Android 必知必会 - Glide 加载圆形图片和圆角图片的两种方法
shellqqq
8年前
<p>两种使用 BitmapTransformation 来实现 Glide 加载圆形图片和圆角图片的方法。</p> <h2>背景</h2> <p>Glide 并不能直接支持 Round Pictures ,需要使用 BitmapTransformation 来进行处理。</p> <p>Round Pictures: CircleImageView / CircularImageView / RoundedImageView are known to have <a href="/misc/goto?guid=4959713459881245067" rel="nofollow,noindex">issues</a> 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.</p> <p>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:</p> <ul> <li>使用 Canvas 和 Paint 来绘制</li> <li>使用 Android.support.v4.graphics.drawable.RoundedBitmapDrawable</li> </ul> <p>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: <a href="/misc/goto?guid=4959713459958914601" rel="nofollow,noindex">Android 必知必会-使用 supportV4 的 RoundedBitmapDrawable 实现圆角</a> 。</p> <h2>代码实现</h2> <h3>方法一</h3> <p>实现圆形图片:</p> <pre> <code class="language-java">/** * 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(); } } </code></pre> <p>实现圆角图片:</p> <pre> <code class="language-java">/** * 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); } } </code></pre> <h3>方法二</h3> <pre> <code class="language-java">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(); */ </code></pre> <p>实现圆形:</p> <pre> <code class="language-java">RoundedBitmapDrawable drawableA = RoundedBitmapDrawableFactory.create(getResources(), bitmap); drawableA.setCircular(true); Bitmap a = drawableToBitmap(drawableA); </code></pre> <p>实现圆角:</p> <pre> <code class="language-java">RoundedBitmapDrawable drawableB = RoundedBitmapDrawableFactory.create(getResources(), bitmap); drawableB.setCornerRadius(30L); Bitmap b = drawableToBitmap(drawableB); </code></pre> <p> </p> <p>来自:http://likfe.com/2016/08/31/android-glide-roundedBitmapTransformation/</p> <p> </p>