htmlcell.h

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/////////////////////////////////////////////////////////////////////////////
// Name:        htmlcell.h
// Purpose:     wxHtmlCell class is used by wxHtmlWindow/wxHtmlWinParser
//              as a basic visual element of HTML page
// Author:      Vaclav Slavik
// RCS-ID:      $Id: htmlcell.h,v 1.58 2005/02/24 14:33:32 VZ Exp $
// Copyright:   (c) 1999-2003 Vaclav Slavik
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////


#ifndef _WX_HTMLCELL_H_
#define _WX_HTMLCELL_H_

#if defined(__GNUG__) && !defined(NO_GCC_PRAGMA)
#pragma interface "htmlcell.h"
#endif

#include "wx/defs.h"

#if wxUSE_HTML

#include "wx/html/htmltag.h"
#include "wx/html/htmldefs.h"
#include "wx/window.h"


class WXDLLIMPEXP_HTML wxHtmlLinkInfo;
class WXDLLIMPEXP_HTML wxHtmlCell;
class WXDLLIMPEXP_HTML wxHtmlContainerCell;


// wxHtmlSelection is data holder with information about text selection.
// Selection is defined by two positions (beginning and end of the selection)
// and two leaf(!) cells at these positions.
class WXDLLIMPEXP_HTML wxHtmlSelection
{
public:
    wxHtmlSelection()
        : m_fromPos(wxDefaultPosition), m_toPos(wxDefaultPosition),
          m_fromPrivPos(wxDefaultPosition), m_toPrivPos(wxDefaultPosition),
          m_fromCell(NULL), m_toCell(NULL) {}

    void Set(const wxPoint& fromPos, const wxHtmlCell *fromCell,
             const wxPoint& toPos, const wxHtmlCell *toCell);
    void Set(const wxHtmlCell *fromCell, const wxHtmlCell *toCell);

    const wxHtmlCell *GetFromCell() const { return m_fromCell; }
    const wxHtmlCell *GetToCell() const { return m_toCell; }

    // these values are in absolute coordinates:
    const wxPoint& GetFromPos() const { return m_fromPos; }
    const wxPoint& GetToPos() const { return m_toPos; }

    // these are From/ToCell's private data
    const wxPoint& GetFromPrivPos() const { return m_fromPrivPos; }
    const wxPoint& GetToPrivPos() const { return m_toPrivPos; }
    void SetFromPrivPos(const wxPoint& pos) { m_fromPrivPos = pos; }
    void SetToPrivPos(const wxPoint& pos) { m_toPrivPos = pos; }
    void ClearPrivPos() { m_toPrivPos = m_fromPrivPos = wxDefaultPosition; }

    bool IsEmpty() const
        { return m_fromPos == wxDefaultPosition &&
                 m_toPos == wxDefaultPosition; }

private:
    wxPoint m_fromPos, m_toPos;
    wxPoint m_fromPrivPos, m_toPrivPos;
    const wxHtmlCell *m_fromCell, *m_toCell;
};



enum wxHtmlSelectionState
{
    wxHTML_SEL_OUT,     // currently rendered cell is outside the selection
    wxHTML_SEL_IN,      // ... is inside selection
    wxHTML_SEL_CHANGING // ... is the cell on which selection state changes
};

// Selection state is passed to wxHtmlCell::Draw so that it can render itself
// differently e.g. when inside text selection or outside it.
class WXDLLIMPEXP_HTML wxHtmlRenderingState
{
public:
    wxHtmlRenderingState() : m_selState(wxHTML_SEL_OUT) {}

    void SetSelectionState(wxHtmlSelectionState s) { m_selState = s; }
    wxHtmlSelectionState GetSelectionState() const { return m_selState; }

    void SetFgColour(const wxColour& c) { m_fgColour = c; }
    const wxColour& GetFgColour() const { return m_fgColour; }
    void SetBgColour(const wxColour& c) { m_bgColour = c; }
    const wxColour& GetBgColour() const { return m_bgColour; }

private:
    wxHtmlSelectionState  m_selState;
    wxColour              m_fgColour, m_bgColour;
};


// HTML rendering customization. This class is used when rendering wxHtmlCells
// as a callback:
class WXDLLIMPEXP_HTML wxHtmlRenderingStyle
{
public:
    virtual ~wxHtmlRenderingStyle() {}
    virtual wxColour GetSelectedTextColour(const wxColour& clr) = 0;
    virtual wxColour GetSelectedTextBgColour(const wxColour& clr) = 0;
};

