一、简介：

介绍两种使用 BitmapTransformation 来实现 Glide 加载圆形图片和圆角图片的方法。Glide 并不能直接支持 Round Pictures ，需要使用 BitmapTransformation 来进行处理。

二、网上的实现方式

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

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); }}

三、笔者比较喜欢的简便的实现方式

//加载圆角图片 public static void loadRoundImage(final Context context, String url,final ImageView imageView){ Glide.with(context) .load(url) .asBitmap() .placeholder(placeholder) .error(placeholder) .diskCacheStrategy(DiskCacheStrategy.ALL) //设置缓存 .into(new BitmapImageViewTarget(imageView){ @Override protected void setResource(Bitmap resource) { super.setResource(resource); RoundedBitmapDrawable circularBitmapDrawable = RoundedBitmapDrawableFactory.create(context.getResources(), resource); circularBitmapDrawable.setCornerRadius(10); //设置圆角弧度 imageView.setImageDrawable(circularBitmapDrawable); } }); } //加载圆形图片 public static void loadCirclePic(final Context context, String url, final ImageView imageView) { Glide.with(context) .load(url) .asBitmap() .placeholder(placeholder) .error(placeholder) .diskCacheStrategy(DiskCacheStrategy.ALL) //设置缓存 .into(new BitmapImageViewTarget(imageView) { @Override protected void setResource(Bitmap resource) { RoundedBitmapDrawable circularBitmapDrawable = RoundedBitmapDrawableFactory.create(context.getResources(), resource); circularBitmapDrawable.setCircular(true); imageView.setImageDrawable(circularBitmapDrawable); } }); }

关于drawableToBitmap的源码的实现是这样的

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 * Bitmap bitmap = ((BitmapDrawable)xxx).getBitmap(); */

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。