💾 Archived View for lofi.haiku-os.org › docs › develop › servers › app_server › DisplayDriver.gmi captured on 2023-09-28 at 16:08:19. Gemini links have been rewritten to link to archived content

-=-=-=-=-=-=-

DisplayDriver class

The DisplayDriver class is not a useful class unto itself. It is to provide a consistent interface for the rest of the app_server to whatever rendering context it is utilizing, whether it be a remote screen, a ServerBitmap, installed graphics hardware, or whatever. Documentation below will describe the role of each function.

Member Functions

DisplayDriver(void)

~DisplayDriver(void)

bool Initialize(void)

void Shutdown(void)

These four are for general start and stop procedures. The constructor and destructor concern themselves with the internal members common to all drivers, such as the current cursor and the access semaphore. Subclasses will probably end up using these to handle memory allocation-related issues, but likely not much else. Initialize() and Shutdown() are for general setup internal to the module. Note that if Initialize() returns false, the server will not use the module, call Shutdown(), and then delete it as accordingly.

void CopyBits(BRect src, BRect dest)

void InvertRect(BRect r)

void DrawBitmap(ServerBitmap *bmp, BRect src, BRect dest, render_mode mode)

void DrawPicture(SPicture *pic, BPoint pt)

void DrawChar(char c, BPoint pt)

void DrawString(const char string, int32 length, BPoint pt, escapement_delta delta=NULL)

void StrokeArc(BRect r, float angle, float span, layerdata d, int8 pattern)

void FillArc(BRect r, float angle, float span, layerdata d, int8 pattern)

void StrokeBezier(BPoint pts, layerdata d, int8 *pat)

void FillBezier(BPoint pts, layerdata d, int8 *pat)

void StrokeEllipse(BRect r, layerdata d, int8 pattern)

void FillEllipse(BRect r, layerdata d, int8 pattern)

void StrokeLine(BPoint start, BPoint end, layerdata d, int8 pattern)

void StrokeLineArray(BPoint pts, int32 numlines, rgb_color colors, layerdata *d)

void StrokePolygon(BPoint ptlist, int32 numpts, BRect rect, layerdata d, int8 *pattern, bool is_closed=true)

void FillPolygon(BPoint ptlist, int32 numpts, BRect rect, layerdata d, int8 *pattern)

void StrokeRect(BRect r, layerdata d, int8 pattern)

void FillRect(BRect r, layerdata d, int8 pattern)

void StrokeRoundRect(BRect r, float xrad, float yrad, layerdata d, int8 pattern)

void FillRoundRect(BRect r, float xrad, float yrad, layerdata d, int8 pattern)

void StrokeShape(SShape sh, layerdata d, int8 *pattern)

void FillShape(SShape sh, layerdata d, int8 *pattern)

void StrokeTriangle(BPoints pts, BRect r, layerdata d, int8 *pattern)

void FillTriangle(BPoints pts, BRect r, layerdata d, int8 *pattern)

void ShowCursor(void)

void HideCursor(void)

void ObscureCursor(void)

bool IsCursorHidden(void)

void SetCursor(ServerCursor *csr)

float StringWidth(const char string, int32 length, LayerData d)

float StringHeight(const char string, int32 length, LayerData d)

These drawing functions are the meat and potatoes of the graphics module. Defining any or all of them is completely optional. However, the default versions of these functions will do nothing. Thus, implementing them is likely a good idea, even if not required.

Protected Functions

uint8 GetDepth(void)

uint16 GetHeight(void)

uint16 GetWidth(void)

screen_mode GetMode(void)

void SetMode(screen_mode mode)

These five functions are called internally in order to get information about the current state of the buffer in the module. GetDepth should return 8, 16, or 32, in any event because the server handles RGB color spaces of these depths only.

bool DumpToFile(const char *path)

DumpToFile is completely optional, providing a hook which allows screenshots to be taken. The default version does nothing but return false. If a screenshot is successful, return true.

void Lock(void)

void Unlock(void)

These two functions provide a locking scheme for the driver in order to easily make it thread safe. Note that it is not publicly callable.

void SetDepthInternal(uint8 d)

void SetHeightInternal(uint16 h)

void SetWidthInternal(uint16 w)

void SetModeInternal(int32 m)

These four functions set the internal state variables for height, width, etc. If the driver reimplements the public members SetDepth(), etc, be sure to call the respective internal call so that calls to GetDepth(), etc. return the proper values.

void SetCursorHidden(bool state)

void SetCursorObscured(bool state)

bool IsCursorObscured(void)

These calls handle internal state tracking so that subclasses don’t have to.