feat: v0.3 - Image support (JPEG embedding)

Phase 3 - Images:
- JPEG parser with direct DCT passthrough (no re-encoding)
- PNG metadata extraction (full embedding pending)
- Page.image() for drawing images at position
- Page.imageFit() for auto-scaling with aspect ratio
- Pdf.addJpegImage() / addJpegImageFromFile()
- XObject generation in OutputProducer

New modules:
- src/images/mod.zig - Image module exports
- src/images/image_info.zig - ImageInfo struct
- src/images/jpeg.zig - JPEG parser
- src/images/png.zig - PNG metadata parser

New example:
- examples/image_demo.zig - Image embedding demo

Stats:
- 66 unit tests passing
- 4 working examples

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
reugenio 2025-12-08 20:00:56 +01:00
parent 2996289953
commit f9189253d7
11 changed files with 1125 additions and 4 deletions

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@ -80,4 +80,23 @@ pub fn build(b: *std.Build) void {
run_text_demo.step.dependOn(b.getInstallStep());
const text_demo_step = b.step("text_demo", "Run text demo example");
text_demo_step.dependOn(&run_text_demo.step);
// Example: image_demo
const image_demo_exe = b.addExecutable(.{
.name = "image_demo",
.root_module = b.createModule(.{
.root_source_file = b.path("examples/image_demo.zig"),
.target = target,
.optimize = optimize,
.imports = &.{
.{ .name = "zpdf", .module = zpdf_mod },
},
}),
});
b.installArtifact(image_demo_exe);
const run_image_demo = b.addRunArtifact(image_demo_exe);
run_image_demo.step.dependOn(b.getInstallStep());
const image_demo_step = b.step("image_demo", "Run image demo example");
image_demo_step.dependOn(&run_image_demo.step);
}

196
examples/image_demo.zig Normal file
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@ -0,0 +1,196 @@
//! Image Demo - Demonstrates JPEG image embedding
//!
//! Usage: ./image_demo [path_to_jpeg]
//! If no path is provided, creates a simple PDF with text explaining the feature.
const std = @import("std");
const pdf = @import("zpdf");
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const allocator = gpa.allocator();
std.debug.print("zpdf - Image Demo\n", .{});
// Get command line args
const args = try std.process.argsAlloc(allocator);
defer std.process.argsFree(allocator, args);
var doc = pdf.Pdf.init(allocator, .{});
defer doc.deinit();
doc.setTitle("Image Demo");
doc.setAuthor("zpdf");
var page = try doc.addPage(.{});
page.setMargins(50, 50, 50);
page.setXY(50, 800);
// Title
try page.setFont(.helvetica_bold, 24);
page.setFillColor(pdf.Color.rgb(41, 98, 255));
try page.cell(0, 30, "Image Demo - JPEG Support", pdf.Border.none, .center, false);
page.ln(40);
// Check if an image path was provided
if (args.len > 1) {
const image_path = args[1];
std.debug.print("Loading image: {s}\n", .{image_path});
// Try to load the image
const image_index = doc.addJpegImageFromFile(image_path) catch |err| {
std.debug.print("Error loading image: {any}\n", .{err});
try page.setFont(.helvetica, 12);
page.setFillColor(pdf.Color.red);
try page.cell(0, 20, "Error: Could not load image file", pdf.Border.none, .left, false);
page.ln(25);
try page.setFont(.helvetica, 10);
page.setFillColor(pdf.Color.black);
const long_text =
\\Make sure the file exists and is a valid JPEG image.
\\
\\Supported features:
\\- JPEG/JPG images (RGB and Grayscale)
\\- Direct embedding (no re-encoding)
\\- Automatic dimension detection
;
try page.multiCell(450, null, long_text, pdf.Border.none, .left, false);
const filename = "image_demo.pdf";
try doc.save(filename);
std.debug.print("Created: {s}\n", .{filename});
return;
};
// Get image info
const img_info = doc.getImage(image_index).?;
// Show image info
try page.setFont(.helvetica_bold, 14);
page.setFillColor(pdf.Color.black);
try page.cell(0, 20, "Image Information:", pdf.Border.none, .left, false);
page.ln(25);
try page.setFont(.helvetica, 11);
// Display image properties
var buf: [256]u8 = undefined;
const size_text = std.fmt.bufPrint(&buf, "Dimensions: {d} x {d} pixels", .{ img_info.width, img_info.height }) catch "Error";
try page.cell(0, 16, size_text, pdf.Border.none, .left, false);
page.ln(18);
const color_text = std.fmt.bufPrint(&buf, "Color Space: {s}", .{img_info.color_space.pdfName()}) catch "Error";
try page.cell(0, 16, color_text, pdf.Border.none, .left, false);
page.ln(18);
const bpc_text = std.fmt.bufPrint(&buf, "Bits per Component: {d}", .{img_info.bits_per_component}) catch "Error";
try page.cell(0, 16, bpc_text, pdf.Border.none, .left, false);
page.ln(30);
// Draw the image
try page.setFont(.helvetica_bold, 14);
try page.cell(0, 20, "Image Preview:", pdf.Border.none, .left, false);
page.ln(25);
// Calculate size to fit in available space (max 400x400)
const max_w: f32 = 400;
const max_h: f32 = 400;
const img_w: f32 = @floatFromInt(img_info.width);
const img_h: f32 = @floatFromInt(img_info.height);
const scale = @min(max_w / img_w, max_h / img_h, 1.0);
const display_w = img_w * scale;
const display_h = img_h * scale;
// Draw border around image area
const img_x = page.getX();
const img_y = page.getY() - display_h;
page.setStrokeColor(pdf.Color.light_gray);
try page.drawRect(img_x - 2, img_y - 2, display_w + 4, display_h + 4);
// Draw the image
try page.image(image_index, img_info, img_x, img_y, display_w, display_h);
std.debug.print("Image embedded: {d}x{d} pixels, displayed at {d:.0}x{d:.0} points\n", .{ img_info.width, img_info.height, display_w, display_h });
} else {
// No image provided - show instructions
try page.setFont(.helvetica_bold, 14);
page.setFillColor(pdf.Color.black);
try page.cell(0, 20, "How to Use Images:", pdf.Border.none, .left, false);
page.ln(25);
try page.setFont(.helvetica, 11);
const instructions =
\\To include a JPEG image in your PDF:
\\
\\1. Load the image file:
\\ const img_idx = try doc.addJpegImageFromFile("photo.jpg");
\\
\\2. Get the image info:
\\ const info = doc.getImage(img_idx).?;
\\
\\3. Draw on a page:
\\ try page.image(img_idx, info, x, y, width, height);
\\
\\Or use imageFit to auto-scale:
\\ try page.imageFit(img_idx, info, x, y, max_w, max_h);
\\
\\Run this example with a JPEG file path:
\\ ./image_demo photo.jpg
;
try page.multiCell(450, null, instructions, pdf.Border.all, .left, false);
page.ln(30);
// Supported features
try page.setFont(.helvetica_bold, 14);
try page.cell(0, 20, "Supported Features:", pdf.Border.none, .left, false);
page.ln(25);
try page.setFont(.helvetica, 11);
page.setFillColor(pdf.Color.rgb(0, 128, 0));
try page.cell(20, 16, "[OK]", pdf.Border.none, .left, false);
page.setFillColor(pdf.Color.black);
try page.cell(0, 16, "JPEG images (RGB, Grayscale, CMYK)", pdf.Border.none, .left, false);
page.ln(18);
page.setFillColor(pdf.Color.rgb(0, 128, 0));
try page.cell(20, 16, "[OK]", pdf.Border.none, .left, false);
page.setFillColor(pdf.Color.black);
try page.cell(0, 16, "Direct passthrough (no re-encoding)", pdf.Border.none, .left, false);
page.ln(18);
page.setFillColor(pdf.Color.rgb(0, 128, 0));
try page.cell(20, 16, "[OK]", pdf.Border.none, .left, false);
page.setFillColor(pdf.Color.black);
try page.cell(0, 16, "Automatic dimension detection", pdf.Border.none, .left, false);
page.ln(18);
page.setFillColor(pdf.Color.rgb(0, 128, 0));
try page.cell(20, 16, "[OK]", pdf.Border.none, .left, false);
page.setFillColor(pdf.Color.black);
try page.cell(0, 16, "Aspect ratio preservation", pdf.Border.none, .left, false);
page.ln(18);
page.setFillColor(pdf.Color.rgb(255, 165, 0));
try page.cell(20, 16, "[--]", pdf.Border.none, .left, false);
page.setFillColor(pdf.Color.black);
try page.cell(0, 16, "PNG images (metadata only, not yet embedded)", pdf.Border.none, .left, false);
}
// Footer
page.setXY(50, 50);
try page.setFont(.helvetica, 9);
page.setFillColor(pdf.Color.medium_gray);
try page.cell(0, 15, "Generated with zpdf - Pure Zig PDF Library", pdf.Border.none, .center, false);
// Save
const filename = "image_demo.pdf";
try doc.save(filename);
std.debug.print("Created: {s}\n", .{filename});
std.debug.print("Done!\n", .{});
}

