include/coreinit/screen: Add Doxygen docs for OSScreen

include/coreinit/screen.h

@@ -4,6 +4,35 @@
 /**
  * \defgroup coreinit_screen Screen
  * \ingroup coreinit
+ *
+ * <!-- quick blurb - may show up on Modules page -->
+ * Software-rendered graphics system, suitable for text output and simple
+ * graphics.
+ *
+ * OSScreen is much more straightforward than GX2, which makes it appealing for
+ * situations that do not require complex graphics. It can draw text and pixels
+ * (one at a time!) to both the Gamepad and TV.
+ *
+ * To use OSScreen, first call \link OSScreenInit \endlink. Then, allocate a
+ * memory area and pass it to OSScreen with \link OSScreenSetBufferEx \endlink -
+ * after enabling the screens with \link OSScreenEnableEx \endlink, the library
+ * will be ready to draw! Drawing is accomplished with \link
+ * OSScreenClearBufferEx \endlink, \link OSScreenPutFontEx \endlink and \link
+ * OSScreenPutPixelEx \endlink. Once drawing is complete, call \link
+ * OSScreenFlipBuffersEx \endlink to show the results on-screen. Rinse and
+ * repeat!
+ *
+ * <!-- Documentation meta: OSScreen has a weird naming convention, especially
+ *      around the word "buffer". So, here's what we're doing:
+ *      - A single framebuffer is a "buffer".
+ *      - The framebuffer that is visible is the "visible buffer" while the one
+ *        being drawn to is the "work buffer"
+ *      - The pointers going to OSScreenSetBufferEx are not buffers. Try "memory
+ *        area", "location", whatever.
+ *      - A "screen" refers to the Gamepad or TV.
+ *      - Members of OSScreenID are not buffers. Try "screen ID".
+ *      This should help prevent confusion. If you change this, make sure to
+ *      update all the docs to keep everything consistent. -->
  * @{
  */
 
@@ -11,44 +40,187 @@
 extern "C" {
 #endif
 
+//! Defines the ID of a display usable with OSScreen.
 typedef enum OSScreenID
 {
+   //! Represents the TV connected to the system.
    SCREEN_TV      = 0,
+   //! Represents the screen in the DRC (gamepad).
    SCREEN_DRC     = 1,
 } OSScreenID;
 
+/**
+ * Initialises the OSScreen library for use. This function must be called before
+ * using any other OSScreen functions.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenSetBufferEx \endlink</li>
+ * <li>\link OSScreenEnableEx \endlink</li>
+ * <li>\link OSScreenShutdown \endlink</li>
+ * </ul>
+ */
 void
 OSScreenInit();
 
+/**
+ * Cleans up and shuts down the OSScreen library.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenEnableEx \endlink</li>
+ * </ul>
+ */
 void
 OSScreenShutdown();
 
+/**
+ * Gets the amount of memory required to fit both buffers of a given screen.
+ *
+ * \param screen
+ * The ID of the screen to be sized.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenSetBufferEx \endlink</li>
+ * </ul>
+ */
 uint32_t
 OSScreenGetBufferSizeEx(OSScreenID screen);
 
+/**
+ * Sets the memory location for both buffers of a given screen. This location
+ * must be of the size prescribed by \link OSScreenGetBufferSizeEx \endlink and
+ * at an address aligned to 0x100 bytes.
+ *
+ * \param screen
+ * The ID of the screen whose memory location should be changed.
+ *
+ * \param addr
+ * Pointer to the memory to use. This area must be 0x100 aligned, and of the
+ * size given by \link OSScreenGetBufferSizeEx \endlink.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenGetBufferSizeEx \endlink</li>
+ * </ul>
+ */
 void
 OSScreenSetBufferEx(OSScreenID screen,
                     void *addr);
 
