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Comment: create page, add content (Wed Mar 10 ver; changeset 4428)
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| ||<tablewidth="100%" style="color: #FF0000;" :> DRAFT|| | |
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| Use this function ^(macro)^ to *call the seek function pointer in an SDL_RWops structure*. | Use this function to seek within an SDL_RWops data source. |
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| SDL_RWseek(ctx, offset, whence) | long SDL_RWseek(SDL_RWops* context, long offset, int whence) |
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| <<Color2(green,Should there be anything to indicate a RV at the beginning of the syntax? Should the 3 params be on separate lines like a regular function even though the rest of the syntax is different?)>> | <<Color2(green,Seems like the type for '''context''' might have changed from SDL_RWops* to struct SDL_RWops*. Which is correct?)>> |
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| ||'''ctx'''||*a pointer to an SDL_RWops structure* <<Color2(green,why isn't there a pointer symbol?)>>|| ||'''offset'''||*an offset in bytes^, relative to '''whence''' location^; can be negative*|| |
||'''context'''||a pointer to an SDL_RWops structure|| ||'''offset'''||an offset in bytes, relative to '''whence''' location; can be negative|| |
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| Returns the final offset in the data source. ??? | Returns the final offset in the data source after the seek. |
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| int length; | long length; |
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| ,,Note: ,,This is not a predefined function, just a macro that calls whatever seek function has been placed in the SDL_RWops structure. | This is not a predefined function, just a macro that calls whatever seek function has been placed in the SDL_RWops structure. |
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| ||RW_SEEK_SET||0||seek from the beginning of data|| ||RW_SEEK_CUR||1||seek relative to current read point|| ||RW_SEEK_END||2||seek relative to the end of data|| <<Color2(green,What does the number in the center column represent? Thought it was the value you'd put in the macro but the code example suggests otherwise. Is that one of those things that we're leaving out?)>> |
||RW_SEEK_SET||seek from the beginning of data|| ||RW_SEEK_CUR||seek relative to current read point|| ||RW_SEEK_END||seek relative to the end of data|| |
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| .[[SDL_OtherFunction]] <<Color2(green,Not sure how to determine which functions to list here. 1.2 list is no longer valid (SDL_RWread SDL_RWwrite SDL_RWclose). Not finding any that directly reference SDL_RWseek. Should I list all the current read and write functions?)>> | .[[SDL_RWclose]] .[[SDL_RWread]] .[[SDL_RWtell]] .[[SDL_RWwrite]] |
SDL_RWseek
Use this function to seek within an SDL_RWops data source.
Syntax
long SDL_RWseek(SDL_RWops* context,
long offset,
int whence)
green
Function Parameters
context |
a pointer to an SDL_RWops structure |
offset |
an offset in bytes, relative to whence location; can be negative |
whence |
any of RW_SEEK_SET, RW_SEEK_CUR, RW_SEEK_END; see Remarks for details |
Return Value
Returns the final offset in the data source after the seek.
Code Examples
#include <stdio.h>
#include "SDL_rwops.h"
int main()
{
long length;
SDL_RWops *rw=SDL_RWFromFile("myfile.bin","rb");
if(rw==NULL)
{
fprintf(stderr,"Couldn't open myfile.bin\n");
return(1);
}
/* Seek to 0 bytes from the end of the file -- i.e. the exact end of file */
length=SDL_RWseek(rw,0,SEEK_END);
SDL_RWclose(rw);
if(length<0)
{
fprintf(stderr,"Could not seek inside myfile.bin\n");
return(2);
}
fprintf(stderr,"myfile.bin is %d bytes long\n",length);
return(0);
}
Remarks
This is not a predefined function, just a macro that calls whatever seek function has been placed in the SDL_RWops structure.
whence may be any of the following values:
RW_SEEK_SET |
seek from the beginning of data |
RW_SEEK_CUR |
seek relative to current read point |
RW_SEEK_END |
seek relative to the end of data |
