zcatpdf/examples/gradient_demo.zig

//! Gradient Demo - Linear and Radial Gradients
//!
//! Demonstrates gradient fills for rectangles, circles and ellipses.

const std = @import("std");
const zpdf = @import("zpdf");
const Pdf = zpdf.Pdf;
const Color = zpdf.Color;
const GradientDirection = zpdf.GradientDirection;

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    var pdf = Pdf.init(allocator, .{});
    defer pdf.deinit();

    pdf.setTitle("Gradient Demo");
    pdf.setAuthor("zpdf");

    var page = try pdf.addPage(.{});

    // Title
    try page.setFont(.helvetica_bold, 28);
    page.setFillColor(Color.hex(0x333333));
    try page.drawText(50, 780, "Gradient Demo");

    try page.setFont(.helvetica, 12);
    page.setFillColor(Color.hex(0x666666));
    try page.drawText(50, 760, "Linear and radial gradients in zpdf");

    // Section 1: Linear Gradients
    try page.setFont(.helvetica_bold, 16);
    page.setFillColor(Color.black);
    try page.drawText(50, 720, "Linear Gradients");

    // Horizontal gradient (left to right)
    try page.setFont(.helvetica, 10);
    try page.drawText(50, 700, "Horizontal (Red to Blue)");
    try page.linearGradientRect(50, 620, 150, 70, Color.red, Color.blue, .horizontal);

    // Vertical gradient (bottom to top)
    try page.drawText(220, 700, "Vertical (Green to Yellow)");
    try page.linearGradientRect(220, 620, 150, 70, Color.green, Color.yellow, .vertical);

    // Diagonal gradient
    try page.drawText(390, 700, "Diagonal (Purple to Cyan)");
    try page.linearGradientRect(390, 620, 150, 70, Color.hex(0x800080), Color.cyan, .diagonal);

    // Section 2: Radial Gradients
    try page.setFont(.helvetica_bold, 16);
    try page.drawText(50, 580, "Radial Gradients");

    // Radial gradient circle
    try page.setFont(.helvetica, 10);
    try page.drawText(50, 555, "Circle (White to Blue)");
    try page.radialGradientCircle(125, 490, 50, Color.white, Color.blue);

    // Radial gradient with warm colors
    try page.drawText(220, 555, "Circle (Yellow to Red)");
    try page.radialGradientCircle(295, 490, 50, Color.yellow, Color.red);

    // Dark theme circle
    try page.drawText(390, 555, "Circle (Cyan to Dark)");
    try page.radialGradientCircle(465, 490, 50, Color.cyan, Color.hex(0x001122));

    // Section 3: Ellipse Gradients
    try page.setFont(.helvetica_bold, 16);
    try page.drawText(50, 410, "Ellipse Gradients");

    // Horizontal ellipse
    try page.setFont(.helvetica, 10);
    try page.drawText(50, 385, "Horizontal Ellipse");
    try page.radialGradientEllipse(125, 330, 70, 40, Color.white, Color.hex(0xFF6600));

    // Vertical ellipse
    try page.drawText(220, 385, "Vertical Ellipse");
    try page.radialGradientEllipse(295, 330, 40, 55, Color.hex(0xFFFF99), Color.hex(0x006600));

    // Wide ellipse
    try page.drawText(390, 385, "Wide Ellipse");
    try page.radialGradientEllipse(465, 330, 80, 35, Color.hex(0xFFCCFF), Color.hex(0x660066));

    // Section 4: Real-world examples
    try page.setFont(.helvetica_bold, 16);
    try page.drawText(50, 250, "Real-world Examples");

    // Button effect with gradient
    try page.setFont(.helvetica, 10);
    try page.drawText(50, 225, "Button Effect");
    try page.linearGradientRect(50, 180, 120, 35, Color.hex(0x4A90D9), Color.hex(0x2E5C8A), .vertical);
    // Button text
    try page.setFont(.helvetica_bold, 12);
    page.setFillColor(Color.white);
    try page.drawText(78, 193, "Click Me");

    // Metallic effect
    try page.setFont(.helvetica, 10);
    page.setFillColor(Color.black);
    try page.drawText(200, 225, "Metallic Bar");
    try page.linearGradientRect(200, 180, 120, 35, Color.hex(0xC0C0C0), Color.hex(0x606060), .vertical);

    // Sunset gradient
    try page.drawText(350, 225, "Sunset");
    try page.linearGradientRect(350, 180, 120, 35, Color.hex(0xFF6600), Color.hex(0x330066), .horizontal);

    // Orb/sphere effect
    try page.drawText(500, 225, "Sphere");
    try page.radialGradientCircle(535, 197, 25, Color.white, Color.hex(0x0066CC));

    // Footer
    try page.setFont(.helvetica_oblique, 10);
    page.setFillColor(Color.hex(0x999999));
    try page.drawText(50, 50, "Generated with zpdf - Linear and Radial Gradient Support");

    try pdf.save("gradient_demo.pdf");

    std.debug.print("Generated gradient_demo.pdf\n", .{});
}