How to create a gradient border that rotates in android

Question

I have created a RoundedImageView control which draws a circular border around an image, clipping the image to within the circle bounds. Currently it has a flat colour border but I would like this to be a gradient effect that repeats around the border or even just a single radial gradient around the border but I would like this to "spin", ie rotate the gradient fill indefinitely to show the user the application hasn't frozen. Can anyone think how to achieve this?

My current layout

<lc.controls.RoundedImageView
        android:id="@+id/progressimage"
        android:layout_width="150dip"
        android:layout_height="150dip"
        android:padding="10dip"
        android:src="@drawable/ocean"
        android:scaleType="centerCrop"
        app:border_width="4dip"
        app:oval="false"
        app:border_color="@color/border_background_colour" />

My rounded imageview if required

public class RoundedImageView extends ImageView {

  public static final String TAG = "RoundedImageView";
  public static final float DEFAULT_RADIUS = 0f;
  public static final float DEFAULT_BORDER_WIDTH = 0f;
  private static final ScaleType[] SCALE_TYPES = {
      ScaleType.MATRIX,
      ScaleType.FIT_XY,
      ScaleType.FIT_START,
      ScaleType.FIT_CENTER,
      ScaleType.FIT_END,
      ScaleType.CENTER,
      ScaleType.CENTER_CROP,
      ScaleType.CENTER_INSIDE
  };

  private float cornerRadius = DEFAULT_RADIUS;
  private float borderWidth = DEFAULT_BORDER_WIDTH;
  private ColorStateList borderColor =
      ColorStateList.valueOf(RoundedDrawable.DEFAULT_BORDER_COLOR);
  private boolean isOval = false;
  private boolean mutateBackground = false;

  private int mResource;
  private Drawable mDrawable;
  private Drawable mBackgroundDrawable;

  private ScaleType mScaleType;

  public RoundedImageView(Context context) {
    super(context);
  }

  public RoundedImageView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public RoundedImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundedImageView, defStyle, 0);

    int index = a.getInt(R.styleable.RoundedImageView_android_scaleType, -1);
    if (index >= 0) {
      setScaleType(SCALE_TYPES[index]);
    } else {
      setScaleType(ScaleType.FIT_CENTER);
    }

    cornerRadius = a.getDimensionPixelSize(R.styleable.RoundedImageView_corner_radius, -1);
    borderWidth = a.getDimensionPixelSize(R.styleable.RoundedImageView_border_width, -1);

    // don't allow negative values for radius and border
    if (cornerRadius < 0) {
      cornerRadius = DEFAULT_RADIUS;
    }
    if (borderWidth < 0) {
      borderWidth = DEFAULT_BORDER_WIDTH;
    }

    borderColor = a.getColorStateList(R.styleable.RoundedImageView_border_color);
    if (borderColor == null) {
      borderColor = ColorStateList.valueOf(RoundedDrawable.DEFAULT_BORDER_COLOR);
    }

    mutateBackground = a.getBoolean(R.styleable.RoundedImageView_mutate_background, false);
    isOval = a.getBoolean(R.styleable.RoundedImageView_oval, false);

    updateDrawableAttrs();
    updateBackgroundDrawableAttrs(true);

    a.recycle();
  }

  @Override
  protected void drawableStateChanged() {
    super.drawableStateChanged();
    invalidate();
  }

  @Override
  public ScaleType getScaleType() {
    return mScaleType;
  }

  @Override
  public void setScaleType(ScaleType scaleType) {
    assert scaleType != null;

    if (mScaleType != scaleType) {
      mScaleType = scaleType;

      switch (scaleType) {
        case CENTER:
        case CENTER_CROP:
        case CENTER_INSIDE:
        case FIT_CENTER:
        case FIT_START:
        case FIT_END:
        case FIT_XY:
          super.setScaleType(ScaleType.FIT_XY);
          break;
        default:
          super.setScaleType(scaleType);
          break;
      }

      updateDrawableAttrs();
      updateBackgroundDrawableAttrs(false);
      invalidate();
    }
  }

  @Override
  public void setImageDrawable(Drawable drawable) {
    mResource = 0;
    mDrawable = RoundedDrawable.fromDrawable(drawable);
    updateDrawableAttrs();
    super.setImageDrawable(mDrawable);
  }

