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<head> <title="...forever..."> <font=monaco10.fnt> <font=newy36.fnt> <font=time24.fnt> <image=back.raw w=256 h=256 t=-1> <buf=4502> <bgcolor=-1> <background=0> <link_color=000> <module=console.mod> <pal=back.pal> colors: 251 - black </head> <body> <frame x=0 y=0 w=640 h=4502 b=-1 c=-1> .: GEM in one pill :. ----------------------------- 5) VDI (Virtual Device Interface) -------------------------------------- AES and VDI are independent. As it's well known AES relays on VDI graphical functions. From time to time they can get in conflict, one with each other. We can use VDI without calling the AES and we can use AES (functions displaying menu and dialog boxes) without the initialisation of VDI. But in the most cases, our programs will be using both of them. Why use the VDI? There are 200% faster solutions of drawing with the use of BIOS and XBIOS. The answer is simple, each addition such as graphics card or extended resolutions on Falcon are fully compatible with VDI, but not for sure with BIOS and XBIOS. It's rather question of reaching the widest user audience. REPETITION FROM THE VDI INITIALISATION Firstly we have to find the physical screen handle (PHYS_HANDLE from now on). AES sets it in the beginning, so we can get it with graf_handle() call. We need also the height in pixels of our standard text character. Using this handle (PHYS_HANDLE) we can open virtual workstation (screen is "virtual", the others are "real".) with v_openvwk(). This call returns an information about displayed screen together with VDI workstation handle (STAT_HANDLE) and this handle is used with all further VDI calls. If we have handle of VDI workstation, we open the sample window to display something. Problem is that VDI doesn't understand the absolute screen coordinates (640*480 or anything else).How to find the correct coordinates? Remember that size of the area to display is (overall size of the window MINUS size of all gadgets like closers, sliders etc.). There is a solution. We know how to handle windows to draw within them. We use wind_get() with WORKXYWH flag to get four words filled with appropriate values (x,y,w,h). Now we have to convert them into VDI coordinates(x1,y1,x2,y2): VDI 3rd word = AES 3rd word + AES 1st word VDI 4rd word = AES 4th word + AES 2nd word AES 3rd word = VDI 3rd word - AES 1st word AES 4th word = VDI 4th word - AES 2nd word Now we have the rectangle in which we can do something. We need to specify the VDI clipping rectangle with vs_clip() to prevent the content of the window "spilling out" of it. As a parameter to this call we use handle of workstation, coordinates and TRUE flag to switch on the clipping and 0 flag with NULL rectangle to switch off the clipping. We have to switch off the clipping before we exit the program. Everything lets us to draw anything on the screen but in theory. BASIC IO There are two possible forms of the text output: text and graphical. The text one is easier one so we start with it first. Output comandds through VDI are quite simple. Firstly we can set all the details of the displayed text as we like. We do it with the following call. And remember that everything should be set BEFORE the outputting the text: - colour vst_color(handle, colour); colour is BLACK(1) as default. - rotate sets the text angle. Bitmap fonts can be turned in 90 degree steps, and vector ones freely: vst_rotate(handle, angle in degrees) angle = 0-normal, 90 - to the top of the screen, 180- upside down, 270 - to the bottom of hte screen. - justification this doesn't cover only right /left /center justification, but it has also vertical justification (with several "levels" of justify): SUBSCRIPT - text is jusified to the bottom line (descent) SUPERSCRIPT - text is jusified to the upper line (ascent) Normally, the standard settings are used with justification to the left and to the base. Justified text with microspaces is available through VDI (justified text where words are in one line without creating big gaps between them). But we have to use the special version of "text print" to use it. It cannot be setted by default. vst_alignment (handle, HALIGN, VALIGN, &HSET, &VSET); You set the flags that you want in HALIGN and VALIGN, but those that are set are returned in HSET and VSET. Some devices are not accepting all kinds of justification (but hopefully, screen accepts everything :) ). - effects we can add various effects. In case of GDOS fonts, it's better to use the bold version of the font rather than transform it to bold. We have several effects to choose: bold, underline, italic, outline, grey, shadow. Shadow isn't working at all with all the GDOS versions. vst_effects(handle, effect); Effects are set like oridinary binary flags. If effect = 0 text is normal. FUNCTIONS DISPLAYING TEXT Most basic one: v_gtext(handle,x,y,string); handle - VDI handle as usual, x,y -start coordinates, string - NULL terminated string. For text with microspaces: v_justified (handle, x,y,string, lenght, word_flag, character_flag); handle, x, y, string are as above. lenght is a area in pixels on which we want to spread the text. Flag of word /character indicates the justification between words /characters (0- no/ 1-yes). The best solution is to display all the characters that are fitting inside the window plus one additionally, automatically reducing screen area to redraw. We know the working area ( WORKXYWH flag with wind_get() remember?). So we can check the lenght of the each text string with: vqt_extent(handle, string, points); handle and string are obvious. points are four pairs of four words defining the minimal area in which fits the text. The proble is in the order of these pairs, the order depends from the mode (is the text displayed in 90 degree steps or is rotated freelly). So, we can loop everything, until we receive one (or a part) of the character, print the string and let the system to clean up everything (both variant of outputting text). BASIC VDI GRAPHIC FUNCTIONS VDI has several standard shapes to draw called GDP (Graphic Device Primitives). This means that EVERY device driver should support those functions (and we can assume that they are always available). One of the values from WORK_OUT [14] contains the number of available GDP functions in given device. They also contain the old settings (like colour), but they require other parameters before they can be used. GDP functions: a) filled