/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef COMMON_SYSTEM_H
#define COMMON_SYSTEM_H
#include "common/scummsys.h"
#include "common/mutex.h"
#include "common/noncopyable.h"
#include "common/rect.h"
namespace Audio {
class Mixer;
}
namespace Graphics {
struct Surface;
}
namespace Common {
struct Event;
class EventManager;
class SaveFileManager;
class TimerManager;
}
/**
* Interface for ScummVM backends. If you want to port ScummVM to a system
* which is not currently covered by any of our backends, this is the place
* to start. ScummVM will create an instance of a subclass of this interface
* and use it to interact with the system.
*
* In particular, a backend provides a video surface for ScummVM to draw in;
* methods to create timers, to handle user input events,
* control audio CD playback, and sound output.
*/
class OSystem : Common::NonCopyable {
protected:
OSystem();
virtual ~OSystem();
public:
/**
* The following method is called once, from main.cpp, after all
* config data (including command line params etc.) are fully loaded.
*
* @note Subclasses should always invoke the implementation of their
* parent class. They should do so near the end of their own
* implementation.
*/
virtual void initBackend() { }
/**
* Allows the backend to perform engine specific init.
* Called just before the engine is run.
*/
virtual void engineInit() { }
/**
* Allows the backend to perform engine specific de-init.
* Called after the engine finishes.
*/
virtual void engineDone() { }
/** @name Feature flags */
//@{
/**
* A feature in this context means an ability of the backend which can be
* either on or off. Examples include:
* - fullscreen mode
* - aspect ration correction
* - a virtual keyboard for text entry (on PDAs)
*/
enum Feature {
/**
* If your backend supports both a windowed and a fullscreen mode,
* then this feature flag can be used to switch between the two.
*/
kFeatureFullscreenMode,
/**
* Control aspect ratio correction. Aspect ratio correction is used to
* correct games running at 320x200 (i.e with an aspect ratio of 8:5),
* but which on their original hardware were displayed with the
* standard 4:3 ratio (that is, the original graphics used non-square
* pixels). When the backend support this, then games running at
* 320x200 pixels should be scaled up to 320x240 pixels. For all other
* resolutions, ignore this feature flag.
* @note You can find utility functions in common/scaler.h which can
* be used to implement aspect ratio correction. In particular,
* stretch200To240() can stretch a rect, including (very fast)
* interpolation, and works in-place.
*/
kFeatureAspectRatioCorrection,
/**
* Determine whether a virtual keyboard is too be shown or not.
* This would mostly be implemented by backends for hand held devices,
* like PocketPC, Palms, Symbian phones like the P800, Zaurus, etc.
*/
kFeatureVirtualKeyboard,
/**
* This flag is a bit more obscure: it gives a hint to the backend that
* the frontend code is very inefficient in doing screen updates. So
* the frontend might do a lot of fullscreen blits even though only a
* tiny portion of the actual screen data changed. In that case, it
* might pay off for the backend to compute which parts actual changed,
* and then only mark those as dirty.
* Implementing this is purely optional, and no harm should arise
* when not doing so (except for decreased speed in said frontends).
*/
kFeatureAutoComputeDirtyRects,
/**
* This flag determines either cursor can have its own palette or not
* It is currently used only by some Macintosh versions of Humongous
* Entertainment games. If backend doesn't implement this feature then
* engine switches to b/w version of cursors.
*/
kFeatureCursorHasPalette,
/**
* Set to true if the overlay pixel format has an alpha channel.
* This should only be set if it offers at least 3-4 bits of accuracy,
* as opposed to a single alpha bit.
*/
kFeatureOverlaySupportsAlpha,
/**
* Set to true to iconify the window.
*/
kFeatureIconifyWindow,
/**
* This feature, set to true, is a hint toward the backend to disable all
* key filtering/mapping, in cases where it would be beneficial to do so.
* As an example case, this is used in the agi engine's predictive dialog.
