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Tutorial 03 Colors And Transparency

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Dries Horions edited this page Feb 13, 2026 · 1 revision

Tutorial 03: Colors and Transparency

This tutorial demonstrates:

  • Setting cell fill colors (background)
  • Setting text colors
  • Using the alpha channel for transparency
  • Creating visual effects with color combinations
  • RGB and RGBA color specifications

View Source on GitHub | Download PDF

Tutorial03_ColorsAndTransparency

Source Code

package be.quodlibet.boxable.tutorial;

import be.quodlibet.boxable.BaseTable;
import be.quodlibet.boxable.Cell;
import be.quodlibet.boxable.HorizontalAlignment;
import be.quodlibet.boxable.Row;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.common.PDRectangle;
import org.apache.pdfbox.pdmodel.font.PDType1Font;
import org.apache.pdfbox.pdmodel.font.Standard14Fonts;
import org.junit.Test;

import java.awt.Color;
import java.io.File;
import java.io.IOException;

/**
 * Tutorial 03: Colors and Transparency
 * 
 * This tutorial demonstrates:
 * - Setting cell fill colors (background)
 * - Setting text colors
 * - Using the alpha channel for transparency
 * - Creating visual effects with color combinations
 * - RGB and RGBA color specifications
 */
public class Tutorial03_ColorsAndTransparency {

    @Test
    public void demonstrateColorsAndTransparency() throws IOException {
        // Initialize PDF Document
        PDDocument document = new PDDocument();
        PDPage page = new PDPage(PDRectangle.A4);
        document.addPage(page);

        // Define table dimensions
        float margin = 50;
        float yStart = page.getMediaBox().getHeight() - margin;
        float tableWidth = page.getMediaBox().getWidth() - (2 * margin);
        float yStartNewPage = page.getMediaBox().getHeight() - margin;
        float bottomMargin = 70;

        // Create the table
        BaseTable table = new BaseTable(yStart, yStartNewPage, bottomMargin, 
                                        tableWidth, margin, document, page, 
                                        true, true);

        // Title Row
        Row<PDPage> titleRow = table.createRow(30f);
        Cell<PDPage> titleCell = titleRow.createCell(100, "Tutorial 03: Colors and Transparency");
        titleCell.setFont(new PDType1Font(Standard14Fonts.FontName.HELVETICA_BOLD));
        titleCell.setFontSize(16f);
        titleCell.setFillColor(new Color(155, 89, 182));  // Purple background
        titleCell.setTextColor(Color.WHITE);
        titleCell.setAlign(HorizontalAlignment.CENTER);

        // Description
        Row<PDPage> descRow = table.createRow(20f);
        Cell<PDPage> descCell = descRow.createCell(100, 
            "Explore RGB colors, text colors, and alpha channel transparency effects.");
        descCell.setFillColor(new Color(236, 240, 241));
        descCell.setAlign(HorizontalAlignment.CENTER);

        // Section 1: Basic RGB Colors
        addSectionHeader(table, "Basic RGB Colors");
        
        Row<PDPage> rgbHeader = table.createRow(15f);
        rgbHeader.createCell(25, "Color Name");
        rgbHeader.createCell(25, "RGB Values");
        rgbHeader.createCell(25, "Fill Color");
        rgbHeader.createCell(25, "Text Color");
        styleHeaderRow(rgbHeader);

        // Red
        addColorRow(table, "Red", "255, 0, 0", 
                   new Color(255, 0, 0), new Color(255, 0, 0));
        
        // Green
        addColorRow(table, "Green", "0, 255, 0", 
                   new Color(0, 255, 0), new Color(0, 128, 0));
        
        // Blue
        addColorRow(table, "Blue", "0, 0, 255", 
                   new Color(0, 0, 255), new Color(0, 0, 255));
        
        // Yellow
        addColorRow(table, "Yellow", "255, 255, 0", 
                   new Color(255, 255, 0), new Color(184, 134, 11));
        
        // Cyan
        addColorRow(table, "Cyan", "0, 255, 255", 
                   new Color(0, 255, 255), new Color(0, 139, 139));
        
        // Magenta
        addColorRow(table, "Magenta", "255, 0, 255", 
                   new Color(255, 0, 255), new Color(139, 0, 139));

        // Section 2: Transparency (Alpha Channel)
        addSectionHeader(table, "Transparency with Alpha Channel");
        
        Row<PDPage> alphaHeader = table.createRow(15f);
        alphaHeader.createCell(25, "Description");
        alphaHeader.createCell(25, "Alpha Value");
        alphaHeader.createCell(50, "Visual Effect");
        styleHeaderRow(alphaHeader);

        // Demonstrate different alpha values
        addAlphaRow(table, "Opaque Red", "255 (100%)", 
                   new Color(255, 0, 0, 255));
        
        addAlphaRow(table, "Semi-Transparent Red", "180 (70%)", 
                   new Color(255, 0, 0, 180));
        
        addAlphaRow(table, "Half-Transparent Red", "128 (50%)", 
                   new Color(255, 0, 0, 128));
        
        addAlphaRow(table, "Very Transparent Red", "50 (20%)", 
                   new Color(255, 0, 0, 50));

