glide加载圆角图片

附录1简单介绍了Android开源的图片加载框架。在实际的开发中，虽然Glide解决了快速加载图片的问题，但还有一个问题悬而未决：比如用户的头像，往往用户的头像是从服务器端读出的一个普通矩形图片，但是现在的设计一般要求在APP端的用户头像显示成圆形头像，那么此时虽然Glide可以加载，但加载出来的是一个矩形，如果要Glide在加载过程中就把矩形图转换成圆形的，则需要在Glide之上引入一个开源项目：glide-transformations
glide-transformations在github上的项目主页是：https://github.com/wasabeef/glide-transformations 

写一个例子说明。

package zhangphil.app;    import android.support.v7.app.AppCompatActivity;  import android.os.Bundle;  import android.widget.ImageView;    import com.bumptech.glide.Glide;    import jp.wasabeef.glide.transformations.BlurTransformation;  import jp.wasabeef.glide.transformations.CropCircleTransformation;  import jp.wasabeef.glide.transformations.RoundedCornersTransformation;    public class MainActivity extends AppCompatActivity {        //我csdn博客头像      String url = "http://avatar.csdn.net/9/7/A/1_zhangphil.jpg";        @Override      protected void onCreate(Bundle savedInstanceState) {          super.onCreate(savedInstanceState);          setContentView(R.layout.activity_main);            //原图，是我博客的头像          ImageView image1 = (ImageView) findViewById(R.id.image1);          Glide.with(this).load(url).crossFade(1000).into(image1);            //原图 -> 圆图          ImageView image2 = (ImageView) findViewById(R.id.image2);          Glide.with(this).load(url).bitmapTransform(new CropCircleTransformation(this)).crossFade(1000).into(image2);            //原图的毛玻璃、高斯模糊效果          ImageView image3 = (ImageView) findViewById(R.id.image3);          Glide.with(this).load(url).bitmapTransform(new BlurTransformation(this, 25)).crossFade(1000).into(image3);            //原图基础上复合变换成圆图 +毛玻璃（高斯模糊）          ImageView image4 = (ImageView) findViewById(R.id.image4);          Glide.with(this).load(url).bitmapTransform(new BlurTransformation(this, 25), new CropCircleTransformation(this)).crossFade(1000).into(image4);            //原图处理成圆角，如果是四周都是圆角则是RoundedCornersTransformation.CornerType.ALL          ImageView image5 = (ImageView) findViewById(R.id.image5);          Glide.with(this).load(url).bitmapTransform(new RoundedCornersTransformation(this, 30, 0, RoundedCornersTransformation.CornerType.BOTTOM)).crossFade(1000).into(image5);      }  }  