* When the dialog is displayed this feature is set so that backends with
* phone-like keypad temporarily unmap all user actions which leads to
* comfortable word entry. Conversely, when the dialog exits the feature
* is set to false.
* TODO: Fingolfin suggests that the way the feature is used can be
* generalized in this sense: Have a keyboard mapping feature, which the
* engine queries for to assign keys to actions ("Here's my default key
* map for these actions, what do you want them set to?").
*/
kFeatureDisableKeyFiltering
};
/**
* Determine whether the backend supports the specified feature.
*/
virtual bool hasFeature(Feature f) { return false; }
/**
* En-/disable the specified feature. For example, this may be used to
* enable fullscreen mode, or to deactivate aspect correction, etc.
*/
virtual void setFeatureState(Feature f, bool enable) {}
/**
* Query the state of the specified feature. For example, test whether
* fullscreen mode is active or not.
*/
virtual bool getFeatureState(Feature f) { return false; }
//@}
/**
* @name Graphics
*
* The way graphics work in the class OSystem are meant to make
* it possible for game frontends to implement all they need in
* an efficient manner. The downside of this is that it may be
* rather complicated for backend authors to fully understand and
* implement the semantics of the OSystem interface.
*
*
* The graphics visible to the user in the end are actually
* composed in three layers: the game graphics, the overlay
* graphics, and the mouse.
*
* First, there are the game graphics. They are always 8bpp, and
* the methods in this section deal with them exclusively. In
* particular, the size of the game graphics is defined by a call
* to initSize(), and copyRectToScreen() blits 8bpp data into the
* game layer. Let W and H denote the width and height of the
* game graphics.
*
* Before the user sees these graphics, the backend may apply some
* transformations to it; for example, the may be scaled to better
* fit on the visible screen; or aspect ratio correction may be
* performed (see kFeatureAspectRatioCorrection). As a result of
* this, a pixel of the game graphics may occupy a region bigger
* than a single pixel on the screen. We define p_w and p_h to be
* the width resp. height of a game pixel on the screen.
*
* In addition, there is a vertical "shake offset" (as defined by
* setShakePos) which is used in some games to provide a shaking
* effect. Note that shaking is applied to all three layers, i.e.
* also to the overlay and the mouse. We denote the shake offset
* by S.
*
* Putting this together, a pixel (x,y) of the game graphics is
* transformed to a rectangle of height p_h and width p_w
* appearing at position (p_w * x, p_hw * (y + S)) on the real
* screen (in addition, a backend may choose to offset
* everything, e.g. to center the graphics on the screen).
*
*
* The next layer is the overlay. It is composed over the game
* graphics. By default, it has exactly the same size and
* resolution as the game graphics. However, client code can
* specify an overlay scale (as an additional parameter to
* initSize()). This is meant to increase the resolution of the
* overlay while keeping its size the same as that of the game
* graphics. For example, if the overlay scale is 2, and the game
* graphics have a resolution of 320x200; then the overlay shall
* have a resolution of 640x400, but it still has the same
* physical size as the game graphics.
* The overlay usually uses 16bpp, but on some ports, only 8bpp
* are availble, so that is supported, too, via a compile time
* switch (see also the OverlayColor typedef in scummsys.h).
*
*
* Finally, there is the mouse layer. This layer doesn't have to
* actually exist within the backend -- it all depends on how a
* backend chooses to implement mouse cursors, but in the default
* SDL backend, it really is a separate layer. The mouse is
* always in 8bpp but can have a palette of its own, if the
* backend supports it. The scale of the mouse cursor is called
* 'cursorTargetScale'. This is meant as a hint to the backend.
* For example, let us assume the overlay is not visible, and the
* game graphics are displayed using a 2x scaler. If a mouse
* cursor with a cursorTargetScale of 1 is set, then it should be
* scaled by factor 2x, too, just like the game graphics. But if
* it has a cursorTargetScale of 2, then it shouldn't be scaled
* again by the game graphics scaler.
