// When the user specifically sets a value for width or height static void setDimensionFromStyle(css_node_t *node, css_flex_direction_t axis) { // The parent already computed us a width or height. We just skip it if (!isUndefined(node->layout.dimensions[dim[axis]])) { return; } // We only run if there's a width or height defined if (!isDimDefined(node, axis)) { return; } // The dimensions can never be smaller than the padding and border node->layout.dimensions[dim[axis]] = fmaxf( boundAxis(node, axis, node->style.dimensions[dim[axis]]), getPaddingAndBorderAxis(node, axis) ); }
static void layoutNodeImpl(css_node_t *node, float parentMaxWidth, css_direction_t parentDirection) { /** START_GENERATED **/ css_direction_t direction = resolveDirection(node, parentDirection); css_flex_direction_t mainAxis = resolveAxis(getFlexDirection(node), direction); css_flex_direction_t crossAxis = getCrossFlexDirection(mainAxis, direction); css_flex_direction_t resolvedRowAxis = resolveAxis(CSS_FLEX_DIRECTION_ROW, direction); // Handle width and height style attributes setDimensionFromStyle(node, mainAxis); setDimensionFromStyle(node, crossAxis); // Set the resolved resolution in the node's layout node->layout.direction = direction; // The position is set by the parent, but we need to complete it with a // delta composed of the margin and left/top/right/bottom node->layout.position[leading[mainAxis]] += getLeadingMargin(node, mainAxis) + getRelativePosition(node, mainAxis); node->layout.position[trailing[mainAxis]] += getTrailingMargin(node, mainAxis) + getRelativePosition(node, mainAxis); node->layout.position[leading[crossAxis]] += getLeadingMargin(node, crossAxis) + getRelativePosition(node, crossAxis); node->layout.position[trailing[crossAxis]] += getTrailingMargin(node, crossAxis) + getRelativePosition(node, crossAxis); // Inline immutable values from the target node to avoid excessive method // invocations during the layout calculation. int childCount = node->children_count; float paddingAndBorderAxisResolvedRow = getPaddingAndBorderAxis(node, resolvedRowAxis); if (isMeasureDefined(node)) { bool isResolvedRowDimDefined = !isUndefined(node->layout.dimensions[dim[resolvedRowAxis]]); float width = CSS_UNDEFINED; if (isDimDefined(node, resolvedRowAxis)) { width = node->style.dimensions[CSS_WIDTH]; } else if (isResolvedRowDimDefined) { width = node->layout.dimensions[dim[resolvedRowAxis]]; } else { width = parentMaxWidth - getMarginAxis(node, resolvedRowAxis); } width -= paddingAndBorderAxisResolvedRow; // We only need to give a dimension for the text if we haven't got any // for it computed yet. It can either be from the style attribute or because // the element is flexible. bool isRowUndefined = !isDimDefined(node, resolvedRowAxis) && !isResolvedRowDimDefined; bool isColumnUndefined = !isDimDefined(node, CSS_FLEX_DIRECTION_COLUMN) && isUndefined(node->layout.dimensions[dim[CSS_FLEX_DIRECTION_COLUMN]]); // Let's not measure the text if we already know both dimensions if (isRowUndefined || isColumnUndefined) { css_dim_t measureDim = node->measure( node->context, width ); if (isRowUndefined) { node->layout.dimensions[CSS_WIDTH] = measureDim.dimensions[CSS_WIDTH] + paddingAndBorderAxisResolvedRow; } if (isColumnUndefined) { node->layout.dimensions[CSS_HEIGHT] = measureDim.dimensions[CSS_HEIGHT] + getPaddingAndBorderAxis(node, CSS_FLEX_DIRECTION_COLUMN); } } if (childCount == 0) { return; } } bool isNodeFlexWrap = isFlexWrap(node); css_justify_t justifyContent = node->style.justify_content; float leadingPaddingAndBorderMain = getLeadingPaddingAndBorder(node, mainAxis); float leadingPaddingAndBorderCross = getLeadingPaddingAndBorder(node, crossAxis); float paddingAndBorderAxisMain = getPaddingAndBorderAxis(node, mainAxis); float paddingAndBorderAxisCross = getPaddingAndBorderAxis(node, crossAxis); bool isMainDimDefined = !isUndefined(node->layout.dimensions[dim[mainAxis]]); bool isCrossDimDefined = !isUndefined(node->layout.dimensions[dim[crossAxis]]); bool isMainRowDirection = isRowDirection(mainAxis); int i; int ii; css_node_t* child; css_flex_direction_t axis; css_node_t* firstAbsoluteChild = NULL; css_node_t* currentAbsoluteChild = NULL; float definedMainDim = CSS_UNDEFINED; if (isMainDimDefined) { definedMainDim = node->layout.dimensions[dim[mainAxis]] - paddingAndBorderAxisMain; } // We want to execute the next two loops one per line with flex-wrap int startLine = 0; int endLine = 0; // int nextOffset = 0; int alreadyComputedNextLayout = 0; // We aggregate the total dimensions of the container in those two variables float linesCrossDim = 0; float linesMainDim = 0; int linesCount = 0; while (endLine < childCount) { // <Loop A> Layout non flexible children and count children by type // mainContentDim is accumulation of the dimensions and margin of all the // non flexible children. This will be used in order to either set the // dimensions of the node if none already exist, or to compute the // remaining space left for the flexible children. float mainContentDim = 0; // There are three kind of children, non flexible, flexible and absolute. // We need to know how many there are in order to distribute the space. int