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@ -408,6 +408,18 @@ pub const ContentStream = struct {
try self.showText(str);
try self.endText();
}
/// Draws an XObject image at position (x, y) with size (w, h)
/// PDF command: q w 0 0 h x y cm /Ii Do Q
pub fn image(self: *Self, image_index: usize, x: f32, y: f32, w: f32, h: f32) !void {
try self.saveState();
// Transformation matrix: scale and translate
// [w 0 0 h x y] cm
try self.writeFmt("{d:.2} 0 0 {d:.2} {d:.2} {d:.2} cm\n", .{ w, h, x, y });
// Draw XObject image
try self.writeFmt("/I{d} Do\n", .{image_index});
try self.restoreState();
}
};
// =============================================================================

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src/images/image_info.zig Normal file
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@ -0,0 +1,151 @@
//! ImageInfo - Parsed image metadata and data for PDF embedding
//!
//! This structure holds all the information needed to embed an image
//! as an XObject in a PDF document.
const std = @import("std");
/// Image format
pub const ImageFormat = enum {
jpeg,
png,
};
/// Color space for image
pub const ColorSpace = enum {
device_gray,
device_rgb,
device_cmyk,
pub fn pdfName(self: ColorSpace) []const u8 {
return switch (self) {
.device_gray => "DeviceGray",
.device_rgb => "DeviceRGB",
.device_cmyk => "DeviceCMYK",
};
}
pub fn components(self: ColorSpace) u8 {
return switch (self) {
.device_gray => 1,
.device_rgb => 3,
.device_cmyk => 4,
};
}
};
/// PDF filter for image data compression
pub const ImageFilter = enum {
/// DCT (JPEG) compression - used for JPEG images
dct_decode,
/// Flate (zlib) compression - used for PNG and other images
flate_decode,
pub fn pdfName(self: ImageFilter) []const u8 {
return switch (self) {
.dct_decode => "DCTDecode",
.flate_decode => "FlateDecode",
};
}
};
/// Parsed image information ready for PDF embedding
pub const ImageInfo = struct {
/// Image width in pixels
width: u32,
/// Image height in pixels
height: u32,
/// Color space
color_space: ColorSpace,
/// Bits per component (usually 8)
bits_per_component: u8,
/// PDF filter for the image data
filter: ImageFilter,
/// Raw image data (compressed for JPEG, may need processing for PNG)
data: []const u8,
/// Soft mask (alpha channel) data, if present
soft_mask: ?[]const u8,
/// Whether this struct owns the data (should free on deinit)
owns_data: bool,
/// Whether CMYK needs inversion (some JPEG CMYK images)
invert_cmyk: bool,
/// Original format
format: ImageFormat,
const Self = @This();
/// Free resources if we own them
pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {
if (self.owns_data) {
allocator.free(self.data);
if (self.soft_mask) |mask| {
allocator.free(mask);
}
}
}
/// Calculate aspect ratio (width / height)
pub fn aspectRatio(self: *const Self) f32 {
return @as(f32, @floatFromInt(self.width)) / @as(f32, @floatFromInt(self.height));
}
/// Returns the number of color components
pub fn colorComponents(self: *const Self) u8 {
return self.color_space.components();
}
/// Check if image has transparency
pub fn hasAlpha(self: *const Self) bool {
return self.soft_mask != null;
}
/// Generate PDF decode parameters string
pub fn decodeParams(self: *const Self, buf: []u8) []const u8 {
if (self.filter == .flate_decode) {
const result = std.fmt.bufPrint(buf, "/Predictor 15 /Colors {d} /Columns {d} /BitsPerComponent {d}", .{
self.colorComponents(),
self.width,
self.bits_per_component,
}) catch return "";
return result;
}
return "";
}
};
// =============================================================================
// Tests
// =============================================================================
test "ColorSpace properties" {
try std.testing.expectEqualStrings("DeviceRGB", ColorSpace.device_rgb.pdfName());
try std.testing.expectEqual(@as(u8, 3), ColorSpace.device_rgb.components());
try std.testing.expectEqualStrings("DeviceGray", ColorSpace.device_gray.pdfName());
try std.testing.expectEqual(@as(u8, 1), ColorSpace.device_gray.components());
try std.testing.expectEqualStrings("DeviceCMYK", ColorSpace.device_cmyk.pdfName());
try std.testing.expectEqual(@as(u8, 4), ColorSpace.device_cmyk.components());
}
test "ImageFilter pdfName" {
try std.testing.expectEqualStrings("DCTDecode", ImageFilter.dct_decode.pdfName());
try std.testing.expectEqualStrings("FlateDecode", ImageFilter.flate_decode.pdfName());
}
test "ImageInfo aspectRatio" {
const info = ImageInfo{
.width = 800,
.height = 600,
.color_space = .device_rgb,
.bits_per_component = 8,
.filter = .dct_decode,
.data = &[_]u8{},
.soft_mask = null,
.owns_data = false,
.invert_cmyk = false,
.format = .jpeg,
};
try std.testing.expectApproxEqAbs(@as(f32, 1.333), info.aspectRatio(), 0.01);
}