*/
//@{
/**
* Description of a graphics mode.
*/
struct GraphicsMode {
/**
* The 'name' of the graphics mode. This name is matched when selecting
* a mode via the command line, or via the config file.
* Examples: "1x", "advmame2x", "hq3x"
*/
const char *name;
/**
* Human readable description of the scaler.
* Examples: "Normal (no scaling)", "AdvMAME2x", "HQ3x"
*/
const char *description;
/**
* ID of the graphics mode. How to use this is completely up to the
* backend. This value will be passed to the setGraphicsMode(int)
* method by client code.
*/
int id;
};
/**
* Retrieve a list of all graphics modes supported by this backend.
* This can be both video modes as well as graphic filters/scalers;
* it is completely up to the backend maintainer to decide what is
* appropriate here and what not.
* The list is terminated by an all-zero entry.
* @return a list of supported graphics modes
*/
virtual const GraphicsMode *getSupportedGraphicsModes() const = 0;
/**
* Return the ID of the 'default' graphics mode. What exactly this means
* is up to the backend. This mode is set by the client code when no user
* overrides are present (i.e. if no custom graphics mode is selected via
* the command line or a config file).
*
* @return the ID of the 'default' graphics mode
*/
virtual int getDefaultGraphicsMode() const = 0;
/**
* Switch to the specified graphics mode. If switching to the new mode
* failed, this method returns false.
*
* @param mode the ID of the new graphics mode
* @return true if the switch was successful, false otherwise
*/
virtual bool setGraphicsMode(int mode) = 0;
/**
* Switch to the graphics mode with the given name. If 'name' is unknown,
* or if switching to the new mode failed, this method returns false.
*
* @param name the name of the new graphics mode
* @return true if the switch was successful, false otherwise
* @note This is implemented via the setGraphicsMode(int) method, as well
* as getSupportedGraphicsModes() and getDefaultGraphicsMode().
* In particular, backends do not have to overload this!
*/
bool setGraphicsMode(const char *name);
/**
* Determine which graphics mode is currently active.
* @return the active graphics mode
*/
virtual int getGraphicsMode() const = 0;
/**
* Set the size of the virtual screen. Typical sizes include:
* - 320x200 (e.g. for most SCUMM games, and Simon)
* - 320x240 (e.g. for FM-TOWN SCUMM games)
* - 640x480 (e.g. for Curse of Monkey Island)
*
* This is the resolution for which the client code generates data;
* this is not necessarily equal to the actual display size. For example,
* a backend may magnify the graphics to fit on screen (see also the
* GraphicsMode); stretch the data to perform aspect ratio correction;
* or shrink it to fit on small screens (in cell phones).
*
* @param width the new virtual screen width
* @param height the new virtual screen height
*/
virtual void initSize(uint width, uint height) = 0;
/**
* Return an int value which is changed whenever any screen
* parameters (like the resolution) change. That is, whenever a
* EVENT_SCREEN_CHANGED would be sent. You can track this value
* in your code to detect screen changes in case you do not have
* full control over the event loop(s) being used (like the GUI
* code).
*
* @return an integer which can be used to track screen changes
*
* @note Backends which generate EVENT_SCREEN_CHANGED events MUST
* overload this method appropriately.
*/
virtual int getScreenChangeID() const { return 0; }
/**
* Begin a new GFX transaction, which is a sequence of GFX mode changes.
* The idea behind GFX transactions is to make it possible to activate
* several different GFX changes at once as a "batch" operation. For
* example, assume we are running in 320x200 with a 2x scaler (thus using
* 640x400 pixels in total). Now, we want to switch to 640x400 with the 1x
* scaler. Without transactions, we have to choose whether we want to first
* switch the scaler mode, or first to 640x400 mode. In either case,
* depending on the backend implementation, some ugliness may result.
* E.g. the window might briefly switch to 320x200 or 1280x800.
* Using transactions, this can be avoided.
