NativeScript/tns-core-modules/ui/layouts/grid-layout/grid-layout.ios.ts

import {
    GridLayoutBase, ItemSpec, View, layout
} from "./grid-layout-common";

export * from "./grid-layout-common";

export class GridLayout extends GridLayoutBase {
    private helper: MeasureHelper;
    private columnOffsets = new Array<number>();
    private rowOffsets = new Array<number>();
    private map = new Map<View, MeasureSpecs>();

    constructor() {
        super();
        this.helper = new MeasureHelper(this);
    }

    public _onRowAdded(itemSpec: ItemSpec) {
        this.helper.rows.push(new ItemGroup(itemSpec));
    }

    public _onColumnAdded(itemSpec: ItemSpec) {
        this.helper.columns.push(new ItemGroup(itemSpec));
    }

    public _onRowRemoved(itemSpec: ItemSpec, index: number) {
        this.helper.rows[index].children.length = 0;
        this.helper.rows.splice(index, 1);
    }

    public _onColumnRemoved(itemSpec: ItemSpec, index: number) {
        this.helper.columns[index].children.length = 0;
        this.helper.columns.splice(index, 1);
    }

    public _registerLayoutChild(child: View) {
        this.addToMap(child);
    }

    public _unregisterLayoutChild(child: View) {
        this.removeFromMap(child);
    }

    protected invalidate(): void {
        super.invalidate();
        this.requestLayout();
    }

    private getColumnIndex(view: View): number {
        return Math.max(0, Math.min(GridLayout.getColumn(view), this.columnsInternal.length - 1));
    }

    private getRowIndex(view: View): number {
        return Math.max(0, Math.min(GridLayout.getRow(view), this.rowsInternal.length - 1));
    }

    private getColumnSpan(view: View, columnIndex: number): number {
        return Math.max(1, Math.min(GridLayout.getColumnSpan(view), this.columnsInternal.length - columnIndex));
    }

    private getRowSpan(view: View, rowIndex: number): number {
        return Math.max(1, Math.min(GridLayout.getRowSpan(view), this.rowsInternal.length - rowIndex));
    }

    private getColumnSpec(view: View): ItemSpec {
        return this.columnsInternal[this.getColumnIndex(view)] || this.helper.singleColumn;
    }

    private getRowSpec(view: View): ItemSpec {
        return this.rowsInternal[this.getRowIndex(view)] || this.helper.singleRow;
    }

    private updateMeasureSpecs(child: View, measureSpec: MeasureSpecs): void {
        let column = this.getColumnSpec(child);
        let columnIndex = this.getColumnIndex(child);
        let columnSpan = this.getColumnSpan(child, columnIndex);

        let row = this.getRowSpec(child);
        let rowIndex = this.getRowIndex(child);
        let rowSpan = this.getRowSpan(child, rowIndex);

        measureSpec.setColumn(column);
        measureSpec.setColumnIndex(columnIndex);
        measureSpec.setColumnSpan(columnSpan);

        measureSpec.setRow(row);
        measureSpec.setRowIndex(rowIndex);
        measureSpec.setRowSpan(rowSpan);

        measureSpec.autoColumnsCount = 0;
        measureSpec.autoRowsCount = 0;
        measureSpec.measured = false;
        measureSpec.pixelHeight = 0;
        measureSpec.pixelWidth = 0;
        measureSpec.starColumnsCount = 0;
        measureSpec.starRowsCount = 0;
    }

    private addToMap(child: View): void {
        this.map.set(child, new MeasureSpecs(child));
    }

    private removeFromMap(child: View): void {
        this.map.delete(child);
    }

    public onMeasure(widthMeasureSpec: number, heightMeasureSpec: number): void {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        let measureWidth = 0;
        let measureHeight = 0;

        const width = layout.getMeasureSpecSize(widthMeasureSpec);
        const widthMode = layout.getMeasureSpecMode(widthMeasureSpec);

        const height = layout.getMeasureSpecSize(heightMeasureSpec);
        const heightMode = layout.getMeasureSpecMode(heightMeasureSpec);

        const horizontalPaddingsAndMargins = this.effectivePaddingLeft + this.effectivePaddingRight + this.effectiveBorderLeftWidth + this.effectiveBorderRightWidth;
        const verticalPaddingsAndMargins = this.effectivePaddingTop + this.effectivePaddingBottom + this.effectiveBorderTopWidth + this.effectiveBorderBottomWidth;

