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Having thus described my invention, what I claim as new and desire to
secure by Letters Patent is as follows:
1. A method of changing a scale of a drawing in a computer graphics
application program comprising the steps of:
displaying scroll bars along a plurality of axes of the drawing, said
scroll bars each including a slider a position of which within the bar
indicates a relative location of a working area relative to a virtual
screen and a size of which indicates a relative size of the working area
as a function of a total size of the virtual screen;
responding to a user selection of a slider of a first one of said scroll
bars and performing a resizing operation on the slider; and
changing a scale of the drawing as a function of the resizing of the slider
while constraining a center of interest of the drawing to a fixed location
within the working area of the drawing by
calculating a size and location of the selected slider within the scroll
bar as a result of the resizing operation,
comparing the calculated size and location of the selected slider with
maximum and minimum limits,
ignoring a change in scale of the drawing beyond the maximum and minimum
limits, thereby constraining the center of interest of the drawing,
computing sizes of sliders of other scroll bars as a function of the
resizing of the selected slider,
computing the computed sizes of said sliders with maximum and minimum
limits, and
ignoring a change in scale of the drawing beyond the maximum and minimum
limits of any of said sliders, thereby constraining the center of interest
of the drawing.
2. The method as in claim 1 wherein said user selection of the slider and
performing a resizing operation is performed using a two button pointing
device and comprises the steps of:
responding to a press of a second one of said two buttons to change a shape
of a displayed cursor;
responding to a movement of the displayed cursor while said second button
is pressed to change a size of a ghost image of said slider as displayed;
and
responding to a release of said second button to resize said slider.
3. The method as in claim 1 wherein said user selection of the slider and
performing a resizing operation is performed using a two button pointing
device and comprises the step of responding to a press of a second one of
said two buttons when a displayed cursor is within the scroll bar to
change the size of the slider depending on whether the cursor is within or
outside of the slider.
4. The method as in claim 3 wherein the size of the slider is changed by
moving an end of the slider to a location of the cursor.
5. The method as in claim 3 wherein the size of the slider is changed
incrementally with each press of the second button.
6. The method as in claim 1 wherein the steps of responding to a user
selection of the slider and performing a resizing operation on the slider
is performed with a pointing device having at least one button and
comprises the steps of:
in response to a press of said one button, determining if a displayed
cursor is within the scroll bar;
if the displayed cursor is within the scroll bar, changing a shape of the
displayed cursor when the cursor is proximate an end of the slider;
responding to a movement of the cursor while said one button is pressed to
change a size of a ghost image of said slider as displayed; and
responding to a release of said one button to resize said slider.
7. A method of changing a scale of a drawing in a computer graphics
application program comprising the steps of:
displaying scroll bars along a plurality of axes of the drawing, said
scroll bars each including a slider a position of which within the bar
indicates a relative location of a working area relative to a virtual
screen and a size of which indicates a relative size of the working area
as a function of a total size of the virtual screen;
responding to a user selection of a slider of a first one of said scroll
bars and performing a resizing operation of the selected slider;
changing a scale of the drawing along a first axis of the drawing
corresponding to scroll bar of the selected first slider as a function of
the resizing of the slider while constraining a center of interest of the
drawing to a fixed location within the working area of the drawing by
calculating a size and location of the selected first slider within the
scroll bar as a result of the resizing operation,
comparing the calculated size and location of the selected first slider
with maximum and minimum limits, and
ignoring a change in scale of the drawing beyond the maximum and minimum
limits, thereby constraining the center of interest of the drawing;
responding to a user selection of a second slider of a second one of said
scroll bars and performing a resizing operation of the slider; and
changing a scale of the drawing along a second axis of the drawing
corresponding to scroll bar of the selected second slider independent of
the change of scale of the drawing along said first axis while
constraining a center of interest of the drawing to a fixed location
within the working area of the drawing by
calculating a size and location of the selected second slider within the
scroll bar as a result of the resizing operation,
comparing the calculated size and location of the selected second slider
with maximum and minimum limits, and
ignoring a change in scale of the drawing beyond the maximum and minimum
limits, thereby constraining the center of interest of the drawing;
whereby the scale of the drawing is changed along each axis as a function
of the change in size of the slider for the scroll bar for that axis
independent of a change in scale along other axes.
