/** * Zoom to a specified rect IN CSS PIXELS. * * <p>While we usually use device pixels, @zoomToRect must be specified in CSS pixels. */ private boolean animatedZoomTo(RectF zoomToRect) { setState(PanZoomState.ANIMATED_ZOOM); final float startZoom = getMetrics().zoomFactor; RectF viewport = getMetrics().getViewport(); // 1. adjust the aspect ratio of zoomToRect to match that of the current viewport, // enlarging as necessary (if it gets too big, it will get shrunk in the next step). // while enlarging make sure we enlarge equally on both sides to keep the target rect // centered. float targetRatio = viewport.width() / viewport.height(); float rectRatio = zoomToRect.width() / zoomToRect.height(); if (FloatUtils.fuzzyEquals(targetRatio, rectRatio)) { // all good, do nothing } else if (targetRatio < rectRatio) { // need to increase zoomToRect height float newHeight = zoomToRect.width() / targetRatio; zoomToRect.top -= (newHeight - zoomToRect.height()) / 2; zoomToRect.bottom = zoomToRect.top + newHeight; } else { // targetRatio > rectRatio) { // need to increase zoomToRect width float newWidth = targetRatio * zoomToRect.height(); zoomToRect.left -= (newWidth - zoomToRect.width()) / 2; zoomToRect.right = zoomToRect.left + newWidth; } float finalZoom = viewport.width() / zoomToRect.width(); ImmutableViewportMetrics finalMetrics = getMetrics(); finalMetrics = finalMetrics.setViewportOrigin( zoomToRect.left * finalMetrics.zoomFactor, zoomToRect.top * finalMetrics.zoomFactor); finalMetrics = finalMetrics.scaleTo(finalZoom, new PointF(0.0f, 0.0f)); // 2. now run getValidViewportMetrics on it, so that the target viewport is // clamped down to prevent overscroll, over-zoom, and other bad conditions. finalMetrics = getValidViewportMetrics(finalMetrics); bounce(finalMetrics); return true; }