Glide 加载部分圆角图片

一.图片之整理

2.inSampleSize优化

 public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int width = options.outWidth;
        final int height = options.outHeight;
        int inSampleSize = 1;
        if (height > reqHeight || width > reqWidth) {
            //计算图片高度和我们需要高度的最接近比例值
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            //宽度比例值
            final int widthRatio = Math.round((float) width / (float) reqWidth);
            //取比例值中的较大值作为inSampleSize
            inSampleSize = heightRatio > widthRatio ? heightRatio : widthRatio;
        }
        return inSampleSize;
    }

inSampleSize的默认值和最小值为1（当小于1时，解码器将该值当做1来处理），且在大于1时，该值只能为2的幂（当不为2的幂时，解码器会取与该值最接近的2的幂）。

例如，当inSampleSize为2时，一个20001000的图片，将被缩小为1000500，相应地，它的像素数和内存占用都被缩小为了原来的1/4：

但是由于我们平时拍的照片都是长图，这种算法用在浏览相册图片的时候会导致压缩太过严重，导致照片不是很清楚
都是在1080 * 1776 (nexus 5)上load一张满屏图

width	height	Ratio
1536	2048	1
1944	2592	2
3264	2448	3
8264	2446	8

可以看出来如果我们图片是宽度大于高度的图片，图片ratio就会很大导致图片压缩太严重在显示可缩放的图片的时候，图片质量过于差。

    public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int width = options.outWidth;
        final int height = options.outHeight;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            //使用需要的宽高的最大值来计算比率
            final int suitedValue = reqHeight > reqWidth ? reqHeight : reqWidth;
            final int heightRatio = Math.round((float) height / (float) suitedValue);
            final int widthRatio = Math.round((float) width / (float) suitedValue);
            inSampleSize = heightRatio > widthRatio ? heightRatio : widthRatio;//用最大
        }
        return inSampleSize;
    }

使用上面优化过后的方法后

width	height	Ratio
1536	2048	1
1944	2592	1
3264	2448	2
8264	2446	4

在宽大于高的时候对于图片质量有了较大的提升

使用这种算法不适宜用于一些不太在意图片质量，或者不支持缩放图片的地方。正常情况下还是可以用官方的方法。或者在方法中判断宽和高如果宽大于高使用下面的方法计算SampleSize

再贴一个SDK文档的算法，还没有用过～

public static int computeSampleSize(BitmapFactory.Options options,
        int minSideLength, int maxNumOfPixels) {
    int initialSize = computeInitialSampleSize(options, minSideLength,maxNumOfPixels);
    int roundedSize;
    if (initialSize <= 8) {
        roundedSize = 1;
        while (roundedSize < initialSize) {
            roundedSize <<= 1;
        }
    } else {
        roundedSize = (initialSize + 7) / 8 * 8;
    }
    return roundedSize;
}
private static int computeInitialSampleSize(BitmapFactory.Options options,
        int minSideLength, int maxNumOfPixels) {
    double w = options.outWidth;
    double h = options.outHeight;
    int lowerBound = (maxNumOfPixels == -1) ? 1 :
            (int) Math.ceil(Math.sqrt(w * h / maxNumOfPixels));
    int upperBound = (minSideLength == -1) ? 128 :
            (int) Math.min(Math.floor(w / minSideLength),
            Math.floor(h / minSideLength));
    if (upperBound < lowerBound) {
        // return the larger one when there is no overlapping zone.
        return lowerBound;
    }

    if ((maxNumOfPixels == -1) &&  (minSideLength == -1)) {
        return 1;
    } else if (minSideLength == -1) {
        return lowerBound;
    } else {
        return upperBound;
    }
} 
//使用方式
opts.inSampleSize = computeSampleSize(opts, -1, 128*128);

2. 在App开放中经常遇到设置ImageView为部分圆角的情况，但是Glide又没有提供这个方法，该怎么办呢？直接上代码！

/**

* @author csc

* @date 2019-01-18

* Todo 设置图片部分圆角

public class RoundedCornersTransform implements Transformation<Bitmap> {

private BitmapPool mBitmapPool;

private float radius;

private boolean isLeftTop, isRightTop, isLeftBottom, isRightBotoom;

/**

* 需要设置圆角的部分

* @param leftTop 左上角

* @param rightTop 右上角

* @param leftBottom 左下角

* @param rightBottom 右下角

public void setNeedCorner(boolean leftTop, boolean rightTop, boolean leftBottom, boolean rightBottom) {

isLeftTop = leftTop;

isRightTop = rightTop;

isLeftBottom = leftBottom;

isRightBotoom = rightBottom;

}

/**

* @param context 上下文

* @param radius 圆角幅度

public RoundedCornersTransform(Context context, float radius) {

this.mBitmapPool = Glide.get(context).getBitmapPool();

this.radius = radius;

}

@NonNull

@Override

public Resource<Bitmap> transform(@NonNull Context context, @NonNull Resource<Bitmap> resource, int outWidth, int outHeight) {

Bitmap source = resource.get();

int finalWidth, finalHeight;

//输出目标的宽高或高宽比例

float scale;

if (outWidth > outHeight) {

//如果输出宽度 > 输出高度求高宽比

scale = (float) outHeight / (float) outWidth;

finalWidth = source.getWidth();

//固定原图宽度,求最终高度

finalHeight = (int) ((float) source.getWidth() * scale);

if (finalHeight > source.getHeight()) {

//如果求出的最终高度 > 原图高度求宽高比

scale = (float) outWidth / (float) outHeight;

finalHeight = source.getHeight();

//固定原图高度,求最终宽度

finalWidth = (int) ((float) source.getHeight() * scale);

}

} else if (outWidth < outHeight) {

//如果输出宽度 < 输出高度求宽高比

scale = (float) outWidth / (float) outHeight;

finalHeight = source.getHeight();

//固定原图高度,求最终宽度

finalWidth = (int) ((float) source.getHeight() * scale);

if (finalWidth > source.getWidth()) {

//如果求出的最终宽度 > 原图宽度求高宽比

scale = (float) outHeight / (float) outWidth;

finalWidth = source.getWidth();

finalHeight = (int) ((float) source.getWidth() * scale);

}

} else {

//如果输出宽度=输出高度

finalHeight = source.getHeight();

finalWidth = finalHeight;

}

//修正圆角

this.radius *= (float) finalHeight / (float) outHeight;

Bitmap outBitmap = this.mBitmapPool.get(finalWidth, finalHeight, Bitmap.Config.ARGB_8888);

if (outBitmap == null) {

outBitmap = Bitmap.createBitmap(finalWidth, finalHeight, 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);

//计算中心位置,进行偏移

int width = (source.getWidth() - finalWidth) / 2;

int height = (source.getHeight() - finalHeight) / 2;

if (width != 0 || height != 0) {

Matrix matrix = new Matrix();

matrix.setTranslate((float) (-width), (float) (-height));

shader.setLocalMatrix(matrix);

}

paint.setShader(shader);

paint.setAntiAlias(true);

RectF rectF = new RectF(0.0F, 0.0F, (float) canvas.getWidth(), (float) canvas.getHeight());

//先绘制圆角矩形

canvas.drawRoundRect(rectF, this.radius, this.radius, paint);

//左上角圆角

if (!isLeftTop) {

canvas.drawRect(0, 0, radius, radius, paint);

}

//右上角圆角

if (!isRightTop) {

canvas.drawRect(canvas.getWidth() - radius, 0, canvas.getWidth(), radius, paint);

}

//左下角圆角

if (!isLeftBottom) {

canvas.drawRect(0, canvas.getHeight() - radius, radius, canvas.getHeight(), paint);

}

//右下角圆角

if (!isRightBotoom) {

canvas.drawRect(canvas.getWidth() - radius, canvas.getHeight() - radius, canvas.getWidth(), canvas.getHeight(), paint);

}

return BitmapResource.obtain(outBitmap, this.mBitmapPool);

}

@Override

public void updateDiskCacheKey(@NonNull MessageDigest messageDigest) {

}

如何使用？

Glide 4.0+ 的使用

RoundedCornersTransform transform = new RoundedCornersTransform(mContext, DensityUtil.dip2px(10));

transform.setNeedCorner(true, false, true, false);

RequestOptions options = new RequestOptions().placeholder(R.color.color_eee).transform(transform);

Glide.with(mContext).asBitmap().load(mPicturesBeans.get(0).getSrc()).apply(options).into(holder.mPictureComment);

上面的实现效果就是：左上角和左下角为圆角。

Glide 小于4.0的使用：

RoundedCornersTransform transform = new RoundedCornersTransform(mContext, DensityUtil.dip2px(10));

transform.setNeedCorner(true, false, true, false);

Glide.with(this).

load(mPicturesBeans.get(0).getSrc()).

asBitmap().

skipMemoryCache(true).

diskCacheStrategy(DiskCacheStrategy.NONE).

transform(transform).

into(holder.mPictureComment);

posted on 2019-03-09 15:26 左手指月阅读(8290) 评论(0) 编辑收藏举报