        let infinityWidth = widthMode === layout.UNSPECIFIED;
        let infinityHeight = heightMode === layout.UNSPECIFIED;

        this.helper.width = Math.max(0, width - horizontalPaddingsAndMargins);
        this.helper.height = Math.max(0, height - verticalPaddingsAndMargins);

        this.helper.stretchedHorizontally = widthMode === layout.EXACTLY || (this.horizontalAlignment === "stretch" && !infinityWidth);
        this.helper.stretchedVertically = heightMode === layout.EXACTLY || (this.verticalAlignment === "stretch" && !infinityHeight);

        this.helper.setInfinityWidth(infinityWidth);
        this.helper.setInfinityHeight(infinityHeight);

        this.helper.clearMeasureSpecs();
        this.helper.init();

        this.eachLayoutChild((child, last) => {
            let measureSpecs = this.map.get(child);
            this.updateMeasureSpecs(child, measureSpecs);
            this.helper.addMeasureSpec(measureSpecs);
        });

        this.helper.measure();

        // Add in our padding
        measureWidth = this.helper.measuredWidth + horizontalPaddingsAndMargins;
        measureHeight = this.helper.measuredHeight + verticalPaddingsAndMargins;

        // Check against our minimum sizes
        measureWidth = Math.max(measureWidth, this.effectiveMinWidth);
        measureHeight = Math.max(measureHeight, this.effectiveMinHeight);

        const widthSizeAndState = View.resolveSizeAndState(measureWidth, width, widthMode, 0);
        const heightSizeAndState = View.resolveSizeAndState(measureHeight, height, heightMode, 0);

        this.setMeasuredDimension(widthSizeAndState, heightSizeAndState);
    }

    public onLayout(left: number, top: number, right: number, bottom: number): void {
        super.onLayout(left, top, right, bottom);

        let paddingLeft = this.effectiveBorderLeftWidth + this.effectivePaddingLeft;
        let paddingTop = this.effectiveBorderTopWidth + this.effectivePaddingTop;

        this.columnOffsets.length = 0;
        this.rowOffsets.length = 0;

        this.columnOffsets.push(paddingLeft);
        this.rowOffsets.push(paddingTop);

        let offset = this.columnOffsets[0];
        let roundedOffset = paddingLeft;
        let roundedLength = 0;
        let actualLength = 0;

        for (let i = 0, size = this.helper.columns.length; i < size; i++) {
            let columnGroup = this.helper.columns[i];
            offset += columnGroup.length;

            actualLength = offset - roundedOffset;
            roundedLength = Math.round(actualLength);
            columnGroup.rowOrColumn._actualLength = layout.round(layout.toDeviceIndependentPixels(roundedLength));
            roundedOffset += roundedLength;

            this.columnOffsets.push(roundedOffset);
        }

        offset = this.rowOffsets[0];
        roundedOffset = paddingTop;
        roundedLength = 0;
        actualLength = 0;

        for (let i = 0, size = this.helper.rows.length; i < size; i++) {
            let rowGroup = this.helper.rows[i];
            offset += rowGroup.length;

            actualLength = offset - roundedOffset;
            roundedLength = Math.round(actualLength);
            rowGroup.rowOrColumn._actualLength = layout.round(layout.toDeviceIndependentPixels(roundedLength));
            roundedOffset += roundedLength;

            this.rowOffsets.push(roundedOffset);
        }

        for (let i = 0, columns = this.helper.columns.length; i < columns; i++) {
            let columnGroup = this.helper.columns[i];
            for (let j = 0, children = columnGroup.children.length; j < children; j++) {

                let measureSpec = columnGroup.children[j];
                let childLeft = this.columnOffsets[measureSpec.getColumnIndex()];
                let childRight = this.columnOffsets[measureSpec.getColumnIndex() + measureSpec.getColumnSpan()];
                let childTop = this.rowOffsets[measureSpec.getRowIndex()];
                let childBottom = this.rowOffsets[measureSpec.getRowIndex() + measureSpec.getRowSpan()];

