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8: TEXT AND WINDOWS Text Attributes PEN (set colour of text) PEN index The PEN instruction sets the colour of all the text which will be displayed in the current window. This colour can be chosen from one up to 64 different possibilities depending on the gfx mode you're using. Example: PEN 6 =PEN$(n) (change the pen colour using ctrl chrars) a$=PEN$(n) PEN$ returns a special control sequence which changes the pen colour inside a string. The new pen colour will be automatically assigned whenever this string is subsequently printed on the screen. Example: C$=Pen$(2)+"White "+Pen$(6)+"Blue" Print C$ The string returned by PEN$ is in the format: Chr$(27)+"P"+Chr$(48+n) PAPER (set colour of the text background) PAPER index "index" can be a number between 0-63. =PAPER$(n) (return a control sequence to set the paper colour) x$=PAPER$(index) PAPER$ returns a character string which automatically changes the background colour when it's printed on the screen. For example: Pen 1: C$=Paper$(2)+"White "+Paper$(6)+"Blue" Print C$ INVERSE ON/OFF (enter inverse mode) INVERSE ON/OFF The INVERSE command swaps the text and the background colours. SHADE ON/OFF (shade all subsequent text) SHADE ON/OFF SHADE ON highlights your text by reducing the brightness of the characters with a mask pattern. The shade of your text can be returned to normal using SHADE OFF UNDER ON/OFF (set underline mode) UNDER ON/OFF UNDER ON underlines your text when it's printed on the screen. UNDER OFF turns off the mode. WRITING (change text writing mode) WRITING w1 [,w2] The WRITING command allows you to change the writing mode used for all subsequent text operations. This determines precisely how your new text will be combined with the existing screen data. w1=0 REPLACE (Default) Your new text will obliterate anything underneath it. w1=1 OR Merges the characters onto the screen with a logical OR. w1=2 XOR Chars are combined now with XOR. w1=3 IGNORE Printing operations are ignored! The secont number chooses which parts of the text will be printed on the screen. This option can be omitted if required. w2=0 Normal The text is output to the screen along with the background. w2=1 Paper Only the background of the text is drawn on the screen. w2=2 Pen Ignores the paper colour and writes the text on a background of colour zero. Do *NOT* confuse this with GR WRITING! Cursor functions AMOS includes a range of facilities which let you move cursor to any part on the screen. LOCATE (position the cursor) LOCATE x,y LOCATE x, Locate moves the text cursor to the coordinates x,y. LOCATE ,y This sets the starting point for all future printing operations. All screen positions are specified using a special set of text coordinates. These are meadured in units of a single character relative to the top left corner of the text window. For instance the coordinates 15,10 refer to a point 10 chars down and 15 to the right. If you attempt to print something outside window limits an error will be generated. Note that the current screen is always treated as window 0. So you don't have to actually open a window before using one of these functions. CMOVE (relative cursor movement) CMOVE w,h Moves the cursor a fixed distance away from its present position. If your cursor was at 10,10, then typing: CMOVE 5,-5 would move the cursor to 15,5. Like LOCATE you can omit either one of the coordinates as required. =AT (return a sequence of ctrl chars to position the cursor) x$=AT(x,y) The AT function allows you to change the position of text directly from inside a character string. It works by returning a string in the format: Chr$(27)+"X"+Chr$(27)+"Y"+Chr$(48+Y) Whenever this string is printed, the text cursor will be moved to the coordinates x,y. For example: A$="This"+At(10,10)+"Is"+At(1,2)+"The Power Of"+At(20,20)+"AMOS!" Print A$ These AT commands are perfect for hi-score tables as they allow you to position our text once and for all during your programs initialisation phase. You can now update the score at the correct point on the screen using a single print statement. Here's an example: HI_SCORE$=At(20,10)+"Hi Score " SCORE=10000 Print HI_SCORE$;SCORE Conversion functions AMOS Basic provides you with four useful functions which readliy enable you to convert between text and graphics coordinates. =XTEXT (convert an x coordinate gfx->text format) =YTEXT (convert an y coordinate gfx->text format) t=XTEXT(x) t=YTEXT(y) These functions take normal x/y coordinates and convert them to text coordinates relative to