1. Introduction to AlfaCAD

Preface

AlfaCAD was conceived as a simple, universal program for creating technical drawings. But "universal" does not mean "almighty". It is a Swiss Army knife rather than a box full of tools most of which are a secret to the user and will never be used.

AlfaCAD's interface is different from that of most CADs. The idea came from such premises.

• The monitor, especially of our notebook, is small compared to a traditional drawing board. Small, which means that either we are doomed to look at the drawing on a small scale, or to see the details of the drawing only seeing a fragment of the entire sheet. While editing the drawing, we have to change the scale of the presentation many times, move the sheet to see the detail we are working on. Most CADs offer access to many functions in the form of icons scattered around the drawing window, thus limiting the presentation area even more. As a result, we work by looking at a small fragment of the drawing and when we need to introduce an element that goes beyond the presented fragment, we have to change the scale, which usually leads to a loss of control over the details, because usually each element is introduced in relation to other elements.
  AlfaCAD offers an interface that takes up no screen space for buttons and icons. The drawing panning function minimizes the need to change the scale of the presentation.

• All functions are available from the hierarchical menu, and the selection of functions consists either in selecting a function from the menu with the cursor, represented by an icon, or in a one-character shortcut directly from the keyboard.

• The program has an extensive system of keyboard shortcuts allowing for quick selection of functions.

• The menu, in most cases made up of suggestive icons, supplemented with an indication of a keyboard shortcut, as well as a hint describing the function (automatically appearing when the user delays choosing a function, perhaps when the icon turns out to be not very suggestive). The menu appears and disappears after selecting the function, and the entire screen remains at the disposal of the drawing. First we need to see the drawing and then edit it.

• When the pointer touches the edge of the drawing window while viewing a drawing, and in fact a drawing fragment, also when performing any editing operation, the entire drawing is automatically shifted by a certain distance, showing the next part of the drawing. The distance can be dynamically adjusted as needed, eliminating the need to use most drawing presentation functions.

• All dialog boxes are large and the amount of information on the screen has been reduced to a minimum.
  The interface is scalable, which means that the size of the menu font, the size of dialog boxes, and therefore the readability of details, is modifiable in virtually any range, using a single function.

The most important premise is the simplicity of both the interface and the entire program, which works on any computer, new or "old", with a small screen or large, with a large disk or small, and the appetite for RAM is very moderate, without compromising size or complexity of the drawings.
A simple graphical interface does not impose any hardware requirements related to the graphics card and its drivers.

The program is a Microsoft Windows application written in C (with some modules in C ++) built using Microsoft Visual Studio 2017, Allegro graphic library (open source), Python 3 and its auxiliary libraries (open source) for bitmap image conversion and LibDXFrw (open source) to convert DWG files.

1.1. Introduction

An AlfaCAD drawing consists of a number of basic elements, the so-called "graphic primitives", drawn with single commands. Primitives include lines, circles, arcs and texts, among others. To draw a primitive, select the appropriate command from the menu or enter the appropriate sequence of key characters from the keyboard. AlfaCAD initializes the selected drawing function with default parameters. They can be changed at any time (this concerns, for example, options for drawing an arc or text, changing the thickness, color and type of lines, etc.). In each case, the user must indicate the location of the object in the drawing or provide the necessary numerical values. After entering all the necessary data, the element is drawn on the screen. The result of each operation is displayed immediately on the screen, allowing the user full control over the created drawing. A special group of commands allow to modify drawing elements. Primitives can be removed from the drawing, their position can be changed, can be copied, resized and rotated. The positioning of each drawing element can be related to the global or local coordinates as well as to the position of another element. The finished drawing drawn to scale on a worksheet of a given format can be printed using a graphic printer, saved as a graphic file in one of many commonly used formats, saved as a PDF document, or even drawn with a classic vector plotter or cutting plotter .

1.2. Equipment required

The basic computer system necessary to run AlfaCAD is the most common PC with Windows 8 or later. The program uses any pointing device, mouse or touchpad.

1.2.1. RAM

AlfaCAD is a 32-bit as well as 64-bit application. A 32-bit application, it can use 2 GB RAM per process for its own needs, many AlfaCAD processes can be run simultaneously (when working with multiple drawings). A 64-bit application can use all the memory your money can buy.

1.2.2. Monitor

AlfaCAD is an application that uses the basic Windows GDI interface, therefore any single or multi-monitor configuration is supported by AlfaCAD.

1.2.3. Mouse

The mouse is the basic pointing device that allows you to select functions from the menu and indicate the position of the element in the drawing. All functions and operations in the program (except for texts and numerical values entered from the keyboard) are available using the mouse. Any 2- or 3-button mouse can work with AlfaCAD.

A 3-button mouse with a scroll wheel is preferred. The third key allows you to conveniently initiate the auxiliary menu, the wheel allows you to quickly and dynamically change the scale of the drawing presentation.

1.2.4. Printer

AlfaCAD allows you to print your drawings with any graphic printer or raster plotter, in any resolution mode offered by the printer driver. The drawing can be printed entirely as a single sheet (in the case of a sufficiently large format printer or a large-format raster plotter), or in the form of a multi-sheet mosaic with a given size of a single sheet. You can print in color, grayscale, or black and white.

In compression mode, the entire drawing sheet is scaled to the maximum printer paper size. If the printout is made in real scale, drawings whose format exceeds the maximum print sheet format (for page printers) or paper width (for roll printers, i.e. continuous paper printers), printout is divided into sheets with dimensions equal to the size of the print sheet or into sheets with the declared width of the paper and the length equal to the height of the drawing sheet. In each case, the actual line thickness of each type is taken into account in the printout, which can be appropriately set by the user for each of the 5 line thicknesses available in the graphical editor.

The drawing can be printed with rotation, inversion, and even with a mirror reflection, useful when printing on transparent films.

Saving a drawing as a graphic file or a PDF document is also scalable, and depending on the given parameters, it is saved as either a single file or multiple files constituting a mosaic covering the entire drawing sheet. As in the case of printing on a printer, graphic files can be created with rotation, flip as well as mirror image.

AlfaCAD offers a printout of the entire drawing, or a fragment indicated with a window, or a limited sheet in the form of a block applied to the drawing, with automatic selection of the optimal rotation angle of the drawing in the printout, which will be explained in detail in the following chapters.

1.2.5. Plotter

The traditional vector (pen) plotter is not in common use today due to the advanced technology of raster printing and the availability of large-format raster plotters that print in the same way as graphic printers. However, cutting plotters are an exception.

AlfaCAD can work with a drawing or cutting device equipped with an interpreter of virtually any command language, mainly HP-GL (Hewlett Packard Graphic Language). This interpreter is equipped with most of the pen and inkjet plotters, including plotters from Hewlett Packard, Huston Instruments, OCÉ Graphics, Muttoh, Versatec, Roland, Graphtec and many others. AlfaCAD also allows you to print in any scale and in real scale, the entire drawing or its selected fragment, with possible rotation of the sheet during printing or any shift of the format beginning with respect to the origin point of the plotter's working area, which allows you to draw several small drawings on one large sheet paper or paper roll.

1.3. Drawings in AlfaCAD

AlfaCAD saves drawings as binary files with names with a default extension of ".alf". The drawing file contains, among other things, information about individual objects placed in the drawing, their location, and interrelationships (block structures). Each file is provided with an appropriate, unique for AlfaCAD program header, identifying the drawing set and a parameter table containing, inter alia, information about:

- drawing format, scale, drawing units and precision
- drawing presentation form at the time of the last update
- drawing layer definitions and their attributes.

Each drawing file is also completed with the so-called a system plaque containing all information necessary to identify the drawing in order to complete a given project. This information may include, for example:

• the name of the design unit

• the name of the investment

• object definition

• project number

• drawing number and title

• scale

• the name of the designer

• name and surname of the inspector of the project

• date of the last update

• archive number of the drawing

• stage

All this information can be entered and modified while editing the drawing. The information contained therein may be used by application programs generating, for example, a list of elements, a list of documentation, etc.

1.3.1. Creating a drawing

Global Coordinate System

AlfaCAD uses the Cartesian coordinate system to locate a point in a drawing. The X axis marks horizontal distance and the Y axis marks vertical distance. The origin of the coordinate system is the point at which both coordinates assume the value 0.

The point is represented by a pair of (x, y) coordinates. To locate a point in the global coordinate system, imagine a line that intersects the X axis at a point specified by x and perpendicular to the X axis, and a second line, perpendicular to the Y axis, that intersects the y axis at a point specified by y. The point (x, y) lies at the intersection of these two lines.
AlfaCAD allows you to edit drawings in a flat coordinate system (two-dimensional). So spatial modeling is not possible here. But AlfaCAD is not doing all. Most of the technical drawing documentation is 2D. And that's what AlfaCAD is dedicated to.

However, limiting the functions of the graphic editor to operations on the flat coordinate system has a great influence on the speed of drawing. Where it is necessary to make a 3D model, other programs are applicable.

The Global Coordinate System is closely related to the drawing worksheet. This sheet can have the size of one of the formats classified in the ISO standard and marked with the symbols: A4, A3, A2, A1, A0, or the size of the sheet can be selected from a set of predefined sheets or specified by the user (it can be a multiple of one of the basic sheets, e.g. 4xA4). In any case, the origin of the Global Coordinate System is related to the lower left corner of the worksheet.

Increasing the sheet format while editing a drawing does not shift the Global Coordinate System. The worksheet format "grows" in the direction of the positive X and Y axes.

Local Coordinate System

The Global Coordinate System is strictly defined and cannot be changed in AlfaCAD. However, you can define any coordinate system called a Local Coordinate System. The origin of the new coordinate system can be placed at any point on the Global Coordinate System, the axes of this system can be directed in any direction. The Local Coordinate System can be oriented with respect to the Global Coordinate System at any angle. Using the concepts of traditional design techniques, the Local Coordinate System can be understood as a coordinate system defined by rotated at any angle and shifted from the lower left corner of the drawing board, the perpendicular rulers set.

The local coordinate system can be freely changed while editing the drawing, depending on the needs. For example, drawing a machine part may be easier if you define a local system oriented in such a way that, for example, the direction of the X axis coincides with the direction of the main axis of the element or its contour line.

In architectural design, it is convenient to introduce a local coordinate system when drawing rooms with irregular shapes, architectural details of roofs, etc.

The Local Coordinate System is particularly useful in the case of maps and geodetic bases, which may be components of a created drawing. In this case, the Geodetic Coordinate System, available in AlfaCAD as an option for the Cartesian Coordinate System, applies as discussed in the following chapters.

Presentation of the coordinate system

To make it easier for the user to move between different coordinate systems, the coordinate system symbol is in use. It appears only for the local system and represents the direction of the local system relative to the global coordinate system. The rotation angle of the cursor cross is equal to the angle between the local and global coordinate systems. The positive angle between the chips is counterclockwise.

Units and scale of the drawing

All objects placed on the drawing sheet reflect (model) a real object in a given scale. The distance between two points is measured in drawing units. You can assign a drawing unit to one of the following length units: millimeter, centimeter, meter, foot, inch. The drawing can be made in one of the scales: 1: 1, 1: 2, 1: 5, 1:10, 1:20, 1:25, 1:50, 1: 100, 1: 500, 1: 1000, 1: 5000, 1: 10000, 2: 1, 5: 1 or any given scale. Declaring the correct units and scale allows you to numerically express length in technical units of a real object.

The drawing can be printed (or plotted) in a given scale or this scale can be changed on the printout. The adopted scale and units constitute the basis for drawing dimensioning performed with the use of AlfaCAD procedures.

Basic drawing elements

AlfaCAD offers a number of simple drawing elements, the so-called graphic primitives that are placed in the drawing with a single command. The most frequently used elements are lines, polylines, arcs, circles, polygons, and texts. In addition to primitives, the user can place more complex elements. These include, for example, a dimension block composed of lines and texts that describes the dimension (or dimensions) between two (or more) points. The table below shows some of the element types available in AlfaCAD:

Colors, types and thickness of lines

Each element has assigned a color, type and thickness (also called width or weight) of the line that will be drawn.

The program allows to draw all objects with one of 255 colors (16 primary colors and extended 17 ... 255 according to the DAC-Normal table).

24-bit color-depth bitmaps are displayed in the "True color" mode ( 16,777,216 colors ) and are printed in this mode, provided that the depth and color model of the printer allows it.

The color palette is presented on the drawing COLOR256.ALF included in the installation package .
Below is a list of the first 16 basic ones:

• [1] Red

• [2] Yellow

• [3] Green

• [4] turquoise

• [5] Blue

• [6] Crimson

• [7] White

• [8] light gray

• [9] bright red

• [10] Brown

• [11] dark green

• [12] dark turquoise

• [13] dark blue

• [14] dark crimson

• [15] dark gray

• [16] Black

Colors in the range of numbers 17 - 255 are named by number.

The line type (type) is defined by a formula composed of line segments, points and gaps between them. There are 32 types of lines, including the first 5 basic lines:

[1] continuous _____________________
[2] dashed _ _ _ _ _ _ _ _ _ _ _ _
[3] dash-dotted _. _. _. _. _. _. _. _
[4] two-dotted _. . _. . _. . _. . _
[5] dotted ...........................

border, center, hidden, phantom, dashed_2, dash-dotted_2, two-dotted_2, dash-dotted_2, border_2, center_2, Hidden_2, Spectrum_2, dashed_x2, dotted_x2, two-dotted_x2, dash-dotted_x2, border_x2, center_x2, hidden_x2, phantom_x2, three-dotted, two-center, three-dashed, phantom_3, two-center_x2, three-dashed_x2, multi-dashed

Lines marked ....._ 2 are variants with a pattern twice smaller than their equivalents, with markings ......_ x2 are variants with a pattern twice larger.

The line types (for all weights) are shown in the LINIE32.ALF drawing included in the package.
The program offers 5 standard line thicknesses (these thicknesses are distinguished on the monitor):

• [1] Very thin

• [2] Thin (according to majority of national standards)

• [3] Thick (according to majority of national standards)

• [4] Very thick (in accordance to majority of national standards)

• [5] Extra thick

The line weights (for all line types) are shown in the LINES32.ALF drawing included in the package.
When printing a drawing on a graphic printer, each of the 5 line thicknesses will be given a thickness (expressed in [mm]) to be declared in the printing dialog box.
In order to obtain the correct line thicknesses when plotting a drawing on a traditional plotter, you should declare the correct plotter pen numbers for each line thickness. The pens may be 0.1 mm to 2 mm thick.

Layers

AlfaCAD allows to create drawings in the form of "transparent films" combined together into a package. Each "foil" may contain elements that constitute a certain group of information. In this way, is easy to divide the drawing into groups of objects that form, for example, a building plan, and a group of objects describing installations. Even within one group of information (e.g. building plan), it is advisable to divide into a group of elements describing modular axes, masonry structures, joinery, room descriptions, and finally equipment, etc. Such "foils" are called in the AlfaCAD program (as in other design support programs) - layers. AlfaCAD can operate on 255 layers. The first layer is always initialized by default as:

• current layer

• visible layer

• editable layer

• location base layer

Layers can be displayed individually or in any combination, and the appropriate manipulation of activity attributes that can be freely changed makes editing of complex drawing much easier and faster.

Blocks

Drawing parts stored as files are treated as blocks and can be inserted (appended) to the current or any other drawing. This property can be used to create component libraries (e.g. typical machine parts). It is enough to draw a given element on the drawing, indicate any group of elements and save them in a file. Whenever you need it again, you can place it on top of another drawing without having to redraw it. Regardless of its complexity, an inserted drawing is treated as a single block and as such can be copied, moved, deleted, etc. AlfaCAD does not consider the block as a final product. Each block can be individually modified after being inserted into the drawing, while the block remains unchanged in the file.

AlfaCAD includes the basic architectural, construction, electrical and sanitary components library. The DXF file import function (Autocad) extends the block import capabilities with libraries developed in other CAD programs.

Location of a point relative to an object

When introducing new points (e.g. when drawing primitives), you can use objects already existing in the drawing. This is possible thanks to the so-called the location of the point relative to the object. Points can be located e.g. to the end of an indicated line, its center, the center of a circle or arc, the intersection point of lines, arcs or circles, perpendicular to a segment, arc or circle, tangent to an arc or circle, etc. It is also possible to compose a point location function with respect to object with a point shift function in the local Cartesian or polar system. This gives, for example, the possibility of locating a point distant by a given length, measured at a given angle to the X axis, from the one indicated by the so-called “pointfinder”, for example, the intersection of a line and an arc.

The procedures for locating a point in relation to an object (simple and complex) are the most frequently used procedures for all geometric constructions. Basically, the entire design process with AlfaCAD comes down to creating geometric structures. It is important that, for example, two line segments declared by the designer as segments with a common end are actually placed on the sheet in such a way that their end points are described with coordinates with the same numerical values (with the accuracy of the numerical representation of the coordinate values). Since the accuracy of the numbers expressing coordinates in AlfaCAD is high compared to the possibility of visualization on the screen, hence, it is ineffective to place objects (indicate points) based solely on visual observations of the displayed objects. The visual impression of the location of a given point depends on the scale of the drawing presentation (in the range of 1/2000 to 2000). In each case, with such a location, an error is made, which may have consequences in the form of difficulties in performing other procedures (e.g. filling the area with a pattern due to its being unclosed). The program operates on real numbers describing the coordinates of points, angles of arcs, etc. with a finite precision. Hence, when looking to, for example, the point of intersection of segments, the program makes an inevitable error by approximating the actual values of the coordinates of the intersection point to the value of precision expressible by AlfaCAD. However, this error is taken into account in all program procedures and is not a problem when creating a drawing (especially in geometric construction). AlfaCAD has a built-in tolerance control procedure for actual values.

Hatch and pattern fill

Drawing standards provide requirements for hatching or pattern filling of enclosed areas. Pattern (hatching) allows to specify the material from which a given element is made, giving an appropriate texture to architectural elements, showing shadows, etc. AlfaCAD program offers the function of hatching and filling areas with a pattern with the possibility of defining custom patterns.

Hatch patterns

Each hatch pattern is a composition of segments of a specified length and angle. Segments can be drawn with a continuous line or lines consisting of dashes and points. The defined hatch pattern is repeated many times, creating a block that fills exactly the indicated area. The program automatically groups the segments that make up the hatch pattern into a block. This allows you to delete the entire hatch pattern (e.g. in the case of an incorrectly selected pattern, scale, etc., or an incorrectly specified hatch area). In addition to the pattern, hatch parameters include scale, rotation angle, and base point, and for a standard hatch, the distance between lines. AlfaCAD comes with 64 basic hatch patterns.

Defining the boundaries of the area

Hatching may fill a closed area, the boundaries of which are determined by segments, arcs, circles, polylines, bezier curves, polygon sides, edges of areas and traces, fictitious text boundaries. Objects that make up hatch boundaries can meet at their endpoints or cross each other. The points of intersection of objects mark the vertices of any irregular polygon (convex or concave). The bounded area need not be mono-coherent, so inside the closed area there may be other closed areas forming the inner boundaries of the hatch area.