        // Section 3: Color Combinations
        addSectionHeader(table, "Text and Background Color Combinations");
        
        Row<PDPage> comboHeader = table.createRow(15f);
        comboHeader.createCell(50, "Background Color");
        comboHeader.createCell(50, "Text Color Example");
        styleHeaderRow(comboHeader);

        addCombinationRow(table, new Color(41, 128, 185), Color.WHITE, "White on Blue");
        addCombinationRow(table, new Color(46, 204, 113), Color.BLACK, "Black on Green");
        addCombinationRow(table, new Color(241, 196, 15), Color.BLACK, "Black on Yellow");
        addCombinationRow(table, new Color(52, 73, 94), Color.WHITE, "White on Dark Gray");
        addCombinationRow(table, new Color(236, 240, 241), Color.BLACK, "Black on Light Gray");
        addCombinationRow(table, new Color(231, 76, 60), Color.WHITE, "White on Red");

        // Section 4: Gradient-like effects
        addSectionHeader(table, "Simulated Gradient Effect (Using Alpha)");
        
        Row<PDPage> gradientDesc = table.createRow(15f);
        Cell<PDPage> gradCell = gradientDesc.createCell(100, 
            "By varying alpha values, we can create gradient-like visual effects:");
        gradCell.setFillColor(Color.WHITE);

        // Create gradient effect with different alpha values
        for (int i = 0; i <= 5; i++) {
            int alpha = 255 - (i * 40);  // Decreasing opacity
            Row<PDPage> gradRow = table.createRow(12f);
            Cell<PDPage> cell = gradRow.createCell(100, 
                String.format("Level %d - Alpha: %d", i + 1, alpha));
            cell.setFillColor(new Color(52, 152, 219, alpha));
            if (alpha < 150) {
                cell.setTextColor(Color.BLACK);
            } else {
                cell.setTextColor(Color.WHITE);
            }
        }

        // Draw the table
        table.draw();

        // Save the document
        File file = new File("target/tutorials/Tutorial03_ColorsAndTransparency.pdf");
        System.out.println("Tutorial 03 PDF saved at: " + file.getAbsolutePath());
        file.getParentFile().mkdirs();
        document.save(file);
        document.close();
    }

    /**
     * Helper method to add a section header
     */
    private void addSectionHeader(BaseTable table, String title) throws IOException {
        Row<PDPage> sectionRow = table.createRow(18f);
        Cell<PDPage> sectionCell = sectionRow.createCell(100, title);
        sectionCell.setFillColor(new Color(44, 62, 80));
        sectionCell.setTextColor(Color.WHITE);
        sectionCell.setFont(new PDType1Font(Standard14Fonts.FontName.HELVETICA_BOLD));
        sectionCell.setAlign(HorizontalAlignment.CENTER);
    }

    /**
     * Helper method to style header rows
     */
    private void styleHeaderRow(Row<PDPage> row) {
        Color headerColor = new Color(52, 73, 94);
        for (Cell<PDPage> cell : row.getCells()) {
            cell.setFillColor(headerColor);
            cell.setTextColor(Color.WHITE);
            cell.setFont(new PDType1Font(Standard14Fonts.FontName.HELVETICA_BOLD));
        }
    }

    /**
     * Helper method to add a color demonstration row
     */
    private void addColorRow(BaseTable table, String name, String rgb, 
                            Color fillColor, Color textColor) throws IOException {
        Row<PDPage> row = table.createRow(15f);
        row.createCell(25, name);
        row.createCell(25, rgb);
        
        Cell<PDPage> fillCell = row.createCell(25, "Sample");
        fillCell.setFillColor(fillColor);
        fillCell.setTextColor(Color.WHITE);
        fillCell.setAlign(HorizontalAlignment.CENTER);
        
        Cell<PDPage> textCell = row.createCell(25, "Sample Text");
        textCell.setTextColor(textColor);
        textCell.setAlign(HorizontalAlignment.CENTER);
    }

    /**
     * Helper method to add an alpha/transparency demonstration row
     */
    private void addAlphaRow(BaseTable table, String description, String alphaValue, 
                            Color color) throws IOException {
        Row<PDPage> row = table.createRow(15f);
        row.createCell(25, description);
        row.createCell(25, alphaValue);
        
        Cell<PDPage> visualCell = row.createCell(50, "This cell shows the transparency effect");
        visualCell.setFillColor(color);
        visualCell.setAlign(HorizontalAlignment.CENTER);
    }

    /**
     * Helper method to add a color combination row
     */
    private void addCombinationRow(BaseTable table, Color bgColor, Color textColor, 
                                  String text) throws IOException {
        Row<PDPage> row = table.createRow(15f);
        
        Cell<PDPage> bgCell = row.createCell(50, "Background Sample");
        bgCell.setFillColor(bgColor);
        bgCell.setTextColor(Color.WHITE);
        bgCell.setAlign(HorizontalAlignment.CENTER);
        
        Cell<PDPage> textCell = row.createCell(50, text);
        textCell.setFillColor(bgColor);
        textCell.setTextColor(textColor);
        textCell.setAlign(HorizontalAlignment.CENTER);
    }
}

Special thanks to :

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Copyright 2026

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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