the current window. If the screen coordinate lies outside this window then a negative value will be returned. See EXAMPLE 8.1. =XGRAPHIC (convert an x coordinate text->gfx format) =YGRAPHIC (convert an y coordinate text->gfx format) g=XGRAPHIC(x) g=XGRAPHIC(y) These functions are effectively the inverse of XTEXT and YTEXT in that they take a text X (or) Y coordinate ranging from 0 to the width/height of the current window and convert them to absolute screen coordinates. See EXAMPLE 8.2 Cursor commands The text cursor serves as a visible starting point of all future text operations. It's usually displayed as a flashing horizontal bar, although this may be changed using the SET CURS and CURS OFF commands. By moving the cursor on the screen, you can position your text practically anywhere you like. Remember, all coordinate measurements are taken using TEXT coordinates relative to the current window. HOME (cursor home) HOME Moves the text cursor to the top left hand corner of the current window (coordinates 0,0) CDOWN (cursor down) 93 CDOWN Pushes the text cursor down by a single line. =CDOWN$ (return a Chr$(31) character) x$=CDOWN$ CDOWN$ is a function which returns a special control character which automatically moves the cursor when it is printed. So Print CDOWN$ is identical to CDOWN. CDOWN$ allows you to combine several cursor movements in a single string. For example: C$="\"+Cdown$ For A=0 to 20 Print C$; Next A CUP (cursor up) CUP Moves the text cursor up a line in the same way that CDOWN moves down. =CUP$ (return a Chr$(30) character) x$=CUP$ CUP$ returns a control string which moves the cursor up by a single character. CLEFT (cursor left) CLEFT Displaces the text cursor one character to the left. =CLEFT$ (Control string for CLEFT Chr$(29)) x$=CLEFT$ Moves the text cursor one character left. Works like =CUP$. CRIGHT (cursor right) CRIGHT Moves cursor one place to the right. =CRIGHT$ (Generate a Chr$(28) control string for CRIGHT) x$=CRIGHT$ Is the opposite of CLEFT$. XCURS (return the X coordinate of the text cursor) YCURS (return the Y coordinate of the text cursor) x=XCURS y=YCURS XCURS is a variable containing the current X coordinate of the text cursos (in text format). YCURS holds the Y coordinate of the cursor. SET CURS (set text cursor shape) SET CURS L1,L2,L3,L4,L5,L6,L7,L8 This instructoin allows you to change the shape of the cursor to anything you like. The shape is specified by a list of bit-patterns held in the parameters L1-L8, Each parameter determines the appearance of the horizontal line of the cursor, numbered from top to bottom. Every bit represnts a single point in the current cursor line. If it's set to 1 then the point will be drawn using colour number 3 - otherwise it will be displayed in the current PAPER colours. Example: L1=%11111111 L2=%11111110 L3=%11111100 L4=%11111000 L5=%11110000 L6=%11100000 L7=%11000000 L8=%10000000 Set Curs L1,L2,L3,L4,L5,L6,L7,L8 CURS ON/OFF (enable/disable text cursor) CURS ON makes text cursor visible CURS OFF hides the cursor in current window MEMORIZE X/Y (save the X or Y coordinates of the text cursor) MEMORIZE X MEMORIZE Y The Memorize commands store the current cursor position. REMEMBER X/Y (restore the X or Y coordinate of the text cursor) REMEMBER X REMEMBER Y REMEMBER positions the cursor at the coordinates saved by a previous call to MEMORIZE. If MEMORIZE has not been used then the coordinates will be set to zero. See EXAMPLE 8.3 CLINE (clear part or all of the current cursor line) CLINE [n] Clears the line on which the cursor is positioned. If n is present then "n" characters are cleared starting at the current cursor position. CURS PEN (choose a new colour for the text cursor) CURS PEN n Changes the colour of the text cursor to index number n. Text Input/Output CENTRE (print a line of text centred on the screen) CENTRE a$ Takes a string of characters in a$ and prints it in the centre of the screen. This text is always output on the current cursor line. Locate 0,1 Centre "This is a centered TITLE" =TAB$ (print tabulation) x$=TAB$ TAB$ returns a control character known as a TAB (Ascii 9). When this character is printed the text cursor will be immediately moved several places to the right. The size of this movement can be set using the SET TAB kommand. As a default, the tab spacing is set to four (4). SET TAB (change the tabulation) SET TAB n This specifies the distance the text cursor will move when TAB character is printed. REPEAT$ (repeat string) x$=REPEAT$(a$,n) The REPEAT$ function allows you to print out the same