主要实现类如下是所示，可以加载圆形图像，椭圆图像，以及矩形圆角，上圆角，下圆角。

/** * Copyright (C) 2017 Wasabeef * <p> * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapShader;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.RectF;import android.graphics.Shader;import com.bumptech.glide.Glide;import com.bumptech.glide.load.Transformation;import com.bumptech.glide.load.engine.Resource;import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;import com.bumptech.glide.load.resource.bitmap.BitmapResource;public class RoundedCornersTransformation implements Transformation<Bitmap> {    public enum CornerType {        ALL,        TOP_LEFT, TOP_RIGHT, BOTTOM_LEFT, BOTTOM_RIGHT,        TOP, BOTTOM, LEFT, RIGHT,        OTHER_TOP_LEFT, OTHER_TOP_RIGHT, OTHER_BOTTOM_LEFT, OTHER_BOTTOM_RIGHT,        DIAGONAL_FROM_TOP_LEFT, DIAGONAL_FROM_TOP_RIGHT    }    private BitmapPool mBitmapPool;    private int mRadius;    private int mDiameter;    private int mMargin;    private CornerType mCornerType;    public RoundedCornersTransformation(Context context, int radius, int margin) {        this(context, radius, margin, CornerType.ALL);    }    public RoundedCornersTransformation(BitmapPool pool, int radius, int margin) {        this(pool, radius, margin, CornerType.ALL);    }    public RoundedCornersTransformation(Context context, int radius, int margin,                                        CornerType cornerType) {        this(Glide.get(context).getBitmapPool(), radius, margin, cornerType);    }    public RoundedCornersTransformation(BitmapPool pool, int radius, int margin,                                        CornerType cornerType) {        mBitmapPool = pool;        mRadius = radius;        mDiameter = mRadius * 2;        mMargin = margin;        mCornerType = cornerType;    }    @Override    public Resource<Bitmap> transform(Resource<Bitmap> resource, int outWidth, int outHeight) {        Bitmap source = resource.get();        int width = source.getWidth();        int height = source.getHeight();        Bitmap bitmap = mBitmapPool.get(width, height, Bitmap.Config.ARGB_8888);        if (bitmap == null) {            bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);        }        Canvas canvas = new Canvas(bitmap);        Paint paint = new Paint();        paint.setAntiAlias(true);        paint.setShader(new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));        drawRoundRect(canvas, paint, width, height);        return BitmapResource.obtain(bitmap, mBitmapPool);    }    private void drawRoundRect(Canvas canvas, Paint paint, float width, float height) {        float right = width - mMargin;        float bottom = height - mMargin;        switch (mCornerType) {            case ALL:                canvas.drawRoundRect(new RectF(mMargin, mMargin, right, bottom), mRadius, mRadius, paint);                break;            case TOP_LEFT:                drawTopLeftRoundRect(canvas, paint, right, bottom);                break;            case TOP_RIGHT:                drawTopRightRoundRect(canvas, paint, right, bottom);                break;            case BOTTOM_LEFT:                drawBottomLeftRoundRect(canvas, paint, right, bottom);                break;            case BOTTOM_RIGHT:                drawBottomRightRoundRect(canvas, paint, right, bottom);                break;            case TOP:                drawTopRoundRect(canvas, paint, right, bottom);                break;            case BOTTOM:                drawBottomRoundRect(canvas, paint, right, bottom);                break;            case LEFT:                drawLeftRoundRect(canvas, paint, right, bottom);                break;            case RIGHT:                drawRightRoundRect(canvas, paint, right, bottom);                break;            case OTHER_TOP_LEFT:                drawOtherTopLeftRoundRect(canvas, paint, right, bottom);                break;            case OTHER_TOP_RIGHT:                drawOtherTopRightRoundRect(canvas, paint, right, bottom);                break;            case OTHER_BOTTOM_LEFT:                drawOtherBottomLeftRoundRect(canvas, paint, right, bottom);                break;            case OTHER_BOTTOM_RIGHT:                drawOtherBottomRightRoundRect(canvas, paint, right, bottom);                break;            case DIAGONAL_FROM_TOP_LEFT:                drawDiagonalFromTopLeftRoundRect(canvas, paint, right, bottom);                break;            case DIAGONAL_FROM_TOP_RIGHT:                drawDiagonalFromTopRightRoundRect(canvas, paint, right, bottom);                break;            default:                canvas.drawRoundRect(new RectF(mMargin, mMargin, right, bottom), mRadius, mRadius, paint);                break;        }    }    private void drawTopLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, mMargin + mDiameter, mMargin + mDiameter),                mRadius, mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin + mRadius, mMargin + mRadius, bottom), paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin, right, bottom), paint);    }    private void drawTopRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(right - mDiameter, mMargin, right, mMargin + mDiameter), mRadius,                mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin, right - mRadius, bottom), paint);        canvas.drawRect(new RectF(right - mRadius, mMargin + mRadius, right, bottom), paint);    }    private void drawBottomLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, bottom - mDiameter, mMargin + mDiameter, bottom),                mRadius, mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin, mMargin + mDiameter, bottom - mRadius), paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin, right, bottom), paint);    }    private void drawBottomRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(right - mDiameter, bottom - mDiameter, right, bottom), mRadius,                mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin, right - mRadius, bottom), paint);        canvas.drawRect(new RectF(right - mRadius, mMargin, right, bottom - mRadius), paint);    }    private void drawTopRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, right, mMargin + mDiameter), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin, mMargin + mRadius, right, bottom), paint);    }    private void drawBottomRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, bottom - mDiameter, right, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin, mMargin, right, bottom - mRadius), paint);    }    private void drawLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, mMargin + mDiameter, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin, right, bottom), paint);    }    private void drawRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(right - mDiameter, mMargin, right, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin, mMargin, right - mRadius, bottom), paint);    }    private void drawOtherTopLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, bottom - mDiameter, right, bottom), mRadius, mRadius,                paint);        canvas.drawRoundRect(new RectF(right - mDiameter, mMargin, right, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin, mMargin, right - mRadius, bottom - mRadius), paint);    }    private void drawOtherTopRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, mMargin + mDiameter, bottom), mRadius, mRadius,                paint);        canvas.drawRoundRect(new RectF(mMargin, bottom - mDiameter, right, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin, right, bottom - mRadius), paint);    }    private void drawOtherBottomLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, right, mMargin + mDiameter), mRadius, mRadius,                paint);        canvas.drawRoundRect(new RectF(right - mDiameter, mMargin, right, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin, mMargin + mRadius, right - mRadius, bottom), paint);    }    private void drawOtherBottomRightRoundRect(Canvas canvas, Paint paint, float right,                                               float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, right, mMargin + mDiameter), mRadius, mRadius,                paint);        canvas.drawRoundRect(new RectF(mMargin, mMargin, mMargin + mDiameter, bottom), mRadius, mRadius,                paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin + mRadius, right, bottom), paint);    }    private void drawDiagonalFromTopLeftRoundRect(Canvas canvas, Paint paint, float right,                                                  float bottom) {        canvas.drawRoundRect(new RectF(mMargin, mMargin, mMargin + mDiameter, mMargin + mDiameter),                mRadius, mRadius, paint);        canvas.drawRoundRect(new RectF(right - mDiameter, bottom - mDiameter, right, bottom), mRadius,                mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin + mRadius, right - mDiameter, bottom), paint);        canvas.drawRect(new RectF(mMargin + mDiameter, mMargin, right, bottom - mRadius), paint);    }    private void drawDiagonalFromTopRightRoundRect(Canvas canvas, Paint paint, float right,                                                   float bottom) {        canvas.drawRoundRect(new RectF(right - mDiameter, mMargin, right, mMargin + mDiameter), mRadius,                mRadius, paint);        canvas.drawRoundRect(new RectF(mMargin, bottom - mDiameter, mMargin + mDiameter, bottom),                mRadius, mRadius, paint);        canvas.drawRect(new RectF(mMargin, mMargin, right - mRadius, bottom - mRadius), paint);        canvas.drawRect(new RectF(mMargin + mRadius, mMargin + mRadius, right, bottom), paint);    }    @Override    public String getId() {        return "RoundedTransformation(radius=" + mRadius + ", margin=" + mMargin + ", diameter="                + mDiameter + ", cornerType=" + mCornerType.name() + ")";    }}

如有疑问，大家共勉