Android 根据item大小实现自动排列的GridLayout

源码

1. res/values/attrs.xml

2. res/drawable-hdpi/bugdroid.png

3. res/layout/main.xml

4. src/com/example/android/fixedgridlayout/FixedGridLayout.java

package com.example.android.fixedgridlayout;

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

/**
 * A layout that arranges its children in a grid. The size of the cells is set
 * by the {@link #setCellSize} method and the android:cell_width and
 * android:cell_height attributes in XML. The number of rows and columns is
 * determined at runtime. Each cell contains exactly one view, and they flow in
 * the natural child order (the order in which they were added, or the index in
 * {@link #addViewAt}. Views can not span multiple cells.
 */
public class FixedGridLayout extends ViewGroup {
    int mCellWidth;
    int mCellHeight;

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

    public FixedGridLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        // Read the resource attributes.
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.FixedGridLayout);
        mCellWidth = a.getDimensionPixelSize(R.styleable.FixedGridLayout_cellWidth, -1);
        mCellHeight = a.getDimensionPixelSize(R.styleable.FixedGridLayout_cellHeight, -1);
        a.recycle();
    }

    public void setCellWidth(int px) {
        mCellWidth = px;
        requestLayout();
    }

    public void setCellHeight(int px) {
        mCellHeight = px;
        requestLayout();
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int cellWidthSpec = MeasureSpec.makeMeasureSpec(mCellWidth, MeasureSpec.AT_MOST);
        int cellHeightSpec = MeasureSpec.makeMeasureSpec(mCellHeight, MeasureSpec.AT_MOST);

        int count = getChildCount();
        for (int index = 0; index < count; index++) {
            final View child = getChildAt(index);
            child.measure(cellWidthSpec, cellHeightSpec);
        }
        // Use the size our parents gave us
        setMeasuredDimension(resolveSize(mCellWidth * count, widthMeasureSpec),
                resolveSize(mCellHeight * count, heightMeasureSpec));
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int cellWidth = mCellWidth;
        int cellHeight = mCellHeight;
        int columns = (r - l) / cellWidth;
        if (columns < 0) {
            columns = 1;
        }
        int x = 0;
        int y = 0;
        int i = 0;
        int count = getChildCount();
        for (int index = 0; index < count; index++) {
            final View child = getChildAt(index);

            int w = child.getMeasuredWidth();
            int h = child.getMeasuredHeight();

            int left = x + ((cellWidth - w) / 2);
            int top = y + ((cellHeight - h) / 2);

            child.layout(left, top, left + w, top + h);
            if (i >= (columns - 1)) {
                // advance to next row
                i = 0;
                x = 0;
                y += cellHeight;
            } else {
                i++;
                x += cellWidth;
            }
        }
    }
}

5. com.example.android.fixedgridlayout.FixedGridLayoutTest.java

package com.example.android.fixedgridlayout;

import android.app.Activity;
import android.os.Bundle;

public class FixedGridLayoutTest extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        FixedGridLayout grid = (FixedGridLayout) findViewById(R.id.grid);
        grid.setCellWidth(150);
        grid.setCellHeight(180);
    }
}

说明

FixedGridLayoutTest类，设置如下大小：

        grid.setCellWidth(150);
        grid.setCellHeight(180);

效果图：

FixedGridLayoutTest类，设置如下大小：

        grid.setCellWidth(280);
        grid.setCellHeight(180);

效果图：