string of characters several times using a single PRINT statement. It works by adding a sequenve of control characters into variable X$. When this string is printed, AMOS simply repeats a$ to the screen n times. Possible values for n range between 1 and 207. See EXAMPLE 8.4. The format of the control string is: Chr$(27)+"RO"+A$+Chr$(27)+"R"+Chr$(48+n) Advanced Text Commands ZONE$ (set up a zone around a piece of text) x$=ZONE$(a$,n) The ZONE$ function surrounds a section of text with a screen zone. After you have defined one of these zones you can check for coillisions between the zone and the mouse using the ZONE function. This allows you to create powerful on-screen menus and dialogue boxes without having to resort to any complicated programming tricks. a$ is a string containing the text for one the "Buttons" in your dialogue box. This button will be activated automatically when you print x$ to the screen. n specifies the number of screen zone to be defined. The max. number of these zones depends on the value you specified with RESERVE ZONE. See the EXAMPLE 8.5 program in the MANUAL folder. The format of the control string is: Chr$(27)+"ZO"+A$+Chr$(27)+"R"+Chr$(48+n) BORDER$ (add a border to some text) x$=BORDER$(a$,n) This returns a string of control characters which instructs AMOS to draw a border aound the required text. It's commonly used in conjunction with the ZONE$ command to produve the fancy buttons found in dialogue boxes and alert windows. n is the border number ranging from 1 to 16 and a$ holds the text to be enclosed by the border. The text in a$ will start at the current cursor position so don't be surprised when you get strange results printing at 0,0. To create a screen zone by a border try this: Print Border$(Zone$(" CLICK HERE ",1),2) This would enclose the text with zone number 1 and border 2. The control sequence is: Chr$(27)+"EO"+A$+Chr$(27)+"R"+Chr$(48+n) HSCROLL (horizontal text scrolling) HSCROLL n This scrolls all the text in the currently open window horizontally by a single character position. n can take the following values: 1 = Move current line to the left 2 = Scrolls entire screen to the left 3 = Move current line to the right 4 = Move screen to the right VSCROLL (vertival scroll) VSCROLL n Scrolls the text in the currently open window vertically. 1 = Any text at the cursor line and below is scrolled down 2 = Text at cursor line or below is moved up 3 = Only text from the top of the screen to the cursor line is scrolled up 4 = Text from top of the screen to the current cursor position is scrolled down Blank lines are inserted to pad out the gap left by the scrollingoperation. Windows The AMOS windowing commands allow you to restrict your text and graphics operations just a part of the current screen. AMOS windows can be used with the zone commands to produce effective dialogue boxes such as file selectors and high score tables. A typical warning box, for instance, can be easily generated with just a couple lines of AMOS Basic. WINDOPEN (create a window) WINDOPEN n, x, y, w, h [,border [,set]] The WINDOPEN instruction opens a window and displays it on the screen. This window will now be used for all subsequent text operations. n is the number of the window to be defined. AMOS allows you to create as many windows as you like, limited only by the amount of available memory. As a default, window number zero is assigned to the current screen. So don't attempt to re-open this window using WINDOPEN or change it with WIND SIZE or WIND MOVE. x,y are the graphics coordinates of the top left hand corner of your new window. Since AMOS windows are drawn using the Amiga's blitter chip, the window area must always lie on a 16-pixel boundary. In order to achieve this, the x coordinates are automatically rounded to the nearest multiple of 16. Additionally, if you've included a border for your window, the X coordinate will be incremented by a further eight. This will ensure that the working area of your window always starts at the correct screen boundary. There are no restrictions whatsoever on the y coordinates. w,h specify the size in characters of the new window. These dimensios must always be divisible by 2. "border" selects a border style for your window. There are 16 possible styles, with values ranging between 1 and 16. Window borders can also include up to two optional title lines. One title is displayed along the top of the window and another may be added at the bottom. AMOS windows may contain either text or graphics, just like the intuition system. Each window