8. The method as in claim 7 wherein said user selection of the slider and
performing a resizing operation is performed using a two button pointing
device and comprises the step of responding to a press of a second one of
said two buttons when a displayed cursor is within the scroll bar to
change the size of the slider depending on whether the cursor is within or
outside of the slider.
9. The method as in claim 8 wherein the size of the slider is changed by
moving an end of the slider to a location of the cursor.
10. The method as in claim 8 wherein the size of the slider is changed
incrementally with each press of the second button.
11. A computer graphics apparatus used to generate and edit a drawing in a
graphics application program comprising:
a pointing device with at least one button;
a display device which displays a pointing cursor, directed by the pointing
device, and a plurality of scroll bars each with a slider, a position of a
slider within a scroll bar indicating a relative location of a working
area relative to a virtual screen and a size of said slider indicating a
relative size of the working area as a function of a total size of the
virtual screen; and
a central processing unit responsive to a user selection of a slider by
positioning said pointing cursor within said scroll bar and pressing a
button to perform a resizing operation on the slider and to change a scale
of the drawing as a function of the resizing of the slider while
constraining a center of interest of the drawing within a working area of
the drawing by
calculating a size and location of the selected slider within the scroll
bar as a result of the resizing operation,
comparing the calculated size and location of the selected slider with
maximum and minimum limits,
ignoring a change in scale of the drawing beyond the minimum limit, thereby
constraining the center of interest of the drawing,
computing sizes of sliders of other scroll bars as a function of the
resizing of the selected slider,
comparing the computed sizes of said sliders with maximum and minimum
limits, and
ignoring a change in scale of the drawing beyond the minimum limit of any
of said sliders, thereby constraining the center of interest of the
drawing.
12. A computer graphics apparatus as in claim 11 wherein said pointing
device has two buttons and said central processing unit responds to a
press of a second one of said two buttons to change a shape of a displayed
cursor, responding to a movement of the displayed cursor while said second
button is pressed to change a size of a ghost image of said slider as
displayed, and responding to a release of said second button to resize
said slider.
13. A computer graphics apparatus as in claim 11 wherein said pointing
device has two buttons and said central processing unit responds to a
press of a second one of said two buttons when a displayed cursor is
within the scroll bar to change the size of the slider depending on
whether the cursor is within or outside of the slider.
14. A computer graphics apparatus as in claim 11 wherein a pointing device
has at least one button and said central processing unit responds to a
press of said one button to determine if a displayed cursor is within the
scroll bar, and if the displayed cursor is within the scroll bar, said
central processing unit changes a shape of the displayed cursor when the
cursor is proximate an end of the slider, said central processing unit
further responding to a movement of the cursor while said one button is
pressed to change a size of a ghost image of said slider as displayed, and
said central processing unit responding to a release of said one button to
resize said slider.
15. A computer graphics apparatus as in claim 11 wherein said display
device displays scroll bars along a plurality of axes of the drawing and
wherein when said central processing unit resizes one slider within one of
said scroll bars the central processing then resizes the sliders of other
scroll bars according to the resizing of said one slider corresponding to
a change of scale of the drawing.
16. A computer graphics apparatus as in claim 11 wherein said display
device displays scroll bars along a plurality of axes of the drawing and
wherein said central processing unit resizes one slider within one of said
scroll bars independently of a resizing of a slider within another of said
scroll bars, said central processing unit changing a scale of the drawing
on each axis independent of a change of scale along any other axis.
17. The computer graphics apparatus recited in claim 11 wherein the central
processing unit pans the working area of the drawing along axes of the
other scroll bars in response to a change in scale of the drawing beyond
the maximum limits.
