RTEditor/src/main/java/com/onegravity/rteditor/media/crop/HighlightView.java
void growBy(float dx, float dy) {
        if (mMaintainAspectRatio) {
            if (dx != 0) {
                dy = dx / mInitialAspectRatio;
            } else if (dy != 0) {
                dx = dy * mInitialAspectRatio;
            }
        }

        // Don't let the cropping rectangle grow too fast.
        // Grow at most half of the difference between the image rectangle and
        // the cropping rectangle.
        RectF r = new RectF(mCropRect);
        if (dx > 0F && r.width() + 2 * dx > mImageRect.width()) {
            float adjustment = (mImageRect.width() - r.width()) / 2F;
            dx = adjustment;
            if (mMaintainAspectRatio) {
                dy = dx / mInitialAspectRatio;
            }
        }
        if (dy > 0F && r.height() + 2 * dy > mImageRect.height()) {
            float adjustment = (mImageRect.height() - r.height()) / 2F;
            dy = adjustment;
            if (mMaintainAspectRatio) {
                dx = dy * mInitialAspectRatio;
            }
        }

        r.inset(-dx, -dy);

        // Don't let the cropping rectangle shrink too fast.
        final float widthCap = 25F;
        if (r.width() < widthCap) {
            r.inset(-(widthCap - r.width()) / 2F, 0F);
        }
        float heightCap = mMaintainAspectRatio ? (widthCap / mInitialAspectRatio)
                : widthCap;
        if (r.height() < heightCap) {
            r.inset(0F, -(heightCap - r.height()) / 2F);
        }

        // Put the cropping rectangle inside the image rectangle.
        if (r.left < mImageRect.left) {
            r.offset(mImageRect.left - r.left, 0F);
        } else if (r.right > mImageRect.right) {
            r.offset(-(r.right - mImageRect.right), 0);
        }
        if (r.top < mImageRect.top) {
            r.offset(0F, mImageRect.top - r.top);
        } else if (r.bottom > mImageRect.bottom) {
            r.offset(0F, -(r.bottom - mImageRect.bottom));
        }

        mCropRect.set(r);
        mDrawRect = computeLayout();
        mContext.invalidate();
    }
void growBy(float dx, float dy) {
        if (mMaintainAspectRatio) {
            if (dx != 0) {
                dy = dx / mInitialAspectRatio;
            } else if (dy != 0) {
                dx = dy * mInitialAspectRatio;
            }
        }

        // Don't let the cropping rectangle grow too fast.
        // Grow at most half of the difference between the image rectangle and
        // the cropping rectangle.
        RectF r = new RectF(mCropRect);
        if (dx > 0F && r.width() + 2 * dx > mImageRect.width()) {
            float adjustment = (mImageRect.width() - r.width()) / 2F;
            dx = adjustment;
            if (mMaintainAspectRatio) {
                dy = dx / mInitialAspectRatio;
            }
        }
        if (dy > 0F && r.height() + 2 * dy > mImageRect.height()) {
            float adjustment = (mImageRect.height() - r.height()) / 2F;
            dy = adjustment;
            if (mMaintainAspectRatio) {
                dx = dy * mInitialAspectRatio;
            }
        }

        r.inset(-dx, -dy);

        // Don't let the cropping rectangle shrink too fast.
        final float widthCap = 25F;
        if (r.width() < widthCap) {
            r.inset(-(widthCap - r.width()) / 2F, 0F);
        }
        float heightCap = mMaintainAspectRatio ? (widthCap / mInitialAspectRatio)
                : widthCap;
        if (r.height() < heightCap) {
            r.inset(0F, -(heightCap - r.height()) / 2F);
        }

        // Put the cropping rectangle inside the image rectangle.
        if (r.left < mImageRect.left) {
            r.offset(mImageRect.left - r.left, 0F);
        } else if (r.right > mImageRect.right) {
            r.offset(-(r.right - mImageRect.right), 0);
        }
        if (r.top < mImageRect.top) {
            r.offset(0F, mImageRect.top - r.top);
        } else if (r.bottom > mImageRect.bottom) {
            r.offset(0F, -(r.bottom - mImageRect.bottom));
        }

        mCropRect.set(r);
        mDrawRect = computeLayout();
        mContext.invalidate();
    }
Grows the cropping rectange by (dx, dy) in image space.