flexibleChildrenCount = 0; float totalFlexible = 0; int nonFlexibleChildrenCount = 0; // Use the line loop to position children in the main axis for as long // as they are using a simple stacking behaviour. Children that are // immediately stacked in the initial loop will not be touched again // in <Loop C>. bool isSimpleStackMain = (isMainDimDefined && justifyContent == CSS_JUSTIFY_FLEX_START) || (!isMainDimDefined && justifyContent != CSS_JUSTIFY_CENTER); int firstComplexMain = (isSimpleStackMain ? childCount : startLine); // Use the initial line loop to position children in the cross axis for // as long as they are relatively positioned with alignment STRETCH or // FLEX_START. Children that are immediately stacked in the initial loop // will not be touched again in <Loop D>. bool isSimpleStackCross = true; int firstComplexCross = childCount; css_node_t* firstFlexChild = NULL; css_node_t* currentFlexChild = NULL; float mainDim = leadingPaddingAndBorderMain; float crossDim = 0; float maxWidth; for (i = startLine; i < childCount; ++i) { child = node->get_child(node->context, i); child->line_index = linesCount; child->next_absolute_child = NULL; child->next_flex_child = NULL; css_align_t alignItem = getAlignItem(node, child); // Pre-fill cross axis dimensions when the child is using stretch before // we call the recursive layout pass if (alignItem == CSS_ALIGN_STRETCH && child->style.position_type == CSS_POSITION_RELATIVE && isCrossDimDefined && !isDimDefined(child, crossAxis)) { child->layout.dimensions[dim[crossAxis]] = fmaxf( boundAxis(child, crossAxis, node->layout.dimensions[dim[crossAxis]] - paddingAndBorderAxisCross - getMarginAxis(child, crossAxis)), // You never want to go smaller than padding getPaddingAndBorderAxis(child, crossAxis) ); } else if (child->style.position_type == CSS_POSITION_ABSOLUTE) { // Store a private linked list of absolutely positioned children // so that we can efficiently traverse them later. if (firstAbsoluteChild == NULL) { firstAbsoluteChild = child; } if (currentAbsoluteChild != NULL) { currentAbsoluteChild->next_absolute_child = child; } currentAbsoluteChild = child; // Pre-fill dimensions when using absolute position and both offsets for the axis are defined (either both // left and right or top and bottom). for (ii = 0; ii < 2; ii++) { axis = (ii != 0) ? CSS_FLEX_DIRECTION_ROW : CSS_FLEX_DIRECTION_COLUMN; if (!isUndefined(node->layout.dimensions[dim[axis]]) && !isDimDefined(child, axis) && isPosDefined(child, leading[axis]) && isPosDefined(child, trailing[axis])) { child->layout.dimensions[dim[axis]] = fmaxf( boundAxis(child, axis, node->layout.dimensions[dim[axis]] - getPaddingAndBorderAxis(node, axis) - getMarginAxis(child, axis) - getPosition(child, leading[axis]) - getPosition(child, trailing[axis])), // You never want to go smaller than padding getPaddingAndBorderAxis(child, axis) ); } } } float nextContentDim = 0; // It only makes sense to consider a child flexible if we have a computed // dimension for the node-> if (isMainDimDefined && isFlex(child)) { flexibleChildrenCount++; totalFlexible += child->style.flex; // Store a private linked list of flexible children so that we can // efficiently traverse them later. if (firstFlexChild == NULL) { firstFlexChild = child; } if (currentFlexChild != NULL) { currentFlexChild->next_flex_child = child; } currentFlexChild = child; // Even if we don't know its exact size yet, we already know the padding, // border and margin. We'll use this partial information, which represents // the smallest possible size for the child, to compute the remaining // available space. nextContentDim = getPaddingAndBorderAxis(child, mainAxis) + getMarginAxis(child, mainAxis); } else { maxWidth = CSS_UNDEFINED; if (!isMainRowDirection) { if (isDimDefined(node, resolvedRowAxis)) { maxWidth = node->layout.dimensions[dim[resolvedRowAxis]] - paddingAndBorderAxisResolvedRow; } else { maxWidth = parentMaxWidth - getMarginAxis(node, resolvedRowAxis) - paddingAndBorderAxisResolvedRow; } } // This is the main recursive call. We layout non flexible children. if (alreadyComputedNextLayout == 0) { layoutNode(child, maxWidth, direction); } // Absolute positioned elements do not take part of the layout, so we // don't use them to compute mainContentDim if (child->style.position_type == CSS_POSITION_RELATIVE) { nonFlexibleChildrenCount++; // At this point we know the final size and margin of the element. nextContentDim = getDimWithMargin(child, mainAxis); } } // The element we are about to add would make us go to the next line if (isNodeFlexWrap && isMainDimDefined && mainContentDim + nextContentDim > definedMainDim && // If there's only one element, then it's bigger than the content // and needs its own line i != startLine) { nonFlexibleChildrenCount--; alreadyComputedNextLayout = 1; break; } // Disable simple stacking in the main axis for the current line as // we found a non-trivial child-> The remaining children will be laid out // in <Loop C>. if (isSimpleStackMain && (child->style.position_type != CSS_POSITION_RELATIVE || isFlex(child))) { isSimpleStackMain = false; firstComplexMain = i; } // Disable simple stacking in the cross axis for the current