can be assigned it's own individual character set with the powerful WINDOW FONT command. There's also a powerful WIND SAVE instuction which saves the screen area inside your windows. Whenever you move one of these windows the contents underneath will be automatically redrawn. For example: For W=1 To 3 Windopen W,(W-1)*96,50,10,101 Paper W+3 : Pen W+6 : Clw Print "Window ";W Next W You can flick between these windows using the WINDOW command. Try typing the following statements from the Direct mode: Window 1 : Print "AMOS" Window 3 : Print "in action!" Window 2 : Print "Basic" The active window can always be distinguished by a flashing cursor - through this can be turned off using the CURS OFF command if required. WINDOW FONT (change window font) WINDOW FONT n Changes the font used by the current window to set n. n is the number of a graphics font which has been previously installed with the GET FONT command. This font *must* have dimensions of exactly 8x8. Proportional fonts are not allowed. Since the window vborders make use of some of these characters, you may get rather odd results when you're using standard WBench fonts. WIND SAVE (save the contents of the current window) WIND SAVE The WIND SAVE command allows you to move your windows anywhere on the screen without corrputing your existing display. Once you've activated this feature, any windows you subsequently open will automatically save the entire contents of the windows underneath. This area will be redrawn whenever you close a window or move it to a new position. It's important to note that this option saves the contents of the current window, rather than the one you are defining with WIND OPEN. At the start of your program the current window will be the default screen and will take up a massive 32k of memory. If you wished to save the background underneath a dialogue box the most of this memory would be completely wasted. The solution is to create a dummy window of the required size, and to position it over the zone you wish to save. You can now execute a WIND SAVE command and continue with your program as normal. When you subsequently call up your dialogue box the area underneath will be saved as part of your dummy window. So it will be automatically restored after your box has been removed. BORDER (change the window border of the) current screen) BORDER n,paper,pen The BORDER command sets the border of the current window to style number n. This border is drawn using a group of characters installed in the default font. It is therefore possible to create your own border styles using the font definer accessory. The paper and pen options allow you to freely choose the colours of your border. Acceptable border numbers range from 1 to 16. Any of the parameters may be omitted from this instuction so the following commands are legal: BORDER 2,, BORDER 2,,3 TITLE TOP (define the upper title for the current window) TITLE TOP t$ This instruction sets the top line of the current window to the title string in t$. Only bordered windows may be titled in this way. Windopen 5,1,1,20,10 Title Top "Window Number 5" Wait Key TITLE BOTTOM (define the lower title for the current window) TITLE BOTTOM b$ This command assigns the string b$ to the bottom title of the current window. WINDOW (change current window) WINDOW n WINDOW activates the window n as the current window. If the automatic saving system has been initiated, this window be immediately redrawn along with any of its contents. See EXAMPLE 8.6 in the Manual folder. =WINDON (Return the value current window) w=WINDOW WINDON returns the identification number of the currently active window. WIND CLOSE (close the current window) WIND CLOSE Deletes the current window. Use the WIND SAVE command if you want the area that was hidden be redrawn by. WIND MOVE (move a window) WINDMOVE x,y Windmove moves the current window to graphics coordinates x,y. As with the original window definitions the x coordinate will be rounded to the nearest 16-pixel boundary. WIND SIZE (change the size of the current window) WIND SIZE sx,sy This command changes the size of an AMOS window. The new sizes, sx and sy, are specified in units of a single character. Sx must be divisible by two. See EXAMPLE 8.7. If you've previously called the WIND SAVE command, the original contents of your window will be redrawn by this instruction. If the new window is smaller than the original one, any parts of the image which lie outside will be lost. Alternatively, if you've expanded your window, the area around your saved region