// Standard style:
class WXDLLIMPEXP_HTML wxDefaultHtmlRenderingStyle : public wxHtmlRenderingStyle
{
public:
    virtual wxColour GetSelectedTextColour(const wxColour& clr);
    virtual wxColour GetSelectedTextBgColour(const wxColour& clr);
};


// Information given to cells when drawing them. Contains rendering state,
// selection information and rendering style object that can be used to
// customize the output.
class WXDLLIMPEXP_HTML wxHtmlRenderingInfo
{
public:
    wxHtmlRenderingInfo() : m_selection(NULL), m_style(NULL) {}

    void SetSelection(wxHtmlSelection *s) { m_selection = s; }
    wxHtmlSelection *GetSelection() const { return m_selection; }

    void SetStyle(wxHtmlRenderingStyle *style) { m_style = style; }
    wxHtmlRenderingStyle& GetStyle() { return *m_style; }

    wxHtmlRenderingState& GetState() { return m_state; }

protected:
    wxHtmlSelection      *m_selection;
    wxHtmlRenderingStyle *m_style;
    wxHtmlRenderingState m_state;
};


// Flags for wxHtmlCell::FindCellByPos
enum
{
    wxHTML_FIND_EXACT             = 1,
    wxHTML_FIND_NEAREST_BEFORE    = 2,
    wxHTML_FIND_NEAREST_AFTER     = 4
};




// ---------------------------------------------------------------------------
// wxHtmlCell
//                  Internal data structure. It represents fragments of parsed
//                  HTML page - a word, picture, table, horizontal line and so
//                  on.  It is used by wxHtmlWindow to represent HTML page in
//                  memory.
// ---------------------------------------------------------------------------


class WXDLLIMPEXP_HTML wxHtmlCell : public wxObject
{
public:
    wxHtmlCell();
    virtual ~wxHtmlCell();

    void SetParent(wxHtmlContainerCell *p) {m_Parent = p;}
    wxHtmlContainerCell *GetParent() const {return m_Parent;}

    int GetPosX() const {return m_PosX;}
    int GetPosY() const {return m_PosY;}
    int GetWidth() const {return m_Width;}

    // Returns the maximum possible length of the cell.
    // Call Layout at least once before using GetMaxTotalWidth()
    virtual int GetMaxTotalWidth() const { return m_Width; }

    int GetHeight() const {return m_Height;}
    int GetDescent() const {return m_Descent;}

    // Formatting cells are not visible on the screen, they only alter
    // renderer's state.
    bool IsFormattingCell() const { return m_Width == 0 && m_Height == 0; }

    const wxString& GetId() const { return m_id; }
    void SetId(const wxString& id) { m_id = id; }

    // returns the link associated with this cell. The position is position
    // within the cell so it varies from 0 to m_Width, from 0 to m_Height
    virtual wxHtmlLinkInfo* GetLink(int WXUNUSED(x) = 0,
                                    int WXUNUSED(y) = 0) const
        { return m_Link; }

    // Returns cursor to be used when mouse is over the cell:
    virtual wxCursor GetCursor() const;

    // return next cell among parent's cells
    wxHtmlCell *GetNext() const {return m_Next;}
    // returns first child cell (if there are any, i.e. if this is container):
    virtual wxHtmlCell* GetFirstChild() const { return NULL; }

    // members writing methods
    virtual void SetPos(int x, int y) {m_PosX = x, m_PosY = y;}
    void SetLink(const wxHtmlLinkInfo& link);
    void SetNext(wxHtmlCell *cell) {m_Next = cell;}

    // 1. adjust cell's width according to the fact that maximal possible width
    //    is w.  (this has sense when working with horizontal lines, tables
    //    etc.)
    // 2. prepare layout (=fill-in m_PosX, m_PosY (and sometime m_Height)
    //    members) = place items to fit window, according to the width w
    virtual void Layout(int w);

    // renders the cell
    virtual void Draw(wxDC& WXUNUSED(dc),
                      int WXUNUSED(x), int WXUNUSED(y),
                      int WXUNUSED(view_y1), int WXUNUSED(view_y2),
                      wxHtmlRenderingInfo& WXUNUSED(info)) {}

