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androidbitmapgeometryandroid-imageviewaspect-ratio

How to have a circular, center-cropped imageView, without creating a new bitmap?


Note: I know there are a lot of questions and repositories about this, but none seems to fit what I try to achieve.

Background

Given a bitmap of any aspect-ratio, I wish to set it as the content of an ImageView (using a drawable only, without extending the ImageView), so that the content will be center-cropped, and yet in the shape of a circle.

All of this, with minimal memory usage, because the images could be quite large sometimes. I do not want to create a whole new Bitmap just for this. The content is already there...

The problem

All solutions I've found lack one of the things I've written: some do not center-crop, some assume the image is square-shaped, some create a new bitmap from the given bitmap...

What I've tried

Other than trying various repositories, I've tried this tutorial, and I tried to fix it for the case of non-square aspect ratios, but I've failed.

Here's its code, in case the website will get closed:

public class RoundImage extends Drawable {
      private final Bitmap mBitmap;
      private final Paint mPaint;
      private final RectF mRectF;
      private final int mBitmapWidth;
      private final int mBitmapHeight;

      public RoundImage(Bitmap bitmap) {
            mBitmap = bitmap;
            mRectF = new RectF();
            mPaint = new Paint();
            mPaint.setAntiAlias(true);
            mPaint.setDither(true);
            final BitmapShader shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            mPaint.setShader(shader);

            mBitmapWidth = mBitmap.getWidth();
            mBitmapHeight = mBitmap.getHeight();
      }

      @Override
      public void draw(Canvas canvas) {
            canvas.drawOval(mRectF, mPaint);
      }

      @Override
      protected void onBoundsChange(Rect bounds) {
            super.onBoundsChange(bounds);
            mRectF.set(bounds);
      }

      @Override
      public void setAlpha(int alpha) {
            if (mPaint.getAlpha() != alpha) {
                  mPaint.setAlpha(alpha);
                  invalidateSelf();
            }
      }

      @Override
      public void setColorFilter(ColorFilter cf) {
            mPaint.setColorFilter(cf);
      }

      @Override
      public int getOpacity() {
            return PixelFormat.TRANSLUCENT;
      }

      @Override
      public int getIntrinsicWidth() {
            return mBitmapWidth;
      }

      @Override
      public int getIntrinsicHeight() {
            return mBitmapHeight;
      }

      public void setAntiAlias(boolean aa) {
            mPaint.setAntiAlias(aa);
            invalidateSelf();
      }

      @Override
      public void setFilterBitmap(boolean filter) {
            mPaint.setFilterBitmap(filter);
            invalidateSelf();
      }

      @Override
      public void setDither(boolean dither) {
            mPaint.setDither(dither);
            invalidateSelf();
      }

      public Bitmap getBitmap() {
            return mBitmap;
      }

}

A very good solution I've found (here) does exactly what I need, except it uses it all in the ImageView itself, instead of creating a drawable. This means that I can't set it, for example, as the background of a view.

The question

How can I achieve this?


EDIT: this is the current code, and as I wanted to add border, it also has this code for it:

public class SimpleRoundedDrawable extends BitmapDrawable {
    private final Path p = new Path();
    private final Paint mBorderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

    public SimpleRoundedDrawable(final Resources res, final Bitmap bitmap) {
        super(res, bitmap);
        mBorderPaint.setStyle(Paint.Style.STROKE);
    }

    public SimpleRoundedDrawable setBorder(float borderWidth, @ColorInt int borderColor) {
        mBorderPaint.setStrokeWidth(borderWidth);
        mBorderPaint.setColor(borderColor);
        invalidateSelf();
        return this;
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        super.onBoundsChange(bounds);
        p.rewind();
        p.addCircle(bounds.width() / 2,
                bounds.height() / 2,
                Math.min(bounds.width(), bounds.height()) / 2,
                Path.Direction.CW);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.clipPath(p);
        super.draw(canvas);
        final float width = getBounds().width(), height = getBounds().height();
        canvas.drawCircle(width / 2, height / 2, Math.min(width, height) / 2, mBorderPaint);
    }
}

I hope this is how things should really work.


EDIT: It seems that the solution works only from specific Android version, as it doesn't work on Android 4.2.2. Instead, it shows a squared image.