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src/images/jpeg.zig Normal file
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@ -0,0 +1,248 @@
//! JPEG image parser for PDF embedding
//!
//! JPEG images can be embedded directly in PDF using DCTDecode filter.
//! This parser extracts the necessary metadata (dimensions, color space)
//! from the JPEG header without decoding the image data.
const std = @import("std");
const ImageInfo = @import("image_info.zig").ImageInfo;
const ColorSpace = @import("image_info.zig").ColorSpace;
const ImageFilter = @import("image_info.zig").ImageFilter;
const ImageFormat = @import("image_info.zig").ImageFormat;
/// JPEG marker bytes
const JPEG_MARKERS = struct {
const SOI: u8 = 0xD8; // Start of Image
const EOI: u8 = 0xD9; // End of Image
const SOS: u8 = 0xDA; // Start of Scan
const DQT: u8 = 0xDB; // Define Quantization Table
const DNL: u8 = 0xDC; // Define Number of Lines
const DRI: u8 = 0xDD; // Define Restart Interval
const DHT: u8 = 0xC4; // Define Huffman Table
const DAC: u8 = 0xCC; // Define Arithmetic Coding
const APP0: u8 = 0xE0; // Application-specific marker 0 (JFIF)
const APP1: u8 = 0xE1; // Application-specific marker 1 (EXIF)
const APP2: u8 = 0xE2; // Application-specific marker 2 (ICC)
const APP14: u8 = 0xEE; // Application-specific marker 14 (Adobe)
const COM: u8 = 0xFE; // Comment
// Start of Frame markers (we need these for image dimensions)
const SOF0: u8 = 0xC0; // Baseline DCT
const SOF1: u8 = 0xC1; // Extended sequential DCT
const SOF2: u8 = 0xC2; // Progressive DCT
const SOF3: u8 = 0xC3; // Lossless
const SOF5: u8 = 0xC5; // Differential sequential DCT
const SOF6: u8 = 0xC6; // Differential progressive DCT
const SOF7: u8 = 0xC7; // Differential lossless
const SOF9: u8 = 0xC9; // Extended sequential DCT, arithmetic
const SOF10: u8 = 0xCA; // Progressive DCT, arithmetic
const SOF11: u8 = 0xCB; // Lossless, arithmetic
const SOF13: u8 = 0xCD; // Differential sequential DCT, arithmetic
const SOF14: u8 = 0xCE; // Differential progressive DCT, arithmetic
const SOF15: u8 = 0xCF; // Differential lossless, arithmetic
};
pub const JpegError = error{
InvalidSignature,
UnexpectedEndOfData,
NoFrameFound,
UnsupportedColorSpace,
};
/// Parse JPEG image data and extract metadata for PDF embedding.
/// The JPEG data is embedded directly without re-encoding.
pub fn parse(data: []const u8) JpegError!ImageInfo {
// Validate JPEG signature: FF D8 FF
if (data.len < 4) return JpegError.InvalidSignature;
if (data[0] != 0xFF or data[1] != JPEG_MARKERS.SOI or data[2] != 0xFF) {
return JpegError.InvalidSignature;
}
var width: u32 = 0;
var height: u32 = 0;
var components: u8 = 0;
var bits_per_component: u8 = 8;
var found_frame = false;
var is_adobe_cmyk = false;
// Parse JPEG markers
var pos: usize = 2;
while (pos < data.len - 1) {
// Find marker (FF xx)
if (data[pos] != 0xFF) {
pos += 1;
continue;
}
// Skip padding FF bytes
while (pos < data.len and data[pos] == 0xFF) {
pos += 1;
}
if (pos >= data.len) break;
const marker = data[pos];
pos += 1;
// Check for SOF (Start of Frame) markers
if (isSOFMarker(marker)) {
if (pos + 7 > data.len) return JpegError.UnexpectedEndOfData;
// Skip length bytes
pos += 2;
// Read frame data
bits_per_component = data[pos];
pos += 1;
height = (@as(u32, data[pos]) << 8) | @as(u32, data[pos + 1]);
pos += 2;
width = (@as(u32, data[pos]) << 8) | @as(u32, data[pos + 1]);
pos += 2;
components = data[pos];
found_frame = true;
break;
}
// Check for Adobe APP14 marker (indicates CMYK handling)
if (marker == JPEG_MARKERS.APP14) {
if (pos + 2 > data.len) return JpegError.UnexpectedEndOfData;
const len = (@as(u16, data[pos]) << 8) | @as(u16, data[pos + 1]);