  @Override
  public void setImageBitmap(Bitmap bm) {
    mResource = 0;
    mDrawable = RoundedDrawable.fromBitmap(bm);
    updateDrawableAttrs();
    super.setImageDrawable(mDrawable);
  }

  @Override
  public void setImageResource(int resId) {
    if (mResource != resId) {
      mResource = resId;
      mDrawable = resolveResource();
      updateDrawableAttrs();
      super.setImageDrawable(mDrawable);
    }
  }

  @Override public void setImageURI(Uri uri) {
    super.setImageURI(uri);
    setImageDrawable(getDrawable());
  }

  private Drawable resolveResource() {
    Resources rsrc = getResources();
    if (rsrc == null) { return null; }

    Drawable d = null;

    if (mResource != 0) {
      try {
        d = rsrc.getDrawable(mResource);
      } catch (Exception e) {
        Log.w(TAG, "Unable to find resource: " + mResource, e);
        // Don't try again.
        mResource = 0;
      }
    }
    return RoundedDrawable.fromDrawable(d);
  }

  @Override
  public void setBackground(Drawable background) {
    setBackgroundDrawable(background);
  }

  private void updateDrawableAttrs() {
    updateAttrs(mDrawable);
  }

  private void updateBackgroundDrawableAttrs(boolean convert) {
    if (mutateBackground) {
      if (convert) {
        mBackgroundDrawable = RoundedDrawable.fromDrawable(mBackgroundDrawable);
      }
      updateAttrs(mBackgroundDrawable);
    }
  }

  private void updateAttrs(Drawable drawable) {
    if (drawable == null) { return; }

    cornerRadius = drawable.getIntrinsicWidth();

    if (drawable instanceof RoundedDrawable) {
      ((RoundedDrawable) drawable)
          .setScaleType(mScaleType)
          .setCornerRadius(cornerRadius)
          .setBorderWidth(borderWidth)
          .setBorderColor(borderColor)
          .setOval(isOval);
    } else if (drawable instanceof LayerDrawable) {
      // loop through layers to and set drawable attrs
      LayerDrawable ld = ((LayerDrawable) drawable);
      for (int i = 0, layers = ld.getNumberOfLayers(); i < layers; i++) {
        updateAttrs(ld.getDrawable(i));
      }
    }
  }

  @Override
  @Deprecated
  public void setBackgroundDrawable(Drawable background) {
    mBackgroundDrawable = background;
    updateBackgroundDrawableAttrs(true);
    super.setBackgroundDrawable(mBackgroundDrawable);
  }

  public float getCornerRadius() {
    return cornerRadius;
  }

  public void setCornerRadius(int resId) {
    setCornerRadius(getResources().getDimension(resId));
  }

  public void setCornerRadius(float radius) {
    if (cornerRadius == radius) { return; }

    cornerRadius = radius;
    updateDrawableAttrs();
    updateBackgroundDrawableAttrs(false);
  }

  public float getBorderWidth() {
    return borderWidth;
  }

  public void setBorderWidth(int resId) {
    setBorderWidth(getResources().getDimension(resId));
  }

  public void setBorderWidth(float width) {
    if (borderWidth == width) { return; }

    borderWidth = width;
    updateDrawableAttrs();
    updateBackgroundDrawableAttrs(false);
    invalidate();
  }

  public int getBorderColor() {
    return borderColor.getDefaultColor();
  }

  public void setBorderColor(int color) {
    setBorderColor(ColorStateList.valueOf(color));
  }

  public ColorStateList getBorderColors() {
    return borderColor;
  }

  public void setBorderColor(ColorStateList colors) {
    if (borderColor.equals(colors)) { return; }

    borderColor =
        (colors != null) ? colors : ColorStateList.valueOf(RoundedDrawable.DEFAULT_BORDER_COLOR);
    updateDrawableAttrs();
    updateBackgroundDrawableAttrs(false);
    if (borderWidth > 0) {
      invalidate();
    }
  }

  public boolean isOval() {
    return isOval;
  }

  public void setOval(boolean oval) {
    isOval = oval;
    updateDrawableAttrs();
    updateBackgroundDrawableAttrs(false);
    invalidate();
  }