    // proceed drawing actions in case the cell is not visible (scrolled out of
    // screen).  This is needed to change fonts, colors and so on.
    virtual void DrawInvisible(wxDC& WXUNUSED(dc),
                               int WXUNUSED(x), int WXUNUSED(y),
                               wxHtmlRenderingInfo& WXUNUSED(info)) {}

    // This method returns pointer to the FIRST cell for that
    // the condition
    // is true. It first checks if the condition is true for this
    // cell and then calls m_Next->Find(). (Note: it checks
    // all subcells if the cell is container)
    // Condition is unique condition identifier (see htmldefs.h)
    // (user-defined condition IDs should start from 10000)
    // and param is optional parameter
    // Example : m_Cell->Find(wxHTML_COND_ISANCHOR, "news");
    //   returns pointer to anchor news
    virtual const wxHtmlCell* Find(int condition, const void* param) const;

    // This function is called when mouse button is clicked over the cell.
    //
    // Parent is pointer to wxHtmlWindow that generated the event
    // HINT: if this handling is not enough for you you should use
    //       wxHtmlWidgetCell
    virtual void OnMouseClick(wxWindow *parent, int x, int y, const wxMouseEvent& event);

    // This method used to adjust pagebreak position. The parameter is variable
    // that contains y-coordinate of page break (= horizontal line that should
    // not be crossed by words, images etc.). If this cell cannot be divided
    // into two pieces (each one on another page) then it moves the pagebreak
    // few pixels up.
    //
    // Returned value : true if pagebreak was modified, false otherwise
    // Usage : while (container->AdjustPagebreak(&p)) {}
    virtual bool AdjustPagebreak(int *pagebreak,
                                 int *known_pagebreaks = NULL,
                                 int number_of_pages = 0) const;

    // Sets cell's behaviour on pagebreaks (see AdjustPagebreak). Default
    // is true - the cell can be split on two pages
    void SetCanLiveOnPagebreak(bool can) { m_CanLiveOnPagebreak = can; }

    // Can the line be broken before this cell?
    virtual bool IsLinebreakAllowed() const
        { return !IsFormattingCell(); }

    // Returns true for simple == terminal cells, i.e. not composite ones.
    // This if for internal usage only and may disappear in future versions!
    virtual bool IsTerminalCell() const { return true; }

    // Find a cell inside this cell positioned at the given coordinates
    // (relative to this's positions). Returns NULL if no such cell exists.
    // The flag can be used to specify whether to look for terminal or
    // nonterminal cells or both. In either case, returned cell is deepest
    // cell in cells tree that contains [x,y].
    virtual wxHtmlCell *FindCellByPos(wxCoord x, wxCoord y,
                                  unsigned flags = wxHTML_FIND_EXACT) const;

    // Returns absolute position of the cell on HTML canvas
    wxPoint GetAbsPos() const;

    // Returns first (last) terminal cell inside this cell. It may return NULL,
    // but it is rare -- only if there are no terminals in the tree.
    virtual wxHtmlCell *GetFirstTerminal() const
        { return wxConstCast(this, wxHtmlCell); }
    virtual wxHtmlCell *GetLastTerminal() const
        { return wxConstCast(this, wxHtmlCell); }

    // Returns cell's depth, i.e. how far under the root cell it is
    // (if it is the root, depth is 0)
    unsigned GetDepth() const;

    // Returns true if the cell appears before 'cell' in natural order of
    // cells (= as they are read). If cell A is (grand)parent of cell B,
    // then both A.IsBefore(B) and B.IsBefore(A) always return true.
    bool IsBefore(wxHtmlCell *cell) const;

    // Converts the cell into text representation. If sel != NULL then
    // only part of the cell inside the selection is converted.
    virtual wxString ConvertToText(wxHtmlSelection *WXUNUSED(sel)) const
        { return wxEmptyString; }

protected:
    wxHtmlCell *m_Next;
            // pointer to the next cell
    wxHtmlContainerCell *m_Parent;
            // pointer to parent cell
    long m_Width, m_Height, m_Descent;
            // dimensions of fragment
            // m_Descent is used to position text&images..
    long m_PosX, m_PosY;
            // position where the fragment is drawn
    wxHtmlLinkInfo *m_Link;
            // destination address if this fragment is hypertext link, NULL otherwise