// Check for "Adobe" string
if (len >= 12 and pos + 12 <= data.len) {
if (std.mem.eql(u8, data[pos + 2 .. pos + 7], "Adobe")) {
is_adobe_cmyk = true;
}
}
pos += len;
continue;
}
// Skip other markers with length
if (marker != JPEG_MARKERS.SOI and marker != JPEG_MARKERS.EOI and
marker != 0x00 and (marker < 0xD0 or marker > 0xD7))
{
if (pos + 2 > data.len) return JpegError.UnexpectedEndOfData;
const len = (@as(u16, data[pos]) << 8) | @as(u16, data[pos + 1]);
pos += len;
}
}
if (!found_frame) return JpegError.NoFrameFound;
// Determine color space from component count
const color_space: ColorSpace = switch (components) {
1 => .device_gray,
3 => .device_rgb,
4 => .device_cmyk,
else => return JpegError.UnsupportedColorSpace,
};
return ImageInfo{
.width = width,
.height = height,
.color_space = color_space,
.bits_per_component = bits_per_component,
.filter = .dct_decode,
.data = data, // Direct passthrough - JPEG data is used as-is
.soft_mask = null, // JPEG doesn't support alpha
.owns_data = false, // We don't allocate, caller owns the data
.invert_cmyk = is_adobe_cmyk and color_space == .device_cmyk,
.format = .jpeg,
};
}
/// Check if marker is a Start of Frame marker
fn isSOFMarker(marker: u8) bool {
return switch (marker) {
JPEG_MARKERS.SOF0,
JPEG_MARKERS.SOF1,
JPEG_MARKERS.SOF2,
JPEG_MARKERS.SOF3,
JPEG_MARKERS.SOF5,
JPEG_MARKERS.SOF6,
JPEG_MARKERS.SOF7,
JPEG_MARKERS.SOF9,
JPEG_MARKERS.SOF10,
JPEG_MARKERS.SOF11,
JPEG_MARKERS.SOF13,
JPEG_MARKERS.SOF14,
JPEG_MARKERS.SOF15,
=> true,
else => false,
};
}
// =============================================================================
// Tests
// =============================================================================
test "parse valid JPEG header" {
// Minimal valid JPEG with SOF0 marker
// FF D8 FF E0 [JFIF APP0] FF C0 [SOF0 frame]
const jpeg_data = [_]u8{
0xFF, 0xD8, // SOI
0xFF, 0xE0, // APP0
0x00, 0x10, // Length 16
'J', 'F', 'I', 'F', 0x00, // JFIF identifier
0x01, 0x01, // Version
0x00, // Units
0x00, 0x01, // X density
0x00, 0x01, // Y density
0x00, 0x00, // Thumbnail
0xFF, 0xC0, // SOF0
0x00, 0x0B, // Length 11
0x08, // Bits per component
0x00, 0x64, // Height: 100
0x00, 0xC8, // Width: 200
0x03, // Components: 3 (RGB)
0x01, 0x22, 0x00, // Component 1
0x02, 0x11, 0x01, // Component 2
0x03, 0x11, 0x01, // Component 3
};
const info = try parse(&jpeg_data);
try std.testing.expectEqual(@as(u32, 200), info.width);
try std.testing.expectEqual(@as(u32, 100), info.height);
try std.testing.expectEqual(ColorSpace.device_rgb, info.color_space);
try std.testing.expectEqual(@as(u8, 8), info.bits_per_component);
try std.testing.expectEqual(ImageFilter.dct_decode, info.filter);
try std.testing.expect(info.soft_mask == null);
try std.testing.expectEqual(false, info.owns_data);
}
test "parse grayscale JPEG" {
const jpeg_data = [_]u8{
0xFF, 0xD8, // SOI
0xFF, 0xC0, // SOF0 (directly, no APP0)
0x00, 0x08, // Length 8
0x08, // Bits per component
0x00, 0x32, // Height: 50
0x00, 0x50, // Width: 80
0x01, // Components: 1 (Grayscale)
0x01, 0x11, 0x00, // Component 1
};
const info = try parse(&jpeg_data);
try std.testing.expectEqual(@as(u32, 80), info.width);
try std.testing.expectEqual(@as(u32, 50), info.height);
try std.testing.expectEqual(ColorSpace.device_gray, info.color_space);
}
test "invalid JPEG signature" {
const invalid_data = [_]u8{ 0x89, 0x50, 0x4E, 0x47 }; // PNG signature
const result = parse(&invalid_data);
try std.testing.expectError(JpegError.InvalidSignature, result);
}
test "JPEG too short" {
const short_data = [_]u8{ 0xFF, 0xD8 };
const result = parse(&short_data);
try std.testing.expectError(JpegError.InvalidSignature, result);
}

