Ottenere una schermata (screenshot) del desktop con le risorse del API di X11 e di Imlib2
Da Gambas-it.org - Wikipedia.
Versione del 25 giu 2024 alle 16:12 di Vuott (Discussione | contributi)
E' possibile ottenere una schermata del desktop utilizzando alcune risorse esterne del API di X11 e di Imlib2.
Per poter fruire di tali risorse, è necessario richiamare in Gambas le librerie dinamiche e condivise:
- libX11.so.6.4.0
- libImlib2.so.1.12.2
Mostriamo un esempio, nel quale verrà effettuata una schermata dell'intero desktop. In fine la schermata verrà salvata in un file di formato .png:
Library "libX11:6.4.0" Private Enum XYBitmap = 0, XYPixmap, ZPixmap ' Display *XOpenDisplay(char *display_name) ' Opens a connection to the X server that controls a display. Private Extern XOpenDisplay(display_name As String) As Pointer ' int XDefaultScreen(display) ' Returns the default screen number. Private Extern XDefaultScreen(display As Pointer) As Integer ' Window XDefaultRootWindow(display) ' Returns the root window for the default screen. Private Extern XDefaultRootWindow(display As Pointer) As Long ' Visual *XDefaultVisual(display, screen_number) ' Returns the default visual type for the specified screen. Private Extern XDefaultVisual(display As Pointer, scr_num As Integer) As Pointer ' int XDisplayWidth(display, screen_number) ' Returns the width of the screen in pixels. Private Extern XDisplayWidth(display As Pointer, scr_num As Integer) As Integer ' int XDisplayHeight(display, screen_number) ' Returns an integer that describes the height of the screen in pixels. Private Extern XDisplayHeight(display As Pointer, scr_num As Integer) As Integer ' unsigned long XAllPlanes() ' Returns a value with all bits set to 1 suitable for use in a plane argument to a procedure. Private Extern XAllPlanes() As Long ' XImage *XGetImage(Display *display, Drawable d, int x, int y, unsigned int width, unsigned int height, unsigned long plane_mask, int format) ' Returns a pointer to an XImage structure. Private Extern XGetImage(displayP As Pointer, d As Long, xI As Integer, yI As Integer, wid As Integer, hei As Integer, plane_mask As Long, formatI As Integer) As Pointer ' XCloseDisplay(Display *display) ' Closes the connection to the X server for the display specified in the Display structure and destroys all windows. Private Extern XCloseDisplay(display As Pointer) Library "libImlib2:1.12.2" ' Imlib_Image imlib_create_image_using_data(int width, int height, DATA32 * data) ' Creates an image from the image data - in the format of a DATA32 (32 bits) per pixel in a linear array - specified with the width and the height specified. Private Extern imlib_create_image_using_data(width As Integer, height As Integer, data As Pointer) As Pointer ' void imlib_context_set_image(Imlib_Image image) ' Sets the current image Imlib2 will be using with its function calls. Private Extern imlib_context_set_image(Imlib_Image As Pointer) ' void imlib_save_image(const char *filename) ' Saves the current image in the format specified by the current image's format settings to the filename. Private Extern imlib_save_image(filename As String) Public Sub Main() Dim dsp, vis, XImage, imago As Pointer Dim root As Long Dim scr, wi, he As Integer ' Si connette con il display: dsp = XOpenDisplay(0) If dsp == 0 Then Error.Raise("Impossibile aprire una connessione al server X !") scr = XDefaultScreen(dsp) root = XDefaultRootWindow(dsp) vis = XDefaultVisual(dsp, scr) If vis == 0 Then Error.Raise("Errore !") wi = XDisplayWidth(dsp, scr) he = XDisplayHeight(dsp, scr) ' Otteniamo un puntatore alla "Struttura" contenente i dati-immagine del desktop: XImage = XGetImage(dsp, root, 0, 0, wi, he, XAllPlanes(), ZPixmap) If XImage == 0 Then Error.Raise("Impossibile ottenere un 'Puntatore' ai dati-immagine del desktop !") XImage = XImage + (SizeOf(gb.Pointer) * 2) imago = imlib_create_image_using_data(wi, he, Pointer@(XImage)) If imago == 0 Then Error.Raise("Impossibile creare l'immagine dai dati grezzi acquisiti !") imlib_context_set_image(imago) ' L'immagine creata viene salvata in un file immagine. Al nome del file immagine da creare va indicata l'estensione del formato immagine desiderato: imlib_save_image("/tmp/immagine.png") ' Va in chiusura: XCloseDisplay(dsp) End