src/com/android/launcher2/PagedViewCellLayoutChildren.java

/*
 * Copyright (C) 2010 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 com.android.launcher2;

import android.content.Context;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewGroup;

/**
 * An abstraction of the original CellLayout which supports laying out items
 * which span multiple cells into a grid-like layout.  Also supports dimming
 * to give a preview of its contents.
 */
public class PagedViewCellLayoutChildren extends ViewGroup {
    static final String TAG = "PagedViewCellLayout";

    private boolean mCenterContent;

    private int mCellWidth;
    private int mCellHeight;
    private int mWidthGap;
    private int mHeightGap;

    public PagedViewCellLayoutChildren(Context context) {
        super(context);
    }

    @Override
    public void cancelLongPress() {
        super.cancelLongPress();

        // Cancel long press for all children
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            child.cancelLongPress();
        }
    }

    public void setGap(int widthGap, int heightGap) {
        mWidthGap = widthGap;
        mHeightGap = heightGap;
        requestLayout();
    }

    public void setCellDimensions(int width, int height) {
        mCellWidth = width;
        mCellHeight = height;
        requestLayout();
    }

    @Override
    public void requestChildFocus(View child, View focused) {
        super.requestChildFocus(child, focused);
        if (child != null) {
            Rect r = new Rect();
            child.getDrawingRect(r);
            requestRectangleOnScreen(r);
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);

        int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSpecSize =  MeasureSpec.getSize(heightMeasureSpec);

        if (widthSpecMode == MeasureSpec.UNSPECIFIED || heightSpecMode == MeasureSpec.UNSPECIFIED) {
            throw new RuntimeException("CellLayout cannot have UNSPECIFIED dimensions");
        }

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            View child = getChildAt(i);
            PagedViewCellLayout.LayoutParams lp =
                (PagedViewCellLayout.LayoutParams) child.getLayoutParams();
            lp.setup(mCellWidth, mCellHeight, mWidthGap, mHeightGap,
                    ((ViewGroup)getParent()).getPaddingLeft(),
                    ((ViewGroup)getParent()).getPaddingTop());

            int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(lp.width,
                    MeasureSpec.EXACTLY);
            int childheightMeasureSpec = MeasureSpec.makeMeasureSpec(lp.height,
                    MeasureSpec.EXACTLY);

            child.measure(childWidthMeasureSpec, childheightMeasureSpec);
        }

        setMeasuredDimension(widthSpecSize, heightSpecSize);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int count = getChildCount();

        int offsetX = 0;
        if (mCenterContent) {
            // determine the max width of all the rows and center accordingly
            int maxRowWidth = 0;
            for (int i = 0; i < count; i++) {
                View child = getChildAt(i);
                if (child.getVisibility() != GONE) {
                    PagedViewCellLayout.LayoutParams lp =
                        (PagedViewCellLayout.LayoutParams) child.getLayoutParams();
                    maxRowWidth = Math.max(maxRowWidth, lp.x + lp.width);
                }
            }
            offsetX = (getMeasuredWidth() / 2) - (maxRowWidth / 2);
        }

        for (int i = 0; i < count; i++) {
            View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                PagedViewCellLayout.LayoutParams lp =
                    (PagedViewCellLayout.LayoutParams) child.getLayoutParams();

                int childLeft = offsetX + lp.x;
                int childTop = lp.y;
                child.layout(childLeft, childTop, childLeft + lp.width, childTop + lp.height);
            }
        }
    }

    void destroyHardwareLayer() {
        if (getLayerType() != LAYER_TYPE_NONE) {
            setLayerType(LAYER_TYPE_NONE, null);
        }
    }
    void createHardwareLayer() {
        if (getLayerType() != LAYER_TYPE_HARDWARE) {
            setLayerType(LAYER_TYPE_HARDWARE, null);
        }
    }

    public void enableCenteredContent(boolean enabled) {
        mCenterContent = enabled;
    }

    @Override
    protected void setChildrenDrawingCacheEnabled(boolean enabled) {
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View view = getChildAt(i);
            view.setDrawingCacheEnabled(enabled);
            // Update the drawing caches
            if (!view.isHardwareAccelerated()) {
                view.buildDrawingCache(true);
            }
        }
    }
}