView extends ImageView {

    private Paint mPaint;
    private Xfermode mXfermode = new PorterDuffXfermode(PorterDuff.Mode.DST_IN);
    private Bitmap mMaskBitmap;
    private WeakReference<Bitmap> mWeakBitmap;

    //图片相关的属性
    private int type;                           //类型，圆形或者圆角
    public static final int TYPE_CIRCLE = 0;
    public static final int TYPE_ROUND = 1;
    private static final int BODER_RADIUS_DEFAULT = 10;     //圆角默认大小值
    private int mBorderRadius;                  //圆角大小


    public CircleImageView(Context context) {
        this(context, null);
    }

    public CircleImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        //取出attrs中我们为View设置的相关值
        TypedArray tArray = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView);
        mBorderRadius = tArray.getDimensionPixelSize(R.styleable.CircleImageView_Radius, BODER_RADIUS_DEFAULT);
        type = tArray.getInt(R.styleable.CircleImageView_type, TYPE_CIRCLE);
        tArray.recycle();
    }

    public CircleImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (type == TYPE_CIRCLE) {
            int width = Math.min(getMeasuredWidth(), getMeasuredHeight());
            setMeasuredDimension(width, width);    //设置当前View的大小
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {

        //在缓存中取出bitmap
        Bitmap bitmap = mWeakBitmap == null ? null : mWeakBitmap.get();
        if (bitmap == null || bitmap.isRecycled()) {
            //获取图片宽高
            Drawable drawable = getDrawable();
            int width = drawable.getIntrinsicWidth();
            int height = drawable.getIntrinsicHeight();

            if (drawable != null) {
                bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
                Canvas drawCanvas = new Canvas(bitmap);
                float scale = 1.0f;
                if (type == TYPE_ROUND) {
                    scale = Math.max(getWidth() * 1.0f / width, getHeight()
                            * 1.0f / height);
                } else {
                    scale = getWidth() * 1.0F / Math.min(width, height);
                }
                //根据缩放比例，设置bounds，相当于缩放图片了
                drawable.setBounds(0, 0, (int) (scale * width),(int)(scale * height));

                drawable.draw(drawCanvas);if(mMaskBitmap ==null|| mMaskBitmap.isRecycled()){
                    mMaskBitmap = getBitmap();}

                mPaint.reset();
                mPaint.setFilterBitmap(false);
                mPaint.setXfermode(mXfermode);//绘制形状
                drawCanvas.drawBitmap(mMaskBitmap,0,0, mPaint);//bitmap缓存起来，避免每次调用onDraw，分配内存
                mWeakBitmap =newWeakReference<Bitmap>(bitmap);//绘制图片
                canvas.drawBitmap(bitmap,0,0,null);
                mPaint.setXfermode(null);}}if(bitmap !=null){
            mPaint.setXfermode(null);
            canvas.drawBitmap(bitmap,0.0f,0.0f, mPaint);return;}}//缓存Bitmap，避免每次OnDraw都重新分配内存与绘图@Overridepublicvoid invalidate(){
        mWeakBitmap =null;if(mWeakBitmap !=null){
            mMaskBitmap.recycle();
            mMaskBitmap =null;}super.invalidate();}//定义一个绘制形状的方法privateBitmap getBitmap(){Bitmap bitmap =Bitmap.createBitmap(getWidth(), getHeight(),Bitmap.Config.ARGB_8888);Canvas canvas =newCanvas(bitmap);Paint paint =newPaint(Paint.ANTI_ALIAS_FLAG);//抗锯齿
        paint.setColor(Color.BLACK);if(type == TYPE_ROUND){
            canvas.drawRoundRect(newRectF(0,0, getWidth(), getHeight()),
                    mBorderRadius, mBorderRadius, paint);}else{
            canvas.drawCircle(getWidth()/2, getWidth()/2, getWidth()/2, paint);}return bitmap;}}

最后在布局文件那里调用下:activity_main.xml：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.jay.xfermodedemo1.CircleImageView
        android:layout_width="160dp"
        android:layout_height="240dp"
        android:layout_margin="10dp"
        android:src="@mipmap/ic_bg_meizi2"
        app:type="circle" />

    <com.jay.xfermodedemo1.CircleImageView
        android:layout_width="160dp"
        android:layout_height="280dp"
        android:layout_margin="10dp"
        android:src="@mipmap/ic_bg_meizi1"
        app:Radius="30dp"
        app:type="round" />
    
</LinearLayout>