*
* @note Transaction support is optional, and the default implementations
* of the relevant methods simply do nothing.
* @see endGFXTransaction
*/
virtual void beginGFXTransaction() {}
/**
* End (and thereby commit) the current GFX transaction.
* @see beginGFXTransaction
*/
virtual void endGFXTransaction() {}
/**
* Returns the currently set virtual screen height.
* @see initSize
* @return the currently set virtual screen height
*/
virtual int16 getHeight() = 0;
/**
* Returns the currently set virtual screen width.
* @see initSize
* @return the currently set virtual screen width
*/
virtual int16 getWidth() = 0;
/**
* Replace the specified range of the palette with new colors.
* The palette entries from 'start' till (start+num-1) will be replaced - so
* a full palette update is accomplished via start=0, num=256.
*
* The palette data is specified in interleaved RGBA format. That is, the
* first byte of the memory block 'colors' points at is the red component
* of the first new color; the second byte the blue component of the first
* new color; the third byte the green component, the last byte to the alpha
* (transparency) value. Then the second color starts, and so on. So memory
* looks like this: R1-G1-B1-A1-R2-G2-B2-A2-R3-...
*
* @param colors the new palette data, in interleaved RGB format
* @param start the first palette entry to be updated
* @param num the number of palette entries to be updated
*
* @note It is an error if start+num exceeds 256, behaviour is undefined
* in that case (the backend may ignore it silently or assert).
* @note The alpha value is not actually used, and future revisions of this
* API are probably going to remove it.
*/
virtual void setPalette(const byte *colors, uint start, uint num) = 0;
/**
* Grabs a specified part of the currently active palette.
* The format is the same as for setPalette.
*
* @see setPalette
* @param colors the palette data, in interleaved RGBA format
* @param start the first platte entry to be read
* @param num the number of palette entries to be read
*/
virtual void grabPalette(byte *colors, uint start, uint num) = 0;
/**
* Blit a bitmap to the virtual screen.
* The real screen will not immediately be updated to reflect the changes.
* Client code has to to call updateScreen to ensure any changes are
* visible to the user. This can be used to optimize drawing and reduce
* flicker.
* The graphics data uses 8 bits per pixel, using the palette specified
* via setPalette.
*
* @param buf the buffer containing the graphics data source
* @param pitch the pitch of the buffer (number of bytes in a scanline)
* @param x the x coordinate of the destination rectangle
* @param y the y coordinate of the destination rectangle
* @param w the width of the destination rectangle
* @param h the height of the destination rectangle
*
* @note The specified destination rectangle must be completly contained
* in the visible screen space, and must be non-empty. If not, a
* backend may or may not perform clipping, trigger an assert or
* silently corrupt memory.
*
* @see updateScreen
*/
virtual void copyRectToScreen(const byte *buf, int pitch, int x, int y, int w, int h) = 0;
/**
* Lock the active screen framebuffer and return a Graphics::Surface
* representing it. The caller can then perform arbitrary graphics
* transformations on the framebuffer (blitting, scrolling, etc.).
* Must be followed by matching call to unlockScreen(). Calling code
* should make sure to only lock the framebuffer for the briefest
* periods of time possible, as the whole system is potentially stalled
* while the lock is active.
* Returns 0 if an error occurred. Otherwise an 8bit surface is returned.
*
* The returned surface must *not* be deleted by the client code.
*/
virtual Graphics::Surface *lockScreen() = 0;
/**
* Unlock the screen framebuffer, and mark it as dirty (i.e. during the
* next updateScreen() call, the whole screen will be updated.
*/
virtual void unlockScreen() = 0;
/**
* Clear the screen to black.
*/
virtual void clearScreen();
/**
* Flush the whole screen, that is render the current content of the screen
* framebuffer (resp. the dirty/changed parts of it) to the display.
