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### WxStyledTextCtrl - Margins

- GetMarginLeft
- GetMarginMask
- GetMarginRight
- GetMarginSensitive
- GetMarginType
- GetMarginWidth
- SetMarginLeft
- SetMarginMask
- SetMarginRight
- SetMargins
- SetMarginSensitive
- SetMarginType
- SetMarginWidth

Summary:

The STC can have up to five margins: a blank margin on each side of the text and three additional margins between the left-side blank margin and the text. This is illustrated in the figure below. Margins can be used for line numbers or symbols, and can be sensitive to mouse clicks either to send an event or to select a line of text.

You need to chose whether or not a margin is used for line numbers or symbols. If you want line numbers, use margin 0 for the line numbers by calling SetMarginType(0,wxSTC_MARGIN_NUMBER). If you want symbols and/or folding, call SetMarginType(n, wxSTC_MARGIN_SYMBOL) where n is 1 or 2. It's a convention that margin 0 is reserved for line numbers.

When you instantiate a STC, defaults related to margins are:

margin | settings
left | 1 pixel wide
right | 1 pixel wide
0 | number margin 0 pixels wide mask=0
1 | symbol margin 16 pixels wide mask=0x01FFFFFF
2 | symbol margin 0 pixels wide mask=0

As you can see, the default width for the left and right margins is 1 pixel. You can change these with SetMarginLeft and SetMarginRight, or you can use SetMargins which affects both margins with one method call.

For margins 0, 1, and 2, the net effect of these defaults is that the zeroth margin is set up for line numbers, but is hidden; the first margin is set up for non-folding symbols and is 16 pixels wide, and the second margin is set up for symbols, no mask is set, and zero width. The meaning of mask is discussed a few paragraphs below.

So you can see that the other margins (called 0, 1, and 2) are used for line numbers and symbol display. Again, it seems to be conventional to use margin 0 for line numbers, 1 for symbols of various sorts, and 2 for folding. You set the width of these three margins with the SetMarginWidth method. If you set a margin's width to zero it will be ignored; however, if you set a marker (using MarkerAdd) on a zero-width margin then the background color of the line will change: this is useful for debuggers, editors, etc.

The color for the background is painted one of two ways, depending on whether or not the margin's mask is set to use any of the folding symbols. If folding symbols aren't used (i.e., if mask & wxSTC_MASK_FOLDERS == 0) then a solid color is used: the background color of the wxSTC_STYLE_LINENUMBER style.

If any folding symbols are set for that margin then a checkerboard dithered pattern is used using the system chrome colors: wxSystemSettings::GetColour(wxSYS_COLOUR_3DFACE) and wxSystemSettings::GetColour(wxSYS_COLOUR_3DHIGHLIGHT). For more information on this, see Scintilla src code: Editor.cxx in the Paint() method, ~ line 2025, and PlatWX.cpp around line 866.

It's suggested that you read the Markers section before trying to understand symbol margins.

For symbol margins there's a 32-bit value for each line, where each bit is a on/off flag for a particular symbol. To turn a marker on/off, set the corresponding bit on or off with MarkerAdd.

You may be wondering which marker corresponds to each bit? When the STC is initialized, all bits correspond to wxSTC_MARK_CIRCLE. You use MarkerDefine to set a particular marker bit to correspond to a particular marker symbol. Again, see the Markers section for details on what type of markers are available.

Before you can turn markers on and off, you need to set a so-called margin mask for each symbol margin using the SetMarginMask method. It sounds complicated, but all that's required is to have a bit for each marker number (those set by MarkerDefine), for example, if you set margin 1 to be a symbol margin with SetMarginType(1, wxSTC_MARGIN_SYMBOL), and you set marker 0 to wxSTC_MARK_PLUS with MarkerDefine(0, wxSTC_MARK_PLUS, "white", "black") then you would set margin 1's mask to allow marker 0 to be used on this margin: SetMarginMask(1,0x1). If you were using a number of different symbols on margin 1, you'd create a mask that's the OR of all the symbol numbers and use that for the second argument to SetMarginMask.

If you're using a symbol margin for folding, follow the convention of using the upper seven bits for the folding symbols. there's even a handy constant wxSTC_MASK_FOLDERS (0x7E000000).

Example:

I want to set up margin 0 for numbers, margin 1 for symbols, and margin 2 for folding. This simple example is not tested; it's just to give you an idea. It leaves out some code that is needed to enable folding, as well.

    stcInstance.SetMargins(0,0)    #set left and right outer margins to 0 width
    lines = stcInstance.GetLineCount() #get # of lines, ensure text is loaded first!

