2001-09-08 00:56:30 +00:00
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The way that the GtkTreeView calculates sizing is pretty confusing.
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This is written down to help keep track of it in my head, and thus help
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anyone who hopes to work with the code in the future.
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HOW THE GTKTREEVIEW CALCULATES SIZE:
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====================================
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When the view is given a new model, the first thing it does is walk
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through the model at the top level, creating an GtkRBNode for each
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element of the model. Each node has a height of 0. The RBTree is kept
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updated as the models structure changes. Additionally, the user can
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expand, collapse, and select rows at this stage. The RBTree is accurate
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-- it just doesn't have a height for any row.
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When the TreeView is realized, it calculates the actual height of each
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row by walking the tree and measuring them. While doing so, it gets the
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size of each column.
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Columns are initially marked as 'dirty'. When sized,
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gtk_tree_view_check_dirty_and_clean () is called on each column. This
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function walks through all visible columns, and sees if they're dirty or
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not. If any are dirty, it then walks the tree, calling
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gtk_tree_view_calc_size on each row. gtk_tree_view_calc_size requests
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the size of every dirty column in the tree. Finally, it updates the
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size of the widget (including adjustments).
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HOW THE GTKTREEVIEWCOLUMN STORES SIZE:
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======================================
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There are a number of size related fields in the GtkTreeViewColumn
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2001-09-25 16:44:39 +00:00
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structure. These are all valid after realization:
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2001-09-08 00:56:30 +00:00
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sizing The sizing method to use when calculating the size
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of the column. Can be grow_only, resizable, auto, and fixed.
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requested_width The width of the column as requested by the column
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width The actual width. This is requested width for all
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columns but possibly the last one.
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fixed_width The requested fixed width for the column iff it's
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sizing type is set to GTK_TREE_VIEW_COLUMN_FIXED.
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min_width The minimum width the column can be
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max_width The maximum width the column can be. This can be
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overridden for the last column, if the tree_view is
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actually wider than the sum of all of the columns
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requested_widths.
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The following invariants are true:
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min_width is less than or equal to width
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max_width is greater than or equal to width
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(sizing == GTK_TREE_VIEW_COLUMN_FIXED) => (requested_width == fixed_width)
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(column != last visible column) => width == requested_width
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/* Functions needed by gtktreeview for gtktreeviewcolumn */
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size_request_button
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set_width (for resizing resizable columns)
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calculate_width
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