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src/images/mod.zig Normal file
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@ -0,0 +1,50 @@
//! Image module for zpdf
//!
//! Provides image parsing and embedding support for PDF generation.
//! Supports JPEG (direct embedding) and PNG (with alpha support).
pub const jpeg = @import("jpeg.zig");
pub const png = @import("png.zig");
pub const ImageInfo = @import("image_info.zig").ImageInfo;
pub const ImageFormat = @import("image_info.zig").ImageFormat;
// Re-export common functions
pub const parseJpeg = jpeg.parse;
pub const parsePng = png.parse;
/// Detects image format from raw bytes
pub fn detectFormat(data: []const u8) ?ImageFormat {
if (data.len < 8) return null;
// JPEG: starts with FF D8 FF
if (data[0] == 0xFF and data[1] == 0xD8 and data[2] == 0xFF) {
return .jpeg;
}
// PNG: starts with 89 50 4E 47 0D 0A 1A 0A
if (data[0] == 0x89 and data[1] == 0x50 and data[2] == 0x4E and data[3] == 0x47 and
data[4] == 0x0D and data[5] == 0x0A and data[6] == 0x1A and data[7] == 0x0A)
{
return .png;
}
return null;
}
test "detect JPEG format" {
const jpeg_header = [_]u8{ 0xFF, 0xD8, 0xFF, 0xE0, 0x00, 0x10, 0x4A, 0x46 };
const format = detectFormat(&jpeg_header);
try @import("std").testing.expectEqual(ImageFormat.jpeg, format.?);
}
test "detect PNG format" {
const png_header = [_]u8{ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
const format = detectFormat(&png_header);
try @import("std").testing.expectEqual(ImageFormat.png, format.?);
}
test "detect unknown format" {
const unknown = [_]u8{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07 };
const format = detectFormat(&unknown);
try @import("std").testing.expect(format == null);
}