*/
virtual void updateScreen() = 0;
/**
* Set current shake position, a feature needed for some SCUMM screen
* effects. The effect causes the displayed graphics to be shifted upwards
* by the specified (always positive) offset. The area at the bottom of the
* screen which is moved into view by this is filled with black. This does
* not cause any graphic data to be lost - that is, to restore the original
* view, the game engine only has to call this method again with offset
* equal to zero. No calls to copyRectToScreen are necessary.
* @param shakeOffset the shake offset
*
* @note This is currently used in the SCUMM, QUEEN and KYRA engines.
*/
virtual void setShakePos(int shakeOffset) = 0;
/**
* Sets the area of the screen that has the focus. For example, when a character
* is speaking, they will have the focus. Allows for pan-and-scan style views
* where the backend could follow the speaking character or area of interest on
* the screen.
*
* The backend is responsible for clipping the rectangle and deciding how best to
* zoom the screen to show any shape and size rectangle the engine provides.
*
* @param rect A rectangle on the screen to be focused on
* @see clearFocusRectangle
*/
virtual void setFocusRectangle(const Common::Rect& rect) {}
/**
* Clears the focus set by a call to setFocusRectangle(). This allows the engine
* to clear the focus during times when no particular area of the screen has the
* focus.
* @see setFocusRectangle
*/
virtual void clearFocusRectangle() {}
//@}
/**
* @name Overlay
* In order to be able to display dialogs atop the game graphics, backends
* must provide an overlay mode.
*
* While the game graphics are always 8 bpp, the overlay can be 8 or 16 bpp.
* Depending on which it is, OverlayColor is 8 or 16 bit.
*
* For 'coolness' we usually want to have an overlay which is blended over
* the game graphics. On backends which support alpha blending, this is
* no issue; but on other systems (in particular those which only support
* 8bpp), this needs some trickery.
*
* Essentially, we fake (alpha) blending on these systems by copying the
* current game graphics into the overlay buffer when activating the overlay,
* then manually compose whatever graphics we want to show in the overlay.
* This works because we assume the game to be "paused" whenever an overlay
* is active.
*/
//@{
/** Activate the overlay mode. */
virtual void showOverlay() = 0;
/** Deactivate the overlay mode. */
virtual void hideOverlay() = 0;
/**
* Reset the overlay.
*
* After calling this method while the overlay mode is active, the user
* should be seeing only the game graphics. How this is achieved depends
* on how the backend implements the overlay. Either it sets all pixels of
* the overlay to be transparent (when alpha blending is used).
*
* Or, in case of fake alpha blending, it might just put a copy of the
* current game graphics screen into the overlay.
*/
virtual void clearOverlay() = 0;
/**
* Copy the content of the overlay into a buffer provided by the caller.
* This is only used to implement fake alpha blending.
*/
virtual void grabOverlay(OverlayColor *buf, int pitch) = 0;
/**
* Blit a graphics buffer to the overlay.
* In a sense, this is the reverse of grabOverlay.
* @see copyRectToScreen
* @see grabOverlay
*/
virtual void copyRectToOverlay(const OverlayColor *buf, int pitch, int x, int y, int w, int h) = 0;
/**
* Return the height of the overlay.
* @see getHeight
*/
virtual int16 getOverlayHeight() { return getHeight(); }
/**
* Return the width of the overlay.
* @see getWidth
*/
virtual int16 getOverlayWidth() { return getWidth(); }
/**
* Convert the given RGB triplet into an OverlayColor. A OverlayColor can
* be 8bit, 16bit or 32bit, depending on the target system. The default
* implementation generates a 16 bit color value, in the 565 format
* (that is, 5 bits red, 6 bits green, 5 bits blue).
* @see colorToRGB
* @see ARGBToColor
*/
virtual OverlayColor RGBToColor(uint8 r, uint8 g, uint8 b);
/**
* Convert the given OverlayColor into a RGB triplet. An OverlayColor can
* be 8bit, 16bit or 32bit, depending on the target system. The default
* implementation takes a 16 bit color value and assumes it to be in 565 format
* (that is, 5 bits red, 6 bits green, 5 bits blue).
