Android example source code file (GridLayout.java)

This example Android source code file (GridLayout.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, content, gone, gridlayout, override, runtimeexception, typedarray, ui, unspecified, util, utilities, utils, view, viewgroup

The GridLayout.java Android example source code

/*
 * Copyright (C) 2008 Google Inc.
 *
 * 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.google.android.photostream;

import android.view.ViewGroup;
import android.view.View;
import android.view.animation.GridLayoutAnimationController;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;

/**
 * A GridLayout positions its children in a static grid, defined by a fixed number of rows
 * and columns. The size of the rows and columns is dynamically computed depending on the
 * size of the GridLayout itself. As a result, GridLayout children's layout parameters
 * are ignored.
 *
 * The number of rows and columns are specified in XML using the attributes android:numRows
 * and android:numColumns.
 *
 * The GridLayout cannot be used when its size is unspecified.
 *
 * @attr ref com.google.android.photostream.R.styleable#GridLayout_numColumns
 * @attr ref com.google.android.photostream.R.styleable#GridLayout_numRows  
 */
public class GridLayout extends ViewGroup {
    private int mNumColumns;
    private int mNumRows;

    private int mColumnWidth;
    private int mRowHeight;

    public GridLayout(Context context) {
        this(context, null);
    }

    public GridLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public GridLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.GridLayout, defStyle, 0);

        mNumColumns = a.getInt(R.styleable.GridLayout_numColumns, 1);
        mNumRows = a.getInt(R.styleable.GridLayout_numRows, 1);

        a.recycle();
    }

    @Override
    protected void attachLayoutAnimationParameters(View child,
            ViewGroup.LayoutParams params, int index, int count) {

        GridLayoutAnimationController.AnimationParameters animationParams =
                (GridLayoutAnimationController.AnimationParameters)
                        params.layoutAnimationParameters;

        if (animationParams == null) {
            animationParams = new GridLayoutAnimationController.AnimationParameters();
            params.layoutAnimationParameters = animationParams;
        }

        animationParams.count = count;
        animationParams.index = index;
        animationParams.columnsCount = mNumColumns;
        animationParams.rowsCount = mNumRows;

        animationParams.column = index % mNumColumns;
        animationParams.row = index / mNumColumns;
    }

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

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

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

        final int width = widthSpecSize - getPaddingLeft() - getPaddingRight();
        final int height = heightSpecSize - getPaddingTop() - getPaddingBottom();

        final int columnWidth = mColumnWidth = width / mNumColumns;
        final int rowHeight = mRowHeight = height / mNumRows;

        final int count = getChildCount();

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);

            int childWidthSpec = MeasureSpec.makeMeasureSpec(columnWidth, MeasureSpec.EXACTLY);
            int childheightSpec = MeasureSpec.makeMeasureSpec(rowHeight, MeasureSpec.EXACTLY);

            child.measure(childWidthSpec, childheightSpec);
        }

        setMeasuredDimension(widthSpecSize, heightSpecSize);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        final int columns = mNumColumns;
        final int paddingLeft = getPaddingLeft();
        final int paddingTop = getPaddingTop();
        final int columnWidth = mColumnWidth;
        final int rowHeight = mRowHeight;
        final int count = getChildCount();

        for (int i = 0; i < count; i++) {
            View child = getChildAt(i);
            if (child.getVisibility() != GONE) {
                final int column = i % columns;
                final int row = i / columns;

                int childLeft = paddingLeft + column * columnWidth;
                int childTop = paddingTop + row * rowHeight;

                child.layout(childLeft, childTop, childLeft + child.getMeasuredWidth(),
                        childTop + child.getMeasuredHeight());
            }
        }
    }
}