line as // we found a non-trivial child-> The remaining children will be laid out // in <Loop D>. if (isSimpleStackCross && (child->style.position_type != CSS_POSITION_RELATIVE || (alignItem != CSS_ALIGN_STRETCH && alignItem != CSS_ALIGN_FLEX_START) || isUndefined(child->layout.dimensions[dim[crossAxis]]))) { isSimpleStackCross = false; firstComplexCross = i; } if (isSimpleStackMain) { child->layout.position[pos[mainAxis]] += mainDim; if (isMainDimDefined) { setTrailingPosition(node, child, mainAxis); } mainDim += getDimWithMargin(child, mainAxis); crossDim = fmaxf(crossDim, boundAxis(child, crossAxis, getDimWithMargin(child, crossAxis))); } if (isSimpleStackCross) { child->layout.position[pos[crossAxis]] += linesCrossDim + leadingPaddingAndBorderCross; if (isCrossDimDefined) { setTrailingPosition(node, child, crossAxis); } } alreadyComputedNextLayout = 0; mainContentDim += nextContentDim; endLine = i + 1; } // <Loop B> Layout flexible children and allocate empty space // In order to position the elements in the main axis, we have two // controls. The space between the beginning and the first element // and the space between each two elements. float leadingMainDim = 0; float betweenMainDim = 0; // The remaining available space that needs to be allocated float remainingMainDim = 0; if (isMainDimDefined) { remainingMainDim = definedMainDim - mainContentDim; } else { remainingMainDim = fmaxf(mainContentDim, 0) - mainContentDim; } // If there are flexible children in the mix, they are going to fill the // remaining space if (flexibleChildrenCount != 0) { float flexibleMainDim = remainingMainDim / totalFlexible; float baseMainDim; float boundMainDim; // If the flex share of remaining space doesn't meet min/max bounds, // remove this child from flex calculations. currentFlexChild = firstFlexChild; while (currentFlexChild != NULL) { baseMainDim = flexibleMainDim * currentFlexChild->style.flex + getPaddingAndBorderAxis(currentFlexChild, mainAxis); boundMainDim = boundAxis(currentFlexChild, mainAxis, baseMainDim); if (baseMainDim != boundMainDim) { remainingMainDim -= boundMainDim; totalFlexible -= currentFlexChild->style.flex; } currentFlexChild = currentFlexChild->next_flex_child; } flexibleMainDim = remainingMainDim / totalFlexible; // The non flexible children can overflow the container, in this case // we should just assume that there is no space available. if (flexibleMainDim < 0) { flexibleMainDim = 0; } currentFlexChild = firstFlexChild; while (currentFlexChild != NULL) { // At this point we know the final size of the element in the main // dimension currentFlexChild->layout.dimensions[dim[mainAxis]] = boundAxis(currentFlexChild, mainAxis, flexibleMainDim * currentFlexChild->style.flex + getPaddingAndBorderAxis(currentFlexChild, mainAxis) ); maxWidth = CSS_UNDEFINED; if (isDimDefined(node, resolvedRowAxis)) { maxWidth = node->layout.dimensions[dim[resolvedRowAxis]] - paddingAndBorderAxisResolvedRow; } else if (!isMainRowDirection) { maxWidth = parentMaxWidth - getMarginAxis(node, resolvedRowAxis) - paddingAndBorderAxisResolvedRow; } // And we recursively call the layout algorithm for this child layoutNode(currentFlexChild, maxWidth, direction); child = currentFlexChild; currentFlexChild = currentFlexChild->next_flex_child; child->next_flex_child = NULL; } // We use justifyContent to figure out how to allocate the remaining // space available } else if (justifyContent != CSS_JUSTIFY_FLEX_START) { if (justifyContent == CSS_JUSTIFY_CENTER) { leadingMainDim = remainingMainDim / 2; } else if (justifyContent == CSS_JUSTIFY_FLEX_END) { leadingMainDim = remainingMainDim; } else if (justifyContent == CSS_JUSTIFY_SPACE_BETWEEN) { remainingMainDim = fmaxf(remainingMainDim, 0); if (flexibleChildrenCount + nonFlexibleChildrenCount - 1 != 0) { betweenMainDim = remainingMainDim / (flexibleChildrenCount + nonFlexibleChildrenCount - 1); } else { betweenMainDim = 0; } } else if (justifyContent == CSS_JUSTIFY_SPACE_AROUND) { // Space on the edges is half of the space between elements betweenMainDim = remainingMainDim / (flexibleChildrenCount + nonFlexibleChildrenCount); leadingMainDim = betweenMainDim / 2; } } // <Loop C> Position elements in the main axis and compute dimensions // At this point, all the children have their dimensions set. We need to // find their position. In order to do that, we accumulate data in // variables that are also useful to compute the total dimensions of the // container! mainDim += leadingMainDim; for (i = firstComplexMain; i < endLine; ++i) { child = node->get_child(node->context, i); if (child->style.position_type == CSS_POSITION_ABSOLUTE && isPosDefined(child, leading[mainAxis])) { // In case the child is position absolute and has left/top being // defined, we override the position to whatever the user said // (and margin/border). child->layout.position[pos[mainAxis]] = getPosition(child, leading[mainAxis]) + getLeadingBorder(node, mainAxis) + getLeadingMargin(child, mainAxis); } else { // If the child is position absolute (without top/left) or relative, // we put it at the current accumulated offset. child->layout.position[pos[mainAxis]] += mainDim; // Define the trailing position