    #now figure out the optimum width for the number margin based on how long the
    #line number string would be. 'lines' is the number of lines, so we
    #need to make it a string and add an extra char for safety. For example,
    #if it's 500 lines, str(lines)+' ' = "500 " and we'd figure out the
    #number of pixels needed for up to 9999 lines. Note that this isn't
    #dynamic, although it does allow for some growth in the document size.
    #Could also do this check at idle time and adjust the width as one
    #scrolls thru the document, i.e., at line 10 have a different line number
    #margin width than at line 1000. The UltraEdit text editor does this....

    width = stcInstance.TextWidth(wxSTC_STYLE_LINENUMBER,str(lines)+' ')
    stcInstance.SetMarginWidth(0,width)

    stcInstance.SetMarginWidth(1, 16)   #margin 1 for symbols, 16 px wide
    stcInstance.SetMarginType(1, wxSTC_MARGIN_SYMBOL)

    #Setup a margin to hold fold markers
    stcInstance.SetMarginType(2, wxSTC_MARGIN_SYMBOL) #margin 2 for symbols
    stcInstance.SetMarginMask(2, wxSTC_MASK_FOLDERS)  #set up mask for folding symbols
    stcInstance.SetMarginSensitive(2, true)           #this one needs to be mouse-aware
    stcInstance.SetMarginWidth(2, 16)                 #set margin 2 16 px wide

    #define folding markers
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDEREND,     wxSTC_MARK_BOXPLUSCONNECTED,  "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDEROPENMID, wxSTC_MARK_BOXMINUSCONNECTED, "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDERMIDTAIL, wxSTC_MARK_TCORNER,  "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDERTAIL,    wxSTC_MARK_LCORNER,  "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDERSUB,     wxSTC_MARK_VLINE,    "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDER,        wxSTC_MARK_BOXPLUS,  "white", "black")
    stcInstance.MarkerDefine(wxSTC_MARKNUM_FOLDEROPEN,    wxSTC_MARK_BOXMINUS, "white", "black")

There are two defined variables in wxPython that you can use to to define or test for the margin types in SetMarginType and GetMarginType: wxSTC_MARGIN_NUMBER and wxSTC_MARGIN_SYMBOL

n.b. I don't like these explanations yet.

GetMarginLeft()

Returns an integer object with the left-outer margin size in pixels.

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GetMarginMask(margin)

Returns an integer object with the margin mask for the margin specified by the input parameter margin (0,1,2).

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GetMarginRight()

Returns an integer object with the right-outer margin size in pixels.

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GetMarginSensitive(margin)

Returns an integer object with the value 1 (aka TRUE) if the margin specified by the input parameter margin (0,1,2) is mouse-sensitive or 0 if it is not.

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GetMarginType(margin)

Returns an integer object with the margin type (wxSTC_MARGIN_NUMBER or wxSTC_MARGIN_SYMBOL) for the margin specified by the input parameter margin (0,1,2).

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GetMarginWidth(margin)

Returns an integer object with the margin width in pixels for the margin specified by the input parameter margin (0,1,2).

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SetMarginLeft(pixelwidth)

Sets the width of the left-outer margin to the number of pixels specified by the integer argument pixelwidth. Returns None.

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SetMarginMask(margin,mask)

Sets the marker-mask for the margin specified by the integer argument margin (0,1,2) to the value of the integer argument mask. Returns None.

From the Scintilla documentation:

The mask is a 32-bit value. Each bit corresponds to one of 32 logical symbols that can be displayed in a margin that is enabled for symbols. There is a useful constant, wxSTC_MASK_FOLDERS (0xFE000000 or -33554432), that is a mask for the 7 logical symbols used to denote folding. You can assign a wide range of symbols and colours to each of the 32 logical symbols, see Markers for more information. If (mask & wxSTC_MASK_FOLDERS)==0, the margin background colour is controlled by style 33 (wxSTC_STYLE_LINENUMBER).

You add logical markers to a line with MarkerAdd. If a line has an associated marker that does not not appear in the mask of any margin with a non-zero width, the marker changes the background colour of the line. For example, suppose you decide to use logical marker 10 to mark lines with a syntax error and you want to show such lines by changing the background colour. The mask for this marker is 1 shifted left 10 times (1<<10) which is 0x400. If you make sure that no symbol margin includes 0x400 in its mask, any line with the marker gets the background colour changed.

To set a non-folding margin 1 use SetMarginMask(1, ~wxSTC_MASK_FOLDERS); to set a folding margin 2 use SetMarginMask(2, wxSTC_MASK_FOLDERS). This is the default set by Scintilla. ~wxSTC_MASK_FOLDERS is 0x1FFFFFF in hexadecimal. Of course, you may need to display all 32 symbols in a margin, in which case use SetMarginMask(margin, -1).

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SetMarginRight(pixelWidth)

Sets the width of the right-outer margin to the number of pixels specified by the integer argument pixelwidth. Returns None.

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SetMargins(left,right)

This method permits setting both outer-margins at once, using the integer parameters left and right. Returns None.

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SetMarginSensitive(margin,sensitive)

Sets the margin specified by the integer parameter margin (0,1,2) to be sensitive to mouse clicks if the integer parameter sensitive is nonzero, or insensitive if sensitive is 0. Returns None.

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SetMarginType(margin,marginType)

Sets the margin specified by the integer parameter margin (0,1,2) to the mode specified by the integer parameter marginType. Use one of the values `wxSTC_MARGIN_NUMBER` or `wxSTC_MARGIN_SYMBOL` as the marginType argument. Returns None.

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SetMarginWidth(margin,pixelWidth)

Sets the margin specified by the integer parameter margin (0,1,2) to be the width pixelWidth. Returns None. top