  public boolean isMutateBackground() {
    return mutateBackground;
  }

  public void setMutateBackground(boolean mutate) {
    if (mutateBackground == mutate) { return; }

    mutateBackground = mutate;
    updateBackgroundDrawableAttrs(true);
    invalidate();
  }
}

public class RoundedDrawable extends Drawable {

  public static final String TAG = "RoundedDrawable";
  public static final int DEFAULT_BORDER_COLOR = Color.BLACK;

  private final RectF mBounds = new RectF();
  private final RectF mDrawableRect = new RectF();
  private final RectF mBitmapRect = new RectF();
  private final BitmapShader mBitmapShader;
  private final Paint mBitmapPaint;
  private final int mBitmapWidth;
  private final int mBitmapHeight;
  private final RectF mBorderRect = new RectF();
  private final Paint mBorderPaint;
  private final Matrix mShaderMatrix = new Matrix();

  private float mCornerRadius = 0;
  private boolean mOval = false;
  private float mBorderWidth = 0;
  private ColorStateList mBorderColor = ColorStateList.valueOf(DEFAULT_BORDER_COLOR);
  private ScaleType mScaleType = ScaleType.FIT_CENTER;

  public RoundedDrawable(Bitmap bitmap) {

    mBitmapWidth = bitmap.getWidth();
    mBitmapHeight = bitmap.getHeight();
    mBitmapRect.set(0, 0, mBitmapWidth, mBitmapHeight);

    mBitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
    mBitmapShader.setLocalMatrix(mShaderMatrix);

    mBitmapPaint = new Paint();
    mBitmapPaint.setStyle(Paint.Style.FILL);
    mBitmapPaint.setAntiAlias(true);
    mBitmapPaint.setShader(mBitmapShader);

    mBorderPaint = new Paint();
    mBorderPaint.setStyle(Paint.Style.STROKE);
    mBorderPaint.setAntiAlias(true);
    mBorderPaint.setColor(mBorderColor.getColorForState(getState(), DEFAULT_BORDER_COLOR));
    mBorderPaint.setStrokeWidth(mBorderWidth);
  }

  public static RoundedDrawable fromBitmap(Bitmap bitmap) {
    if (bitmap != null) {
      return new RoundedDrawable(bitmap);
    } else {
      return null;
    }
  }

  public static Drawable fromDrawable(Drawable drawable) {
    if (drawable != null) {
      if (drawable instanceof RoundedDrawable) {
        // just return if it's already a RoundedDrawable
        return drawable;
      } else if (drawable instanceof LayerDrawable) {
        LayerDrawable ld = (LayerDrawable) drawable;
        int num = ld.getNumberOfLayers();

        // loop through layers to and change to RoundedDrawables if possible
        for (int i = 0; i < num; i++) {
          Drawable d = ld.getDrawable(i);
          ld.setDrawableByLayerId(ld.getId(i), fromDrawable(d));
        }
        return ld;
      }

      // try to get a bitmap from the drawable and
      Bitmap bm = drawableToBitmap(drawable);
      if (bm != null) {
        return new RoundedDrawable(bm);
      } else {
        Log.w(TAG, "Failed to create bitmap from drawable!");
      }
    }
    return drawable;
  }

  public static Bitmap drawableToBitmap(Drawable drawable) {
    if (drawable instanceof BitmapDrawable) {
      return ((BitmapDrawable) drawable).getBitmap();
    }

    Bitmap bitmap;
    int width = Math.max(drawable.getIntrinsicWidth(), 1);
    int height = Math.max(drawable.getIntrinsicHeight(), 1);
    try {
      bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
      Canvas canvas = new Canvas(bitmap);
      drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
      drawable.draw(canvas);
    } catch (Exception e) {
      e.printStackTrace();
      bitmap = null;
    }

    return bitmap;
  }

  @Override
  public boolean isStateful() {
    return mBorderColor.isStateful();
  }