accordingly. if (isMainDimDefined) { setTrailingPosition(node, child, mainAxis); } // Now that we placed the element, we need to update the variables // We only need to do that for relative elements. Absolute elements // do not take part in that phase. if (child->style.position_type == CSS_POSITION_RELATIVE) { // The main dimension is the sum of all the elements dimension plus // the spacing. mainDim += betweenMainDim + getDimWithMargin(child, mainAxis); // The cross dimension is the max of the elements dimension since there // can only be one element in that cross dimension. crossDim = fmaxf(crossDim, boundAxis(child, crossAxis, getDimWithMargin(child, crossAxis))); } } } float containerCrossAxis = node->layout.dimensions[dim[crossAxis]]; if (!isCrossDimDefined) { containerCrossAxis = fmaxf( // For the cross dim, we add both sides at the end because the value // is aggregate via a max function. Intermediate negative values // can mess this computation otherwise boundAxis(node, crossAxis, crossDim + paddingAndBorderAxisCross), paddingAndBorderAxisCross ); } // <Loop D> Position elements in the cross axis for (i = firstComplexCross; i < endLine; ++i) { child = node->get_child(node->context, i); if (child->style.position_type == CSS_POSITION_ABSOLUTE && isPosDefined(child, leading[crossAxis])) { // In case the child is absolutely positionned and has a // top/left/bottom/right being set, we override all the previously // computed positions to set it correctly. child->layout.position[pos[crossAxis]] = getPosition(child, leading[crossAxis]) + getLeadingBorder(node, crossAxis) + getLeadingMargin(child, crossAxis); } else { float leadingCrossDim = leadingPaddingAndBorderCross; // For a relative children, we're either using alignItems (parent) or // alignSelf (child) in order to determine the position in the cross axis if (child->style.position_type == CSS_POSITION_RELATIVE) { css_align_t alignItem = getAlignItem(node, child); if (alignItem == CSS_ALIGN_STRETCH) { // You can only stretch if the dimension has not already been set // previously. if (!isDimDefined(child, crossAxis)) { child->layout.dimensions[dim[crossAxis]] = fmaxf( boundAxis(child, crossAxis, containerCrossAxis - paddingAndBorderAxisCross - getMarginAxis(child, crossAxis)), // You never want to go smaller than padding getPaddingAndBorderAxis(child, crossAxis) ); } } else if (alignItem != CSS_ALIGN_FLEX_START) { // The remaining space between the parent dimensions+padding and child // dimensions+margin. float remainingCrossDim = containerCrossAxis - paddingAndBorderAxisCross - getDimWithMargin(child, crossAxis); if (alignItem == CSS_ALIGN_CENTER) { leadingCrossDim += remainingCrossDim / 2; } else { // CSS_ALIGN_FLEX_END leadingCrossDim += remainingCrossDim; } } } // And we apply the position child->layout.position[pos[crossAxis]] += linesCrossDim + leadingCrossDim; // Define the trailing position accordingly. if (isCrossDimDefined) { setTrailingPosition(node, child, crossAxis); } } } linesCrossDim += crossDim; linesMainDim = fmaxf(linesMainDim, mainDim); linesCount += 1; startLine = endLine; } // <Loop E> // // Note(prenaux): More than one line, we need to layout the crossAxis // according to alignContent. // // Note that we could probably remove <Loop D> and handle the one line case // here too, but for the moment this is safer since it won't interfere with // previously working code. // // See specs: // http://www.w3.org/TR/2012/CR-css3-flexbox-20120918/#layout-algorithm // section 9.4 // if (linesCount > 1 && isCrossDimDefined) { float nodeCrossAxisInnerSize = node->layout.dimensions[dim[crossAxis]] - paddingAndBorderAxisCross; float remainingAlignContentDim = nodeCrossAxisInnerSize - linesCrossDim; float crossDimLead = 0; float currentLead = leadingPaddingAndBorderCross; css_align_t alignContent = node->style.align_content; if (alignContent == CSS_ALIGN_FLEX_END) { currentLead += remainingAlignContentDim; } else if (alignContent == CSS_ALIGN_CENTER) { currentLead += remainingAlignContentDim / 2; } else if (alignContent == CSS_ALIGN_STRETCH) { if (nodeCrossAxisInnerSize > linesCrossDim) { crossDimLead = (remainingAlignContentDim / linesCount); } } int endIndex = 0; for (i = 0; i < linesCount; ++i) { int startIndex = endIndex; // compute the line's height and find the endIndex float lineHeight = 0; for (ii = startIndex; ii < childCount; ++ii) { child = node->get_child(node->context, ii); if (child->style.position_type != CSS_POSITION_RELATIVE) { continue; } if (child->line_index != i) { break; } if (!isUndefined(child->layout.dimensions[dim[crossAxis]])) { lineHeight = fmaxf( lineHeight, child->layout.dimensions[dim[crossAxis]] + getMarginAxis(child, crossAxis) ); } } endIndex = ii; lineHeight += crossDimLead; for (ii = startIndex; ii < endIndex; ++ii) { child = node->get_child(node->context, ii); if (child->style.position_type != CSS_POSITION_RELATIVE) { continue; } css_align_t alignContentAlignItem = getAlignItem(node, child); if (alignContentAlignItem == CSS_ALIGN_FLEX_START) { child->layout.position[pos[crossAxis]] = currentLead + getLeadingMargin(child, crossAxis); } else if (alignContentAlignItem == CSS_ALIGN_FLEX_END) { child->layout.position[pos[crossAxis]] = currentLead + lineHeight - getTrailingMargin(child, crossAxis) - child->layout.dimensions[dim[crossAxis]]; } else if (alignContentAlignItem == CSS_ALIGN_CENTER) { float childHeight = child->layout.dimensions[dim[crossAxis]]; child->layout.position[pos[crossAxis]] = currentLead + (lineHeight - childHeight) / 2; } else if (alignContentAlignItem == CSS_ALIGN_STRETCH) { child->layout.position[pos[crossAxis]] = currentLead + getLeadingMargin(child, crossAxis); // TODO(prenaux): Correctly set the height of items with undefined // (auto) crossAxis dimension. } } currentLead += lineHeight; } } bool needsMainTrailingPos = false; bool needsCrossTrailingPos = false; // If the user didn't specify a width or height, and it has not been set // by the container, then we set it via the children. if (!isMainDimDefined) { node->layout.dimensions[dim[mainAxis]] = fmaxf( // We're missing the last padding at this point to get the final // dimension boundAxis(node, mainAxis, linesMainDim + getTrailingPaddingAndBorder(node, mainAxis)), // We can never assign a width smaller than the padding and borders paddingAndBorderAxisMain ); if (mainAxis == CSS_FLEX_DIRECTION_ROW_REVERSE || mainAxis == CSS_FLEX_DIRECTION_COLUMN_REVERSE) { needsMainTrailingPos = true; } } if (!isCrossDimDefined) { node->layout.dimensions[dim[crossAxis]] = fmaxf( // For the cross dim, we add both sides at the end because the value // is aggregate via a max function. Intermediate negative values // can mess this computation otherwise boundAxis(node, crossAxis, linesCrossDim + paddingAndBorderAxisCross), paddingAndBorderAxisCross ); if (crossAxis == CSS_FLEX_DIRECTION_ROW_REVERSE || crossAxis == CSS_FLEX_DIRECTION_COLUMN_REVERSE) { needsCrossTrailingPos = true; } } // <Loop F> Set trailing position if necessary if (needsMainTrailingPos || needsCrossTrailingPos) { for (i = 0; i < childCount; ++i) { child = node->get_child(node->context, i); if (needsMainTrailingPos) { setTrailingPosition(node, child, mainAxis); } if (needsCrossTrailingPos) { setTrailingPosition(node, child, crossAxis); } } } // <Loop G> Calculate dimensions for absolutely positioned elements currentAbsoluteChild = firstAbsoluteChild; while (currentAbsoluteChild != NULL) { // Pre-fill dimensions when using absolute position and both offsets for // the axis are defined (either both left and right or top and bottom). for (ii = 0; ii < 2; ii++) { axis = (ii != 0) ? CSS_FLEX_DIRECTION_ROW : CSS_FLEX_DIRECTION_COLUMN; if (!isUndefined(node->layout.dimensions[dim[axis]]) && !isDimDefined(currentAbsoluteChild, axis) && isPosDefined(currentAbsoluteChild, leading[axis]) && isPosDefined(currentAbsoluteChild, trailing[axis])) { currentAbsoluteChild->layout.dimensions[dim[axis]] = fmaxf( boundAxis(currentAbsoluteChild, axis, node->layout.dimensions[dim[axis]] - getBorderAxis(node, axis) - getMarginAxis(currentAbsoluteChild, axis) - getPosition(currentAbsoluteChild, leading[axis]) - getPosition(currentAbsoluteChild, trailing[axis]) ), // You never want to go smaller than padding getPaddingAndBorderAxis(currentAbsoluteChild, axis) ); } if (isPosDefined(currentAbsoluteChild, trailing[axis]) && !isPosDefined(currentAbsoluteChild, leading[axis])) { currentAbsoluteChild->layout.position[leading[axis]] = node->layout.dimensions[dim[axis]] - currentAbsoluteChild->layout.dimensions[dim[axis]] - getPosition(currentAbsoluteChild, trailing[axis]); } } child = currentAbsoluteChild; currentAbsoluteChild = currentAbsoluteChild->next_absolute_child; child->next_absolute_child = NULL; } /** END_GENERATED **/ }
static void layoutNodeImpl(css_node_t *node, float parentMaxWidth, css_direction_t parentDirection) { /** START_GENERATED **/ css_direction_t direction = resolveDirection(node, parentDirection); css_flex_direction_t mainAxis = resolveAxis(getFlexDirection(node), direction); css_flex_direction_t crossAxis = getCrossFlexDirection(mainAxis, direction); css_flex_direction_t resolvedRowAxis = resolveAxis(CSS_FLEX_DIRECTION_ROW, direction); // Handle width and height style attributes setDimensionFromStyle(node, mainAxis); setDimensionFromStyle(node, crossAxis); // The position is set by the parent, but we need to complete it with a // delta composed of the margin and left/top/right/bottom node->layout.position[leading[mainAxis]] += getMargin(node, leading[mainAxis]) + getRelativePosition(node, mainAxis); node->layout.position[trailing[mainAxis]] += getMargin(node, trailing[mainAxis]) + getRelativePosition(node, mainAxis); node->layout.position[leading[crossAxis]] += getMargin(node, leading[crossAxis]) + getRelativePosition(node, crossAxis); node->layout.position[trailing[crossAxis]] += getMargin(node, trailing[crossAxis]) + getRelativePosition(node, crossAxis); if (isMeasureDefined(node)) { float width = CSS_UNDEFINED; if (isDimDefined(node, resolvedRowAxis)) { width = node->style.dimensions[CSS_WIDTH]; } else if (!isUndefined(node->layout.dimensions[dim[resolvedRowAxis]])) { width = node->layout.dimensions[dim[resolvedRowAxis]]; } else { width = parentMaxWidth - getMarginAxis(node, resolvedRowAxis); } width -= getPaddingAndBorderAxis(node, resolvedRowAxis); // We only need to give a dimension