bar v_bar (handle, points); handle - VDI handle points - points in VDI format b) arc v_arc (handle, x, y, radius,angle at start, angle at end); handle - VDI handle x,y - the coordinates of the centre of the circle radius - horizontal circle radius (horizontal is set by device coordinate system) angle at start, angle at end - the angle are in 1/10 of a degree with EAST as a 0. c) filled pie Problematic. Atari Compedium talks about v_pieslice(), compute! about v_pie(). Check better the documentation of your compiler. Arguments are similar to those in v_arc (). d) filled circle v_circle (handle, x,y, radius); Everything self explanatory. handle - VDI handle x,y - the coordinates of the centre of the circle e) filled ellipse v_ellipse (handle, x, y, radius x, radius y); handle - VDI handle x,y - the coordinates of the centre of the circle radius x- horizontal radius radius y- vertical radius WARNING! If you don't use NDC, the shape is looking different in different resolutions. f) elliptic arc v_ellarc ( handle, x, y, radius x, radius y, angle at start, angle at end); g) filled elliptic pie v_ellpie (handle, x, y, radius x, radius y, angle at start, angle at end); h) rounded rectangle v_rbox(handle, points); handle - VDI handle points - in VDI format i) filled rounded rectangle v_rfbox(handle, points); as above... That's all if it comes about GDP, which with justified text should be present within every VDI. To be sure we can check all the functions after the opening of the VDI workstation. There are soe functions that are modyfying the VDI default settings: clipping rectangle (we know that already to well...) fill colour vsf_color(); fill style vsf_interior(); style index fill vsf_style(); outline fill perimeter vsf_perimeter(); line colour vsl_color(); line style vsl_type(); line width vsl_width(); VDI BASIC DRAWING FUNCTIONS To draw anything we have to: - prepare the screen and palette, - set the required attributes. VDI can draw following shapes: pixels, crosses, stars, rectangles, x and diamonds. Attributes of drawing shapes we set with functions: vsm_color() - sets the colour (colour number from the palette), which is used by shape. vsm_height() - sets the size of the shape (doesn't work pixels). vsm_type() - sets the shape from the list of VDI shapes mentioned above. After setting of these parameters we can draw with v_pmarker(). We can also take a look at actually setted attributes with vqm_attributes(). Lines are much more complex. They take the attributes (colour, style, width, style of the lineend) setted by the group of functions vsl_xxx(). VDI function responsible for drawing lines is very flexible, but complicated a little: void v_pline (WORD handle, WORD amount of points, WORD *table of points); handle - VDI handle amount of points - an amount of pairs of the coordinates (x,y) in array of points describing vertices to draw. The end of the first line is treated, as the beginning of the second one: points_table[0], points_table[1] points_table[2], points_table[3] *---------------------------------* | | | | | | *---------------------------------* points_table[6],points_table[7] points_table[4],points_table[5] To draw every shape we need an array: (amount of sides+1) * 2 points. In a closed shape the first coordinates should be equal to the last in an array. VDI INQUIRE FUNCTIONS This group of functions is used to check the actual informations about the VDI. Most frequently used are: vq_chcells() - returns the size of screen in characters. vq_color() - returns the RGB value of specified colour number fro the palette. vq_curraddres() - returns the actual text cursor position. vq_extnd() - additional informations about actual device. vq_gdos() - checks if GDOS is installed and returns it type and version. vq_key_s() - returns the state of SHIFT/ ALT/ CONTROL keys. vq_mouse() - returns the state and position of mouse arrow. vqf_attributes() - returns the actual fill style vql_attributes() - returns the actual line settings vqm_attributes() - returns the actual marker (shape) settings. vqt_attributes() - returns the actual text settings. vqt_extent() - returns (in pixels) the area covered by text. v_get_pixel() - returns the colours of the chosen point on the screen. Most functions are working in similar way, they return the pointer to the array filled with values. (Take a look into Atari Compedium!). VDI INPUT FUNCTIONS Atari ST / TT/ Falcon have two major input devices - mouse and keyboard. Both sources can be read by VDI and AES. The differences lay are in the method getting the information. AES uses the message system and VDI must to ask the device for information (inquire or "poll"). Both methods have their merits and flaws. The AES way consumes less cpu time, but VDI is able to fetch the info which we need, not when the message will be in the beginning of the que. Mouse VDI: uses vq_mouse() and vq_keys_s(). vq_mouse() returns 3 words. Two of them contain x, y coordinates and one word with two first bits reflecting the actual state of the mouse buttons. AES: uses evnt_mouse(). This call sits and waits until the desired event will occur, which is a mouse pointer entering the specified part of the screen and returns the information as above. BUT if the mouse pointer will not enter the specified part of the screen, system will not answer on other messages (will "jam"). Similar function call evnt_button() waits for specified mouse button press. Monitoring of both (and many other) messages requires the use of monolithic "combi-harvester" in shape of evnt_multi(). This function is ENORMOUS and takes 22 parameters which lets us to observe anything that AES reports. Keyboard: VDI: There are two possible ways of using the keyboard under VDI, which depend from the nature of the data at input. The input can be sampled (system doesn't wait for the RETURN before sending the keypresses) or inquired. But firstly we need to set correctly the text cursor. We have to set input mode: vrq_string() - inquiry mode vsm_string() - sample mode AES - is much simplier. During keyboard read the evnt_keybd() is used, which waits for a keypress or alternatively use the evnt_multi(). Both functions return one word. Less significant byte in word contains ASCII code, the most significant byte contains the keyboard code. The keyboard code is useful when the desired key doesn't posses the ASCII value (HELP key for instance). <link=art52e.scr>Go to PART #5</l> </frame> </body>