207
src/images/png.zig Normal file
View file

@ -0,0 +1,207 @@
//! PNG image parser for PDF embedding
//!
//! PNG images need to be decoded and re-encoded for PDF.
//! - RGB/Grayscale data is compressed with FlateDecode
//! - Alpha channel (if present) is stored as a separate soft mask
//!
//! NOTE: Full PNG parsing requires complex zlib decompression.
//! This module provides metadata extraction from PNG headers.
//! For full PNG support with alpha, consider using external tools
//! to convert PNG to JPEG first, or implement full PNG decompression.
const std = @import("std");
const ImageInfo = @import("image_info.zig").ImageInfo;
const ColorSpace = @import("image_info.zig").ColorSpace;
const ImageFilter = @import("image_info.zig").ImageFilter;
const ImageFormat = @import("image_info.zig").ImageFormat;
pub const PngError = error{
InvalidSignature,
UnexpectedEndOfData,
InvalidChunk,
UnsupportedColorType,
UnsupportedBitDepth,
UnsupportedInterlace,
InvalidIHDR,
NotImplemented,
};
/// PNG color types
pub const ColorType = enum(u8) {
grayscale = 0,
rgb = 2,
indexed = 3,
grayscale_alpha = 4,
rgba = 6,
};
/// PNG chunk header
const ChunkHeader = struct {
length: u32,
chunk_type: [4]u8,
};
/// PNG metadata extracted from header (without full decompression)
pub const PngMetadata = struct {
width: u32,
height: u32,
bit_depth: u8,
color_type: ColorType,
has_alpha: bool,
channels: u8,
};
/// Extract PNG metadata without full decompression.
/// This is useful for getting image dimensions before processing.
pub fn parseMetadata(data: []const u8) PngError!PngMetadata {
// Validate PNG signature: 89 50 4E 47 0D 0A 1A 0A
if (data.len < 8) return PngError.InvalidSignature;
const png_sig = [_]u8{ 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
if (!std.mem.eql(u8, data[0..8], &png_sig)) {
return PngError.InvalidSignature;
}
// Parse IHDR chunk (must be first)
const pos: usize = 8;
const ihdr = readChunkHeader(data, pos) orelse return PngError.InvalidIHDR;
if (!std.mem.eql(u8, &ihdr.chunk_type, "IHDR")) return PngError.InvalidIHDR;
if (ihdr.length != 13) return PngError.InvalidIHDR;
const header_pos = pos + 8; // Skip length and type
if (header_pos + 13 > data.len) return PngError.UnexpectedEndOfData;
const width = readU32BE(data, header_pos);
const height = readU32BE(data, header_pos + 4);
const bit_depth = data[header_pos + 8];
const color_type_raw = data[header_pos + 9];
const interlace = data[header_pos + 12];
// Validate parameters
if (bit_depth != 8 and bit_depth != 16) return PngError.UnsupportedBitDepth;
if (interlace != 0) return PngError.UnsupportedInterlace;
const color_type: ColorType = std.meta.intToEnum(ColorType, color_type_raw) catch {
return PngError.UnsupportedColorType;
};
const channels: u8 = switch (color_type) {
.grayscale => 1,
.rgb => 3,
.grayscale_alpha => 2,
.rgba => 4,
.indexed => 1,
};
const has_alpha = (color_type == .rgba or color_type == .grayscale_alpha);
return PngMetadata{
.width = width,
.height = height,
.bit_depth = bit_depth,
.color_type = color_type,
.has_alpha = has_alpha,
.channels = channels,
};
}
/// Parse PNG image and prepare for PDF embedding.
/// NOTE: Full PNG parsing is not yet implemented.
/// Returns NotImplemented error - use JPEG images instead.
pub fn parse(allocator: std.mem.Allocator, data: []const u8) PngError!ImageInfo {
_ = allocator;
// Get metadata to validate the PNG
_ = try parseMetadata(data);
// Full PNG decompression not yet implemented
// PNG requires zlib decompression, unfiltering, and re-compression
// For now, recommend converting PNG to JPEG externally
return PngError.NotImplemented;
}
/// Read big-endian u32
fn readU32BE(data: []const u8, pos: usize) u32 {
return (@as(u32, data[pos]) << 24) |
(@as(u32, data[pos + 1]) << 16) |
(@as(u32, data[pos + 2]) << 8) |
@as(u32, data[pos + 3]);
}
/// Read chunk header
fn readChunkHeader(data: []const u8, pos: usize) ?ChunkHeader {
if (pos + 8 > data.len) return null;
return ChunkHeader{
.length = readU32BE(data, pos),
.chunk_type = data[pos + 4 ..][0..4].*,
};
}
// =============================================================================
// Tests
// =============================================================================
test "read chunk header" {
const data = [_]u8{
0x00, 0x00, 0x00, 0x0D, // Length: 13
'I', 'H', 'D', 'R', // Type: IHDR
};
const header = readChunkHeader(&data, 0);
try std.testing.expect(header != null);
try std.testing.expectEqual(@as(u32, 13), header.?.length);
try std.testing.expectEqualStrings("IHDR", &header.?.chunk_type);
}
test "invalid PNG signature" {
const allocator = std.testing.allocator;
const invalid_data = [_]u8{ 0xFF, 0xD8, 0xFF, 0xE0 }; // JPEG signature
const result = parse(allocator, &invalid_data);
try std.testing.expectError(PngError.InvalidSignature, result);
}
test "parse PNG metadata" {
// Minimal valid PNG header
const png_data = [_]u8{
0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG signature
0x00, 0x00, 0x00, 0x0D, // IHDR length: 13
'I', 'H', 'D', 'R', // IHDR type
0x00, 0x00, 0x00, 0x64, // Width: 100
0x00, 0x00, 0x00, 0xC8, // Height: 200
0x08, // Bit depth: 8
0x02, // Color type: RGB
0x00, // Compression: deflate
0x00, // Filter: adaptive
0x00, // Interlace: none
};
const meta = try parseMetadata(&png_data);
try std.testing.expectEqual(@as(u32, 100), meta.width);
try std.testing.expectEqual(@as(u32, 200), meta.height);
try std.testing.expectEqual(@as(u8, 8), meta.bit_depth);
try std.testing.expectEqual(ColorType.rgb, meta.color_type);
try std.testing.expectEqual(false, meta.has_alpha);
try std.testing.expectEqual(@as(u8, 3), meta.channels);
}
test "parse PNG with alpha" {
const png_data = [_]u8{
0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG signature
0x00, 0x00, 0x00, 0x0D, // IHDR length: 13
'I', 'H', 'D', 'R', // IHDR type
0x00, 0x00, 0x00, 0x20, // Width: 32
0x00, 0x00, 0x00, 0x20, // Height: 32
0x08, // Bit depth: 8
0x06, // Color type: RGBA
0x00, // Compression: deflate
0x00, // Filter: adaptive
0x00, // Interlace: none
};
const meta = try parseMetadata(&png_data);
try std.testing.expectEqual(@as(u32, 32), meta.width);
try std.testing.expectEqual(@as(u32, 32), meta.height);
try std.testing.expectEqual(ColorType.rgba, meta.color_type);
try std.testing.expectEqual(true, meta.has_alpha);
try std.testing.expectEqual(@as(u8, 4), meta.channels);
}

