docs/architecture/CPU.dot

// Skia CPU Backend Dataflow Diagram
// This helps show how data flows through the CPU backend during a draw.
//
// LEGEND:
//
// Colors:
//   - Blue: Actors/Processors (Objects that perform actions)
//   - Yellow: Data/Configuration (Objects that hold information)
//
// Line Styles:
//   - Solid: Data Flow (Objects passed in as parameters in function calls)
//   - Dashed: Owns (An object holds a smart pointer (sk_sp) to another)
//   - Dotted: Borrows (An object holds a raw pointer or temporary view of another)

digraph SkiaCPUBackend {
    rankdir=TB;
    splines=ortho;
    node [shape=box, style="rounded"];

    subgraph cluster_api {
        label="API Layer";
        style="rounded";
        SkCanvas [label="SkCanvas\n(e.g., drawPath)", style=filled, fillcolor=lightblue];
        SkSurface [label="SkSurface", style=filled, fillcolor=lightblue];
        SkPath [label="SkPath", style=filled, fillcolor=lightyellow];
        SkPathRef [label="SkPathRef\n(Heap-allocated Geometry)", style=filled, fillcolor=lightyellow];
        SkImage [label="SkImage\n(Immutable Pixels)", style=filled, fillcolor=lightyellow];

        SkPaintRecord [
            label="{SkPaint | { Color | Style | Stroke Width } | { Stroke Cap | Stroke Join | Stroke Miter Limit } | { <blender> SkBlender | <colorfilter> SkColorFilter | <patheffect> SkPathEffect } | { <maskfilter> SkMaskFilter\n(blur) | <shader> SkShader\n(gradients, etc) | <imagefilter> SkImageFilter\n(shadows, etc) }}",
            shape=record,
            style=filled,
            fillcolor=lightyellow
        ];
    }

    subgraph cluster_font_management {
        label="Font Management";
        style="rounded";
        SkFontMgr [label="SkFontMgr\n(Font Discovery)", style=filled, fillcolor=lightblue];
        SkTypeface [label="SkTypeface\n(Font Data)", style=filled, fillcolor=lightyellow];
        SkFont [label="SkFont\n(Text Style)", style=filled, fillcolor=lightyellow];
    }

    subgraph cluster_cpu_backend {
        label="CPU Backend";
        style="rounded";
        SkDevice [label="SkBitmapDevice\n(Stateful)", style=filled, fillcolor=lightblue];
        SkDraw [label="SkDraw\n(Stateless Orchestrator)", style=filled, fillcolor=lightblue];
        SkScan [label="SkScan\n(Shape -> Scanlines)", style=filled, fillcolor=lightblue];
        SkRasterPipelineBlitter [label="SkRasterPipelineBlitter", style=filled, fillcolor=lightblue];
        SkRasterPipeline [label="SkRasterPipeline\n(Pixel Processing Stages)", style=filled, fillcolor=lightblue];
        SkImage_Raster [label="SkImage_Raster\n(subclass)", style=filled, fillcolor=lightyellow];
        SkBitmap [label="SkBitmap\n(Pixel Accessor)", style=filled, fillcolor=lightyellow];
        SkPixmap [label="SkPixmap\n(Pixel View)", style=filled, fillcolor=lightyellow];
        SkPixelRef [label="SkPixelRef\n(Pixel Owner)", style=filled, fillcolor=lightyellow];
    }

    // Relationships
    SkSurface -> SkCanvas [style=dashed];
    SkSurface -> SkImage;
    SkCanvas -> SkDevice;
    SkPath -> SkCanvas;
    SkPath -> SkPathRef [style=dashed];
    SkPaintRecord -> SkCanvas;
    SkFont -> SkCanvas;
    SkImage -> SkCanvas;

    SkFontMgr -> SkTypeface;
    SkFont -> SkTypeface [style=dashed];

    SkDevice -> SkDraw;
    SkDevice -> SkBitmap [style=dashed];

    SkDraw -> SkScan;
    SkDraw -> SkRasterPipelineBlitter;

    SkScan -> SkRasterPipelineBlitter;

    SkRasterPipelineBlitter -> SkRasterPipeline;
    SkRasterPipeline -> SkPixmap;

    // Pixel Ownership Story
    SkImage -> SkImage_Raster [style=dashed];
    SkImage_Raster -> SkBitmap [style=dashed];
    SkBitmap -> SkPixelRef [style=dashed];
    SkBitmap -> SkPixmap [style=dashed];
    SkPixmap -> SkPixelRef [style=dotted];
}