karm-pdf+print: Fix page density and coordinate system.

l3dlp-sandbox · Sep 3, 2024 · f13f323 · f13f323
1 parent a6af241
commit f13f323
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Showing 4 changed files with 67 additions and 13 deletions.
diff --git a/src/libs/karm-pdf/canvas.h b/src/libs/karm-pdf/canvas.h
@@ -8,20 +8,28 @@ namespace Karm::Pdf {
 
 struct Canvas : public Gfx::Canvas {
     Io::Emit _e;
+    Math::Vec2f _mediaBox{};
+
     Math::Vec2f _p{};
 
-    Canvas(Io::Emit e) : _e{e} {}
+    Canvas(Io::Emit e, Math::Vec2f mediaBox)
+        : _e{e}, _mediaBox{mediaBox} {}
+
+    Math::Vec2f _toPdf(Math::Vec2f p) {
+        return {p.x, _mediaBox.y - p.y};
+    }
 
     Math::Vec2f _mapPoint(Math::Vec2f p, Math::Path::Flags flags) {
         if (flags & Math::Path::RELATIVE)
-            return p;
-        return p - _p;
+            return _toPdf(p + _p);
+        return _toPdf(p);
     }
 
     Math::Vec2f _mapPointAndUpdate(Math::Vec2f p, Math::Path::Flags flags) {
-        p = _mapPoint(p, flags);
-        _p = _p + p;
-        return p;
+        if (flags & Math::Path::RELATIVE)
+            p = p + _p;
+        _p = p;
+        return _toPdf(p);
     }
 
     // MARK: Context Operations ------------------------------------------------

diff --git a/src/libs/karm-print/cli/main.cpp b/src/libs/karm-print/cli/main.cpp
@@ -6,7 +6,15 @@ Async::Task<> entryPointAsync(Sys::Context &) {
     Print::PdfPrinter printer{Print::A4};
     auto &ctx = printer.beginPage();
     ctx.fillStyle(Gfx::RED);
-    ctx.rect({0, 0, 200, 300});
+    ctx.rect({0, 0, 100, 100});
+    ctx.fill(Gfx::FillRule::NONZERO);
+
+    ctx.fillStyle(Gfx::BLUE);
+    ctx.rect({0, 100, 100, 100});
+    ctx.fill(Gfx::FillRule::NONZERO);
+
+    ctx.fillStyle(Gfx::GREEN);
+    ctx.rect({0, 200, 100, 100});
     ctx.fill(Gfx::FillRule::NONZERO);
 
     auto outFile = co_try$(Sys::File::create("file:test.pdf"_url));

diff --git a/src/libs/karm-print/paper.h b/src/libs/karm-print/paper.h
@@ -1,9 +1,37 @@
 #pragma once
 
+#include <karm-base/distinct.h>
 #include <karm-base/string.h>
 
 namespace Karm::Print {
 
+static constexpr f64 INCH_TO_MM = 25.4;
+
+// Print density in Dot Per Mm (DPMM)
+struct Density : public Distinct<f64, struct _DensityTag> {
+    using Distinct::Distinct;
+
+    static Density const DEFAULT;
+
+    static constexpr Density fromDpi(f64 dpi) {
+        return Density{dpi * INCH_TO_MM};
+    }
+
+    static constexpr Density fromDpcm(f64 dpcm) {
+        return Density{dpcm};
+    }
+
+    constexpr f64 toDpi() const {
+        return _value / INCH_TO_MM;
+    }
+
+    constexpr f64 toDpcm() const {
+        return _value;
+    }
+};
+
+inline constexpr Density Density::DEFAULT = Density::fromDpi(72.0);
+
 struct PaperStock {
     Str name;
     f64 width;  // in mm

diff --git a/src/libs/karm-print/pdf.h b/src/libs/karm-print/pdf.h
@@ -8,24 +8,28 @@
 namespace Karm::Print {
 
 struct PdfPrinter : public Printer {
-    PaperStock _stock;
+    Math::Vec2f _paperSize;
+    Density _density;
     Vec<Io::StringWriter> _pages;
     Opt<Pdf::Canvas> _canvas;
 
-    PdfPrinter(PaperStock stock)
-        : _stock{stock} {}
+    PdfPrinter(PaperStock stock, Density density = Density::DEFAULT) {
+        _paperSize.width = (stock.width / INCH_TO_MM) * (density.toDpi());
+        _paperSize.height = (stock.height / INCH_TO_MM) * (density.toDpi());
+        _density = density;
+    }
 
     Gfx::Canvas &beginPage() override {
         _pages.emplaceBack();
-        _canvas = Pdf::Canvas{last(_pages)};
+        _canvas = Pdf::Canvas{last(_pages), _paperSize};
         return *_canvas;
     }
 
     Pdf::File pdf() {
         Pdf::Ref alloc;
 
         Pdf::File file;
-        file.header = "PDF-1.7"s;
+        file.header = "PDF-2.0"s;
 
         Pdf::Array pagesKids;
         Pdf::Ref pagesRef = alloc.alloc();
@@ -65,7 +69,13 @@ struct PdfPrinter : public Printer {
             pagesRef,
             Pdf::Dict{
                 {"Type"s, Pdf::Name{"Pages"s}},
-                {"MediaBox"s, Pdf::Array{usize{0}, usize{0}, _stock.width, _stock.height}},
+                {"MediaBox"s,
+                 Pdf::Array{
+                     usize{0},
+                     usize{0},
+                     _paperSize.width,
+                     _paperSize.height,
+                 }},
                 {"Count"s, _pages.len()},
                 {"Kids"s, std::move(pagesKids)},
             }