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前言

Glide中的 Transformation，多次设置，后面的会覆盖前面的。
如果 ImageView的 scaleType = “centerCrop”，会在 into()方法前自动加上 centerCrop()，即会调用 CenterCrop#transform()。

public class CenterCrop extends BitmapTransformation {private static final String ID = "com.bumptech.glide.load.resource.bitmap.CenterCrop";private static final byte[] ID_BYTES = ID.getBytes(CHARSET);@Overrideprotected Bitmap transform(@NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight) {return TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight);}@Overridepublic boolean equals(Object o) {return o instanceof CenterCrop;}@Overridepublic int hashCode() {return ID.hashCode();}@Overridepublic void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {messageDigest.update(ID_BYTES);}
}

要同时有centerCrop效果与圆角效果，就基于这个类修改就行，即基于 TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight); 这段代码返回的Bitmap对象作处理。

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基于glide-transformations项目中的圆角矩形方案修改

支持dp单位，float精度

/*** Copyright (C) 2018 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.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.RectF;
import android.graphics.Shader;
import android.support.annotation.NonNull;import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.TransformationUtils;import java.security.MessageDigest;import jp.wasabeef.glide.transformations.BitmapTransformation;/*** desc   :* author : stone* email  : aa86799@163.com* time   : 2019/6/12 ‏‎9:42*/
public class RoundedCornersTransformation2 extends BitmapTransformation {private static final int VERSION = 1;private static final String ID = "jp.wasabeef.glide.transformations.RoundedCornersTransformation." + VERSION;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}public enum ScaleType {FIT_CENTER, CENTER_CROP, CENTER_INSIDE}private float radius;private float diameter;private float margin;private CornerType cornerType;private ScaleType scaleType;public RoundedCornersTransformation2(int dpRadius, int marginDp) {this(dpRadius, marginDp, CornerType.ALL, ScaleType.FIT_CENTER);}public RoundedCornersTransformation2(int dpRadius, int marginDp, CornerType cornerType, ScaleType scaleType) {this.radius = Resources.getSystem().getDisplayMetrics().density * dpRadius;this.diameter = this.radius * 2;this.margin =  Resources.getSystem().getDisplayMetrics().density * marginDp;this.cornerType = cornerType;this.scaleType = scaleType;}@Overrideprotected Bitmap transform(@NonNull Context context, @NonNull BitmapPool pool,@NonNull Bitmap toTransform, int outWidth, int outHeight) {Bitmap bitmap;switch (scaleType) {case CENTER_CROP:bitmap = TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight);break;case CENTER_INSIDE:bitmap = TransformationUtils.centerInside(pool, toTransform, outWidth, outHeight);break;case FIT_CENTER:default:bitmap = TransformationUtils.fitCenter(pool, toTransform, outWidth, outHeight);break;}return roundCrop(pool, bitmap);}private Bitmap roundCrop(BitmapPool pool, Bitmap source) {if (source == null) return null;Bitmap result = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);result.setHasAlpha(true);Canvas canvas = new Canvas(result);canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));Paint paint = new Paint();paint.setAntiAlias(true);paint.setShader(new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));drawRoundRect(canvas, paint, source.getWidth(), source.getHeight());return result;}private void drawRoundRect(Canvas canvas, Paint paint, float width, float height) {float right = width - margin;float bottom = height - margin;switch (cornerType) {case ALL:canvas.drawRoundRect(new RectF(margin, margin, right, bottom), radius, radius, 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(margin, margin, right, bottom), radius, radius, paint);break;}}private void drawTopLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, margin, margin + diameter, margin + diameter), radius,radius, paint);canvas.drawRect(new RectF(margin, margin + radius, margin + radius, bottom), paint);canvas.drawRect(new RectF(margin + radius, margin, right, bottom), paint);}private void drawTopRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(right - diameter, margin, right, margin + diameter), radius,radius, paint);canvas.drawRect(new RectF(margin, margin, right - radius, bottom), paint);canvas.drawRect(new RectF(right - radius, margin + radius, right, bottom), paint);}private void drawBottomLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, bottom - diameter, margin + diameter, bottom), radius,radius, paint);canvas.drawRect(new RectF(margin, margin, margin + diameter, bottom - radius), paint);canvas.drawRect(new RectF(margin + radius, margin, right, bottom), paint);}private void drawBottomRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(right - diameter, bottom - diameter, right, bottom), radius,radius, paint);canvas.drawRect(new RectF(margin, margin, right - radius, bottom), paint);canvas.drawRect(new RectF(right - radius, margin, right, bottom - radius), paint);}private void drawTopRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, margin, right, margin + diameter), radius, radius,paint);canvas.drawRect(new RectF(margin, margin + radius, right, bottom), paint);}private void drawBottomRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, bottom - diameter, right, bottom), radius, radius,paint);canvas.drawRect(new RectF(margin, margin, right, bottom - radius), paint);}private void drawLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, margin, margin + diameter, bottom), radius, radius,paint);canvas.drawRect(new RectF(margin + radius, margin, right, bottom), paint);}private void drawRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(right - diameter, margin, right, bottom), radius, radius, paint);canvas.drawRect(new RectF(margin, margin, right - radius, bottom), paint);}private void drawOtherTopLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, bottom - diameter, right, bottom), radius, radius,paint);canvas.drawRoundRect(new RectF(right - diameter, margin, right, bottom), radius, radius, paint);canvas.drawRect(new RectF(margin, margin, right - radius, bottom - radius), paint);}private void drawOtherTopRightRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, margin, margin + diameter, bottom), radius, radius,paint);canvas.drawRoundRect(new RectF(margin, bottom - diameter, right, bottom), radius, radius,paint);canvas.drawRect(new RectF(margin + radius, margin, right, bottom - radius), paint);}private void drawOtherBottomLeftRoundRect(Canvas canvas, Paint paint, float right, float bottom) {canvas.drawRoundRect(new RectF(margin, margin, right, margin + diameter), radius, radius,paint);canvas.drawRoundRect(new RectF(right - diameter, margin, right, bottom), radius, radius, paint);canvas.drawRect(new RectF(margin, margin + radius, right - radius, bottom), paint);}private void drawOtherBottomRightRoundRect(Canvas canvas, Paint paint, float right,float bottom) {canvas.drawRoundRect(new RectF(margin, margin, right, margin + diameter), radius, radius,paint);canvas.drawRoundRect(new RectF(margin, margin, margin + diameter, bottom), radius, radius,paint);canvas.drawRect(new RectF(margin + radius, margin + radius, right, bottom), paint);}private void drawDiagonalFromTopLeftRoundRect(Canvas canvas, Paint paint, float right,float bottom) {canvas.drawRoundRect(new RectF(margin, margin, margin + diameter, margin + diameter), radius,radius, paint);canvas.drawRoundRect(new RectF(right - diameter, bottom - diameter, right, bottom), radius,radius, paint);canvas.drawRect(new RectF(margin, margin + radius, right - diameter, bottom), paint);canvas.drawRect(new RectF(margin + diameter, margin, right, bottom - radius), paint);}private void drawDiagonalFromTopRightRoundRect(Canvas canvas, Paint paint, float right,float bottom) {canvas.drawRoundRect(new RectF(right - diameter, margin, right, margin + diameter), radius,radius, paint);canvas.drawRoundRect(new RectF(margin, bottom - diameter, margin + diameter, bottom), radius,radius, paint);canvas.drawRect(new RectF(margin, margin, right - radius, bottom - radius), paint);canvas.drawRect(new RectF(margin + radius, margin + radius, right, bottom), paint);}@NonNull@Overridepublic String toString() {return "RoundedTransformation(radius=" + radius + ", margin=" + margin + ", diameter="+ diameter + ", cornerType=" + cornerType.name() + ")";}@Overridepublic boolean equals(Object o) {return o instanceof RoundedCornersTransformation2 &&((RoundedCornersTransformation2) o).radius == radius &&((RoundedCornersTransformation2) o).diameter == diameter &&((RoundedCornersTransformation2) o).margin == margin &&((RoundedCornersTransformation2) o).cornerType == cornerType;}@Overridepublic int hashCode() {return (int) (ID.hashCode() + radius * 10000 + diameter * 1000 + margin * 100 + cornerType.ordinal() * 10);}@Overridepublic void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {messageDigest.update((ID + radius + diameter + margin + cornerType).getBytes(CHARSET));}
}