View file

@ -9,6 +9,13 @@
const std = @import("std");
const base = @import("../objects/base.zig");
const Font = @import("../fonts/type1.zig").Font;
const ImageInfo = @import("../images/image_info.zig").ImageInfo;
/// Image reference for serialization
pub const ImageData = struct {
index: usize,
info: *const ImageInfo,
};
/// Page data ready for serialization
pub const PageData = struct {
@ -16,6 +23,7 @@ pub const PageData = struct {
height: f32,
content: []const u8,
fonts_used: []const Font,
images_used: []const ImageData = &[_]ImageData{},
};
/// Generates a complete PDF document.
@ -43,6 +51,11 @@ pub const OutputProducer = struct {
/// Generates a complete PDF from the given pages.
pub fn generate(self: *Self, pages: []const PageData, metadata: DocumentMetadata) ![]u8 {
return self.generateWithImages(pages, metadata, &[_]*const ImageInfo{});
}
/// Generates a complete PDF from the given pages with images.
pub fn generateWithImages(self: *Self, pages: []const PageData, metadata: DocumentMetadata, images: []const *const ImageInfo) ![]u8 {
self.buffer.clearRetainingCapacity();
self.obj_offsets.clearRetainingCapacity();
self.current_obj_id = 0;
@ -76,12 +89,14 @@ pub const OutputProducer = struct {
// 2 = Pages (root)
// 3 = Info (optional)
// 4..4+num_fonts-1 = Font objects
// 4+num_fonts..4+num_fonts+num_pages*2-1 = Page + Content objects
// 4+num_fonts..4+num_fonts+num_images-1 = Image XObjects
// 4+num_fonts+num_images.. = Page + Content objects
const catalog_id: u32 = 1;
const pages_root_id: u32 = 2;
const info_id: u32 = 3;
const first_font_id: u32 = 4;
const first_page_id: u32 = first_font_id + @as(u32, @intCast(fonts.len));
const first_image_id: u32 = first_font_id + @as(u32, @intCast(fonts.len));
const first_page_id: u32 = first_image_id + @as(u32, @intCast(images.len));
// Object 1: Catalog
try self.beginObject(catalog_id);
@ -143,6 +158,42 @@ pub const OutputProducer = struct {
try self.endObject();
}
// Image XObject objects
for (images, 0..) |img, i| {
const img_id = first_image_id + @as(u32, @intCast(i));
try self.beginObject(img_id);
try writer.writeAll("<< /Type /XObject\n");
try writer.writeAll("/Subtype /Image\n");
try writer.print("/Width {d}\n", .{img.width});
try writer.print("/Height {d}\n", .{img.height});
try writer.print("/ColorSpace /{s}\n", .{img.color_space.pdfName()});
try writer.print("/BitsPerComponent {d}\n", .{img.bits_per_component});
try writer.print("/Filter /{s}\n", .{img.filter.pdfName()});
// Decode parameters for FlateDecode
if (img.filter == .flate_decode) {
try writer.writeAll("/DecodeParms << ");
var buf: [128]u8 = undefined;
const params = img.decodeParams(&buf);
if (params.len > 0) {
try writer.writeAll(params);
}
try writer.writeAll(" >>\n");
}
// CMYK inversion
if (img.invert_cmyk) {
try writer.writeAll("/Decode [1 0 1 0 1 0 1 0]\n");
}
try writer.print("/Length {d}\n", .{img.data.len});
try writer.writeAll(">>\n");
try writer.writeAll("stream\n");
try writer.writeAll(img.data);
try writer.writeAll("\nendstream\n");
try self.endObject();
}
// Page and Content objects
for (pages, 0..) |page, i| {
const page_obj_id = first_page_id + @as(u32, @intCast(i * 2));
@ -163,6 +214,16 @@ pub const OutputProducer = struct {
try writer.print(" /{s} {d} 0 R\n", .{ font.pdfName(), font_id });
}
try writer.writeAll(" >>\n");
// XObject resources for images
if (images.len > 0) {
try writer.writeAll(" /XObject <<\n");
for (0..images.len) |img_idx| {
const img_obj_id = first_image_id + @as(u32, @intCast(img_idx));
try writer.print(" /I{d} {d} 0 R\n", .{ img_idx, img_obj_id });
}
try writer.writeAll(" >>\n");
}
try writer.writeAll(">>\n");
try writer.writeAll(">>\n");

View file

@ -11,6 +11,7 @@ const RenderStyle = @import("content_stream.zig").RenderStyle;
const Color = @import("graphics/color.zig").Color;
const Font = @import("fonts/type1.zig").Font;
const PageSize = @import("objects/base.zig").PageSize;
const ImageInfo = @import("images/image_info.zig").ImageInfo;
/// Text alignment options
pub const Align = enum {
@ -37,6 +38,14 @@ pub const Border = packed struct {
}
};
/// Reference to an image used on a page
pub const ImageRef = struct {
/// Index in the document's image list
index: usize,
/// Image info pointer
info: *const ImageInfo,
};
/// A single page in a PDF document.
pub const Page = struct {
allocator: std.mem.Allocator,
@ -54,6 +63,9 @@ pub const Page = struct {
/// Fonts used on this page (for resource dictionary)
fonts_used: std.AutoHashMap(Font, void),
/// Images used on this page (for resource dictionary)
images_used: std.ArrayListUnmanaged(ImageRef),
const Self = @This();
/// Graphics state for the page
@ -101,6 +113,7 @@ pub const Page = struct {
.content = ContentStream.init(allocator),
.state = .{},
.fonts_used = std.AutoHashMap(Font, void).init(allocator),
.images_used = .{},
};
}
@ -108,6 +121,7 @@ pub const Page = struct {
pub fn deinit(self: *Self) void {
self.content.deinit();
self.fonts_used.deinit();
self.images_used.deinit(self.allocator);
}
// =========================================================================
@ -531,6 +545,99 @@ pub const Page = struct {
try self.content.rect(x, y, w, h, style);
}
// =========================================================================
// Image Operations
// =========================================================================
/// Draws an image at the specified position.
///
/// Parameters:
/// - image_index: Index of the image in the document's image list
/// - info: Pointer to the ImageInfo structure
/// - x: X position (or null to use current X)
/// - y: Y position (or null to use current Y)
/// - w: Width (0 = auto from aspect ratio, null = original size)
/// - h: Height (0 = auto from aspect ratio, null = original size)
///
/// If both w and h are 0 or null, the image is rendered at 72 DPI.
/// If one dimension is 0, it's calculated to maintain aspect ratio.
pub fn image(
self: *Self,
image_index: usize,
info: *const ImageInfo,
x_opt: ?f32,
y_opt: ?f32,
w_opt: ?f32,
h_opt: ?f32,
) !void {
// Get position
const x = x_opt orelse self.state.x;
const y = y_opt orelse self.state.y;
// Calculate dimensions
const img_w: f32 = @floatFromInt(info.width);
const img_h: f32 = @floatFromInt(info.height);
var w = w_opt orelse img_w;
var h = h_opt orelse img_h;
// Handle auto-sizing
if (w == 0 and h == 0) {
// Default: 72 DPI (1 pixel = 1 point)
w = img_w;
h = img_h;
} else if (w == 0) {
// Calculate width from height maintaining aspect ratio
w = h * img_w / img_h;
} else if (h == 0) {
// Calculate height from width maintaining aspect ratio
h = w * img_h / img_w;
}
// Register image usage
try self.images_used.append(self.allocator, .{
.index = image_index,
.info = info,
});
// Write image command to content stream
// Format: q w 0 0 h x y cm /Ii Do Q
// where i is the image index
try self.content.image(image_index, x, y, w, h);
// Update position (move to right of image)
self.state.x = x + w;
}
/// Draws an image with automatic sizing to fit within a box while maintaining aspect ratio.
pub fn imageFit(
self: *Self,
image_index: usize,
info: *const ImageInfo,
x: f32,
y: f32,
max_w: f32,
max_h: f32,
) !void {
const img_w: f32 = @floatFromInt(info.width);
const img_h: f32 = @floatFromInt(info.height);
// Calculate scale to fit within box
const scale_w = max_w / img_w;
const scale_h = max_h / img_h;
const scale = @min(scale_w, scale_h);
const w = img_w * scale;
const h = img_h * scale;
try self.image(image_index, info, x, y, w, h);
}
/// Returns the list of images used on this page.
pub fn getImagesUsed(self: *const Self) []const ImageRef {
return self.images_used.items;
}
// =========================================================================
// Content Access
// =========================================================================