                // No need to include margins in the width, height
                View.layoutChild(this, measureSpec.child, childLeft, childTop, childRight, childBottom);
            }
        }
    }
}

class MeasureSpecs {
    private _columnSpan = 1;
    private _rowSpan = 1;

    public pixelWidth = 0;
    public pixelHeight = 0;

    public starColumnsCount = 0;
    public starRowsCount = 0;

    public autoColumnsCount = 0;
    public autoRowsCount = 0;

    public measured = false;

    public child: View;
    private column: ItemSpec;
    private row: ItemSpec
    private columnIndex: number = 0;
    private rowIndex: number = 0;

    constructor(child: View) {
        this.child = child;
    }

    public getSpanned(): boolean {
        return this._columnSpan > 1 || this._rowSpan > 1;
    }

    public getIsStar(): boolean {
        return this.starRowsCount > 0 || this.starColumnsCount > 0;
    }

    public getColumnSpan(): number {
        return this._columnSpan;
    }

    public getRowSpan(): number {
        return this._rowSpan;
    }

    public setRowSpan(value: number): void {
        // cannot have zero rowSpan.
        this._rowSpan = Math.max(1, value);
    }

    public setColumnSpan(value: number): void {
        // cannot have zero colSpan.
        this._columnSpan = Math.max(1, value);
    }

    public getRowIndex(): number {
        return this.rowIndex;
    }

    public getColumnIndex(): number {
        return this.columnIndex;
    }

    public setRowIndex(value: number): void {
        this.rowIndex = value;
    }

    public setColumnIndex(value: number): void {
        this.columnIndex = value;
    }

    public getRow(): ItemSpec {
        return this.row;
    }

    public getColumn(): ItemSpec {
        return this.column;
    }

    public setRow(value: ItemSpec): void {
        this.row = value;
    }

    public setColumn(value: ItemSpec): void {
        this.column = value;
    }
}

class ItemGroup {
    public length = 0;
    public measuredCount = 0;
    public rowOrColumn: ItemSpec;
    public children: Array<MeasureSpecs> = new Array<MeasureSpecs>();

    public measureToFix = 0;
    public currentMeasureToFixCount = 0;
    private infinityLength = false;

    constructor(spec: ItemSpec) {
        this.rowOrColumn = spec;
    }

    public setIsLengthInfinity(infinityLength: boolean): void {
        this.infinityLength = infinityLength;
    }

    public init(density): void {
        this.measuredCount = 0;
        this.currentMeasureToFixCount = 0;
        this.length = this.rowOrColumn.isAbsolute ? this.rowOrColumn.value * density : 0;
    }

    public getAllMeasured(): boolean {
        return this.measuredCount === this.children.length;
    }

    public getCanBeFixed(): boolean {
        return this.currentMeasureToFixCount === this.measureToFix;
    }

    public getIsAuto(): boolean {
        return this.rowOrColumn.isAuto || (this.rowOrColumn.isStar && this.infinityLength);
    }

    public getIsStar(): boolean {
        return this.rowOrColumn.isStar && !this.infinityLength;
    }

    public getIsAbsolute(): boolean {
        return this.rowOrColumn.isAbsolute;
    }
}

class MeasureHelper {
    singleRow: ItemSpec;
    singleColumn: ItemSpec;
    grid: GridLayout;

    infinity: number = layout.makeMeasureSpec(0, layout.UNSPECIFIED);
    rows: Array<ItemGroup> = new Array<ItemGroup>();
    columns: Array<ItemGroup> = new Array<ItemGroup>();

    width: number = 0;
    height: number = 0;
    stretchedHorizontally: boolean = false;
    stretchedVertically: boolean = false;

    infinityWidth: boolean = false;
    infinityHeight: boolean = false;

    private minColumnStarValue: number = 0;
    private maxColumnStarValue: number = 0;

    private minRowStarValue: number = 0;
    private maxRowStarValue: number = 0;

    measuredWidth: number = 0;
    measuredHeight: number = 0;

    private fakeRowAdded: boolean = false;
    private fakeColumnAdded: boolean = false;

    private singleRowGroup: ItemGroup;
    private singleColumnGroup: ItemGroup;

    constructor(grid: GridLayout) {
        this.grid = grid;
        this.singleRow = new ItemSpec();
        this.singleColumn = new ItemSpec();
        this.singleRowGroup = new ItemGroup(this.singleRow);
        this.singleColumnGroup = new ItemGroup(this.singleColumn);
    }

    public setInfinityWidth(value: boolean): void {
        this.infinityWidth = value;
        for (let i = 0, size = this.columns.length; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            columnGroup.setIsLengthInfinity(value);
        }
    }

    public setInfinityHeight(value: boolean): void {
        this.infinityHeight = value;
        for (let i = 0, size = this.rows.length; i < size; i++) {
            let rowGroup: ItemGroup = this.rows[i];
            rowGroup.setIsLengthInfinity(value);
        }
    }

