In this chapter, we will go trough procedures that control the way how drawing is displayed in AlfaCAD window. With the help of the commands described below, the user can select the part of the drawing that is to be visible on the screen, as well as the drawing presentation scale.
The commands controlling the display of the drawing on the screen are always available from the level of the auxiliary menu in the / View / option . The menu line tips frame always shows the current scale of the drawing presentation related to the accuracy, set as a parameter (option / Parameters / of main menu). As an alternative to selecting a display option from the popup menu, you can use keyboard shortcuts. They are a group of {Ctrl-Fx} keys, such as {Ctrl-F1} - "Window" or {Ctrl-F10} - "All".
Most of the keyboard shortcuts are presented in the "Help" function ({F1})
Drawing view options are available at any time, also when performing any drawing, editing, dimensioning etc. functions.
Panning the drawing sheet
After starting the drawing editing session, the automatic panning mode is active. This mode is active regardless of the currently performed function. Moving the cursor to the edge of the screen automatically moves the drawing by a fragment of the width or height of the drawing. This procedure allows for "gentle" movement on the drawing sheet without the necessity to indicate its proper fragment.
After moving the drawing, it is automatically redrawn (refreshed). If there is a need to refresh the drawing multiple times due to the multiple change of the displayed fragment of the drawing, in the case of complex drawings this procedure can be accelerated by pressing the {Esc} key to interrupt the refresh. Of course, refreshing the last part of the drawing should be completed in its entirety. Otherwise, you will not be able to perform editing functions on objects whose redraw has been stopped. The drawing refreshing interrupted accidentally can be resumed in the screen function /Refresh/ in auxiliary menu.
Automatic panning of the drawing sheet can be disabled in the function / auto Pan / in auxiliary menu. This can sometimes be helpful for long-term editing of a small fragment of a drawing with high graphical complexity, especially on a computer that is not very fast. This protects against accidental shifting of the drawing on the monitor and the need to refresh it.
Saving views (viewports)
The command allows you to save in one of 5 views the parameters of the currently displayed drawing, that is, the coordinates of the extreme points of the drawing visible on the monitor and the presentation scale. After calling the function / Save view / an additional menu with 5 items ( / 1 / , / 2 / , / 3 / , / 4 / , / 5 / ) is shown. Selecting any of them causes the " + " sign to be inserted in the appropriate menu field, which means that the screen parameters are saved.
The saved drawing presentation parameters (views) can be restored by selecting the appropriate position in the /Find view/ function.
The technique of saving and retrieving views allows you to freely navigate through 5 selected fragments of a drawing or switch appropriately programmed presentation scales, thus accelerating the process of creating a complex drawing, e.g. from a general view and details.
Restoring (finding) views
If in the procedure / Save view / one of the editing parameter buffers has been previously saved, the appropriate form of drawing presentation can be obtained in the option / Find view / by selecting the appropriate item of the additional menu (/ 1 // 2 // 3 // 4 // 5 /). Only the item completed with the "+" sign allows you to restore the previously saved views. The other items are not active and their possible selection is signaled with an error message.
Refreshing display
When performing some editing operations (in particular deleting), some parts of objects remaining unchanged in the drawing may be erased on the screen as a result of raster operations typical for the monitor. In order to restore the drawing to its full form, it is possible to "redraw" it, hereinafter referred to as screen refresh.
Of course, the refreshing operation or its omission does not affect the drawing content, and it is performed automatically in the procedure of panning, changing the drawing presentation scale or other screen procedures. Calling the screen function / Refresh / is justified when the previously performed operation caused changes on the screen as a result of which a part of the drawing became unreadable. Refreshing the screen also removes point markers placed on the screen in some editing operations, such as filleting.
Displaying all drawing elements
The screen function / All / allows see the entire drawing, and actually all its elements. The scale and position of the sheet in relation to the working area of the screen is selected in such a way that all drawing elements will be simultaneously visible on the screen.
Centering the screen
The / Center / option allows to define a new view in a way ensuring the central position of the cursor in its current position in the drawing, in relation to the screen center. The editing scale is not changed.
This option is useful when it is necessary to perform editing operations around the current cursor position.