Characteristics and geometric moments of figures (closed areas)

AlfaCAD allows you to calculate geometric moments of figures (any closed areas), such as:

• surface area

• center of area

• first moment of area

• area moment of inertia

• central area moments of inertia and section modulus

The procedure uses the numerical integration method.

Sketching

AlfaCAD offers a sketching function. A sketch line consists of line segments that are connected to each other. It allows, for example, to draw contours of a map, a drawing of wood grains in a cross-section, etc. The length of a sketch line segment can be set by the user depending on the required sketching accuracy.

Drawing dimensioning

Making a drawing on a certain scale, as a rule, is not sufficient to accurately draw the designed object. Most of the technical drawings should be supplemented with information about the dimensions of objects, angles, distances, etc. The method of applying information about dimensions is determined by the technical drawing standards appropriate for a given design industry, defining it with the term "dimensioning".

AlfaCAD offers the user four basic types of dimensioning:

• complex linear dimensioning

• diameter dimensioning

• radius dimensioning

• angle dimensioning

• dimensioning the arc length

Dimensioning can be performed using graphic primitives such as line, triangular areas (dimension lines delimiters in the form of points), circles (delimiters as points) and text (numerical value of the dimension). However, AlfaCAD allows you to automatically generate dimension blocks based on the calculated values of a given dimension, which greatly shortens the time of drawing preparation with minimal effort.

1.3.2. Drawing presentation

Despite the limited working area of the screen, AlfaCAD allows you to move freely throughout the drawing and its presentation. This is done through the zoom in and out and panning procedures . Zooming out allows you to see more of the drawing. Zooming in allows you to see details but on a smaller part of the drawing. The current zoom scale of the image can be set by the user or selected by the program in such a way that the selected part of the drawing fills the full working space of the screen. Individual parts of the drawing can also be viewed without changing the scale. It consists in "panning" the image of the drawing and is similar to watching it through the viewfinder of the camera changing its position in relation to the object.

The panning procedure was recognized by the program's author as an important element of the user's communication with the program. Almost every function of the program is performed after the user indicates a point or object in the drawing. The necessity to operate on detail alternately with the "plan" of the drawing requires frequent changes to the scale of the image or continuous movement over it due to the scale used, suitable for manipulating the detail but giving too little field of view. Panning of the drawing is related to the movement of the pointer device in the program. Successive portions of the drawing are displayed when the cursor reaches the boundary of the drawing's display field.

Resolution is related to the amount of detail that can be observed. The physical resolution of devices cooperating with the program affects only the accuracy of work on a given device, not the internal resolution. For example, by making a large magnification of a small drawing, it is possible to define a point much more accurately than the resolution of a printer allows. This feature is useful for precise geometric construction as well as for calculating the moments of geometric figures of any shape.

User can turn on the mode in which the cursor moves in a stepwise motion with a given step. This allows the user to define a resolution other than the standard one. The location grid of a given density, applied in the form of a "mask" of points (or crosses) on the drawing sheet. These points help you locate the objects you draw. Of course, the mesh can be turned on or off at any time, and its density can be modified by the user.

When editing a drawing, the user can work alternately on several of its fragments thanks to the procedures of saving the current editing parameters and then selecting them again, in the form of viewports. These parameters include the current display scale, the coordinates of the extreme points of the fragment of the drawing visible on the screen in global coordinates, and the cursor position. This makes it easier, for example, to create, on one part of the sheet, a general arrangement drawing consisting of elements drawn (e.g. on a smaller scale) on other parts of the sheet.