EDIT: it seems that the above solution is also much less efficient than using BitmapShader (Link here). It would be really great to know how to use it within a drawable instead of within a customized ImageView

-- Here's the current modified version of the below solutions. I hope it will be handy for some people:

public class SimpleRoundedDrawable extends Drawable {
    final Paint mMaskPaint = new Paint(Paint.ANTI_ALIAS_FLAG), mBorderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    Bitmap mBitmap;
    int mSide;
    float mRadius;

    public SimpleRoundedDrawable() {
        this(null);
    }

    public SimpleRoundedDrawable(Bitmap bitmap) {
        this(bitmap, 0, 0);
    }

    public SimpleRoundedDrawable(Bitmap bitmap, float width, @ColorInt int color) {
        mBorderPaint.setStyle(Paint.Style.STROKE);
        mBitmap = bitmap;
        mSide = mBitmap == null ? 0 : Math.min(bitmap.getWidth(), bitmap.getHeight());
        mBorderPaint.setStrokeWidth(width);
        mBorderPaint.setColor(color);
    }

    public SimpleRoundedDrawable setBitmap(final Bitmap bitmap) {
        mBitmap = bitmap;
        mSide = Math.min(bitmap.getWidth(), bitmap.getHeight());
        invalidateSelf();
        return this;
    }

    public SimpleRoundedDrawable setBorder(float width, @ColorInt int color) {
        mBorderPaint.setStrokeWidth(width);
        mBorderPaint.setColor(color);
        invalidateSelf();
        return this;
    }

    @Override
    protected void onBoundsChange(Rect bounds) {
        if (mBitmap == null)
            return;
        Matrix matrix = new Matrix();
        RectF src = new RectF(0, 0, mSide, mSide);
        src.offset((mBitmap.getWidth() - mSide) / 2f, (mBitmap.getHeight() - mSide) / 2f);
        RectF dst = new RectF(bounds);
        final float strokeWidth = mBorderPaint.getStrokeWidth();
        if (strokeWidth > 0)
            dst.inset(strokeWidth, strokeWidth);
        matrix.setRectToRect(src, dst, Matrix.ScaleToFit.CENTER);
        Shader shader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        shader.setLocalMatrix(matrix);
        mMaskPaint.setShader(shader);
        matrix.mapRect(src);
        mRadius = src.width() / 2f;
    }

    @Override
    public void draw(Canvas canvas) {
        Rect b = getBounds();
        if (mBitmap != null)
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), mRadius, mMaskPaint);
        final float strokeWidth = mBorderPaint.getStrokeWidth();
        if (strokeWidth > 0)
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), mRadius + strokeWidth / 2, mBorderPaint);
    }

    @Override
    public void setAlpha(int alpha) {
        mMaskPaint.setAlpha(alpha);
        invalidateSelf();
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        mMaskPaint.setColorFilter(cf);
        invalidateSelf();
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}

Solution

  • try this minimalist custom Drawable and modify it to meet your needs:

    class D extends Drawable {
        Bitmap bitmap;
        Paint maskPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        Paint borderPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        int side;
        float radius;
    
        public D(Bitmap wrappedBitmap) {
            bitmap = wrappedBitmap;
            borderPaint.setStyle(Paint.Style.STROKE);
            borderPaint.setStrokeWidth(16);
            borderPaint.setColor(0xcc220088);
            side = Math.min(bitmap.getWidth(), bitmap.getHeight());
        }
    
        @Override
        protected void onBoundsChange(Rect bounds) {
            Matrix matrix = new Matrix();
            RectF src = new RectF(0, 0, side, side);
            src.offset((bitmap.getWidth() - side) / 2f, (bitmap.getHeight() - side) / 2f);
            RectF dst = new RectF(bounds);
            dst.inset(borderPaint.getStrokeWidth(), borderPaint.getStrokeWidth());
            matrix.setRectToRect(src, dst, Matrix.ScaleToFit.CENTER);
    
            Shader shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
            shader.setLocalMatrix(matrix);
            maskPaint.setShader(shader);
            matrix.mapRect(src);
            radius = src.width() / 2f;
        }
    
        @Override
        public void draw(Canvas canvas) {
            Rect b = getBounds();
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), radius, maskPaint);
            canvas.drawCircle(b.exactCenterX(), b.exactCenterY(), radius + borderPaint.getStrokeWidth() / 2, borderPaint);
        }
    
        @Override public void setAlpha(int alpha) {}
        @Override public void setColorFilter(ColorFilter cf) {}
        @Override public int getOpacity() {return PixelFormat.TRANSLUCENT;}
    }