Display views in a grid with customizable cells sizes an position

SimpleGridLayout.java

import android.content.Context;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class SimpleGridLayout extends ViewGroup {

	private int cellMarginPx = 0;
	private int columnCount = 2;
	private int rowCount = -1;

	public SimpleGridLayout(Context context) {
		super(context);
		init();
	}

	public SimpleGridLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}

	public SimpleGridLayout(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		init();
	}

	private void init() {
		if (isInEditMode()) {
			setColumnCount(2);
			setRowCount(3);

			for (int y = 0; y < getRowCount(); y++) {
				for (int x = 0; x < getColumnCount(); x++) {
					TextView textView = new TextView(getContext());
					textView.setText(String.format("%d %d", x, y));
					textView.setGravity(Gravity.CENTER);
					addView(textView, new LayoutParams(x, 1, y, 1));
				}
			}
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		int totalWidth = MeasureSpec.getSize(widthMeasureSpec);
		int totalHeight = MeasureSpec.getSize(heightMeasureSpec);

		int contentWidth = totalWidth - getPaddingLeft() - getPaddingRight();
		int contentHeight;
		if (hasUnlimitedRows()) {
			contentHeight = 0;
		} else {
			contentHeight = totalHeight - getPaddingTop() - getPaddingBottom();
		}

		int cellBaseWidth = (contentWidth - (columnCount - 1) * cellMarginPx) / columnCount;
		int cellBaseHeight;
		if (hasUnlimitedRows()) {
			cellBaseHeight = 0;
		} else {
			cellBaseHeight = (contentHeight - (rowCount - 1) * cellMarginPx) / rowCount;
		}

		int maxCellHeightForRow = 0;
		for (int i = 0, childCount = getChildCount(); i < childCount; i++) {
			final View view = getChildAt(i);
			final LayoutParams layoutParams = (LayoutParams) view.getLayoutParams();

			int cellWidth = cellBaseWidth * layoutParams.colSpan + ((layoutParams.colSpan - 1) * cellMarginPx);
			int cellWidthSpec = MeasureSpec.makeMeasureSpec(cellWidth, MeasureSpec.EXACTLY);

			int cellHeightSpec;
			if (hasUnlimitedRows()) {
				cellHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
			} else {
				int cellHeight = cellBaseHeight * layoutParams.rowSpan + ((layoutParams.rowSpan - 1) * cellMarginPx);
				cellHeightSpec = MeasureSpec.makeMeasureSpec(cellHeight, MeasureSpec.EXACTLY);
			}

			view.measure(cellWidthSpec, cellHeightSpec);

			maxCellHeightForRow = Math.max(maxCellHeightForRow, view.getMeasuredHeight());
			if (i > 0 && i % getColumnCount() == 0) {
				contentHeight += maxCellHeightForRow;
			}
		}
		contentHeight += maxCellHeightForRow;

		if (hasUnlimitedRows()) {
			setMeasuredDimension(widthMeasureSpec, MeasureSpec.makeMeasureSpec(contentHeight, MeasureSpec.EXACTLY));
		} else {
			setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
		}
	}

	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
		if (getChildCount() == 0)
			return;

		int contentWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight();
		int contentHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom();

		int rowCount = this.rowCount;
		if (hasUnlimitedRows()) {
			rowCount = (int) Math.ceil(getChildCount() / (float) getColumnCount());
		}

		int cellBaseWidth = (contentWidth - (columnCount - 1) * cellMarginPx) / columnCount;
		int cellBaseHeight = (contentHeight - (rowCount - 1) * cellMarginPx) / rowCount;

		for (int i = 0, childCount = getChildCount(); i < childCount; i++) {
			final View view = getChildAt(i);
			final LayoutParams layoutParams = (LayoutParams) view.getLayoutParams();

			int childLeft = getPaddingLeft() + (cellBaseWidth + cellMarginPx) * layoutParams.colIndex;
			int childTop = getPaddingTop() + (cellBaseHeight + cellMarginPx) * layoutParams.rowIndex;
			int childWidth = view.getMeasuredWidth();
			int childHeight = view.getMeasuredHeight();

			view.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
		}
	}

	public int getColumnCount() {
		return columnCount;
	}

	public void setColumnCount(int columnCount) {
		this.columnCount = columnCount;
	}

	public int getRowCount() {
		return rowCount;
	}

	public void setRowCount(int rowCount) {
		this.rowCount = rowCount;
	}

	public int getCellMargin() {
		return cellMarginPx;
	}

	public void setCellMargin(int marginInDp) {
		this.cellMarginPx = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, marginInDp, getContext().getResources().getDisplayMetrics());
	}

	public void setCellMarginRes(int marginRes) {
		this.cellMarginPx = getContext().getResources().getDimensionPixelSize(marginRes);
	}

	private boolean hasUnlimitedRows() {
		return rowCount <= 0;
	}

	public static class LayoutParams extends ViewGroup.LayoutParams {
		public final int colIndex;
		public final int colSpan;
		public final int rowIndex;
		public final int rowSpan;

		public LayoutParams(int colIndex, int colSpan, int rowIndex, int rowSpan) {
			super(MATCH_PARENT, MATCH_PARENT);
			this.colIndex = colIndex;
			this.colSpan = colSpan;
			this.rowIndex = rowIndex;
			this.rowSpan = rowSpan;
		}
	}
}