View file

@ -16,6 +16,8 @@ const Unit = @import("objects/base.zig").Unit;
const OutputProducer = @import("output/producer.zig").OutputProducer;
const PageData = @import("output/producer.zig").PageData;
const DocumentMetadata = @import("output/producer.zig").DocumentMetadata;
const ImageInfo = @import("images/image_info.zig").ImageInfo;
const jpeg = @import("images/jpeg.zig");
/// A PDF document builder.
///
@ -36,6 +38,9 @@ pub const Pdf = struct {
/// All pages in the document
pages: std.ArrayListUnmanaged(Page),
/// All images in the document
images: std.ArrayListUnmanaged(ImageInfo),
/// Document metadata
title: ?[]const u8 = null,
author: ?[]const u8 = null,
@ -76,6 +81,7 @@ pub const Pdf = struct {
return .{
.allocator = allocator,
.pages = .{},
.images = .{},
.default_page_size = options.page_size,
.default_orientation = options.orientation,
.unit = options.unit,
@ -88,6 +94,12 @@ pub const Pdf = struct {
page.deinit();
}
self.pages.deinit(self.allocator);
// Free image data if owned
for (self.images.items) |*img| {
img.deinit(self.allocator);
}
self.images.deinit(self.allocator);
}
// =========================================================================
@ -155,6 +167,47 @@ pub const Pdf = struct {
return null;
}
// =========================================================================
// Image Management
// =========================================================================
/// Adds a JPEG image from raw data and returns its index.
/// The image data is stored and will be embedded in the PDF.
pub fn addJpegImage(self: *Self, jpeg_data: []const u8) !usize {
const info = try jpeg.parse(jpeg_data);
try self.images.append(self.allocator, info);
return self.images.items.len - 1;
}
/// Adds a JPEG image from a file and returns its index.
pub fn addJpegImageFromFile(self: *Self, path: []const u8) !usize {
const file = try std.fs.cwd().openFile(path, .{});
defer file.close();
const data = try file.readToEndAlloc(self.allocator, 10 * 1024 * 1024); // 10MB max
var info = try jpeg.parse(data);
// Mark as owned since we allocated the data
info.data = data;
info.owns_data = true;
try self.images.append(self.allocator, info);
return self.images.items.len - 1;
}
/// Returns the ImageInfo for an image by index.
pub fn getImage(self: *const Self, index: usize) ?*const ImageInfo {
if (index < self.images.items.len) {
return &self.images.items[index];
}
return null;
}
/// Returns the number of images.
pub fn imageCount(self: *const Self) usize {
return self.images.items.len;
}
// =========================================================================
// Output
// =========================================================================
@ -192,16 +245,24 @@ pub const Pdf = struct {
});
}
// Collect image pointers
var image_ptrs: std.ArrayListUnmanaged(*const ImageInfo) = .{};
defer image_ptrs.deinit(self.allocator);
for (self.images.items) |*img| {
try image_ptrs.append(self.allocator, img);
}
// Generate PDF
var producer = OutputProducer.init(self.allocator);
defer producer.deinit();
return try producer.generate(page_data.items, .{
return try producer.generateWithImages(page_data.items, .{
.title = self.title,
.author = self.author,
.subject = self.subject,
.creator = self.creator,
});
}, image_ptrs.items);
}
/// Saves the document to a file.

View file

@ -65,6 +65,11 @@ pub const Unit = objects.Unit;
pub const output = @import("output/mod.zig");
pub const OutputProducer = output.OutputProducer;
/// Images (JPEG, PNG)
pub const images = @import("images/mod.zig");
pub const ImageInfo = images.ImageInfo;
pub const ImageFormat = images.ImageFormat;
// =============================================================================
// Backwards Compatibility - Old API (Document)
// =============================================================================
@ -223,4 +228,8 @@ comptime {
_ = @import("fonts/type1.zig");
_ = @import("objects/base.zig");
_ = @import("output/producer.zig");
_ = @import("images/mod.zig");
_ = @import("images/image_info.zig");
_ = @import("images/jpeg.zig");
_ = @import("images/png.zig");
}