com.wzdsqyy.commonview.ScrollUtil.java Source code

Introduction

Here is the source code for com.wzdsqyy.commonview.ScrollUtil.java

Source

/**
 * Copyright 2015 bingoogolapple
 * <p/>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.wzdsqyy.commonview;

import android.content.Context;
import android.os.Build;
import android.support.v4.view.ViewCompat;
import android.view.View;
import android.widget.AbsListView;

public class ScrollUtil {

    private ScrollUtil() {
    }

    /**
     * ???
     */
    public static boolean canChildScrollUp(View target) {
        if (target == null) {
            return false;
        }
        if (Build.VERSION.SDK_INT < 14) {
            if (target instanceof AbsListView) {
                final AbsListView absListView = (AbsListView) target;
                return absListView.getChildCount() > 0 && (absListView.getFirstVisiblePosition() > 0
                        || absListView.getChildAt(0).getTop() < absListView.getPaddingTop());
            } else {
                return ViewCompat.canScrollVertically(target, -1) || target.getScrollY() > 0;
            }
        } else {
            return ViewCompat.canScrollVertically(target, -1);
        }
    }

    /**
     * Whether it is possible for the child view of this layout to scroll down. Override this if the child view is a custom view.
     * ??
     */
    public static boolean canChildScrollDown(View target) {
        if (Build.VERSION.SDK_INT < 14) {
            if (target instanceof AbsListView) {
                final AbsListView absListView = (AbsListView) target;
                return absListView.getChildCount() > 0
                        && (absListView.getLastVisiblePosition() < absListView.getChildCount() - 1
                                || absListView.getChildAt(absListView.getChildCount() - 1).getBottom() > absListView
                                        .getPaddingBottom());
            } else {
                return ViewCompat.canScrollVertically(target, 1) || target.getScrollY() < 0;
            }
        } else {
            return ViewCompat.canScrollVertically(target, 1);
        }
    }

    /**
     * ? dp ?? ? px(?)
     */
    public static int dp2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }

    /**
     * ? px(?) ?? ? dp
     */
    public static int px2dp(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }
}