Android 必知必会 - Glide 加载圆形和圆角图片的两种方法

两种使用 BitmapTransformation 来实现Glide 加载圆形图片和圆角图片的方法。

背景

Glide 并不能直接支持 Round Pictures ，需要使用 BitmapTransformation 来进行处理。

Round Pictures: CircleImageView / CircularImageView / RoundedImageView are known to have issues with TransitionDrawable (.crossFade() with .thumbnail() or .placeholder()) and animated GIFs, use a BitmapTransformation (.circleCrop() will be available in v4) or .dontAnimate() to fix the issue.

这里介绍下网上常见的方式和使用 RoundedBitmapDrawable 两种方法，本质上是差不多的：

• 使用 Canvas 和 Paint 来绘制
• 使用 Android.support.v4.graphics.drawable.RoundedBitmapDrawable

PS： RoundedBitmapDrawable 是 support.v4 下的一个类，想了解更多，可以阅读我之前的文章：Android 必知必会-使用 supportV4 的 RoundedBitmapDrawable 实现圆角 。

代码实现

方法一

实现圆形图片：

/**
 * Glide 圆形图片 Transform
 */

public class GlideCircleTransform extends BitmapTransformation {
    public GlideCircleTransform(Context context) {
        super(context);
    }

    @Override
    protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
        return circleCrop(pool, toTransform);
    }

    private static Bitmap circleCrop(BitmapPool pool, Bitmap source) {
        if (source == null) return null;
        int size = Math.min(source.getWidth(), source.getHeight());
        int x = (source.getWidth() - size) / 2;
        int y = (source.getHeight() - size) / 2;
        Bitmap squared = Bitmap.createBitmap(source, x, y, size, size);
        Bitmap result = pool.get(size, size, Bitmap.Config.ARGB_8888);
        if (result == null) {
            result = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
        }
        Canvas canvas = new Canvas(result);
        Paint paint = new Paint();
        paint.setShader(new BitmapShader(squared, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
        paint.setAntiAlias(true);
        float r = size / 2f;
        canvas.drawCircle(r, r, r, paint);
        return result;
    }

    @Override
    public String getId() {
        return getClass().getName();
    }
}

实现圆角图片：

/**
 * Glide 圆角 Transform
 */

public class GlideRoundTransform extends BitmapTransformation {

    private static float radius = 0f;

    /**
     * 构造函数 默认圆角半径 4dp
     *
     * @param context Context
     */
    public GlideRoundTransform(Context context) {
        this(context, 4);
    }

    /**
     * 构造函数
     *
     * @param context Context
     * @param dp      圆角半径
     */
    public GlideRoundTransform(Context context, int dp) {
        super(context);
        radius = Resources.getSystem().getDisplayMetrics().density * dp;
    }

    @Override
    protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
        return roundCrop(pool, toTransform);
    }

    private static Bitmap roundCrop(BitmapPool pool, Bitmap source) {
        if (source == null) return null;

        Bitmap result = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
        if (result == null) {
            result = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(result);
        Paint paint = new Paint();
        paint.setShader(new BitmapShader(source, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
        paint.setAntiAlias(true);
        RectF rectF = new RectF(0f, 0f, source.getWidth(), source.getHeight());
        canvas.drawRoundRect(rectF, radius, radius, paint);
        return result;
    }

    @Override
    public String getId() {
        return getClass().getName() + Math.round(radius);
    }
}

方法二

public static Bitmap drawableToBitmap(Drawable drawable) {
        // 取 drawable 的长宽
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();

        // 取 drawable 的颜色格式
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                : Bitmap.Config.RGB_565;
        // 建立对应 bitmap
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        // 建立对应 bitmap 的画布
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, w, h);
        // 把 drawable 内容画到画布中
        drawable.draw(canvas);
        return bitmap;
    }
/**
  * RoundedBitmapDrawable 是 V4 下的一个类，不能简单的通过：强制转换成 BitmapDrawable 来获取 bitmap
  * Bitmap bitmap = ((BitmapDrawable)xxx).getBitmap();
  */

实现圆形：

RoundedBitmapDrawable drawableA = RoundedBitmapDrawableFactory.create(getResources(), bitmap);
        drawableA.setCircular(true);
        Bitmap a = drawableToBitmap(drawableA);

实现圆角：

RoundedBitmapDrawable drawableB = RoundedBitmapDrawableFactory.create(getResources(), bitmap);
       drawableB.setCornerRadius(30L);
       Bitmap b = drawableToBitmap(drawableB);