vcl: separate SalLayout from the rest of sallayout.hxx

This way SalLayout can be created separately (and potentially reused)
outside vcl as well. Don't reformat the moved code, so git blame keeps
working.

This is a first step towards the goal of
<https://wiki.documentfoundation.org/Development/Budget2017#Text_layout_performance>,
in the context of code outside vcl.

Change-Id: I8b40313b5fa531d3b56c153cbc4b5ca3cec8f8df
Reviewed-on: https://gerrit.libreoffice.org/58851
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins

1 files changed, 130 insertions, 0 deletions

diff --git a/include/vcl/vcllayout.hxx b/include/vcl/vcllayout.hxx
new file mode 100644
index 000000000000..d9d4e0c42b99
--- /dev/null
+++ b/include/vcl/vcllayout.hxx
@@ -0,0 +1,130 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#ifndef INCLUDED_VCL_VCLLAYOUT_HXX
+#define INCLUDED_VCL_VCLLAYOUT_HXX
+
+#include <memory>
+
+#include <basegfx/polygon/b2dpolypolygon.hxx>
+#include <tools/gen.hxx>
+#include <vcl/devicecoordinate.hxx>
+#include <vcl/dllapi.h>
+
+class ImplLayoutArgs;
+class PhysicalFontFace;
+class SalGraphics;
+struct GlyphItem;
+namespace vcl
+{
+class TextLayoutCache;
+}
+
+// all positions/widths are in font units
+// one exception: drawposition is in pixel units
+
+// Unfortunately there is little documentation to help implementors of
+// new classes derived from SalLayout ("layout engines"), and the code
+// and data structures are far from obvious.
+
+// For instance, I *think* the important virtual functions in the
+// layout engines are called in this order:
+
+// * InitFont()
+// * LayoutText()
+// * AdjustLayout(), any number of times (but presumably
+// usually not at all or just once)
+// * Optionally, DrawText()
+
+// Functions that just return information like GetTexWidth() and
+// FillDXArray() are called after LayoutText() and before DrawText().
+
+// Another important questions is which parts of an ImplLayoutArgs can
+// be changed by callers between LayoutText() and AdjustLayout()
+// calls. It probably makes sense only if one assumes that the "string
+// related inputs" part are not changed after LayoutText().
+
+// But why use the same ImplLayoutArgs structure as parameter for both
+// LayoutText() and AdjustLayout() in the first place? And why
+// duplicate some of the fields in both SalLayout and ImplLayoutArgs
+// (mnMinCharPos, mnEndCharPos, mnLayoutFlags==mnFlags,
+// mnOrientation)? Lost in history...
+
+class VCL_DLLPUBLIC SalLayout
+{
+public:
+    virtual         ~SalLayout();
+    // used by upper layers
+    Point&          DrawBase()                              { return maDrawBase; }
+    const Point&    DrawBase() const                        { return maDrawBase; }
+    Point&          DrawOffset()                            { return maDrawOffset; }
+    const Point&    DrawOffset() const                      { return maDrawOffset; }
+    Point           GetDrawPosition( const Point& rRelative = Point(0,0) ) const;
+
+    virtual bool    LayoutText( ImplLayoutArgs& ) = 0;  // first step of layouting
+    virtual void    AdjustLayout( ImplLayoutArgs& );    // adjusting after fallback etc.
+    virtual void    InitFont() const {}
+    virtual void    DrawText( SalGraphics& ) const = 0;
+
+    int             GetUnitsPerPixel() const                { return mnUnitsPerPixel; }
+    int             GetOrientation() const                  { return mnOrientation; }
+
+    // methods using string indexing
+    virtual sal_Int32 GetTextBreak(DeviceCoordinate nMaxWidth, DeviceCoordinate nCharExtra, int nFactor) const = 0;
+    virtual DeviceCoordinate FillDXArray( DeviceCoordinate* pDXArray ) const = 0;
+    virtual DeviceCoordinate GetTextWidth() const { return FillDXArray( nullptr ); }
+    virtual void    GetCaretPositions( int nArraySize, long* pCaretXArray ) const = 0;
+    virtual bool    IsKashidaPosValid ( int /*nCharPos*/ ) const { return true; } // i60594
+
+    // methods using glyph indexing
+    virtual bool    GetNextGlyph(const GlyphItem** pGlyph, Point& rPos, int&,
+                                 const PhysicalFontFace** pFallbackFont = nullptr) const = 0;
+    virtual bool    GetOutline( SalGraphics&, basegfx::B2DPolyPolygonVector& ) const;
+    virtual bool    GetBoundRect( SalGraphics&, tools::Rectangle& ) const;
+
+    // used by glyph+font+script fallback
+    virtual void    MoveGlyph( int nStart, long nNewXPos ) = 0;
+    virtual void    DropGlyph( int nStart ) = 0;
+    virtual void    Simplify( bool bIsBase ) = 0;
+
+    virtual std::shared_ptr<vcl::TextLayoutCache>
+        CreateTextLayoutCache(OUString const&) const;
+
+protected:
+    // used by layout engines
+                    SalLayout();
+
+private:
+                    SalLayout( const SalLayout& ) = delete;
+                    SalLayout& operator=( const SalLayout& ) = delete;
+
+protected:
+    int             mnMinCharPos;
+    int             mnEndCharPos;
+
+    int             mnUnitsPerPixel;
+    int             mnOrientation;
+
+    mutable Point   maDrawOffset;
+    Point           maDrawBase;
+};
+
+#endif // INCLUDED_VCL_VCLLAYOUT_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */