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platform.gc

148 bytes added, 13:10, 6 June 2012
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Returns a dummy [[:Category:gc|graphics context]].<br />
 
Returns a dummy [[:Category:gc|graphics context]].<br />
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As a consequence, you are able to use the functions made for the "normal" [[:Category:gc|gc]].
    
It is typically used to measure pixel lengths and heights of strings when a normal graphics context is not available.<br />
 
It is typically used to measure pixel lengths and heights of strings when a normal graphics context is not available.<br />
 
This may be the case when creating new text elements when the script app is initialized.<br />
 
This may be the case when creating new text elements when the script app is initialized.<br />
A graphics context is available only during paint events, and that may be too late to create and size the containers for text fields.
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A graphics context is available only during paint events, and that may be too late to create and size the containers for text fields.<br />
 
This graphics context cannot be used to draw graphics since it is not tied to a window. It can however do that if this gc is used in a function called within [[on.paint]].
 
This graphics context cannot be used to draw graphics since it is not tied to a window. It can however do that if this gc is used in a function called within [[on.paint]].
Here is an example of using the dummy graphics context to get the pixel length and height of a string.
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<br />
<syntaxhighlight>local gc = platform.gc()                  -- Get the dummy graphics context
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gc:begin()                                -- Makes it the current graphics context
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local width = gc:getStringWidth(a_string) -- Gets the pixel length of a_string
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local height = gc:getStringHeight(a_string)      -- Gets the pixel height of a_string
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Here is an example of using the dummy graphics context to get the pixel length and height of a string :
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<syntaxhighlight>local gc = platform.gc()                    -- Get the dummy graphics context
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gc:begin()                                  -- Makes it the current graphics context
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local width = gc:getStringWidth(a_string)    -- Gets the pixel length of a_string
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local height = gc:getStringHeight(a_string)  -- Gets the pixel height of a_string
 
-- do things here --
 
-- do things here --
gc:finish()                               -- Restores previous graphics context</syntaxhighlight>
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gc:finish()                                 -- Restores previous graphics context</syntaxhighlight>
 
It is important to use [[gc:begin]]() to set up the graphics context before using it in the getString routines and to call [[gc:finish]]() to relinquish it when finished with it.
 
It is important to use [[gc:begin]]() to set up the graphics context before using it in the getString routines and to call [[gc:finish]]() to relinquish it when finished with it.
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{{Since|3.0}}
 
{{Since|3.0}}
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{{ObsoleteSince|3.2}}
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[[Category:gc]]
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[[Category:platform]]

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