4
o I need to check the bounds are being calculated correctly so that they
5
are correct for all zoom settings. Since cairo uses fixed point maths
6
and I think only calculates up to a certain tolerance there might be
7
slight errors in our gdouble results. So as the canvas is scaled this
8
could eventually lead to the bounds being a pixel out, leading to painting
9
errors. Maybe we should extend any bounds returned from cairo slightly to
10
cover the maximum possible errors.
12
o button press events are generating leave-notify and enter-notify signals.
13
Seems to be a GTK+/X problem.
15
o The GooCairo* types are used for some properties but aren't documented.
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Maybe we could point to the cairo docs.
18
Features definitely needed:
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o Editable text item - a port of GtkTextView.
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o Tooltips - I have code to support tooltips using the new API in GTK+ 2.12.
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o Need a function to setup a given cairo context with the defaults settings
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of a GooCanvas, e.g. default line width.
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o Check canvas and all items can be completely configured with properties
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so that GtkBuilder can be used to load hierarchies of items/models.
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Add "root-item" and "root-item-model" properties? Will GtkBuilder be able
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to handle the tree of items/models like that? What about GUI builders?
30
How can gradients be specified by object properties?
33
Possible additional features:
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o Need a way to efficiently notify items about changes in canvas scale, if
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they request it. Could use something similar to the update flags.
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o Change GooCanvasStyle so it doesn't expose GValues in the API.
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Use get/set_boolean/int/double/boxed() instead.
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o Drag-and-Drop - probably copy all the GTK+ widget signals so items can
42
implement their own behavior.
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o Caching of rendered items to improve performance. Items would have a cache
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option with choices like Never, Always and WhenVisible.
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o Sticky items that don't move at all as the canvas is scrolled & zoomed.
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o Filters like in SVG, to add graphical effects.
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o Support using the same item in different places, like SVG 'use'.
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o Support using system color names, like SVG, e.g. "ActiveBorder".
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This helps you write widget-like items that fit in with the rest of GTK+.
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o "scale-line-width" boolean property to specify if the line width scales
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with the canvas? The item bounds will change at different scale settings.
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o Arrows on path items, just like on polyline.
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Requests from GTK+ people:
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o Use separate GooCanvasContainer[Model] interfaces? May help bindings.
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o GooCanvasWidget width & height are redundant - use widget's requested size.
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o Make PathCommand and LineDash structs opaque.
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o Use floating flag and sink() for objects.
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o Use 1-byte integer percentage for xalign/yalign instead of doubles?
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o Make it easy to add a border and background to items. "border-width",
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"border-color" and "background-color" properties? Might also need "x-pad",
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"y-pad", "x-radius", "y-radius" etc. Maybe have a related border item.
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Note that we only have the bounds in device coords, so drawing a border of
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a rotated item would be awkward. (Maybe we store the user bounds somewhere.)
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o Link/URL item, or enable URLs in the markup of text items.
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o A button item, with different children displayed for different states,
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maybe with optional automatic prelighting.