18. A method of changing a scale of a drawing in a computer graphics
application program comprising the steps of:
displaying scroll bars along a plurality of axes of the drawing, said
scroll bars each including a slider a position of which within the bar
indicates a relative location of a working area relative to a virtual
screen and a size of which indicates a relative size of the working area
as a function of a total size of the virtual screen;
responding to a user selection of a slider of a first one of said scroll
bars and performing a resizing operation on the slider; and
changing a scale of the drawing as a function of the resizing of the slider
while constraining a center of interest of the drawing to a fixed location
within the working area of the drawing by
calculating a size and location of the selected slider within the scroll
bar as a result of the resizing operation,
comparing the calculated size and location of the selected slider with
maximum and minimum limits,
ignoring a change in scale of the drawing beyond the minimum limit, thereby
constraining the center of interest of the drawing, and panning the
working area of the drawing along an axis of the scroll bar of the
selected slider in response to a change in scale of the drawing beyond the
maximum limit,
computing sizes of sliders of other scroll bars as a function of the
resizing of the selected slider,
comparing the computed sizes of said sliders with maximum and minimum
limits, and
ignoring a change in scale of the drawing beyond the maximum limit of any
of said sliders, thereby constraining the center of interest of the
drawing, and panning the working area of the drawing along axes of the
other scroll bars in response to a change in scale of the drawing beyond
the maximum limit.
19. The method as in claim 18 wherein said user selection of the slider and
performing a resizing operation is performed using a two button pointing
device and comprises the step of responding to a press of a second one of
said two buttons when a displayed cursor is within the scroll bar to
change the size of the slider depending on whether the cursor is within or
outside of the slider.
20. The method as in claim 19 wherein the size of the slider is changed by
moving an end of the slider to a location of the cursor.
21. The method as in claim 19 wherein the size of the slider is changed
incrementally with each press of the second button. |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to computer user interfaces
presented on a display screen and, more particularly, to a graphic user
interface (GUI) which easily accomplishes both a scale change function
with a panning or scrolling function.
2. Description of the Prior Art
In many computer application programs, and in particular graphics programs
such as computer aided design and drafting (CAD) programs, the drawing is
much larger than the physical display. The physical display shows the
"working area" of the drawing which is some subset of the entire drawing
or map, sometimes referred to as the "virtual screen". That is, the
physical screen size, which is determined by the physical dimensions of
the display device connected to the computer system, typically displays
only a portion of the total drawing or map. This portion of the total
drawing or map, or the "working area", is the current area of interest for
viewing, drawing or editing. CAD programs therefore implement a scrolling
function, called panning, to allow the user to move about in the virtual
screen thereby changing the working area, and a scaling function, called
zooming, to allow the user to view either a larger or smaller portion of
the working area, depending on the level of detail that the user wishes to
see.
Any sort of drawing or viewing program requires a means of moving around,
by scrolling or panning, a virtual screen which may be larger than the
physical screen area, as well as a means of changing scale (to zoom in or
zoom out). For panning control, the use of scroll bars is well
established, but there is no method in common use for changing the display
scale. There are, in fact, a multitude of ways to change the display
scale; however, all require extra steps by the user and/or take up screen
space that could be better used for the task at hand. For example, there
are many methods in use for changing the display's scale that involve
bringing up additional controls or interfaces on the screen. These
include, but are not limited to, prompted entry fields, sliders, spin
buttons, single-selection (radio) buttons, multiplier buttons (e.g.,
2.times., 1/2.times. scale), etc. found within pull-down menus, pop-up
dialogues, fixed screen areas, etc. All of these methods have one thing in
common, and that is they take up space on the display that could better be
used for an end task, such as a CAD drawing or a map. Additionally, some
require one or more extra operations to invoke them (e.g., select Menu Bar
options, then select Scale Change from the pull-down menu's list).
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method of
changing the screen display scale in an easy and intuitive manner, without
intermediate steps or operations, and without taking up additional screen
display area.
According to the invention, there is provided a method which requires that
at least one so-called scroll bar be displayed on the screen and be
functional at any time that the scale could be changed by the user. More
particularly, the method according to the invention loads additional
function onto screen scroll bars to support the change of scale function
as well as the scrolling function. The scroll bar is composed of a bar and
a slider, and the slider position and size respectively indicate the
location of working area relative to the virtual screen and the relative
size of the working area as a function of the total size of the virtual
screen area, as is conventional. Scrolling, or panning, is accomplished by
moving the slider within the bar, as is also conventional. However,
according to the invention, the size of the slider can be changed in order
to effect a change in the scale of the working area, thereby providing a
zoom function for the scroll bar. The size of the slider can be changed in
a number of ways, but all of them are intuitive and easily used by the
user without requiring either intermediate steps or operations or taking
up additional screen display area.