    public addMeasureSpec(measureSpec: MeasureSpecs): void {
        // Get column stats
        let size = measureSpec.getColumnIndex() + measureSpec.getColumnSpan();
        for (let i = measureSpec.getColumnIndex(); i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            if (columnGroup.getIsAuto()) {
                measureSpec.autoColumnsCount++;
            }
            else if (columnGroup.getIsStar()) {
                measureSpec.starColumnsCount += columnGroup.rowOrColumn.value;
            }
            else if (columnGroup.getIsAbsolute()) {
                measureSpec.pixelWidth += layout.toDevicePixels(columnGroup.rowOrColumn.value);
            }
        }

        if (measureSpec.autoColumnsCount > 0 && measureSpec.starColumnsCount === 0) {
            // Determine which auto columns are affected by this element
            for (let i = measureSpec.getColumnIndex(); i < size; i++) {
                let columnGroup: ItemGroup = this.columns[i];
                if (columnGroup.getIsAuto()) {
                    columnGroup.measureToFix++;
                }
            }
        }

        // Get row stats
        size = measureSpec.getRowIndex() + measureSpec.getRowSpan();
        for (let i = measureSpec.getRowIndex(); i < size; i++) {
            let rowGroup: ItemGroup = this.rows[i];
            if (rowGroup.getIsAuto()) {
                measureSpec.autoRowsCount++;
            }
            else if (rowGroup.getIsStar()) {
                measureSpec.starRowsCount += rowGroup.rowOrColumn.value;
            }
            else if (rowGroup.getIsAbsolute()) {
                measureSpec.pixelHeight += layout.toDevicePixels(rowGroup.rowOrColumn.value);
            }
        }

        if (measureSpec.autoRowsCount > 0 && measureSpec.starRowsCount === 0) {
            // Determine which auto rows are affected by this element
            for (let i = measureSpec.getRowIndex(); i < size; i++) {
                let rowGroup: ItemGroup = this.rows[i];
                if (rowGroup.getIsAuto()) {
                    rowGroup.measureToFix++;
                }
            }
        }

        this.columns[measureSpec.getColumnIndex()].children.push(measureSpec);
        this.rows[measureSpec.getRowIndex()].children.push(measureSpec);
    }

    public clearMeasureSpecs(): void {
        for (let i = 0, size = this.columns.length; i < size; i++) {
            this.columns[i].children.length = 0;
        }

        for (let i = 0, size = this.rows.length; i < size; i++) {
            this.rows[i].children.length = 0;
        }
    }

    private static initList(list: Array<ItemGroup>): void {
        let density = layout.getDisplayDensity();
        for (let i = 0, size = list.length; i < size; i++) {
            let item: ItemGroup = list[i];
            item.init(density);
        }
    }

    init(): void {

        let rows = this.rows.length;
        if (rows === 0) {
            this.singleRowGroup.setIsLengthInfinity(this.infinityHeight);
            this.rows.push(this.singleRowGroup);
            this.fakeRowAdded = true;
        } else if (rows > 1 && this.fakeRowAdded) {
            this.rows.splice(0, 1);
            this.fakeRowAdded = false;
        }

        let cols = this.columns.length;
        if (cols === 0) {
            this.fakeColumnAdded = true;
            this.singleColumnGroup.setIsLengthInfinity(this.infinityWidth);
            this.columns.push(this.singleColumnGroup);
        }
        else if (cols > 1 && this.fakeColumnAdded) {
            this.columns.splice(0, 1);
            this.fakeColumnAdded = false;
        }

        MeasureHelper.initList(this.rows);
        MeasureHelper.initList(this.columns);

        this.minColumnStarValue = -1;
        this.minRowStarValue = -1;
        this.maxColumnStarValue = -1;
        this.maxRowStarValue = -1;
    }

    private itemMeasured(measureSpec: MeasureSpecs, isFakeMeasure: boolean): void {
        if (!isFakeMeasure) {
            this.columns[measureSpec.getColumnIndex()].measuredCount++;
            this.rows[measureSpec.getRowIndex()].measuredCount++;
            measureSpec.measured = true;
        }

        if (measureSpec.autoColumnsCount > 0 && measureSpec.starColumnsCount === 0) {
            let size = measureSpec.getColumnIndex() + measureSpec.getColumnSpan();
            for (let i = measureSpec.getColumnIndex(); i < size; i++) {
                let columnGroup: ItemGroup = this.columns[i];
                if (columnGroup.getIsAuto()) {
                    columnGroup.currentMeasureToFixCount++;
                }
            }
        }

