Android圆角图—自定义控件

╰+哭是因爲堅強的太久メ 2022-07-11 12:07 354阅读 0赞

定义圆角图片，可以使用一些现成的工具类，详见《[Android设置圆角图，如两个圆角–工具类》][Android]，也可以使用自定义控件，本文介绍自定义方式实现图片圆角。

也可以参考另外一篇[Android圆角图][Android 1]

基本思路dst和src求交集，借助Xfermode实现：

1.自定义属性attrs  
2.自定义控件RoundByXfermode  
3.布局文件中摆放自定义控件

先看下效果图：  
![这里写图片描述][SouthEast]

![这里写图片描述][SouthEast 1]

首先自定义属性

![这里写图片描述][SouthEast 2]

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

第二步自定义控件：

package com.interjoy.demoguagualka.CustomView;
    
    import android.content.Context;
    import android.content.res.TypedArray;
    import android.graphics.Bitmap;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Paint;
    import android.graphics.PorterDuff;
    import android.graphics.PorterDuffXfermode;
    import android.graphics.RectF;
    import android.graphics.Xfermode;
    import android.graphics.drawable.Drawable;
    import android.util.AttributeSet;
    import android.util.TypedValue;
    import android.widget.ImageView;
    
    import com.interjoy.demoguagualka.R;
    
    import java.lang.ref.WeakReference;
    
    /** * Created by ylwang on 2017/1/23. */
    public class RoundByXfermode extends ImageView { 
    
        private Paint mPaint;
        //求交集
        private Xfermode mXfermode = new PorterDuffXfermode(PorterDuff.Mode.DST_IN);
        private Bitmap mMaskBitmap;//遮罩层
    
        private WeakReference<Bitmap> mWeakBitmap;
    
        /** * 图片的类型，圆形or圆角 */
        private int type;
        public static final int TYPE_CIRCLE = 0;
        public static final int TYPE_ROUND = 1;
        /** * 圆角大小的默认值 */
        private static final int BODER_RADIUS_DEFAULT = 10;
        /** * 圆角的大小 */
        private int mBorderRadius;
    
        public RoundByXfermode(Context context) {
    // super(context);
            this(context, null);
        }
    
        //系统会默认主动调用两个参数的构造方法
        public RoundByXfermode(Context context, AttributeSet attrs) {
            super(context, attrs);
            init(context, attrs);
        }
    
        private void init(Context context, AttributeSet attrs) {
            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);//获取画笔对象并抗锯齿效果
    
            TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundByXfermode);
    
            /** * setTextSize(TypedValue.COMPLEX_UNIT_PX,22); //22像素 *setTextSize(TypedValue.COMPLEX_UNIT_SP,22); //22SP *setTextSize(TypedValue.COMPLEX_UNIT_DIP,22);//22DIP */
            int value = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP
                    , BODER_RADIUS_DEFAULT
                    , getResources().getDisplayMetrics());
            mBorderRadius = a.getDimensionPixelSize(R.styleable.RoundByXfermode_borderRadius, value);// 默认为10dp
    
            type = a.getInt(R.styleable.RoundByXfermode_type, TYPE_CIRCLE);// 默认为Circle
    
            a.recycle();
        }
    
    
        public RoundByXfermode(Context context, AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
        }
    
        @Override
        protected void onDraw(Canvas canvas) {
    // super.onDraw(canvas);
            Bitmap bitmap = (mWeakBitmap == null) ? null : mWeakBitmap.get();
            if (null == bitmap || bitmap.isRecycled()) {
                //拿到Drawable
                Drawable drawable = getDrawable();
                //获取drawable的宽和高
                int dWidth = drawable.getIntrinsicWidth();
                int dHeight = drawable.getIntrinsicHeight();
    
                if (drawable != null) {
                    //创建bitmap
                    bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
                    float scale = 1.0f;
                    //创建画布
                    Canvas drawCanvas = new Canvas(bitmap);
                    //按照bitmap的宽高，以及view的宽高，计算缩放比例；
                    // 因为设置的src宽高比例可能和imageview的宽高比例不同，这里我们不希望图片失真；
                    if (type == TYPE_ROUND) {
                        // 如果图片的宽或者高与view的宽高不匹配，计算出需要缩放的比例；
                        // 缩放后的图片的宽高，一定要大于我们view的宽高；所以我们这里取大值；
                        scale = Math.max(getWidth() * 1.0f / dWidth, getHeight()
                                * 1.0f / dHeight);
                    } else {
                        scale = getWidth() * 1.0F / Math.min(dWidth, dHeight);
                    }
                    //根据缩放比例，设置bounds，相当于缩放图片了
                    drawable.setBounds(0, 0, (int) (scale * dWidth),
                            (int) (scale * dHeight));
                    drawable.draw(drawCanvas);
                    if (mMaskBitmap == null || mMaskBitmap.isRecycled()) {
                        mMaskBitmap = getBitmap();
                    }
                    // Draw Bitmap.
                    mPaint.reset();
                    mPaint.setFilterBitmap(false);
                    mPaint.setXfermode(mXfermode);
                    //绘制形状
                    drawCanvas.drawBitmap(mMaskBitmap, 0, 0, mPaint);
                    mPaint.setXfermode(null);
                    //将准备好的bitmap绘制出来
                    canvas.drawBitmap(bitmap, 0, 0, null);
                    //bitmap缓存起来，避免每次调用onDraw，分配内存
                    mWeakBitmap = new WeakReference<Bitmap>(bitmap);
                }
            }
            //如果bitmap还存在，则直接绘制即可
            if (bitmap != null) {
                mPaint.setXfermode(null);
                canvas.drawBitmap(bitmap, 0.0f, 0.0f, mPaint);
                return;
            }
        }
    
        /** * 绘制形状 * * @return */
        public Bitmap getBitmap() {
            Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(),
                    Bitmap.Config.ARGB_8888);
            Canvas canvas = new Canvas(bitmap);
            Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
            paint.setColor(Color.BLACK);
    
            if (type == TYPE_ROUND) {
                canvas.drawRoundRect(new RectF(0, 0, getWidth(), getHeight()),
                        mBorderRadius, mBorderRadius, paint);
            } else {
                canvas.drawCircle(getWidth() / 2, getWidth() / 2, getWidth() / 2,
                        paint);
            }
    
            return bitmap;
        }
    }

最后在布局文件中摆放我们的自定义控件

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".Activity.SecondActivity">
    
        <ScrollView android:layout_width="match_parent" android:layout_height="match_parent">
    
            <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical">
    
                <com.interjoy.demoguagualka.CustomView.RoundByXfermode android:layout_width="150dp" android:layout_height="150dp" android:src="@drawable/yuanyuan" />
    
                <com.interjoy.demoguagualka.CustomView.RoundByXfermode android:layout_width="200dp" android:layout_height="300dp" android:src="@drawable/yuanyuan" app:borderRadius="100dp" app:type="round" />
            </LinearLayout>
        </ScrollView>
    
    </LinearLayout>

[Android]: http://blog.csdn.net/iblade/article/details/54708631
[Android 1]: http://blog.csdn.net/iblade/article/details/73296672
[SouthEast]: /images/20220711/01888c7efaf1412c8a5192b561d85b06.png
[SouthEast 1]: /images/20220711/686e0b5e14c04d5390da5a9cbef9714e.png
[SouthEast 2]: /images/20220711/2c9fb03c9e6b4601bf6491dc90f47719.png