  @Override
  protected boolean onStateChange(int[] state) {
    int newColor = mBorderColor.getColorForState(state, 0);
    if (mBorderPaint.getColor() != newColor) {
      mBorderPaint.setColor(newColor);
      return true;
    } else {
      return super.onStateChange(state);
    }
  }

  private void updateShaderMatrix() {
    float scale;
    float dx;
    float dy;

    switch (mScaleType) {
      case CENTER:
        mBorderRect.set(mBounds);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);

        mShaderMatrix.set(null);
        mShaderMatrix.setTranslate((int) ((mBorderRect.width() - mBitmapWidth) * 0.5f + 0.5f),
            (int) ((mBorderRect.height() - mBitmapHeight) * 0.5f + 0.5f));
        break;

      case CENTER_CROP:
        mBorderRect.set(mBounds);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);

        mShaderMatrix.set(null);

        dx = 0;
        dy = 0;

        if (mBitmapWidth * mBorderRect.height() > mBorderRect.width() * mBitmapHeight) {
          scale = mBorderRect.height() / (float) mBitmapHeight;
          dx = (mBorderRect.width() - mBitmapWidth * scale) * 0.5f;
        } else {
          scale = mBorderRect.width() / (float) mBitmapWidth;
          dy = (mBorderRect.height() - mBitmapHeight * scale) * 0.5f;
        }

        mShaderMatrix.setScale(scale, scale);
        mShaderMatrix.postTranslate((int) (dx + 0.5f) + mBorderWidth,
            (int) (dy + 0.5f) + mBorderWidth);
        break;

      case CENTER_INSIDE:
        mShaderMatrix.set(null);

        if (mBitmapWidth <= mBounds.width() && mBitmapHeight <= mBounds.height()) {
          scale = 1.0f;
        } else {
          scale = Math.min(mBounds.width() / (float) mBitmapWidth,
              mBounds.height() / (float) mBitmapHeight);
        }

        dx = (int) ((mBounds.width() - mBitmapWidth * scale) * 0.5f + 0.5f);
        dy = (int) ((mBounds.height() - mBitmapHeight * scale) * 0.5f + 0.5f);

        mShaderMatrix.setScale(scale, scale);
        mShaderMatrix.postTranslate(dx, dy);

        mBorderRect.set(mBitmapRect);
        mShaderMatrix.mapRect(mBorderRect);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);
        mShaderMatrix.setRectToRect(mBitmapRect, mBorderRect, Matrix.ScaleToFit.FILL);
        break;

      default:
      case FIT_CENTER:
        mBorderRect.set(mBitmapRect);
        mShaderMatrix.setRectToRect(mBitmapRect, mBounds, Matrix.ScaleToFit.CENTER);
        mShaderMatrix.mapRect(mBorderRect);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);
        mShaderMatrix.setRectToRect(mBitmapRect, mBorderRect, Matrix.ScaleToFit.FILL);
        break;

      case FIT_END:
        mBorderRect.set(mBitmapRect);
        mShaderMatrix.setRectToRect(mBitmapRect, mBounds, Matrix.ScaleToFit.END);
        mShaderMatrix.mapRect(mBorderRect);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);
        mShaderMatrix.setRectToRect(mBitmapRect, mBorderRect, Matrix.ScaleToFit.FILL);
        break;

      case FIT_START:
        mBorderRect.set(mBitmapRect);
        mShaderMatrix.setRectToRect(mBitmapRect, mBounds, Matrix.ScaleToFit.START);
        mShaderMatrix.mapRect(mBorderRect);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);
        mShaderMatrix.setRectToRect(mBitmapRect, mBorderRect, Matrix.ScaleToFit.FILL);
        break;

      case FIT_XY:
        mBorderRect.set(mBounds);
        mBorderRect.inset((mBorderWidth) / 2, (mBorderWidth) / 2);
        mShaderMatrix.set(null);
        mShaderMatrix.setRectToRect(mBitmapRect, mBorderRect, Matrix.ScaleToFit.FILL);
        break;
    }

    mDrawableRect.set(mBorderRect);
    mBitmapShader.setLocalMatrix(mShaderMatrix);
  }

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

    mBounds.set(bounds);

    updateShaderMatrix();
  }

  @Override
  public void draw(Canvas canvas) {

    if (mOval) {
      if (mBorderWidth > 0) {
        canvas.drawOval(mDrawableRect, mBitmapPaint);
        canvas.drawOval(mBorderRect, mBorderPaint);
      } else {
        canvas.drawOval(mDrawableRect, mBitmapPaint);
      }
    } else {
      if (mBorderWidth > 0) {
        canvas.drawRoundRect(mDrawableRect, Math.max(mCornerRadius, 0),
            Math.max(mCornerRadius, 0), mBitmapPaint);
        canvas.drawRoundRect(mBorderRect, mCornerRadius, mCornerRadius, mBorderPaint);
      } else {
        canvas.drawRoundRect(mDrawableRect, mCornerRadius, mCornerRadius, mBitmapPaint);
      }
    }
  }

