java - iText 5 : create PdfPcell containing 2 background colors with text overlap

Question

在 java 中使用 iText5 并希望对 PdfPcell 的结果进行颜色编码，如下所示。例如，该表包括2列和3行。

有人知道如何实现这一目标吗？

我可以简单地使用设置背景颜色

PdfPCell cell = new PdfPCell(new Phrase("60 Pass, 40 Fail", myStyle));
cell.setBackgroundColor(new BaseColor(0xff,0x0,0x0));  // red background

然后，做什么，向单元格添加一个绿色矩形？使用模板？不确定。

Answer 1

您可以通过单元格事件监听器来完成此类“有趣”的单元格功能。

例如对于您的任务，您可以像这样实现 PdfPCellEvent:

public class PercentileCellBackground implements PdfPCellEvent {
    public PercentileCellBackground(float percent, BaseColor leftColor, BaseColor rightColor) {
        this.percent = percent;
        this.leftColor = leftColor;
        this.rightColor = rightColor;
    }

    @Override
    public void cellLayout(PdfPCell cell, Rectangle position, PdfContentByte[] canvases) {
        PdfContentByte canvas = canvases[PdfPTable.BACKGROUNDCANVAS];

        float xTransition = position.getLeft() + (position.getRight() - position.getLeft()) * (percent/100.0f);
        float yTransition = (position.getTop() + position.getBottom()) / 2f;
        float radius = (position.getRight() - position.getLeft()) * 0.025f;
        PdfShading axial = PdfShading.simpleAxial(canvas.getPdfWriter(),
                xTransition - radius, yTransition, xTransition + radius, yTransition, leftColor, rightColor);
        PdfShadingPattern shading = new PdfShadingPattern(axial);

        canvas.saveState();
        canvas.setShadingFill(shading);
        canvas.rectangle(position.getLeft(), position.getBottom(), position.getWidth(), position.getHeight());
        canvas.fill();
        canvas.restoreState();
    }

    final float percent;
    final BaseColor leftColor;
    final BaseColor rightColor;
}

( PercentileCellBackground )

然后您可以像这样使用此事件监听器类:

Document document = new Document();
try (OutputStream os = new FileOutputStream(new File(RESULT_FOLDER, "TableWithCellsWithPercentileBackground.pdf"))) {
    PdfWriter.getInstance(document, os);
    document.open();

    Font font = new Font(FontFamily.UNDEFINED, Font.UNDEFINED, Font.UNDEFINED, BaseColor.WHITE);
    PdfPTable table = new PdfPTable(2);
    table.setWidthPercentage(40);
    PdfPCell cell = new PdfPCell(new Phrase("Group A"));
    table.addCell(cell);
    cell = new PdfPCell(new Phrase(new Chunk("60 Pass, 40 Fail", font)));
    cell.setCellEvent(new PercentileCellBackground(60, BaseColor.GREEN, BaseColor.RED));
    table.addCell(cell);
    cell = new PdfPCell(new Phrase("Group B"));
    table.addCell(cell);
    cell = new PdfPCell(new Phrase(new Chunk("70 Pass, 30 Fail", font)));
    cell.setCellEvent(new PercentileCellBackground(70, BaseColor.GREEN, BaseColor.RED));
    table.addCell(cell);
    cell = new PdfPCell(new Phrase("Group C"));
    table.addCell(cell);
    cell = new PdfPCell(new Phrase(new Chunk("50 Pass, 50 Fail", font)));
    cell.setCellEvent(new PercentileCellBackground(50, BaseColor.GREEN, BaseColor.RED));
    table.addCell(cell);
    document.add(table);

    document.close();
}

( CellsWithPercentileBackground 测试 testCreateTableWithCellsWithPercentileBackground)

结果如下所示:

如您所见，我使用了阴影来使绿色/红色过渡不那么刺眼。如果您想要更粗糙，请减小事件 cellLayout 方法中的半径系数 0.025f 或使用其中的矩形绘制指令。