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：
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();
*/