for the text if we haven't got any // for it computed yet. It can either be from the style attribute or because // the element is flexible. bool isRowUndefined = !isDimDefined(node, resolvedRowAxis) && isUndefined(node->layout.dimensions[dim[resolvedRowAxis]]); bool isColumnUndefined = !isDimDefined(node, CSS_FLEX_DIRECTION_COLUMN) && isUndefined(node->layout.dimensions[dim[CSS_FLEX_DIRECTION_COLUMN]]); // Let's not measure the text if we already know both dimensions if (isRowUndefined || isColumnUndefined) { css_dim_t measureDim = node->measure( node->context, width ); if (isRowUndefined) { node->layout.dimensions[CSS_WIDTH] = measureDim.dimensions[CSS_WIDTH] + getPaddingAndBorderAxis(node, resolvedRowAxis); } if (isColumnUndefined) { node->layout.dimensions[CSS_HEIGHT] = measureDim.dimensions[CSS_HEIGHT] + getPaddingAndBorderAxis(node, CSS_FLEX_DIRECTION_COLUMN); } } return; } int i; int ii; css_node_t* child; css_flex_direction_t axis; // Pre-fill some dimensions straight from the parent for (i = 0; i < node->children_count; ++i) { child = node->get_child(node->context, i); // Pre-fill cross axis dimensions when the child is using stretch before // we call the recursive layout pass if (getAlignItem(node, child) == CSS_ALIGN_STRETCH && getPositionType(child) == CSS_POSITION_RELATIVE && !isUndefined(node->layout.dimensions[dim[crossAxis]]) && !isDimDefined(child, crossAxis)) { child->layout.dimensions[dim[crossAxis]] = fmaxf( boundAxis(child, crossAxis, node->layout.dimensions[dim[crossAxis]] - getPaddingAndBorderAxis(node, crossAxis) - getMarginAxis(child, crossAxis)), // You never want to go smaller than padding getPaddingAndBorderAxis(child, crossAxis) ); } else if (getPositionType(child) == CSS_POSITION_ABSOLUTE) { // Pre-fill dimensions when using absolute position and both offsets for the axis are defined (either both // left and right or top and bottom). for (ii = 0; ii < 2; ii++) { axis = (ii != 0) ? CSS_FLEX_DIRECTION_ROW : CSS_FLEX_DIRECTION_COLUMN; if (!isUndefined(node->layout.dimensions[dim[axis]]) && !isDimDefined(child, axis) && isPosDefined(child, leading[axis]) && isPosDefined(child, trailing[axis])) { child->layout.dimensions[dim[axis]] = fmaxf( boundAxis(child, axis, node->layout.dimensions[dim[axis]] - getPaddingAndBorderAxis(node, axis) - getMarginAxis(child, axis) - getPosition(child, leading[axis]) - getPosition(child, trailing[axis])), // You never want to go smaller than padding getPaddingAndBorderAxis(child, axis) ); } } } } float definedMainDim = CSS_UNDEFINED; if (!isUndefined(node->layout.dimensions[dim[mainAxis]])) { definedMainDim = node->layout.dimensions[dim[mainAxis]] - getPaddingAndBorderAxis(node, mainAxis); } // We want to execute the next two loops one per line with flex-wrap int startLine = 0; int endLine = 0; // int nextOffset = 0; int alreadyComputedNextLayout = 0; // We aggregate the total dimensions of the container in those two variables float linesCrossDim = 0; float linesMainDim = 0; while (endLine < node->children_count) { // <Loop A> Layout non flexible children and count children by type // mainContentDim is accumulation of the dimensions and margin of all the // non flexible children. This will be used in order to either set the // dimensions of the node if none already exist, or to compute the // remaining space left for the flexible children. float mainContentDim = 0; // There are three kind of children, non flexible, flexible and absolute. // We need to know how many there are in order to distribute the space. int flexibleChildrenCount = 0; float totalFlexible = 0; int nonFlexibleChildrenCount = 0; float maxWidth; for (i = startLine; i < node->children_count; ++i) { child = node->get_child(node->context, i); float nextContentDim = 0; // It only makes sense to consider a child flexible if we have a computed // dimension for the node-> if (!isUndefined(node->layout.dimensions[dim[mainAxis]]) && isFlex(child)) { flexibleChildrenCount++; totalFlexible += getFlex(child); // Even if we don't know its exact size yet, we already know the padding, // border and margin. We'll use this partial information, which represents // the smallest possible size for the child, to compute the remaining // available space. nextContentDim = getPaddingAndBorderAxis(child, mainAxis) + getMarginAxis(child, mainAxis); } else { maxWidth = CSS_UNDEFINED; if (!isRowDirection(mainAxis)) { maxWidth = parentMaxWidth - getMarginAxis(node, resolvedRowAxis) - getPaddingAndBorderAxis(node, resolvedRowAxis); if (isDimDefined(node, resolvedRowAxis)) { maxWidth = node->layout.dimensions[dim[resolvedRowAxis]] - getPaddingAndBorderAxis(node, resolvedRowAxis); } } // This is the main recursive call. We layout non flexible children. if (alreadyComputedNextLayout == 0) { layoutNode(child, maxWidth, direction); } // Absolute positioned elements do not take part of the layout, so we // don't use them to compute mainContentDim if (getPositionType(child) == CSS_POSITION_RELATIVE) { nonFlexibleChildrenCount++; // At this point we know the final size and margin of the element. nextContentDim = getDimWithMargin(child, mainAxis); } } // The element we are about to add would make us go to the