/*
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
package com.facebook.drawee.view;
import android.view.View;
import android.view.ViewGroup;
/**
* A utility class that performs measuring based on the desired aspect ratio.
*/
public class AspectRatioMeasure {
/**
* Holder for width and height measure specs.
*/
public static class Spec {
public int width;
public int height;
}
/**
* Updates the given measure spec with respect to the aspect ratio.
*
* <p>Note: Measure spec is not changed if the aspect ratio is not greater than zero.
*
* <p>Measure spec of the layout dimension (width or height) specified as "0dp" is updated
* to match the measure spec of the other dimension adjusted by the aspect ratio. Exactly one
* layout dimension should be specified as "0dp".
*
* <p>Padding is taken into account so that the aspect ratio refers to the content without
* padding: {@code aspectRatio == (viewWidth - widthPadding) / (viewHeight - heightPadding)}
*
* <p>Updated measure spec respects the parent's constraints. I.e. measure spec is not changed
* if the parent has specified mode {@code EXACTLY}, and it doesn't exceed measure size if parent
* has specified mode {@code AT_MOST}.
*
* @param spec in/out measure spec to be updated
* @param aspectRatio desired aspect ratio
* @param layoutParams view's layout params
* @param widthPadding view's left + right padding
* @param heightPadding view's top + bottom padding
*/
public static void updateMeasureSpec(
Spec spec,
float aspectRatio,
ViewGroup.LayoutParams layoutParams,
int widthPadding,
int heightPadding) {
if (aspectRatio <= 0) {
return;
}
if (shouldAdjust(layoutParams.height)) {
int widthSpecSize = View.MeasureSpec.getSize(spec.width);
int desiredHeight = (int) ((widthSpecSize - widthPadding) / aspectRatio + heightPadding);
int resolvedHeight = View.resolveSize(desiredHeight, spec.height);
spec.height = View.MeasureSpec.makeMeasureSpec(resolvedHeight, View.MeasureSpec.EXACTLY);
} else if (shouldAdjust(layoutParams.width)) {
int heightSpecSize = View.MeasureSpec.getSize(spec.height);
int desiredWidth = (int) ((heightSpecSize - heightPadding) * aspectRatio + widthPadding);
int resolvedWidth = View.resolveSize(desiredWidth, spec.width);
spec.width = View.MeasureSpec.makeMeasureSpec(resolvedWidth, View.MeasureSpec.EXACTLY);
}
}
private static boolean shouldAdjust(int layoutDimension) {
// Note: wrap_content is supported for backwards compatibility, but should not be used.
return layoutDimension == 0 || layoutDimension == ViewGroup.LayoutParams.WRAP_CONTENT;
}
}