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

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

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

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

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

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

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

  public float getCornerRadius() {
    return mCornerRadius;
  }

  public RoundedDrawable setCornerRadius(float radius) {
    mCornerRadius = radius;
    return this;
  }

  public float getBorderWidth() {
    return mBorderWidth;
  }

  public RoundedDrawable setBorderWidth(float width) {
    mBorderWidth = width;
    mBorderPaint.setStrokeWidth(mBorderWidth);
    return this;
  }

  public int getBorderColor() {
    return mBorderColor.getDefaultColor();
  }

  public RoundedDrawable setBorderColor(int color) {
    return setBorderColor(ColorStateList.valueOf(color));
  }

  public ColorStateList getBorderColors() {
    return mBorderColor;
  }

  public RoundedDrawable setBorderColor(ColorStateList colors) {
    mBorderColor = colors != null ? colors : ColorStateList.valueOf(0);
    mBorderPaint.setColor(mBorderColor.getColorForState(getState(), DEFAULT_BORDER_COLOR));
    return this;
  }

  public boolean isOval() {
    return mOval;
  }

  public RoundedDrawable setOval(boolean oval) {
    mOval = oval;
    return this;
  }

  public ScaleType getScaleType() {
    return mScaleType;
  }

  public RoundedDrawable setScaleType(ScaleType scaleType) {
    if (scaleType == null) {
      scaleType = ScaleType.FIT_CENTER;
    }
    if (mScaleType != scaleType) {
      mScaleType = scaleType;
      updateShaderMatrix();
    }
    return this;
  }

  public Bitmap toBitmap() {
    return drawableToBitmap(this);
  }
}

Answer 1

I would approach it in a bit different way...

I will explain how I would do it if I was going to use the class that you've already created (RoundedImageView), but I advise you to remodel it a bit so it's more efficient.

I haven't gone through your whole code, so I'll just assume few things which you can correct if you believe that my help was not enough.

I assume that your class makes the source image a bit smaller so the border is really AROUND the source, and not ON-TOP of the border of source. So for example if the layout width is 50dp and the width of border is 5dp, then the radius of source image is 20dp (and not 25dp with 5dp being covered by the border).

The first thing you should do is make your class display transparent color instead of flat color (as a border).

The second thing is placing under the RoundedImageView an indeterminate progress bar which has the same size (width and height) as your rounded image. Create a drawable of your progress bar that can look more-less like this:

<rotate xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromDegrees="0"
    android:toDegrees="360" >
    <shape
        android:shape="oval"
        android:useLevel="false" >
        <gradient
            android:centerColor="#000000"
            android:endColor="#e5e5e5"
            android:startColor="#000000"
            android:type="sweep"
            android:useLevel="false" />
    </shape>
</rotate>

In the progress' bar xml set:

android:indeterminateDrawable="@drawable/your_drawable"
android:indeterminateOnly="true"

EDIT:

If the things you want to overlay on top of each other are the same size and you don't want to use any sort of placing in a different place of another view, you should use FrameLayout. If this placing is needed you can easily use RelativeLayout.

with FrameLayout this overlay effect you can achieve like this:

<FrameLayout
    android:layout_width="150dip"
    android:layout_height="150dip"
    android:padding="10dip" >

    <ProgressBar
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:indeterminateDrawable="@drawable/your_drawable"
        android:indeterminateOnly="true" />

    <lc.controls.RoundedImageView
        android:id="@+id/progressimage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:src="@drawable/ocean"
        app:border_color="@android:color/transparent"
        app:border_width="4dip"
        app:oval="false" />

</FrameLayout>

you might need to work on the padding... test it out.

EDIT 2:

About the remodelling of your class. I see two really easy approaches. In both of them you use the padding value to set the border width.

1. Use a normal ImageView with round source image.
2. Use a custom ImageView that draws the round part of your image in the rectangle that considers the padding value.