* @see RGBToColor
* @see colorToARGB
*/
virtual void colorToRGB(OverlayColor color, uint8 &r, uint8 &g, uint8 &b);
/**
* Convert the given ARGB quadruplet into an OverlayColor. A OverlayColor can
* be 8bit, 16bit or 32bit, depending on the target system. The default
* implementation generates a 16 bit color value, in the 565 format
* (that is, 5 bits red, 6 bits green, 5 bits blue).
* @note The alpha component, ranges from 0 (transparent) to 255 (opaque).
* @see colorToRGB
* @see RGBToColor
*/
virtual OverlayColor ARGBToColor(uint8 a, uint8 r, uint8 g, uint8 b);
/**
* Convert the given OverlayColor into an ARGB quadruplet. An OverlayColor can
* be 8bit, 16bit or 32bit, depending on the target system. The default
* implementation takes a 16 bit color value and assumes it to be in 565 format
* (that is, 5 bits red, 6 bits green, 5 bits blue).
* @note The alpha component, ranges from 0 (transparent) to 255 (opaque).
* @see ARGBToColor
* @see colorToRGB
*/
virtual void colorToARGB(OverlayColor color, uint8 &a, uint8 &r, uint8 &g, uint8 &b);
//@}
/** @name Mouse */
//@{
/** Show or hide the mouse cursor. */
virtual bool showMouse(bool visible) = 0;
/**
* Move ("warp") the mouse cursor to the specified position in virtual
* screen coordinates.
* @param x the new x position of the mouse
* @param y the new x position of the mouse
*/
virtual void warpMouse(int x, int y) = 0;
/**
* Set the bitmap used for drawing the cursor.
*
* @param buf the pixmap data to be used (8bit/pixel)
* @param w width of the mouse cursor
* @param h height of the mouse cursor
* @param hotspotX horizontal offset from the left side to the hotspot
* @param hotspotY vertical offset from the top side to the hotspot
* @param keycolor transparency color index
* @param cursorTargetScale scale factor which cursor is designed for
*/
virtual void setMouseCursor(const byte *buf, uint w, uint h, int hotspotX, int hotspotY, byte keycolor = 255, int cursorTargetScale = 1) = 0;
/**
* Replace the specified range of cursor the palette with new colors.
* The palette entries from 'start' till (start+num-1) will be replaced - so
* a full palette update is accomplished via start=0, num=256.
*
* Backends which implement it should have kFeatureCursorHasPalette flag set
*
* @see setPalette
* @see kFeatureCursorHasPalette
*/
virtual void setCursorPalette(const byte *colors, uint start, uint num) {}
/**
* Disable or enable cursor palette.
*
* Backends which implement it should have kFeatureCursorHasPalette flag set
*
* @param disable True to disable, false to enable.
*
* @see setPalette
* @see kFeatureCursorHasPalette
*/
virtual void disableCursorPalette(bool disable) {}
//@}
/** @name Events and Time */
//@{
protected:
friend class DefaultEventManager;
/**
* Get the next event in the event queue.
* @param event point to an Common::Event struct, which will be filled with the event data.
* @return true if an event was retrieved.
*/
virtual bool pollEvent(Common::Event &event) = 0;
public:
/** Get the number of milliseconds since the program was started. */
virtual uint32 getMillis() = 0;
/** Delay/sleep for the specified amount of milliseconds. */
virtual void delayMillis(uint msecs) = 0;
/**
* Return the timer manager singleton. For more information, refer
* to the TimerManager documentation.
*/
virtual Common::TimerManager *getTimerManager() = 0;
/**
* Return the event manager singleton. For more information, refer
* to the EventManager documentation.
*/
virtual Common::EventManager *getEventManager();
//@}
/**
* @name Mutex handling
* Historically, the OSystem API used to have a method which allowed
* creating threads. Hence mutex support was needed for thread syncing.
* To ease portability, though, we decided to remove the threading API.
