wip, a lot of workarounds to be fixed after idea is confirmed

src/vaev-driver/render.cpp

@@ -71,7 +71,7 @@ RenderResult render(Markup::Document const &dom, Style::Media const &media, Vec2
         {
             .small = viewport,
         },
-        Layout::FragmentationContext()
+        Layout::FragmentationContext({Px{900}, Px{100}})
     };
 
     elapsed = Sys::now() - start;
@@ -88,17 +88,45 @@ RenderResult render(Markup::Document const &dom, Style::Media const &media, Vec2
 
     start = Sys::now();
 
-    Layout::layout(
-        tree,
-        tree.root,
-        {
-            .commit = Layout::Commit::YES,
-            .knownSize = {vp.small.width, NONE},
-            .availableSpace = {vp.small.width, Px{0}},
-            .containingBlock = {vp.small.width, vp.small.height},
-        }
-    );
-    Layout::layoutPositioned(tree, tree.root, {vp.small.width, vp.small.height});
+    auto root = Layout::Frag(&tree.root);
+
+    while (true) {
+        tree.fc.createNextFragmentainer();
+
+        auto outDiscovery = Layout::layoutFrag(
+            tree,
+            tree.root,
+            {
+                .knownSize = {vp.small.width, NONE},
+                .availableSpace = {vp.small.width, Px{0}},
+                .containingBlock = {vp.small.width, vp.small.height},
+            },
+            true
+        );
+
+        logDebug("OUT: {} {}", outDiscovery.unwrap().endChildren, outDiscovery.unwrap().size);
+
+        auto outReal = Layout::layoutFrag(
+            tree,
+            tree.root,
+            {
+                .fragment = &root,
+                .knownSize = {vp.small.width, NONE},
+                .availableSpace = {vp.small.width, Px{0}},
+                .containingBlock = {vp.small.width, vp.small.height},
+            },
+            false
+        );
+
+        tree.fc.getCurrentFragmentainer()->root = &root.children[root.children.len() - 1];
+
+        if (tree.fc.getStartPosition(tree.root) == 1)
+            break;
+    }
+
+    Layout::layoutPositioned(tree, root, {vp.small.width, vp.small.height});
+
+    tree.fc.preparePrint();
 
     auto sceneRoot = makeStrong<Scene::Stack>();
 
@@ -107,7 +135,7 @@ RenderResult render(Markup::Document const &dom, Style::Media const &media, Vec2
 
     auto paintStart = Sys::now();
 
-    Layout::paint(tree.root, *sceneRoot);
+    Layout::paint(root, *sceneRoot);
     sceneRoot->prepare();
 
     elapsed = Sys::now() - paintStart;
@@ -117,6 +145,7 @@ RenderResult render(Markup::Document const &dom, Style::Media const &media, Vec2
         std::move(stylebook),
         makeStrong<Layout::Box>(std::move(tree.root)),
         sceneRoot,
+        makeStrong<Layout::Frag>(root)
     };
 }
 
@@ -144,15 +173,16 @@ RenderResult render(Markup::Document &dom, Style::Media const &media, Print::Pap
     Layout::Tree tree = {
         Layout::build(computer, dom),
         vp,
-        Layout::FragmentationContext()
+        Layout::FragmentationContext({Px{800}, Px{100}})
     };
 
+    auto root = Layout::Frag(&tree.root);
+
     while (true) {
         auto outDiscovery = Layout::layoutFrag(
             tree,
             tree.root,
             {
-                .commit = Layout::Commit::YES,
                 .knownSize = {vp.small.width, NONE},
                 .availableSpace = {vp.small.width, Px{0}},
                 .containingBlock = {vp.small.width, vp.small.height},
@@ -164,7 +194,7 @@ RenderResult render(Markup::Document &dom, Style::Media const &media, Print::Pap
             tree,
             tree.root,
             {
-                .commit = Layout::Commit::YES,
+                .fragment = &root,
                 .knownSize = {vp.small.width, NONE},
                 .availableSpace = {vp.small.width, Px{0}},
                 .containingBlock = {vp.small.width, vp.small.height},
@@ -177,14 +207,15 @@ RenderResult render(Markup::Document &dom, Style::Media const &media, Print::Pap
     }
 
     auto sceneRoot = makeStrong<Scene::Page>();
-    Layout::paint(tree.root, *sceneRoot);
+    Layout::paint(root, *sceneRoot);
     sceneRoot->prepare();
 
     return {
         std::move(stylebook),
         makeStrong<Layout::Box>(std::move(tree.root)),
         sceneRoot,
+        makeStrong<Layout::Frag>(root)
     };
-}
+} // namespace Vaev::Driver
 
 } // namespace Vaev::Driver

src/vaev-driver/render.h

@@ -4,6 +4,7 @@
 #include <vaev-base/length.h>
 #include <vaev-layout/box.h>
 #include <vaev-layout/frag.h>
+#include <vaev-layout/tree.h>
 #include <vaev-markup/dom.h>
 #include <vaev-style/media.h>
 

src/vaev-layout/base.h

@@ -22,33 +22,6 @@ struct Viewport {
     RectPx dynamic = small;
 };
 
