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Add a lot of missing documentation

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Peter Evans 2017-12-27 01:14:52 -06:00
parent bcf354989d
commit 76191991c8
1 changed files with 46 additions and 1 deletions
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47
src/vm_screen.c
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@ -12,6 +12,13 @@
#include "log.h"
#include "vm_screen.h"
/*
* Initialize the video of the vm_screen abstraction. This ends up being
* something that depends on our third-party graphics library; in other
* words, what do we need to do before we can even create a drawing
* surface to work with? If we are unable to properly do so, we return
* with an error.
*/
int
vm_screen_init()
{
@ -23,6 +30,10 @@ vm_screen_init()
return OK;
}
/*
* Something to do in the teardown phase of the program, undoing
* whatever we might have set up in the init function.
*/
void
vm_screen_finish()
{
@ -30,7 +41,9 @@ vm_screen_finish()
}
/*
* Return a new screen. We also set the color to black.
* Return a new screen. This ends up blanking out whatever we have here;
* we also do _not_ create any drawing surface, which is done separately
* with the add_window function.
*/
vm_screen *
vm_screen_create()
@ -56,6 +69,14 @@ vm_screen_create()
return screen;
}
/*
* The logical coordinates of a screen is a grid dimension separate from
* what the literal window size of our drawing surface. For instance, a
* machine may assume it has 320x240 pixels, but we are drawing on a
* surface that is twice the size, 640x480. In effect we aim to decouple
* the presumed drawing size from the actual drawing size, so the
* machine we emulate does not need to think about it.
*/
void
vm_screen_set_logical_coords(vm_screen *screen, int xcoords, int ycoords)
{
@ -71,9 +92,16 @@ vm_screen_set_logical_coords(vm_screen *screen, int xcoords, int ycoords)
}
}
/*
* This function will add a physical windowed, drawing surface to the
* screen object. This ends up being done through the third-party
* graphics library.
*/
int
vm_screen_add_window(vm_screen *screen, int width, int height)
{
// If HEADLESS is defined, we will assume we _don't_ want an actual
// drawing surface, but want to pretend we've added one.
#ifndef HEADLESS
SDL_CreateWindowAndRenderer(
width, height, 0, &screen->window, &screen->render);
@ -100,12 +128,21 @@ vm_screen_add_window(vm_screen *screen, int width, int height)
return OK;
}
/*
* Return the limit of the x coordinates our logical size can support.
* (This is not the literal width of the window, but rather the width of
* the drawing surface the machine will want to work with.)
*/
int
vm_screen_xcoords(vm_screen *screen)
{
return screen->xcoords;
}
/*
* Like the xcoords function in every way and meaning; except here we
* return the y coordinate limit.
*/
int
vm_screen_ycoords(vm_screen *screen)
{
@ -123,6 +160,10 @@ vm_screen_free(vm_screen *screen)
free(screen);
}
/*
* Is the screen active? This function will be used by machines to
* determine if there's still a need to continue their run loops.
*/
bool
vm_screen_active(vm_screen *screen)
{
@ -135,6 +176,10 @@ vm_screen_active(vm_screen *screen)
return false;
}
/*
* Do whatever is required to refresh the screen with the changes we've
* made recently.
*/
void
vm_screen_refresh(vm_screen *screen)
{