如何使用颜色调色板

颜色和调色板

调色板是在创建图像时可用的颜色数量。在演示文稿中使用标准调色板可以让用户创建一致的外观。每个Microsoft Excel（97-2003）文件都有一个包含可应用于单元格、字体、网格线、图形对象、填充和图表中的线条的56种颜色的调色板。

使用Aspose.Cells for JavaScript via C++，不仅可以使用调色板的现有颜色，还可以添加自定义颜色。在使用自定义颜色之前，先将其添加到调色板中。

本主题讨论如何向调色板中添加自定义颜色。

向调色板添加自定义颜色

Aspose.Cells 支持 Microsoft Excel 的 56 种颜色调色板。要使用在调色板中未定义的自定义颜色，需要将颜色添加到调色板中。

Aspose.Cells 提供一个类 Workbook，代表一个 Microsoft Excel 文件。Workbook 类提供一个 changePalette(Color, number) 方法，接受以下参数以添加自定义颜色以修改调色板：

  • Custom Color，要添加的自定义颜色。
  • Index，自定义颜色在调色板中的索引，将替换指定的颜色。应该在 0-55 之间。

下面的示例在应用于字体之前向调色板中添加了自定义颜色（兰花紫）。

<!DOCTYPE html>
<html>
    <head>
        <title>Aspose.Cells Example</title>
    </head>
    <body>
        <h1>Aspose.Cells Example</h1>
        <input type="file" id="fileInput" accept=".xls,.xlsx,.csv" />
        <button id="runExample">Run Example</button>
        <a id="downloadLink" style="display: none;">Download Result</a>
        <div id="result"></div>
    </body>

    <script src="aspose.cells.js.min.js"></script>
    <script type="text/javascript">
        const { Workbook, SaveFormat, Color } = AsposeCells;

        AsposeCells.onReady({
            license: "/lic/aspose.cells.enc",
            fontPath: "/fonts/",
            fontList: [
                "arial.ttf",
                "NotoSansSC-Regular.ttf"
            ]
        }).then(() => {
            console.log("Aspose.Cells initialized");
        });

        document.getElementById('runExample').addEventListener('click', async () => {
            const resultDiv = document.getElementById('result');
            const fileInput = document.getElementById('fileInput');
            if (!fileInput.files.length) {
                resultDiv.innerHTML = '<p style="color: red;">Please select an Excel file.</p>';
                return;
            }

            const file = fileInput.files[0];
            const arrayBuffer = await file.arrayBuffer();

            // Instantiating a Workbook object from the uploaded file
            const workbook = new Workbook(new Uint8Array(arrayBuffer));

            // Checks if a color is in the palette for the spreadsheet.
            const isInPaletteBefore = workbook.isColorInPalette(Color.Orchid);
            console.log(isInPaletteBefore);
            resultDiv.innerHTML = `<p>Is Orchid in palette before change: ${isInPaletteBefore}</p>`;

            // Adding Orchid color to the palette at 55th index
            workbook.changePalette(Color.Orchid, 55);

            const isInPaletteAfter = workbook.isColorInPalette(Color.Orchid);
            console.log(isInPaletteAfter);
            resultDiv.innerHTML += `<p>Is Orchid in palette after change: ${isInPaletteAfter}</p>`;

            // Adding a new worksheet to the Excel object
            const i = workbook.worksheets.add();

            // Obtaining the reference of the newly added worksheet by passing its sheet index
            const worksheet = workbook.worksheets.get(i);

            // Accessing the "A1" cell from the worksheet
            const cell = worksheet.cells.get("A1");

            // Adding some value to the "A1" cell
            cell.putValue("Hello Aspose!");

            // Defining new Style object
            const styleObject = workbook.createStyle();
            // Setting the Orchid (custom) color to the font
            styleObject.font.color = workbook.colors[55];

            // Applying the style to the cell
            cell.style = styleObject;

            // Saving the Excel file
            const outputData = workbook.save(SaveFormat.Xlsx);
            const blob = new Blob([outputData]);
            const downloadLink = document.getElementById('downloadLink');
            downloadLink.href = URL.createObjectURL(blob);
            downloadLink.download = 'out.xlsx';
            downloadLink.style.display = 'block';
            downloadLink.textContent = 'Download Modified Excel File';

            resultDiv.innerHTML += '<p style="color: green;">Operation completed successfully! Click the download link to get the modified file.</p>';
        });
    </script>
</html>
设置 Excel 和 ODS 文件的条件格式 Excel 主题和颜色