Glide自定义Transformation实现四个不同圆角图片

Case

Glide4.8想要实现加载图片导四个不同的圆角。如下图1

实现思路

在Canvas的四个图层分别绘制四个不同的圆角矩形（RoundRect），然后分别截取（clipRect）左上、右上、右下、左下四个部分，最终在Canvas上组合起来（save->restore）

关键步骤详解

步骤一：原图bitmap关联画笔：

Paint paint =new Paint();

// source 为 transfrom方法中的toTransform Bitmap对象

BitmapShader shader =new BitmapShader(source,Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);

paint.setShader(shader);

paint.setAntiAlias(true);

步骤二：新建画布：

Bitmap outBitmap =this.mBitmapPool.get(source.getWidth(), source.getHeight(),Bitmap.Config.ARGB_8888);

Canvas canvas =new Canvas(outBitmap);

步骤三：分别绘制不同圆角的四个图层，以左上为例：

RectF rectF =new RectF(0,0,canvas.getWidth(),canvas.getHeight());// 与画布同款高的绘制区域

canvas.save();// 图层入栈

canvas.clipRect(0,0,canvas.getWidth() /2,canvas.getHeight() /2);//只取所绘图片的左上1/4部分

canvas.drawRoundRect(rectF, r, r,paint);//绘制圆角矩形

canvas.restore();//图层出栈

以下为BitmapTransformation的完整实现代码：

/**
 * author : Conan
 * time   : 2019-12-19
 * desc   : 自定义图片四个圆角
 */
public class RoundedCornersTransform extends BitmapTransformation {

    private final String ID = getClass().getName();

    private Float[] radius = new Float[4];

    /**
     * 构造方法
     *
     * @param tl 左上
     * @param tr 右上
     * @param br 右下
     * @param bl 左下
     */
    public RoundedCornersTransform(float tl, float tr, float br, float bl) {
        this.radius[0] = tl;
        this.radius[1] = tr;
        this.radius[2] = br;
        this.radius[3] = bl;
    }

    @Override
    protected Bitmap transform(@NonNull BitmapPool pool, @NonNull Bitmap source, int outWidth, int outHeight) {
        Bitmap outBitmap = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(outBitmap);
        Paint paint = new Paint();
        //关联画笔绘制的原图bitmap
        BitmapShader shader = new BitmapShader(source, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        paint.setShader(shader);
        paint.setAntiAlias(true);

        RectF rectF = new RectF(0, 0, canvas.getWidth(), canvas.getHeight());
        // 左上
        float r = radius[0];
        canvas.save();
        canvas.clipRect(0, 0, canvas.getWidth() / 2, canvas.getHeight() / 2);
        canvas.drawRoundRect(rectF, r, r, paint);
        canvas.restore();
        // 右上
        r = radius[1];
        canvas.save();
        canvas.clipRect(canvas.getWidth() / 2, 0, canvas.getWidth(), canvas.getHeight() / 2);
        canvas.drawRoundRect(rectF, r, r, paint);
        canvas.restore();
        // 右下
        r = radius[2];
        canvas.save();
        canvas.clipRect(canvas.getWidth() / 2, canvas.getHeight() / 2, canvas.getWidth(), canvas.getHeight());
        canvas.drawRoundRect(rectF, r, r, paint);
        canvas.restore();
        // 左下
        r = radius[3];
        canvas.save();
        canvas.clipRect(0, canvas.getHeight() / 2, canvas.getWidth() / 2, canvas.getHeight());
        canvas.drawRoundRect(rectF, r, r, paint);
        canvas.restore();
        return outBitmap;
    }

    @Override
    public void updateDiskCacheKey(MessageDigest messageDigest) {
        messageDigest.update(ID.getBytes(CHARSET));
        byte[] radiusData = ByteBuffer.allocate(4).putInt(Arrays.hashCode(radius)).array();
        messageDigest.update(radiusData);
    }

    @Override
    public boolean equals(Object o) {
        if (o instanceof RoundedCornersTransform) {
            return Arrays.equals(this.radius, ((RoundedCornersTransform) o).radius);
        }
        return false;
    }

    @Override
    public int hashCode() {
        return Util.hashCode(ID.hashCode(), Arrays.hashCode(radius));
    }
}

使用示例

RequestOptions options = new RequestOptions()
                .fitCenter() /*处理源图片ScaleType*/
                .transform(new RoundedCornersTransform(px, px, px, px));
        Glide.with(context).load("url").apply(options).into(imageView);

Canvas基础

Android关于Canvas你所知道的和不知道的一切