        if (measureSpec.autoRowsCount > 0 && measureSpec.starRowsCount === 0) {
            let size = measureSpec.getRowIndex() + measureSpec.getRowSpan();
            for (let i = measureSpec.getRowIndex(); i < size; i++) {
                let rowGroup: ItemGroup = this.rows[i];
                if (rowGroup.getIsAuto()) {
                    rowGroup.currentMeasureToFixCount++;
                }
            }
        }
    }

    private fixColumns(): void {
        let currentColumnWidth = 0;
        let columnStarCount = 0;

        let columnCount = this.columns.length;
        for (let i = 0; i < columnCount; i++) {
            let item: ItemGroup = this.columns[i];
            if (item.rowOrColumn.isStar) {
                columnStarCount += item.rowOrColumn.value;
            }
            else {
                // Star columns are still zeros (not calculated).
                currentColumnWidth += item.length;
            }
        }

        let widthForStarColumns = Math.max(0, this.width - currentColumnWidth);
        this.maxColumnStarValue = columnStarCount > 0 ? widthForStarColumns / columnStarCount : 0;

        MeasureHelper.updateStarLength(this.columns, this.maxColumnStarValue);
    }

    private fixRows(): void {
        let currentRowHeight = 0;
        let rowStarCount = 0;

        let rowCount = this.rows.length;
        for (let i = 0; i < rowCount; i++) {
            let item: ItemGroup = this.rows[i];
            if (item.rowOrColumn.isStar) {
                rowStarCount += item.rowOrColumn.value;
            }
            else {
                // Star rows are still zeros (not calculated).
                currentRowHeight += item.length;
            }
        }

        let heightForStarRows = Math.max(0, this.height - currentRowHeight);
        this.maxRowStarValue = rowStarCount > 0 ? heightForStarRows / rowStarCount : 0;

        MeasureHelper.updateStarLength(this.rows, this.maxRowStarValue);
    }

    private static updateStarLength(list: Array<ItemGroup>, starValue: number): void {
        let offset = 0;
        let roundedOffset = 0;
        for (let i = 0, rowCount = list.length; i < rowCount; i++) {
            let item = list[i];
            if (item.getIsStar()) {
                offset += item.rowOrColumn.value * starValue;

                let actualLength = offset - roundedOffset;
                let roundedLength = Math.round(actualLength);
                item.length = roundedLength;
                roundedOffset += roundedLength;
            }
        }
    }

    private fakeMeasure(): void {
        // Fake measure - measure all elements that have star rows and auto columns - with infinity Width and infinity Height
        for (let i = 0, size = this.columns.length; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            if (columnGroup.getAllMeasured()) {
                continue;
            }

            for (let j = 0, childrenCount = columnGroup.children.length; j < childrenCount; j++) {
                let measureSpec: MeasureSpecs = columnGroup.children[j];
                if (measureSpec.starRowsCount > 0 && measureSpec.autoColumnsCount > 0 && measureSpec.starColumnsCount === 0) {
                    this.measureChild(measureSpec, true);
                }
            }
        }
    }

    private measureFixedColumnsNoStarRows(): void {
        for (let i = 0, size = this.columns.length; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            for (let j = 0, childrenCount = columnGroup.children.length; j < childrenCount; j++) {
                let measureSpec: MeasureSpecs = columnGroup.children[j];
                if (measureSpec.starColumnsCount > 0 && measureSpec.starRowsCount === 0) {
                    this.measureChildFixedColumns(measureSpec);
                }
            }
        }
    }

    private measureNoStarColumnsFixedRows(): void {
        for (let i = 0, size = this.columns.length; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            for (let j = 0, childrenCount = columnGroup.children.length; j < childrenCount; j++) {
                let measureSpec: MeasureSpecs = columnGroup.children[j];
                if (measureSpec.starRowsCount > 0 && measureSpec.starColumnsCount === 0) {
                    this.measureChildFixedRows(measureSpec);
                }
            }
        }
    }

    private static canFix(list: Array<ItemGroup>): boolean {
        for (let i = 0, size = list.length; i < size; i++) {
            let item: ItemGroup = list[i];
            if (!item.getCanBeFixed()) {
                return false;
            }
        }