* Instead, we now use timers (see setTimerCallback() and Common::Timer).
* But since those may be implemented using threads (and in fact, that's
* how our primary backend, the SDL one, does it on many systems), we
* still have to do mutex syncing in our timer callbacks.
*
* Hence backends which do not use threads to implement the timers simply
* can use dummy implementations for these methods.
*/
//@{
typedef Common::MutexRef MutexRef;
/**
* Create a new mutex.
* @return the newly created mutex, or 0 if an error occured.
*/
virtual MutexRef createMutex() = 0;
/**
* Lock the given mutex.
* @param mutex the mutex to lock.
*/
virtual void lockMutex(MutexRef mutex) = 0;
/**
* Unlock the given mutex.
* @param mutex the mutex to unlock.
*/
virtual void unlockMutex(MutexRef mutex) = 0;
/**
* Delete the given mutex. Make sure the mutex is unlocked before you delete it.
* If you delete a locked mutex, the behavior is undefined, in particular, your
* program may crash.
* @param mutex the mutex to delete.
*/
virtual void deleteMutex(MutexRef mutex) = 0;
//@}
/** @name Sound */
//@{
/**
* Return the audio mixer. For more information, refer to the
* Audio::Mixer documentation.
*/
virtual Audio::Mixer *getMixer() = 0;
/**
* Determine the output sample rate. Audio data provided by the sound
* callback will be played using this rate.
* @note Client code other than the sound mixer should _not_ use this
* method. Instead, call Mixer::getOutputRate()!
* @return the output sample rate
*/
virtual int getOutputSampleRate() const = 0;
//@}
/**
* @name Audio CD
* The methods in this group deal with Audio CD playback.
* The default implementation simply does nothing.
*/
//@{
/**
* Initialise the specified CD drive for audio playback.
* @return true if the CD drive was inited succesfully
*/
virtual bool openCD(int drive);
/**
* Poll CD status.
* @return true if CD audio is playing
*/
virtual bool pollCD();
/**
* Start audio CD playback.
* @param track the track to play.
* @param num_loops how often playback should be repeated (-1 = infinitely often).
* @param start_frame the frame at which playback should start (75 frames = 1 second).
* @param duration the number of frames to play.
*/
virtual void playCD(int track, int num_loops, int start_frame, int duration);
/**
* Stop audio CD playback.
*/
virtual void stopCD();
/**
* Update cdrom audio status.
*/
virtual void updateCD();
//@}
/** @name Miscellaneous */
//@{
/** Quit (exit) the application. */
virtual void quit() = 0;
/**
* Set a window caption or any other comparable status display to the
* given value. The caption must be a pure ASCII string. Passing a
* non-ASCII string may lead to unexpected behavior, even crashes.
*
* In a future revision of this API, this may be changed to allowing
* UTF-8 or UTF-16 encoded data, or maybe ISO LATIN 1.
*
* @param caption the window caption to use, as an ASCII string
*/
virtual void setWindowCaption(const char *caption) {}
/**
* Display a message in an 'on screen display'. That is, display it in a
* fashion where it is visible on or near the screen (e.g. in a transparent
* rectangle over the regular screen content; or in a message box beneath
* it; etc.).
*
* @note There is a default implementation which uses a TimedMessageDialog
* to display the message. Hence implementing this is optional.
*
* @param msg the message to display on screen
*/
virtual void displayMessageOnOSD(const char *msg);
/**
* Return the SaveFileManager, used to store and load savestates
* and other modifiable persistent game data. For more information,
* refer to the SaveFileManager documentation.
*/
virtual Common::SaveFileManager *getSavefileManager() = 0;
/**
* Return String which is used for backend-specific addition to theme
* config.
*
* Typical usage is to disable unneeded GUI widgets or defining
* theme-specific tab.
*/
virtual Common::String getExtraThemeConfig() {
return "";
}
//@}
};
/** The global OSystem instance. Initialised in main(). */
extern OSystem *g_system;
#endif