xref: /frameworks/support/v7/cardview/src/android/support/v7/widget/CardView.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 android.support.v7.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Rect;
import android.os.Build;
import android.support.v7.cardview.R;
import android.util.AttributeSet;
import android.widget.FrameLayout;

/**
 * A FrameLayout with a rounded corner background and shadow.
 * <p>
 * CardView uses <code>elevation</code> property on L for shadows and falls back to a custom shadow
 * implementation on older platforms.
 * <p>
 * Due to expensive nature of rounded corner clipping, on platforms before L, CardView does not
 * clip its children that intersect with rounded corners. Instead, it adds padding to avoid such
 * intersection.
 * <p>
 * Before L, CardView adds padding to its content and draws shadows to that area. This padding
 * amount is equal to {@link #getMaxCardElevation()} on the sides and
 * <code>1.5 * {@link #getMaxCardElevation()}</code> on top and bottom. Since padding is used to
 * offset content for shadows, you cannot set custom padding on CardView.
 * <p>
 * To change CardView's elevation in a backward compatible way, use
 * {@link #setCardElevation(float)}. CardView will use elevation API on L and before L, it will
 * change the shadow size. To avoid moving the View while shadow size is changing, shadow size is
 * clamped by {@link #getMaxCardElevation()}. If you want to change elevation dynamically, you
 * should call {@link #setMaxCardElevation(float)} when CardView is initialized.
 *
 * @attr ref android.support.v7.cardview.R.styleable#CardView_cardBackgroundColor
 * @attr ref android.support.v7.cardview.R.styleable#CardView_cardCornerRadius
 * @attr ref android.support.v7.cardview.R.styleable#CardView_cardElevation
 * @attr ref android.support.v7.cardview.R.styleable#CardView_cardMaxElevation
 */
public class CardView extends FrameLayout implements CardViewDelegate {

    private final static CardViewImpl IMPL;

    static {
        if ("L".equals(Build.VERSION.CODENAME) || Build.VERSION.SDK_INT >= 21) {
            IMPL = new CardViewApi21();
        } else if (Build.VERSION.SDK_INT >= 17) {
            IMPL = new CardViewJellybeanMr1();
        } else {
            IMPL = new CardViewEclairMr1();
        }
        IMPL.initStatic();
    }

    public CardView(Context context) {
        super(context);
        initialize(context, null, 0);
    }

    public CardView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initialize(context, attrs, 0);
    }

    public CardView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initialize(context, attrs, defStyleAttr);
    }

    private Rect mShadowRect = new Rect();

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (IMPL instanceof CardViewApi21 == false) {
            final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
            int extraWidth = 0;
            int extraHeight = 0;
            switch (widthMode) {
                case MeasureSpec.EXACTLY:
                case MeasureSpec.AT_MOST:
                    final int minWidth = (int) Math.ceil(IMPL.getMinWidth(this));
                    widthMeasureSpec = MeasureSpec.makeMeasureSpec(Math.max(minWidth,
                            MeasureSpec.getSize(widthMeasureSpec)), widthMode);
                    break;
                case MeasureSpec.UNSPECIFIED:
                    extraWidth = mShadowRect.left + mShadowRect.right;
                    break;
            }

            final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
            switch (heightMode) {
                case MeasureSpec.EXACTLY:
                case MeasureSpec.AT_MOST:
                    final int minHeight = (int) Math.ceil(IMPL.getMinHeight(this));
                    heightMeasureSpec = MeasureSpec.makeMeasureSpec(Math.max(minHeight,
                            MeasureSpec.getSize(heightMeasureSpec)), heightMode);
                    break;
                case MeasureSpec.UNSPECIFIED:
                    extraHeight = mShadowRect.top + mShadowRect.bottom;
                    break;
            }
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            if (extraWidth != 0 || extraHeight != 0) {
                setMeasuredDimension(getMeasuredWidth() + extraWidth,
                        getMeasuredHeight() + extraHeight);
            }
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }

    }

    private void initialize(Context context, AttributeSet attrs, int defStyleAttr) {
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CardView, defStyleAttr,
                R.style.CardView_Light);
        int backgroundColor = a.getColor(R.styleable.CardView_cardBackgroundColor, 0);
        float radius = a.getDimension(R.styleable.CardView_cardCornerRadius, 0);
        float elevation = a.getDimension(R.styleable.CardView_cardElevation, 0);
        float maxElevation = a.getDimension(R.styleable.CardView_cardMaxElevation, 0);
        if (elevation > maxElevation) {
            maxElevation = elevation;
        }
        a.recycle();

        IMPL.initialize(this, context, backgroundColor, radius, elevation, maxElevation);
    }

    /**
     * Updates the corner radius of the CardView.
     *
     * @param radius The radius in pixels of the corners of the rectangle shape
     * @attr ref android.support.v7.cardview.R.styleable#CardView_cardCornerRadius
     * @see #setRadius(float)
     */
    public void setRadius(float radius) {
        IMPL.setRadius(this, radius);
    }

    /**
     * Returns the corner radius of the CardView.
     *
     * @return Corner radius of the CardView
     * @see #getRadius()
     */
    public float getRadius() {
        return IMPL.getRadius(this);
    }

    /**
     * Updates the backward compatible elevation of the CardView.
     *
     * @param radius The backward compatible elevation in pixels.
     * @attr ref android.support.v7.cardview.R.styleable#CardView_cardElevation
     * @see #getCardElevation()
     * @see #setMaxCardElevation(float)
     */
    public void setCardElevation(float radius) {
        IMPL.setElevation(this, radius);
    }

    /**
     * Returns the backward compatible elevation of the CardView.
     *
     * @return Elevation of the CardView
     * @see #setCardElevation(float)
     * @see #getMaxCardElevation()
     */
    public float getCardElevation() {
        return IMPL.getElevation(this);
    }

    /**
     * Updates the backward compatible elevation of the CardView.
     * <p>
     * Calling this method has no effect if device OS version is L or newer.
     *
     * @param radius The backward compatible elevation in pixels.
     * @attr ref android.support.v7.cardview.R.styleable#CardView_cardElevation
     * @see #setCardElevation(float)
     * @see #getMaxCardElevation()
     */
    public void setMaxCardElevation(float radius) {
        IMPL.setMaxElevation(this, radius);
    }

    /**
     * Returns the backward compatible elevation of the CardView.
     * <p>
     * If device OS version is L or newer, this method returns 0.
     *
     * @return Elevation of the CardView
     * @see #setMaxCardElevation(float)
     * @see #getCardElevation()
     */
    public float getMaxCardElevation() {
        return IMPL.getMaxElevation(this);
    }
}