-struct Frag;
-
-/// Input to the layout algorithm.
-struct Input {
-    /// Parent fragment where the layout will be attached.
-    MutCursor<Frag> fragment;
-    IntrinsicSize intrinsic = IntrinsicSize::AUTO;
-    Math::Vec2<Opt<Px>> knownSize = {};
-    Vec2Px position = {};
-    Vec2Px availableSpace = {};
-    Vec2Px containingBlock = {};
-};
-
-/// Output of the layout algorithm.
-struct Output {
-    Vec2Px size;
-
-    static Output fromSize(Vec2Px size) {
-        return Output{size};
-    }
-};
-
-struct OutputFrag {
-    Vec2Px size;
-    usize endChildren;
-};
-
 /// Computed layout values.
 
 struct Box;

src/vaev-layout/block.cpp

@@ -1,7 +1,7 @@
-#include "block.h"
+#include "input_output.h"
 
-#include "box.h"
 #include "layout.h"
+#include "tree.h"
 
 namespace Vaev::Layout {
 
@@ -32,6 +32,13 @@ struct BlockFormatingContext {
             return _determineWidth(tree, box, input);
         });
 
+        if (not tree.fc.getCurrentFragmentainer()->acceptsFit(input.position, {
+                                                                                  inlineSize,
+                                                                                  blockSize,
+                                                                              })) {
+            return NONE;
+        }
+
         usize endChildren = stopAt.unwrapOr(box.children().len());
 
         for (usize i = startAt; i < endChildren; ++i) {
@@ -79,7 +86,7 @@ struct BlockFormatingContext {
 
             currentBreakpoint = OutputFrag{
                 .size = Vec2Px{inlineSize, blockSize},
-                .endChildren = i,
+                .endChildren = i + 1,
             };
         }
 
@@ -90,7 +97,7 @@ struct BlockFormatingContext {
                 inlineSize,
                 blockSize,
             },
-            .endChildren = endChildren
+            .endChildren = endChildren,
         };
     }
 };

src/vaev-layout/block.h

@@ -1,6 +1,8 @@
 #pragma once
 
-#include "base.h"
+#include "input_output.h"
+
+#include "tree.h"
 
 namespace Vaev::Layout {
 

src/vaev-layout/box.cpp

@@ -2,6 +2,7 @@
 #include <karm-text/loader.h>
 
 #include "box.h"
+#include "frag.h"
 
 namespace Vaev::Layout {
 

src/vaev-layout/box.h

@@ -11,6 +11,8 @@ namespace Vaev::Layout {
 
 // MARK: Box ------------------------------------------------------------------
 
+struct Box;
+
 using Content = Union<
     None,
     Vec<Box>,
@@ -46,65 +48,4 @@ struct Box : public Meta::NoCopy {
     void repr(Io::Emit &e) const;
 };
 
-// TODO: if we have columns inside a page, who determines the position of the columns? the page or the column?
-
-// https://www.w3.org/TR/css-break-3/#fragmentainer
-struct Fragmentainer {
-    Vec2Px size;
-
-    bool acceptsFit(Vec2Px position, Vec2Px sizeBox) {
-        return position.x + sizeBox.x <= size.x and position.x + sizeBox.y <= size.y;
-    }
-};
-
-// https://www.w3.org/TR/css-break-3/#fragmentation-context
-struct FragmentationContext {
-
-    Vec2Px defaultSize;
-    Map<Box *, usize> layoutUntilComitted, layoutUntilNotComitted;
-
-    FragmentationContext() : defaultSize({Px{800}, Px{600}}) {}
-
-    FragmentationContext(Vec2Px defaultSize) : defaultSize(defaultSize) {}
-
-    Vec<Strong<Fragmentainer>> fragmentainers;
-
-    void createNextFragmentainer() {
-        fragmentainers.pushBack(makeStrong<Fragmentainer>(Fragmentainer(defaultSize)));
-    }
-
-    Strong<Fragmentainer> getCurrentFragmentainer() {
-        if (fragmentainers.empty()) {
-            createNextFragmentainer();
-        }
-
-        return fragmentainers[fragmentainers.len() - 1];
-    }
-
-    usize getStartPosition(Box &box) {
-        if (not layoutUntilComitted.has(&box))
-            return 0;
-        else
-            return layoutUntilComitted.get(&box) + 1;
-    }
-
-    usize getDiscoveredEndPosition(Box &box) {
-        return layoutUntilNotComitted.get(&box);
-    }
-
-    void setDiscoveredEndPosition(Box &box, usize pos) {
-        layoutUntilNotComitted.put(&box, pos);
-    }
-
-    void setLaidOutEndPosition(Box &box, usize pos) {
-        layoutUntilComitted.put(&box, pos);
-    }
-};
-
-struct Tree {
-    Box root;
-    Viewport viewport;
-    FragmentationContext fc;
-};
-
 } // namespace Vaev::Layout

src/vaev-layout/flex.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include "layout.h"
+#include "input_output.h"
 
 namespace Vaev::Layout {
 

src/vaev-layout/frag.h

@@ -35,11 +35,11 @@ struct Metrics {
 };
 
 struct Frag {
-    Cursor<Box> box;
+    MutCursor<Box> box;
     Metrics metrics;
     Vec<Frag> children;
 
-    Frag(Cursor<Box> box) : box{std::move(box)} {}
+    Frag(MutCursor<Box> box) : box{std::move(box)} {}
 
     Style::Computed const &style() const {
         return *box->style;