cardview/src/main/java/androidx/cardview/widget/CardViewBaseImpl.java

/*
 * Copyright 2018 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 androidx.cardview.widget;

import android.content.Context;
import android.content.res.ColorStateList;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;

import androidx.annotation.Nullable;

class CardViewBaseImpl implements CardViewImpl {

    private final RectF mCornerRect = new RectF();

    @Override
    public void initStatic() {
        // Draws a round rect using 7 draw operations. This is faster than using
        // canvas.drawRoundRect before JBMR1 because API 11-16 used alpha mask textures to draw
        // shapes.
        RoundRectDrawableWithShadow.sRoundRectHelper =
                new RoundRectDrawableWithShadow.RoundRectHelper() {
            @Override
            public void drawRoundRect(Canvas canvas, RectF bounds, float cornerRadius,
                    Paint paint) {
                final float twoRadius = cornerRadius * 2;
                final float innerWidth = bounds.width() - twoRadius - 1;
                final float innerHeight = bounds.height() - twoRadius - 1;
                if (cornerRadius >= 1f) {
                    // increment corner radius to account for half pixels.
                    float roundedCornerRadius = cornerRadius + .5f;
                    mCornerRect.set(-roundedCornerRadius, -roundedCornerRadius, roundedCornerRadius,
                            roundedCornerRadius);
                    int saved = canvas.save();
                    canvas.translate(bounds.left + roundedCornerRadius,
                            bounds.top + roundedCornerRadius);
                    canvas.drawArc(mCornerRect, 180, 90, true, paint);
                    canvas.translate(innerWidth, 0);
                    canvas.rotate(90);
                    canvas.drawArc(mCornerRect, 180, 90, true, paint);
                    canvas.translate(innerHeight, 0);
                    canvas.rotate(90);
                    canvas.drawArc(mCornerRect, 180, 90, true, paint);
                    canvas.translate(innerWidth, 0);
                    canvas.rotate(90);
                    canvas.drawArc(mCornerRect, 180, 90, true, paint);
                    canvas.restoreToCount(saved);
                    //draw top and bottom pieces
                    canvas.drawRect(bounds.left + roundedCornerRadius - 1f, bounds.top,
                            bounds.right - roundedCornerRadius + 1f,
                            bounds.top + roundedCornerRadius, paint);

                    canvas.drawRect(bounds.left + roundedCornerRadius - 1f,
                            bounds.bottom - roundedCornerRadius,
                            bounds.right - roundedCornerRadius + 1f, bounds.bottom, paint);
                }
                // center
                canvas.drawRect(bounds.left, bounds.top + cornerRadius,
                        bounds.right, bounds.bottom - cornerRadius , paint);
            }
        };
    }

    @Override
    public void initialize(CardViewDelegate cardView, Context context,
            ColorStateList backgroundColor, float radius, float elevation, float maxElevation) {
        RoundRectDrawableWithShadow background = createBackground(context, backgroundColor, radius,
                elevation, maxElevation);
        background.setAddPaddingForCorners(cardView.getPreventCornerOverlap());
        cardView.setCardBackground(background);
        updatePadding(cardView);
    }

    private RoundRectDrawableWithShadow createBackground(Context context,
                    ColorStateList backgroundColor, float radius, float elevation,
                    float maxElevation) {
        return new RoundRectDrawableWithShadow(context.getResources(), backgroundColor, radius,
                elevation, maxElevation);
    }

    @Override
    public void updatePadding(CardViewDelegate cardView) {
        Rect shadowPadding = new Rect();
        getShadowBackground(cardView).getMaxShadowAndCornerPadding(shadowPadding);
        cardView.setMinWidthHeightInternal((int) Math.ceil(getMinWidth(cardView)),
                (int) Math.ceil(getMinHeight(cardView)));
        cardView.setShadowPadding(shadowPadding.left, shadowPadding.top,
                shadowPadding.right, shadowPadding.bottom);
    }

    @Override
    public void onCompatPaddingChanged(CardViewDelegate cardView) {
        // NO OP
    }

    @Override
    public void onPreventCornerOverlapChanged(CardViewDelegate cardView) {
        getShadowBackground(cardView).setAddPaddingForCorners(cardView.getPreventCornerOverlap());
        updatePadding(cardView);
    }

    @Override
    public void setBackgroundColor(CardViewDelegate cardView, @Nullable ColorStateList color) {
        getShadowBackground(cardView).setColor(color);
    }

    @Override
    public ColorStateList getBackgroundColor(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getColor();
    }

    @Override
    public void setRadius(CardViewDelegate cardView, float radius) {
        getShadowBackground(cardView).setCornerRadius(radius);
        updatePadding(cardView);
    }

    @Override
    public float getRadius(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getCornerRadius();
    }

    @Override
    public void setElevation(CardViewDelegate cardView, float elevation) {
        getShadowBackground(cardView).setShadowSize(elevation);
    }

    @Override
    public float getElevation(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getShadowSize();
    }

    @Override
    public void setMaxElevation(CardViewDelegate cardView, float maxElevation) {
        getShadowBackground(cardView).setMaxShadowSize(maxElevation);
        updatePadding(cardView);
    }

    @Override
    public float getMaxElevation(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getMaxShadowSize();
    }

    @Override
    public float getMinWidth(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getMinWidth();
    }

    @Override
    public float getMinHeight(CardViewDelegate cardView) {
        return getShadowBackground(cardView).getMinHeight();
    }

    private RoundRectDrawableWithShadow getShadowBackground(CardViewDelegate cardView) {
        return ((RoundRectDrawableWithShadow) cardView.getCardBackground());
    }
}