will be filled with the current paper colour. Also note that after a WIND SIZE command the text cursor is always reset to coordinates 0,0. CLW (clear the current window) CLW Erases the contents of the current window and fills it with the current PAPER colour. Slider bars AMOS incorporates three insturctions which allow you to display a standard slider bar on the screen. These sliders cannot be manipulated directly with the mouse. In order to create a working slider bar, you'll need to write a small Basic routine to perform this operate in your main program. Due to the sheer power of the AMOS system, this is extremely easy to accomplish, and the results can be extremely impressive, as can be seen from EXAMPLE 8.8. HSLIDER (draw a horizontal slider) HSLIDER x1,y1 OT x2,y2,total,pos,size Draws a horizontal slider bar from x1,y1 to x2,y2. "total" is the number of individual units which the slider will be divided into. Each unit represents a single item in the object you are controlling with the slider. TSo in the editor window, "total" would be set to the number of lines in the current program. The size of each unit is calculated from the following formula: (X2-X1)/Total "pos" is the position of the slider box from the start of the slider, measured in the units you specified using "total". "size" is the length of the slider box in the previous units. See EXAMPLE 8.9. VSLIDER (draw a vertical slider) VSLIDER x1,y1 TO x2,y2,total,pos,size VSLIDER is almost identical to the previous HSLIDER insturction. It displays a simple slider from x1,y1 to x2,y2. See EXAMPLE 8.10. SET SLIDER (sets the fill patterns used in a slider) SET SLIDER b1,b2,b3,pb,s1,s2,s3,ps Although this command looks incredibly complicated, it's actually rather simple. SET SLIDER enters the colours and patterns to be used in the slider bars created with the H/VSLIDER commands. "b1,b2,b3" set the ink, paper and outline colours for the background of the box. "pb" chooses the fill pattern to be used for these regions. "s1,s2,s3" input the colours of the slider box, and "sp" selects the pattern it is to be filled with. "bp" and "sp" can be any fill patterns you wish. As usual, negative value refer to a sprite image from the current sprite bank. This allows you to create amazing colorful slider boxes. Fonts There are two different types of fonts available in AMOS - text fonts and graphic fonts. The text fonts are those used by the PRINT and WINDOW commands. Text fonts are known as character sets and each AMOS Basic window can have its own individual set. The graphic fonts are much more flexible and offer a wider range of styles: Graphic text Your Amiga computer is capable of displaying an impressive variety of different text styles. The original WorkBench disc was supplied with eight attractive fonts in a range of sizes, and many more of these fonts are freely available from the public domain. If you've upgraded to WorkBench 1.3, you'll also be able to design your own fonts using the FED program on the Extras disc. AMOS provides you with total support for these fonts. Text can be printed in any of the available typefaces at any point on the screen. AMOS fonts can be used to add spice to even the most Basic games. These are invaluable for producing the loading screens and hi-score tables in your games. So it's a good idea to make full use of them in your progs. TEXT (print graphical text) TEXT x,y,t$ TEXT prints a line of text in t$ at graphical coordinates x,y. All coordinates are measured relative to the characters baseline. This can be determined using a special TEXT BASE function. Normally the baseline is positioned at the bottom of the character, but some lowercase letters, such as "g", have a "tail" which extends slightly below this point. As a default the type styles is set to eight-point Topaz. This may be changed at any time using the SET FONT instruction. Try the following program and notice how text can be placed at any pixel position on the screen. Do Ink Rnd(15)+1,Rnd(15): Text Rnd(320)+1,Rnd(198)+1,"AMOS Basic" Loop Al so notice how the colour of your text is set with INK rather than the expected PEN and PAPER commands. This emphasizes the fact that the TEXT command is basically a graphical instruction. So the control sequences created by functions like CUP$ will be printed on the screen instead of being correctly interpreted. There is no automatic line feed when the text reaches the end of the current window. If you attempt to print something too large, the text will be neatly clipped at the existing screen boundary. This can be seen by the example below: Print String$("A",100):Text 0,100,String$("A",100) GET FONTS (create a list of all available fonts) GET FONTS The GET FONTS command creates an internal list of the all fonts available from the current start-up disc. This list is essential to the running of the SET FONT command, so you should always call GET FONTS at least once before attempting to change the present font setting. The contents of this list can be examined using the FONT$ function. WARNING! In order for GET FONTS to work, your current AMOS work disc must always contain a copy of the standard LIBS folder along with its contents. It's important to remember this fact when you are distributing run-only or compiled programs because unless your discs contain the required files, AMOS Basic will almost certainly crash! GET DISC FONTS (create a list of the disc fonts) GET DISC FONTS This command is identical to the previous GET FONTS instruction except that it only searches for fonts on the disc. These fonts are contained in the FONTS folder on your current boot-disc. If you want to use your own fonts with AMOS basic, you'll need to copy these onto your normal start-up disc. See the manual supplied with your Amiga for details of this procedure. GET ROM FONTS (create a list of the rom fonts) GET ROM FONTS produces a list of the fonts which are built into Amiga's rom chips. At the present time there are just two of these fonts: Eight-point Topaz and nine-point Topaz. =FONT$ (return details about the available fonts) a$=FONT$(n) Returns a string of 38 chars which describes font number n. This function allows you to examine the font list created by a previous call to one of the GET FONT commands. a$ contains a list of characters which hold the name and type of your font. If a font does not exist, a$ will be loaded a null value "", otherwise a string will be returned in the following format: Character Description 1-29 Font name 30-33 Font height 34-37 Identifier (set to either Disc or Rom) See EXAMPLE 8.11! SET FONT (choose a font for use by the TEXT instruction) SET FONT n SET FONT changes the character set used by the TEXT command to font number n. If the font is stored on the disc it will be automatically loaded into your Amiga's memory. At the same time any previously sets which are not in use will be removed. See EXAMPLE 8.12. SET TEXT (set text style) SET TEXT style Allows you to change the style of a font. There are three styles to choose from. "style" is a bit pattern in the following format: Bit Effect 0 Underline By setting the appropriate bits in this 1 Bold pattern you can choose between a total 2 Italic of eight different text styles. =TEXT STYLE (return the current text style) s=TEXT STYLE This function returns the text style set from the SET TEXT command. The result in "s" is a bit-map in the same format as that used by SET TEXT. =TEXT LENGTH (return the length of a section of graphic text) w=TEXT LENGTH(t$) The TEXT LENGTH function returns the width in pixels of the character string a$ in the current font. The width of a character varies depending on the size of your fonts. In addition, proportional fonts such as Helvetica assign different widths for each individual character. =TEXT BASE (return the current text base) b=TEXT BASE This function returns the position of the baseline of your font. The baseline is the number of pixels between the top of a character and point it will be printed on the screen. It's basically similar to the hot spot of a sprite or bob. Installing new fonts If you wish to use your own fonts within AMOS Basic, you'll need to install them onto a copy of your AMOS program disc. The basic procedure is as follows: - Copy the required font files into the FONTS: directory of your boot- disc. - Further information can be found in the Extra's manual supplied with the Workbench 1.3 upgrade. Troubleshooting Problem: GET FONTS seems to ignore any of the fonts on the current disc. Solution: You've propably removed the original boot disc from your default drive. The Amiga's library routines expect to find the FONTS: directory on your start-up disc. This can be changed using the ASSIGN program in the UTILITIES folder. Problem: GET FONTS crahes the Amiga completely. Solution: This problem can easily occur when you're creating programs in run-only or compiled format. GET FONTS requires the discfont.library in the LIBS folder in order to work. Problem: The SET FONT command returns a "fonts not examined" error. Solution: Add a cal to GET FONTS to the start of your program.