+/**
+ * Clear the work buffer of the given screen by setting all of its pixels to
+ * a given colour.
+ *
+ * \param screen
+ * The ID of the screen to clear. Only the work buffer will be cleared.
+ *
+ * \param colour
+ * The colour to use, in big-endian RGBX8 format - 0xRRGGBBXX, where X bits are
+ * ignored.
+ *
+ * \note
+ * Since this function only affects the <em>work buffer</em>, its effect will
+ * not appear on screen immediately. See \link OSScreenFlipBuffersEx \endlink.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenPutFontEx \endlink</li>
+ * <li>\link OSScreenPutPixelEx \endlink</li>
+ * </ul>
+ *
+ * <!-- TODO: Are the XX bits really ignored? I'm basing this off a vague memory
+ * of setting them to 00 and nothing changing... Check this. -->
+ */
 void
 OSScreenClearBufferEx(OSScreenID screen,
                       uint32_t colour);
 
+/**
+ * Swap the buffers of the given screen. The work buffer will become the visible
+ * buffer and will start being shown on-screen, while the visible buffer becomes
+ * the new work buffer. This operation is known as "flipping" the buffers.
+ *
+ * You must call this function once drawing is complete, otherwise draws will
+ * not appear on-screen.
+ *
+ * \param screen
+ * The ID of the screen to flip.
+ */
 void
 OSScreenFlipBuffersEx(OSScreenID screen);
 
+/**
+ * Draws text at the given position. The text will be drawn to the work
+ * buffer with a built-in monospace font, coloured white, and anti-aliased.
+ * The position coordinates are in <em>characters</em>, not pixels.
+ *
+ * \param screen
+ * The ID of the screen to draw to. Only the work buffer will be affected.
+ *
+ * \param row
+ * The row, in characters, to place the text in. 0 corresponds to the top of
+ * the screen.
+ *
+ * \param column
+ * The column, in characters, to place the text at. 0 corresponds to the left of
+ * the screen.
+ *
+ * \param buffer
+ * Pointer to the string of text to draw. Null-terminated.
+ *
+ * \note
+ * Since this function only affects the <em>work buffer</em>, its effect will
+ * not appear on screen immediately. See \link OSScreenFlipBuffersEx \endlink.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenPutPixelEx \endlink</li>
+ * <li>\link OSScreenClearBufferEx \endlink</li>
+ * </ul>
+ */
 void
 OSScreenPutFontEx(OSScreenID screen,
                   uint32_t row,
                   uint32_t column,
                   const char *buffer);
 
+/**
+ * Draws a single pixel at the given position. The pixel, a 32-bit RGBX
+ * colour, will be placed in the work buffer at the coordinates given.
+ *
+ * \param screen
+ * The ID of the screen to place the pixel in.
+ *
+ * \param x
+ * The x-coordinate, in pixels, to draw the pixel at.
+ *
+ * \param y
+ * The y-coordinate, in pixels, to draw the pixel at.
+ *
+ * \param colour
+ * The desired colour of the pixel to draw, in RGBX32 colour (0xRRGGBBXX, where
+ * the XX value is ignored).
+ *
+ * \note
+ * Since this function only affects the <em>work buffer</em>, its effect will
+ * not appear on screen immediately. See \link OSScreenFlipBuffersEx \endlink.
+ *
+ * \sa <ul>
+ * <li>\link OSScreenPutFontEx \endlink</li>
+ * <li>\link OSScreenClearBufferEx \endlink</li>
+ * </ul>
+ */
 void
 OSScreenPutPixelEx(OSScreenID screen,
                    uint32_t x,
                    uint32_t y,
                    uint32_t colour);
 
+/**
+ * Enables or disables a given screen. If a screen is disabled, it shows black.
+ *
+ * \param screen
+ * The ID of the screen to enable or disable.
+ *
+ * \param enable
+ * \c true if the screen should be enabled, otherwise false.
+ */
 void
 OSScreenEnableEx(OSScreenID screen,
                  BOOL enable);