Android 圆角图片，基于Glide4.9 的 BitmapTransformation，可任意设置某个角

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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);

  @Override
  protected Bitmap transform(
      @NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight) {
    return TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight);
  }

  @Override
  public boolean equals(Object o) {
    return o instanceof CenterCrop;
  }

  @Override
  public int hashCode() {
    return ID.hashCode();
  }

  @Override
  public 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  : [email protected]
 * 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;

    }

    @Override
    protected 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
    @Override
    public String toString() {
        return "RoundedTransformation(radius=" + radius + ", margin=" + margin + ", diameter="
                + diameter + ", cornerType=" + cornerType.name() + ")";
    }

    @Override
    public boolean equals(Object o) {
        return o instanceof RoundedCornersTransformation2 &&
                ((RoundedCornersTransformation2) o).radius == radius &&
                ((RoundedCornersTransformation2) o).diameter == diameter &&
                ((RoundedCornersTransformation2) o).margin == margin &&
                ((RoundedCornersTransformation2) o).cornerType == cornerType;
    }

    @Override
    public int hashCode() {
        return (int) (ID.hashCode() + radius * 10000 + diameter * 1000 + margin * 100 + cornerType.ordinal() * 10);
    }

    @Override
    public 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;

    }

        @Override
    protected 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
    @Override
    public String toString() {
        return "RoundedTransformation(radius=" + radius + ", margin=" + margin + ", diameter="
                + diameter + ", cornerType=" + cornerType + ")";
    }

    @Override
    public boolean equals(Object o) {
        return o instanceof RoundedCornersTransformation &&
                ((RoundedCornersTransformation) o).radius == radius &&
                ((RoundedCornersTransformation) o).diameter == diameter &&
                ((RoundedCornersTransformation) o).margin == margin &&
                ((RoundedCornersTransformation) o).cornerType == cornerType;
    }

    @Override
    public int hashCode() {
        return (int) (ID.hashCode() + radius * 10000 + diameter * 1000 + margin * 100 + cornerType * 10);
    }

    @Override
    public 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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