next line if (isFlexWrap(node) && !isUndefined(node->layout.dimensions[dim[mainAxis]]) && mainContentDim + nextContentDim > definedMainDim && // If there's only one element, then it's bigger than the content // and needs its own line i != startLine) { nonFlexibleChildrenCount--; alreadyComputedNextLayout = 1; break; } alreadyComputedNextLayout = 0; mainContentDim += nextContentDim; endLine = i + 1; } // <Loop B> Layout flexible children and allocate empty space // In order to position the elements in the main axis, we have two // controls. The space between the beginning and the first element // and the space between each two elements. float leadingMainDim = 0; float betweenMainDim = 0; // The remaining available space that needs to be allocated float remainingMainDim = 0; if (!isUndefined(node->layout.dimensions[dim[mainAxis]])) { remainingMainDim = definedMainDim - mainContentDim; } else { remainingMainDim = fmaxf(mainContentDim, 0) - mainContentDim; } // If there are flexible children in the mix, they are going to fill the // remaining space if (flexibleChildrenCount != 0) { float flexibleMainDim = remainingMainDim / totalFlexible; float baseMainDim; float boundMainDim; // Iterate over every child in the axis. If the flex share of remaining // space doesn't meet min/max bounds, remove this child from flex // calculations. for (i = startLine; i < endLine; ++i) { child = node->get_child(node->context, i); if (isFlex(child)) { baseMainDim = flexibleMainDim * getFlex(child) + getPaddingAndBorderAxis(child, mainAxis); boundMainDim = boundAxis(child, mainAxis, baseMainDim); if (baseMainDim != boundMainDim) { remainingMainDim -= boundMainDim; totalFlexible -= getFlex(child); } } } flexibleMainDim = remainingMainDim / totalFlexible; // The non flexible children can overflow the container, in this case // we should just assume that there is no space available. if (flexibleMainDim < 0) { flexibleMainDim = 0; } // We iterate over the full array and only apply the action on flexible // children. This is faster than actually allocating a new array that // contains only flexible children. for (i = startLine; i < endLine; ++i) { child = node->get_child(node->context, i); if (isFlex(child)) { // At this point we know the final size of the element in the main // dimension child->layout.dimensions[dim[mainAxis]] = boundAxis(child, mainAxis, flexibleMainDim * getFlex(child) + getPaddingAndBorderAxis(child, mainAxis) ); maxWidth = CSS_UNDEFINED; if (isDimDefined(node, resolvedRowAxis)) { maxWidth = node->layout.dimensions[dim[resolvedRowAxis]] - getPaddingAndBorderAxis(node, resolvedRowAxis); } else if (!isRowDirection(mainAxis)) { maxWidth = parentMaxWidth - getMarginAxis(node, resolvedRowAxis) - getPaddingAndBorderAxis(node, resolvedRowAxis); } // And we recursively call the layout algorithm for this child layoutNode(child, maxWidth, direction); } } // We use justifyContent to figure out how to allocate the remaining // space available } else { css_justify_t justifyContent = getJustifyContent(node); if (justifyContent == CSS_JUSTIFY_CENTER) { leadingMainDim = remainingMainDim / 2; } else if (justifyContent == CSS_JUSTIFY_FLEX_END) { leadingMainDim = remainingMainDim; } else if (justifyContent == CSS_JUSTIFY_SPACE_BETWEEN) { remainingMainDim = fmaxf(remainingMainDim, 0); if (flexibleChildrenCount + nonFlexibleChildrenCount - 1 != 0) { betweenMainDim = remainingMainDim / (flexibleChildrenCount + nonFlexibleChildrenCount - 1); } else { betweenMainDim = 0; } } else if (justifyContent == CSS_JUSTIFY_SPACE_AROUND) { // Space on the edges is half of the space between elements betweenMainDim = remainingMainDim / (flexibleChildrenCount + nonFlexibleChildrenCount); leadingMainDim = betweenMainDim / 2; } } // <Loop C> Position elements in the main axis and compute dimensions // At this point, all the children have their dimensions set. We need to // find their position. In order to do that, we accumulate data in // variables that are also useful to compute the total dimensions of the // container! float crossDim = 0; float mainDim = leadingMainDim + getPaddingAndBorder(node, leading[mainAxis]); for (i = startLine; i < endLine; ++i) { child = node->get_child(node->context, i); if (getPositionType(child) == CSS_POSITION_ABSOLUTE && isPosDefined(child, leading[mainAxis])) { // In case the child is position absolute and has left/top being // defined, we override the position to whatever the user said // (and margin/border). child->layout.position[pos[mainAxis]] = getPosition(child, leading[mainAxis]) + getBorder(node, leading[mainAxis]) + getMargin(child, leading[mainAxis]); } else { // If the child is position absolute (without top/left) or relative, // we put it at the current accumulated offset. child->layout.position[pos[mainAxis]] += mainDim; // Define the trailing position accordingly. if (!isUndefined(node->layout.dimensions[dim[mainAxis]])) { setTrailingPosition(node, child, mainAxis); } } // Now that we placed the element, we need to update the variables // We only need to do that for relative elements. Absolute elements // do not take part in that phase. if (getPositionType(child) == CSS_POSITION_RELATIVE) { // The main