Restoring the previous (last) view
When creating a drawing, there is often a need to quickly zoom in on a certain area of the drawing, and then return to the previous presentation scale, or alternately edit two or more parts of the drawing. For this purpose, you can use the available functions / Save view / and / Find view / .
However, in the case of frequent changes to the parts of the drawing subject to editing, the option to restore the last parameters of the presentation before the next change of the displayed fragment is useful. This allows, for example, to quickly return to a fragment of the drawing after viewing the drawing in its entirety, without the need to remember the screen editing parameters in the / Save view / procedure.
The program constantly remembers the last 16 parameters of the drawing presentation which can be obtained by selecting the / Last / option again . This procedure allows you to return to the optimal (due to the currently implemented functions) presentation of the drawing.
Panning the sheet options
You can turn off the automatic drawing panning mode. This is done using the / Auto Pan / function. Turning off panning is justified in the case of a graphically complex drawing, when editing its fragment, in order to prevent the editing window from moving (and the related time delay for redrawing the drawing on the screen) as a result of e.g. accidental mouse movement to the border of the working area of the screen.
The size of the panning factor is set in the option / Auto-panning factor / in the function / Options / of the main menu.
Panning mode can be activated at any time.
View scale
The simplest on-screen commands relate to the drawing presentation scale. The scale is related to the "physical" resolution of the screen (parameter / Accuracy / ) declared in the option / Parameters / main menu .
The current presentation scale is displayed in the auxiliary menu line in tips frame to the / View / option. Menu / View / includes standard presentation scales /1.0/ , /0.5/ , /0.2/ , /0.1/ and any scale / x /. Any scale is a real number in the range 1/2000 <x <2000 . With a scale greater than 999, the factor is displayed in tips frame as: > 999 . When the scale is smaller than 0.01, the coefficient is displayed in the auxiliary menu tips frame as: <0.01 .
Changing scale does not change the position of the center of the displayed part of the drawing in relation to the center of the screen.
Displaying selected window
The / Window / option allows to define an area of the drawing sheet which is to fill the working area of the screen. The center of the window is placed in the center of the screen, and the part of the drawing inside the window will be enlarged or reduced in such a way as to fill the screen while maintaining the aspect ratio of the drawing.
The user defines the window by selecting its two opposite vertices by any method. After the operation is performed, the current scale of the drawing presentation is displayed in the auxiliary menu line tips frame next to / View / option.
Displaying the full format of the sheet
The / Format / option enables displaying a drawing on the screen in such a scale of presentation that the full sheet format is visible. This allows for the assessment of the correct arrangement of elements on the sheet, which should precede the drawing printout on a printer or plotter.
Absolute jump
The / move to x, y / option enables to move the cursor (and with it the drawn objects or existing objects that can be edited) to a strictly defined position in the global or local coordinate system.
The procedure is functionally compatible with the procedure of changing the cursor position by editing the coordinates, after moving to the edit line using the {Tab} key.
Performing an absolute jump is not tantamount to selecting (locating) a point. In order to locate a point (eg in the line drawing function) after making a jump, confirm the point by pressing {LMB} or {Enter}.
The coordinate values can be given as numeric values or arithmetic expressions according to the general rules for using the calculator. Values or expressions should be separated by a semicolon.
Relative jump in cartesian coordinates
The / move by dx, dy / option enables to move the cursor (and with it the drawn objects or existing objects that can be edited) to a point distant from the current cursor position by the vector <dx, dy>.
Performing a relative jump is not tantamount to selecting (locating) a point. In order to locate a point (eg in the line drawing function) after making a jump, confirm the point by pressing {LMB} or {Enter}.
The component values of the translation vector can be given as numeric values or arithmetic expressions according to the general rules for using the calculator. Values or expressions should be separated by a semicolon.
Relative jump in polar coordinates
The option / move polar L, angle / enables to move the cursor (and with it the drawn objects or existing objects that can be edited) to a point distant from the current cursor position by a vector of length L lying at a given angle to the global or local X axis.
Performing a relative jump is not tantamount to selecting (locating) a point. In order to locate a point (eg in the line drawing function) after making a jump, confirm the point by pressing {LMB} or {Enter}.
The values of the vector components in the polar system can be given numerically or in the form of arithmetic expressions according to the general rules for using the calculator. Values or expressions should be separated by a semicolon.