        return true;
    }

    private static getMeasureLength(list: Array<ItemGroup>): number {
        let result = 0;
        for (let i = 0, size = list.length; i < size; i++) {
            let item: ItemGroup = list[i];
            result += item.length;
        }

        return result;
    }

    public measure(): void {
        // Measure auto & pixel columns and rows (no spans).
        let size = this.columns.length;
        for (let i = 0; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            for (let j = 0, childrenCount = columnGroup.children.length; j < childrenCount; j++) {
                let measureSpec: MeasureSpecs = columnGroup.children[j];
                if (measureSpec.getIsStar() || measureSpec.getSpanned()) {
                    continue;
                }

                this.measureChild(measureSpec, false);
            }
        }

        // Measure auto & pixel columns and rows (with spans).
        for (let i = 0; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            for (let j = 0, childrenCount = columnGroup.children.length; j < childrenCount; j++) {
                let measureSpec = columnGroup.children[j];
                if (measureSpec.getIsStar() || !measureSpec.getSpanned()) {
                    continue;
                }

                this.measureChild(measureSpec, false);
            }
        }

        // try fix stars!
        let fixColumns: boolean = MeasureHelper.canFix(this.columns);
        let fixRows: boolean = MeasureHelper.canFix(this.rows);

        if (fixColumns) {
            this.fixColumns();
        }

        if (fixRows) {
            this.fixRows();
        }

        if (!fixColumns && !fixRows) {
            // Fake measure - measure all elements that have star rows and auto columns - with infinity Width and infinity Height
            // should be able to fix rows after that
            this.fakeMeasure();

            this.fixColumns();

            // Measure all elements that have star columns(already fixed), but no stars at the rows 
            this.measureFixedColumnsNoStarRows();

            this.fixRows();
        }
        else if (fixColumns && !fixRows) {
            // Measure all elements that have star columns(already fixed) but no stars at the rows
            this.measureFixedColumnsNoStarRows();

            // Then
            this.fixRows();
        }
        else if (!fixColumns && fixRows) {
            // Measure all elements that have star rows(already fixed) but no star at the columns 
            this.measureNoStarColumnsFixedRows();

            // Then
            this.fixColumns();
        }

        // Rows and columns are fixed here - measure remaining elements
        size = this.columns.length;
        for (let i = 0; i < size; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            for (let j = 0, childCount = columnGroup.children.length; j < childCount; j++) {
                let measureSpec: MeasureSpecs = columnGroup.children[j];
                if (!measureSpec.measured) {
                    this.measureChildFixedColumnsAndRows(measureSpec);
                }
            }
        }

        // If we are not stretched and minColumnStarValue is less than maxColumnStarValue
        // we need to reduce the width of star columns.
        if (!this.stretchedHorizontally && this.minColumnStarValue !== -1 && this.minColumnStarValue < this.maxColumnStarValue) {
            MeasureHelper.updateStarLength(this.columns, this.minColumnStarValue);
        }

        // If we are not stretched and minRowStarValue is less than maxRowStarValue
        // we need to reduce the height of star maxRowStarValue.
        if (!this.stretchedVertically && this.minRowStarValue !== -1 && this.minRowStarValue < this.maxRowStarValue) {
            MeasureHelper.updateStarLength(this.rows, this.minRowStarValue);
        }

        this.measuredWidth = MeasureHelper.getMeasureLength(this.columns);
        this.measuredHeight = MeasureHelper.getMeasureLength(this.rows);
    }

    private measureChild(measureSpec: MeasureSpecs, isFakeMeasure: boolean): void {
        let widthMeasureSpec = (measureSpec.autoColumnsCount > 0) ? this.infinity : layout.makeMeasureSpec(measureSpec.pixelWidth, layout.EXACTLY);
        let heightMeasureSpec = (isFakeMeasure || measureSpec.autoRowsCount > 0) ? this.infinity : layout.makeMeasureSpec(measureSpec.pixelHeight, layout.EXACTLY);

        let childSize = View.measureChild(this.grid, measureSpec.child, widthMeasureSpec, heightMeasureSpec);
        let childMeasuredWidth: number = childSize.measuredWidth;
        let childMeasuredHeight: number = childSize.measuredHeight;

        let columnSpanEnd: number = measureSpec.getColumnIndex() + measureSpec.getColumnSpan();
        let rowSpanEnd: number = measureSpec.getRowIndex() + measureSpec.getRowSpan();

