[cairo] Fwd: embedding arbitrary graphics in text

Travis Griggs travisgriggs at gmail.com
Wed Sep 8 08:26:59 PDT 2010

A Pango-Cairo question or two I had sent to the Pango list yesterday,  
hoping someone here on the Cairo list might know the answers.

> On Sep 7, 2010, at 9:15 AM, Behdad Esfahbod wrote:
>> Also see pango/examples/cairoshape.c for an example.
> OK, I followed it, thank you so much. The only thing that I had to  
> look at 3 or so times, before I caught the importance of it, is the  
> translate to the cr current point at the top of the render function.  
> I'm trying to imagine when I wouldn't want to actually do that.
> Question 1
> What is the difference between the ink rect and the logical rect. I  
> mean, I think I mostly get it. But I'm curious if there are cases  
> where portions of the ink would ever lie outside the logical rect?  
> Is the "origin (x,y) of the rects always at the baseline of the  
> characters, I noticed that they all seem to have negative heights to  
> go nominally "upwards". I was curious if there was an example or two  
> in the docs somewhere, that showed something I was missing.
> Question 2
> The example demonstrates how to completely draw something other than  
> the font's glyph in place of a character (or more). I'm curious if  
> it's possible to still let it draw the character glyphs it was going  
> to draw, but do some additional annotation. For example, I'd like to  
> insert a stop sign graphic in front of the character run the  
> attributes stand for, and nudge them to the right by that much. Or  
> do I have to inject filler characters into my text to do that?
> What My Binding Ended up Looking Like (for now)
> With Behdad's and Tony's direction, I established a single shape  
> renderer for any Context I create a binding for in Smalltalk. When  
> I'm creating the attribute, I do it with the two rectangles, and  
> with a Block Closure. Block Closures are Smalltalk arbitrary  
> functions, that close over any current values needed for the  
> function. So I get both data and behavior all in one, a lot, or a  
> little. I keep a table on the Smalltalk side, which maps Smalltalk  
> blocks, to an arbitrary incrementing counter. The index, is what I  
> stuff in the data of the attribute. So when I get the callback, I  
> fetch the Smalltalk block associated with the particular attribute's  
> data key, execute the block with the mapped arguments. Works pretty  
> well.

Travis Griggs
"I did not have time to write you a short program, so I wrote you a  
long one instead."

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