调用方式

Glide.with(...)....transform(new RoundedCornersTransformation2(dpRadius, margin, cornerType, scaleType)).into(...);

这里继承的是 glide-transformations项目中的 BitmapTransformation，而不是glide中的。继承glide中的也是可以的。

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方案2

上面绘制圆角时，分了很多type，不同type分别绘制。代码量很长。
参考了一个文章，改成如下：

public class RoundedCornersTransformation extends BitmapTransformation {private static final int VERSION = 1;//这个ID值 随意private static final String ID = "jp.wasabeef.glide.transformations.RoundedCornersTransformation." + VERSION;public static final int CORNER_NONE = 0;public static final int CORNER_TOP_LEFT = 1;public static final int CORNER_TOP_RIGHT = 1 << 1;public static final int CORNER_BOTTOM_LEFT = 1 << 2;public static final int CORNER_BOTTOM_RIGHT = 1 << 3;public static final int CORNER_ALL = CORNER_TOP_LEFT | CORNER_TOP_RIGHT | CORNER_BOTTOM_LEFT | CORNER_BOTTOM_RIGHT;public static final int CORNER_TOP = CORNER_TOP_LEFT | CORNER_TOP_RIGHT;public static final int CORNER_BOTTOM = CORNER_BOTTOM_LEFT | CORNER_BOTTOM_RIGHT;public static final int CORNER_LEFT = CORNER_TOP_LEFT | CORNER_BOTTOM_LEFT;public static final int CORNER_RIGHT = CORNER_TOP_RIGHT | CORNER_BOTTOM_RIGHT;public static final int FIT_CENTER = 1;public static final int CENTER_CROP = 2;public static final int CENTER_INSIDE = 3;@IntDef({FIT_CENTER, CENTER_CROP, CENTER_INSIDE})public @interface ScaleType {}private float radius;private float diameter;private float margin;private int cornerType;private @ScaleType int scaleType;public RoundedCornersTransformation(int dpRadius, int marginDp) {this(dpRadius, marginDp, CORNER_ALL, FIT_CENTER);}public RoundedCornersTransformation(int dpRadius, int marginDp, int cornerType, @ScaleType int scaleType) {this.radius = Resources.getSystem().getDisplayMetrics().density * dpRadius;this.diameter = this.radius * 2;this.margin = Resources.getSystem().getDisplayMetrics().density * marginDp;this.cornerType = cornerType;this.scaleType = scaleType;}@Overrideprotected Bitmap transform(@NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight) {Bitmap bitmap;switch (scaleType) {case CENTER_CROP:bitmap = TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight);break;case CENTER_INSIDE:bitmap = TransformationUtils.centerInside(pool, toTransform, outWidth, outHeight);break;case FIT_CENTER:default:bitmap = TransformationUtils.fitCenter(pool, toTransform, outWidth, outHeight);break;}return roundCrop(pool, bitmap);}private Bitmap roundCrop(BitmapPool pool, Bitmap source) {if (source == null) return null;Bitmap result = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);result.setHasAlpha(true);Canvas canvas = new Canvas(result);canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));Paint paint = new Paint();paint.setAntiAlias(true);paint.setShader(new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP));drawRoundRect(canvas, paint, source.getWidth(), source.getHeight());return result;}private void drawRoundRect(Canvas canvas, Paint paint, float width, float height) {float right = width - margin;float bottom = height - margin;canvas.drawRoundRect(new RectF(margin, margin, right, bottom), radius, radius, paint);//把不需要的圆角去掉int notRoundedCorners = cornerType ^ CORNER_ALL;if ((notRoundedCorners & CORNER_TOP_LEFT) != 0) {clipTopLeft(canvas, paint, radius);}if ((notRoundedCorners & CORNER_TOP_RIGHT) != 0) {clipTopRight(canvas, paint, radius, right);}if ((notRoundedCorners & CORNER_BOTTOM_LEFT) != 0) {clipBottomLeft(canvas, paint, radius, bottom);}if ((notRoundedCorners & CORNER_BOTTOM_RIGHT) != 0) {clipBottomRight(canvas, paint, radius, right, bottom);}}private static void clipTopLeft(final Canvas canvas, final Paint paint, float offset) {final RectF block = new RectF(0, 0, offset, offset);canvas.drawRect(block, paint);}private static void clipTopRight(final Canvas canvas, final Paint paint, float offset, float width) {final RectF block = new RectF(width - offset, 0, width, offset);canvas.drawRect(block, paint);}private static void clipBottomLeft(final Canvas canvas, final Paint paint, float offset, float height) {final RectF block = new RectF(0, height - offset, offset, height);canvas.drawRect(block, paint);}private static void clipBottomRight(final Canvas canvas, final Paint paint, float offset, float width, float height) {final RectF block = new RectF(width - offset, height - offset, width, height);canvas.drawRect(block, paint);}@NonNull@Overridepublic String toString() {return "RoundedTransformation(radius=" + radius + ", margin=" + margin + ", diameter="+ diameter + ", cornerType=" + cornerType + ")";}@Overridepublic boolean equals(Object o) {return o instanceof RoundedCornersTransformation &&((RoundedCornersTransformation) o).radius == radius &&((RoundedCornersTransformation) o).diameter == diameter &&((RoundedCornersTransformation) o).margin == margin &&((RoundedCornersTransformation) o).cornerType == cornerType;}@Overridepublic int hashCode() {return (int) (ID.hashCode() + radius * 10000 + diameter * 1000 + margin * 100 + cornerType * 10);}@Overridepublic void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {messageDigest.update((ID + radius + diameter + margin + cornerType).getBytes(CHARSET));}
}

先绘一个全圆角，再根据条件绘制 某几的个角小矩形，以覆盖圆角效果

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其它问题

由于transform变换操作，会影响glide的图片缓存。glide文档中是要求重写 equals、hashCode、updateDiskCacheKey这三个方法的。
在调试时，若对同一图片，一会设置左圆角，一会设置右圆角，类似这样，可能就会造成后设置的看不到效果，看到还是之前的设置的效果。这是由于 glide缓存造成的。这时重装项目就可以了。

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参考

android中对Bitmap图片设置任意角为圆角
glide-transformations

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