        if (measureSpec.autoColumnsCount > 0) {
            let remainingSpace = childMeasuredWidth;

            for (let i = measureSpec.getColumnIndex(); i < columnSpanEnd; i++) {
                let columnGroup: ItemGroup = this.columns[i];
                remainingSpace -= columnGroup.length;
            }

            if (remainingSpace > 0) {
                let growSize = remainingSpace / measureSpec.autoColumnsCount;
                for (let i = measureSpec.getColumnIndex(); i < columnSpanEnd; i++) {
                    let columnGroup: ItemGroup = this.columns[i];
                    if (columnGroup.getIsAuto()) {
                        columnGroup.length += growSize;
                    }
                }
            }
        }

        if (!isFakeMeasure && measureSpec.autoRowsCount > 0) {
            let remainingSpace: number = childMeasuredHeight;

            for (let i = measureSpec.getRowIndex(); i < rowSpanEnd; i++) {
                let rowGroup: ItemGroup = this.rows[i];
                remainingSpace -= rowGroup.length;
            }

            if (remainingSpace > 0) {
                let growSize = remainingSpace / measureSpec.autoRowsCount;
                for (let i = measureSpec.getRowIndex(); i < rowSpanEnd; i++) {
                    let rowGroup: ItemGroup = this.rows[i];
                    if (rowGroup.getIsAuto()) {
                        rowGroup.length += growSize;
                    }
                }
            }
        }

        this.itemMeasured(measureSpec, isFakeMeasure);
    }

    private measureChildFixedColumns(measureSpec: MeasureSpecs): void {
        let columnIndex = measureSpec.getColumnIndex();
        let columnSpanEnd = columnIndex + measureSpec.getColumnSpan();
        let rowIndex = measureSpec.getRowIndex();
        let rowSpanEnd = rowIndex + measureSpec.getRowSpan();

        let measureWidth = 0;
        let growSize = 0;

        for (let i = columnIndex; i < columnSpanEnd; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            measureWidth += columnGroup.length;
        }

        let widthMeasureSpec = layout.makeMeasureSpec(measureWidth, this.stretchedHorizontally ? layout.EXACTLY : layout.AT_MOST);
        let heightMeasureSpec = (measureSpec.autoRowsCount > 0) ? this.infinity : layout.makeMeasureSpec(measureSpec.pixelHeight, layout.EXACTLY);

        let childSize = View.measureChild(this.grid, measureSpec.child, widthMeasureSpec, heightMeasureSpec);
        let childMeasuredWidth = childSize.measuredWidth;
        let childMeasuredHeight = childSize.measuredHeight;

        this.updateMinColumnStarValueIfNeeded(measureSpec, childMeasuredWidth);

        // Distribute height over auto rows
        if (measureSpec.autoRowsCount > 0) {
            let remainingSpace = childMeasuredHeight;

            for (let i = rowIndex; i < rowSpanEnd; i++) {
                let rowGroup: ItemGroup = this.rows[i];
                remainingSpace -= rowGroup.length;
            }

            if (remainingSpace > 0) {
                growSize = remainingSpace / measureSpec.autoRowsCount;
                for (let i = rowIndex; i < rowSpanEnd; i++) {
                    let rowGroup: ItemGroup = this.rows[i];
                    if (rowGroup.getIsAuto()) {
                        rowGroup.length += growSize;
                    }
                }
            }
        }

        this.itemMeasured(measureSpec, false);
    }

    private measureChildFixedRows(measureSpec: MeasureSpecs): void {
        let columnIndex = measureSpec.getColumnIndex();
        let columnSpanEnd = columnIndex + measureSpec.getColumnSpan();
        let rowIndex = measureSpec.getRowIndex();
        let rowSpanEnd = rowIndex + measureSpec.getRowSpan();
        let measureHeight = 0;

        for (let i = rowIndex; i < rowSpanEnd; i++) {
            let rowGroup: ItemGroup = this.rows[i];
            measureHeight += rowGroup.length;
        }

        let widthMeasureSpec = (measureSpec.autoColumnsCount > 0) ? this.infinity : layout.makeMeasureSpec(measureSpec.pixelWidth, layout.EXACTLY);
        let heightMeasureSpec = layout.makeMeasureSpec(measureHeight, this.stretchedVertically ? layout.EXACTLY : layout.AT_MOST);

        let childSize = View.measureChild(this.grid, measureSpec.child, widthMeasureSpec, heightMeasureSpec);
        let childMeasuredWidth = childSize.measuredWidth;
        let childMeasuredHeight = childSize.measuredHeight;

        let remainingSpace = 0;
        let growSize = 0;