dimension is the sum of all the elements dimension plus // the spacing. mainDim += betweenMainDim + getDimWithMargin(child, mainAxis); // The cross dimension is the max of the elements dimension since there // can only be one element in that cross dimension. crossDim = fmaxf(crossDim, boundAxis(child, crossAxis, getDimWithMargin(child, crossAxis))); } } float containerCrossAxis = node->layout.dimensions[dim[crossAxis]]; if (isUndefined(node->layout.dimensions[dim[crossAxis]])) { containerCrossAxis = fmaxf( // For the cross dim, we add both sides at the end because the value // is aggregate via a max function. Intermediate negative values // can mess this computation otherwise boundAxis(node, crossAxis, crossDim + getPaddingAndBorderAxis(node, crossAxis)), getPaddingAndBorderAxis(node, crossAxis) ); } // <Loop D> Position elements in the cross axis for (i = startLine; i < endLine; ++i) { child = node->get_child(node->context, i); if (getPositionType(child) == CSS_POSITION_ABSOLUTE && isPosDefined(child, leading[crossAxis])) { // In case the child is absolutely positionned and has a // top/left/bottom/right being set, we override all the previously // computed positions to set it correctly. child->layout.position[pos[crossAxis]] = getPosition(child, leading[crossAxis]) + getBorder(node, leading[crossAxis]) + getMargin(child, leading[crossAxis]); } else { float leadingCrossDim = getPaddingAndBorder(node, leading[crossAxis]); // For a relative children, we're either using alignItems (parent) or // alignSelf (child) in order to determine the position in the cross axis if (getPositionType(child) == CSS_POSITION_RELATIVE) { css_align_t alignItem = getAlignItem(node, child); if (alignItem == CSS_ALIGN_STRETCH) { // You can only stretch if the dimension has not already been set // previously. if (!isDimDefined(child, crossAxis)) { child->layout.dimensions[dim[crossAxis]] = fmaxf( boundAxis(child, crossAxis, containerCrossAxis - getPaddingAndBorderAxis(node, crossAxis) - getMarginAxis(child, crossAxis)), // You never want to go smaller than padding getPaddingAndBorderAxis(child, crossAxis) ); } } else if (alignItem != CSS_ALIGN_FLEX_START) { // The remaining space between the parent dimensions+padding and child // dimensions+margin. float remainingCrossDim = containerCrossAxis - getPaddingAndBorderAxis(node, crossAxis) - getDimWithMargin(child, crossAxis); if (alignItem == CSS_ALIGN_CENTER) { leadingCrossDim += remainingCrossDim / 2; } else { // CSS_ALIGN_FLEX_END leadingCrossDim += remainingCrossDim; } } } // And we apply the position child->layout.position[pos[crossAxis]] += linesCrossDim + leadingCrossDim; } } linesCrossDim += crossDim; linesMainDim = fmaxf(linesMainDim, mainDim); startLine = endLine; } // If the user didn't specify a width or height, and it has not been set // by the container, then we set it via the children. if (isUndefined(node->layout.dimensions[dim[mainAxis]])) { node->layout.dimensions[dim[mainAxis]] = fmaxf( // We're missing the last padding at this point to get the final // dimension boundAxis(node, mainAxis, linesMainDim + getPaddingAndBorder(node, trailing[mainAxis])), // We can never assign a width smaller than the padding and borders getPaddingAndBorderAxis(node, mainAxis) ); // Now that the width is defined, we should update the trailing // positions for the children. for (i = 0; i < node->children_count; ++i) { setTrailingPosition(node, node->get_child(node->context, i), mainAxis); } } if (isUndefined(node->layout.dimensions[dim[crossAxis]])) { node->layout.dimensions[dim[crossAxis]] = fmaxf( // For the cross dim, we add both sides at the end because the value // is aggregate via a max function. Intermediate negative values // can mess this computation otherwise boundAxis(node, crossAxis, linesCrossDim + getPaddingAndBorderAxis(node, crossAxis)), getPaddingAndBorderAxis(node, crossAxis) ); } // <Loop E> Calculate dimensions for absolutely positioned elements for (i = 0; i < node->children_count; ++i) { child = node->get_child(node->context, i); if (getPositionType(child) == CSS_POSITION_ABSOLUTE) { // Pre-fill dimensions when using absolute position and both offsets for the axis are defined (either both // left and right or top and bottom). for (ii = 0; ii < 2; ii++) { axis = (ii != 0) ? CSS_FLEX_DIRECTION_ROW : CSS_FLEX_DIRECTION_COLUMN; if (!isUndefined(node->layout.dimensions[dim[axis]]) && !isDimDefined(child, axis) && isPosDefined(child, leading[axis]) && isPosDefined(child, trailing[axis])) { child->layout.dimensions[dim[axis]] = fmaxf( boundAxis(child, axis, node->layout.dimensions[dim[axis]] - getBorderAxis(node, axis) - getMarginAxis(child, axis) - getPosition(child, leading[axis]) - getPosition(child, trailing[axis]) ), // You never want to go smaller than padding getPaddingAndBorderAxis(child, axis) ); } } for (ii = 0; ii < 2; ii++) { axis = (ii != 0) ? CSS_FLEX_DIRECTION_ROW : CSS_FLEX_DIRECTION_COLUMN; if (isPosDefined(child, trailing[axis]) && !isPosDefined(child, leading[axis])) { child->layout.position[leading[axis]] = node->layout.dimensions[dim[axis]] - child->layout.dimensions[dim[axis]] - getPosition(child, trailing[axis]); } } } } /** END_GENERATED **/ }