1.3.3. Editing drawing elements

AlfaCAD makes it very easy to make changes to your drawings. The drawn objects can be deleted, moved to another position, changed the line type, color or layer, and the size or type of the font of the texts. Drawn objects can be copied to the indicated places, rotated, scaled, shortened or lengthened, rounded or chamfered corners, cut fragments of lines, arcs, circles, cut or lengthen segments and arcs to points of intersection with other objects, etc. All changes are made in dynamic mode in which the process of making changes can be observed on the screen. The texts placed on the drawing can be freely changed by freely editing them, similarly to text editors. Editing functions are not only used to change parameters and features of objects drawn incorrectly, but most of all they allow for geometrical construction, modification of library elements in order to adapt them to the needs of the drawing being developed, etc. As design practice shows, editing functions are used more often than the functions of drawing graphic primitives and, in fact, the strength of computer design techniques lies in the editing functions.

1.4. Program operation

The speed and efficiency of working with the program depends mainly on the efficiency of using its functions, using each of them for the right tasks and continuous improvement of the workshop. Only the wealth of ideas and experiences acquired during many hours of working with the program allows you to master it in a way that allows you to obtain the appropriate technical disposition to achieve the goal for which this program was created. This goal is not the computer-aided design method itself, but the effects of its use manifesting in a significant reduction in the time and labor consumption of technical documentation, increasing its accuracy and aesthetic values, having a large impact on the quality and technical correctness of the implementation of the concepts contained in the documentation.

1.4.1. Entering commands and coordinates of points

AlfaCAD allows you to pick position of a point in several ways. Using the keyboard, you can enter the absolute coordinates of the point or the coordinates relative to the current cursor position. By using the cursor movement control keys, you can move it to the desired point and select it by pressing the {Enter} key. However, the fastest and most convenient method of indicating a point is to use a pointing device which is a mouse, touchpad, trackpad or trackball.

A localization grid (or "raster grid") and a number of auxiliary functions allow to locate the point in relation to other objects in the drawing.

The basic way to enter commands is to select them from a drop-down menu with content depending on the group of functions. The coordinate values of the point indicated in the drawing (as well as other values, e.g. length or angle) can be the result of a given algebraic equation. It is possible thanks to the built-in multifunctional engineering calculator, in which the form of the function is written in simple mathematical notation with the possibility of declaring any variables.

1.4.2. Printout of the drawing

The program allows you to make a “hard copy” of the drawing at any time on a graphic printer or plotter. Often, control drawings are made at various stages of the project to control possible errors that are difficult to see on the computer monitor. The printout can be directed directly to the printer or plotter, or saved in a file, as an image, in various formats.

1.4.3. Graphic editor configuration

Configuration of parameters of the graphic editor including the colors of individual elements of the editing window drawing background frames, cursor, frame, menu background and texts, edit box background and text, etc., configuration of auto-panning, desktop font type and size, desktop background, setting the desktop window on the monitor and its dimensions, can be set using the "Options" menu.

Other parameters related to the drawing, incl. sheet format, precision, cursor step, raster grid density, position of the drawing in relation to the monitor edit field, scale and units are set during the editing of the drawing and are stored in the each drawing individually. When re-editing an existing drawing, these parameters are restored.

1.4.4. Prototype drawing (template)

When you start working on a new drawing, the editing parameters take the values initialized by the program or are read from the prototype drawing file. A standard prototype drawing PROTOTYPE.ALF is provided in the AlfaCAD package.

The user can define any number of his own prototype drawings, e.g. for various design industries. In order to select the appropriate set of parameters in a prototype drawing, simply edit it and after changing any parameters, save the drawing to disk. Any drawing file can be a prototype drawing.

The "New drawing" - "new from Template" function initiates a new drawing based on the previously created prototype drawing.

1.4.5. Interchangeability of drawings

AlfaCAD allows you to save drawing files in DXF format (DXF is a trademark of Autodesk, Inc.).

Drawing files saved in DXF or DWG format (DWG is a trademark of Autodesk, Inc.), created by other graphics programs, can also be loaded by AlfaCAD and then saved in the standard AlfaCAD drawing file format.

Those functions enable full exchange of drawings between different CAD systems, eg AutoCAD (AutoCAD is a registered trademark of Autodesk in the USA).