        // Distribute width over auto columns
        if (measureSpec.autoColumnsCount > 0) {
            remainingSpace = childMeasuredWidth;

            for (let i = columnIndex; i < columnSpanEnd; i++) {
                let columnGroup: ItemGroup = this.columns[i];
                remainingSpace -= columnGroup.length;
            }

            if (remainingSpace > 0) {
                growSize = remainingSpace / measureSpec.autoColumnsCount;
                for (let i = columnIndex; i < columnSpanEnd; i++) {
                    let columnGroup: ItemGroup = this.columns[i];

                    if (columnGroup.getIsAuto()) {
                        columnGroup.length += growSize;
                    }
                }
            }
        }

        this.updateMinRowStarValueIfNeeded(measureSpec, childMeasuredHeight);
        this.itemMeasured(measureSpec, false);
    }

    private measureChildFixedColumnsAndRows(measureSpec: MeasureSpecs): void {
        let columnIndex = measureSpec.getColumnIndex();
        let columnSpanEnd = columnIndex + measureSpec.getColumnSpan();
        let rowIndex = measureSpec.getRowIndex();
        let rowSpanEnd = rowIndex + measureSpec.getRowSpan();

        let measureWidth = 0;
        for (let i = columnIndex; i < columnSpanEnd; i++) {
            let columnGroup: ItemGroup = this.columns[i];
            measureWidth += columnGroup.length;
        }

        let measureHeight = 0;
        for (let i = rowIndex; i < rowSpanEnd; i++) {
            let rowGroup: ItemGroup = this.rows[i];
            measureHeight += rowGroup.length;
        }

        // if (have stars) & (not stretch) - at most
        let widthMeasureSpec = layout.makeMeasureSpec(measureWidth,
            (measureSpec.starColumnsCount > 0 && !this.stretchedHorizontally) ? layout.AT_MOST : layout.EXACTLY);

        let heightMeasureSpec = layout.makeMeasureSpec(measureHeight,
            (measureSpec.starRowsCount > 0 && !this.stretchedVertically) ? layout.AT_MOST : layout.EXACTLY);

        let childSize = View.measureChild(this.grid, measureSpec.child, widthMeasureSpec, heightMeasureSpec);
        let childMeasuredWidth = childSize.measuredWidth;
        let childMeasuredHeight = childSize.measuredHeight;

        this.updateMinColumnStarValueIfNeeded(measureSpec, childMeasuredWidth);
        this.updateMinRowStarValueIfNeeded(measureSpec, childMeasuredHeight);
        this.itemMeasured(measureSpec, false);
    }

    private updateMinRowStarValueIfNeeded(measureSpec: MeasureSpecs, childMeasuredHeight: number): void {
        if (!this.stretchedVertically && measureSpec.starRowsCount > 0) {
            let remainingSpace = childMeasuredHeight;
            let rowIndex = measureSpec.getRowIndex();
            let rowSpanEnd = rowIndex + measureSpec.getRowSpan();
            for (let i = rowIndex; i < rowSpanEnd; i++) {
                let rowGroup = this.rows[i];
                if (!rowGroup.getIsStar()) {
                    remainingSpace -= rowGroup.length;
                }
            }

            if (remainingSpace > 0) {
                this.minRowStarValue = Math.max(remainingSpace / measureSpec.starRowsCount, this.minRowStarValue);
            }
        }
    }

    private updateMinColumnStarValueIfNeeded(measureSpec: MeasureSpecs, childMeasuredWidth: number): void {
        // When not stretched star columns are not fixed so we may grow them here
        // if there is an element that spans on multiple columns
        if (!this.stretchedHorizontally && measureSpec.starColumnsCount > 0) {
            let remainingSpace = childMeasuredWidth;
            let columnIndex = measureSpec.getColumnIndex();
            let columnSpanEnd = columnIndex + measureSpec.getColumnSpan();
            for (let i = columnIndex; i < columnSpanEnd; i++) {
                let columnGroup = this.columns[i];
                if (!columnGroup.getIsStar()) {
                    remainingSpace -= columnGroup.length;
                }
            }

            if (remainingSpace > 0) {
                this.minColumnStarValue = Math.max(remainingSpace / measureSpec.starColumnsCount, this.minColumnStarValue);
            }
        }
    }
}