Loading image data from DB

Devin Asay devin_asay at byu.edu
Wed Apr 12 12:24:26 EDT 2006


Thanks, Jeanne. I suppose one of the drawbacks of high level  
programming is that it insulates us so much from the ones and zeros  
that those of us who came into x-talking from a non-programming  
background never quite got some of the fundamentals. As this example  
shows, there are times when understanding the basics make the  
difference between success and failure.

Devin

On Apr 11, 2006, at 7:42 PM, Jeanne A. E. DeVoto wrote:

> At 10:47 AM -0600 4/7/2006, Devin Asay wrote:
>> Which is essentially what I ended up doing, and it worked. Is it  
>> correct to assume that 'the text' is binary data expressed as  
>> ASCII text and data like 'the imageData' is "lower-level" code  
>> that can't be expressed visually in a meaningful way? Forgive my  
>> naive non-techie questions.
>
> Not exactly - any binary data can be expressed in terms of ASCII  
> (or extended ASCII) characters. Looking at an example:
>
> A typical byte's worth of binary data (8 bits): 01101101
> That same binary number, expressed in decimal (ordinary base-10  
> numbers): 64 + 32 + 8 + 4 + 1, or 109
> ASCII 109 is the character "m", so we could write that byte's worth  
> of binary data as "m".
>
> Any 8-bit segment of binary data can be expressed as a single ASCII  
> character, in the same fashion, so we can always represent binary  
> data as characters. The main fly in the ointment is that some of  
> those characters are control characters, or characters that don't  
> have a glyph to represent them, and some of those will cause real  
> trouble if you try to e.g. display them in a field. (For example,  
> the binary sequence "00000000" is perfectly valid and may show up  
> in the binary data of any picture, but the character it's  
> equivalent to is the null character, ASCII 0 - which can't be  
> displayed on screen.)
>
> This is the basic difference between "binary data" and "text data"  
> - you can represent either one of them as either strings of ones  
> and zeroes, or as sequences of ASCII characters, but text is  
> guaranteed to contain only characters in the subset that can be  
> represented in a text file, whereas in binary data, anything goes,  
> and a sequence of 8 bits might translate into any character.
>
>
>> Am I correct in my understanding that these two statements are  
>> functionally identical:
>>
>> 	put myData into image "myImage"
>> 	set the text of image "myImage" to myData
>>
>> ?
>>
>> In other words, 'put' is simply shorthand for 'set the text of  
>> <object>'?
>
> Yes. The text property of a container object (an image, button, or  
> field) is the same as a reference to that object. It works for  
> images just like for fields.

Devin Asay
Humanities Technology and Research Support Center
Brigham Young University




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