Package org.apache.poi.ss.formula

Class ConditionalFormattingEvaluator

  • public class ConditionalFormattingEvaluator
extends Object
    Evaluates Conditional Formatting constraints.

    For performance reasons, this class keeps a cache of all previously evaluated rules and cells. Be sure to call clearAllCachedFormats() if any conditional formats are modified, added, or deleted, and clearAllCachedValues() whenever cell values change.

    • Method Detail

      • clearAllCachedFormats

        public void clearAllCachedFormats()
        Call this whenever rules are added, reordered, or removed, or a rule formula is changed (not the formula inputs but the formula expression itself)

      • clearAllCachedValues

        public void clearAllCachedValues()
        Call this whenever cell values change in the workbook, so condional formats are re-evaluated for all cells.

        TODO: eventually this should work like EvaluationCache.notifyUpdateCell(int, int, EvaluationCell) and only clear values that need recalculation based on the formula dependency tree.

      • getRules

        protected List<EvaluationConditionalFormatRule> getRules​(Sheet sheet)
        lazy load by sheet since reading can be expensive
        Parameters:
        sheet - The sheet to look at
        Returns:
        unmodifiable list of rules

      • getConditionalFormattingForCell

        public List<EvaluationConditionalFormatRule> getConditionalFormattingForCell​(CellReference cellRef)
        This checks all applicable ConditionalFormattingRules for the cell's sheet, in defined "priority" order, returning the matches if any. This is a property currently not exposed from CTCfRule in XSSFConditionalFormattingRule.

        Most cells will have zero or one applied rule, but it is possible to define multiple rules that apply at the same time to the same cell, thus the List result.

        Note that to properly apply conditional rules, care must be taken to offset the base formula by the relative position of the current cell, or the wrong value is checked. This is handled by WorkbookEvaluator.evaluate(String, CellReference, CellRangeAddressBase).

        If the cell exists and is a formula cell, its cached value may be used for rule evaluation, so make sure it is up to date. If values have changed, it is best to call FormulaEvaluator.evaluateFormulaCell(Cell) or FormulaEvaluator.evaluateAll() first, or the wrong conditional results may be returned.

        Parameters:
        cellRef - NOTE: if no sheet name is specified, this uses the workbook active sheet
        Returns:
        Unmodifiable List of EvaluationConditionalFormatRules that apply to the current cell value, in priority order, as evaluated by Excel (smallest priority # for XSSF, definition order for HSSF), or null if none apply

      • getConditionalFormattingForCell

        public List<EvaluationConditionalFormatRule> getConditionalFormattingForCell​(Cell cell)
        This checks all applicable ConditionalFormattingRules for the cell's sheet, in defined "priority" order, returning the matches if any. This is a property currently not exposed from CTCfRule in XSSFConditionalFormattingRule.

        Most cells will have zero or one applied rule, but it is possible to define multiple rules that apply at the same time to the same cell, thus the List result.

        Note that to properly apply conditional rules, care must be taken to offset the base formula by the relative position of the current cell, or the wrong value is checked. This is handled by WorkbookEvaluator.evaluate(String, CellReference, CellRangeAddressBase).

        If the cell exists and is a formula cell, its cached value may be used for rule evaluation, so make sure it is up to date. If values have changed, it is best to call FormulaEvaluator.evaluateFormulaCell(Cell) or FormulaEvaluator.evaluateAll() first, or the wrong conditional results may be returned.

        Parameters:
        cell - The cell to look for
        Returns:
        Unmodifiable List of EvaluationConditionalFormatRules that apply to the current cell value, in priority order, as evaluated by Excel (smallest priority # for XSSF, definition order for HSSF), or null if none apply

      • getFormatRulesForSheet

        public List<EvaluationConditionalFormatRule> getFormatRulesForSheet​(String sheetName)
        Retrieve all formatting rules for the sheet with the given name.
        Parameters:
        sheetName - The name of the sheet to look at
        Returns:
        unmodifiable list of all Conditional format rules for the given sheet, if any

      • getFormatRulesForSheet

        public List<EvaluationConditionalFormatRule> getFormatRulesForSheet​(Sheet sheet)
        Retrieve all formatting rules for the given sheet.
        Parameters:
        sheet - The sheet to look at
        Returns:
        unmodifiable list of all Conditional format rules for the given sheet, if any

      • getMatchingCells

        public List<Cell> getMatchingCells​(Sheet sheet,
                                   int conditionalFormattingIndex,
                                   int ruleIndex)
        Conditional formatting rules can apply only to cells in the sheet to which they are attached. The POI data model does not have a back-reference to the owning sheet, so it must be passed in separately.

        We could overload this with convenience methods taking a sheet name and sheet index as well.

        Parameters:
        sheet - containing the rule
        conditionalFormattingIndex - of the ConditionalFormatting instance in the sheet's array
        ruleIndex - of the ConditionalFormattingRule instance within the ConditionalFormatting
        Returns:
        unmodifiable List of all cells in the rule's region matching the rule's condition

      • getMatchingCells

        public List<Cell> getMatchingCells​(EvaluationConditionalFormatRule rule)
        Retrieve all cells where the given formatting rule evaluates to true.
        Parameters:
        rule - The rule to look at
        Returns:
        unmodifiable List of all cells in the rule's region matching the rule's condition