This method is available at all times and provides an additional function
for existing constructs (i.e., scroll bars). This solution is most useful
for quick, approximate changes to the display scale. Due to the imprecise
nature of input devices, such as pointing cursor devices, it would be
difficult for a user to enter a precise desired scale (e.g., 5000:1). Such
precise sealing is not commonly needed until it is time to make hardcopy
output, and then an existing solution such as an entry field would be more
appropriate.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, aspects and advantages will be better
understood from the following detailed description of a preferred
embodiment of the invention with reference to the drawings, in which:
FIG. 1 is a block diagram showing a hardware configuration on which the
subject invention may be implemented;
FIG. 2 is an illustration of a horizontal scroll bar as viewed on a
computer display screen;
FIG. 3A is an illustration showing the relationship of a working area to a
virtual screen, and FIG. 3B is an illustration showing typical locations
of horizontal and vertical scroll bars relative to the working area on the
physical display screen;
FIGS. 4 to 6 are illustrations similar to that shown in FIG. 2 showing a
first method in the practice of the invention;
FIGS. 7A and 7B are is a flow chart showing the logic of the process
according to the first method;
FIGS. 8 to 11 are illustrations similar to that shown in FIG. 2 showing a
second method in the practice of the invention;
FIGS. 12A and 12B are is a flow chart showing the logic of the process
according to the second method;
FIGS. 13 to 15 are illustrations similar to that shown in FIG. 2 showing a
third method in the practice of the invention; and
FIGS. 16A and 16B are is a flowchart showing the logic of the process
according to the third method.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Referring now to the drawings, and more particularly to FIG. 1, there is
shown a representative hardware environment on which the subject invention
may be implemented. This hardware environment may be a personal computer
such as the International Business Machines (IBM) Corporation's PS/2
Personal Computers or a workstation such as IBM's RS/6000 Workstations.
The hardware includes a central processing unit (CPU) 10, which may be a
complex instruction set computer (CISC) microprocessor such as the Intel
386, 486 or Pentium microprocessors, generally referred to as X86
microprocessors, or a reduced instruction set computer (RISC)
microprocessor such as IBM's PowerPC microprocessor. The CPU 10 is
attached to a system bus 12 to which are attached a random access memory
(RAM) 14, a read only memory (ROM) 16, an input/output (I/O) adapter 18,
and a user interface adapter 22. The RAM 14 provides temporary storage for
application program code and data, while ROM 16 typically includes the
basic input/output system (BIOS) and boot code. The I/O adapter 18 is
connected to one or more Direct Access Storage Devices (DASDs), here
represented as a disk drive 20. The disk drive 20 typically stores the
computer's operating system (OS) and various application programs, each of
which are selectively loaded into RAM 14 via the system bus 12. The I/O
adapter 18 may support, for example, the Integrated Device Electronics
(IDE) interface standard or the SCSI interface standard. In the former
case, the I/O adapter 18 typically will support two disk drives in
parallel, designated as drives "C:" and "D:". In the latter case, the I/O
adapter 18 will support up to seven disk drives or other SCSI I/O devices
connected in a daisy chain. The user interface adapter 22 has attached to
it a keyboard 24, a mouse 26, a speaker 28, a microphone 32, and/or other
user interface devices (not shown). Most typically, the mouse 26 is a two
button mouse but in some applications may be a one button mouse, although
a three button mouse may be used. A display 38, here represented as a
cathode ray tube (CRT) display but which may be a liquid crystal display
(LCD), is connected to the system bus 12 via a display adapter 34.
Optionally, a communications adapter 34 is connected to the bus 12 and to
a network, such as a local area network (LAN), such as IBM's Token Ring
LAN. Alternatively, the communications adapter may be a modem connecting
the personal computer or workstation to a telephone line as part of a wide
area network (WAN).
The screen of display 38 typically provides a user interface to inputting
commands or accessing functions such as scrolling and panning. To better
understand the invention, the function of a scroll bar will first be
reviewed. Scroll bars control panning (scrolling) along one direction of
the screen. There may be one for vertical or "Y direction" scroll and/or
one for horizontal or "X direction" scrolling. It is possible in three
dimension (3-D) programs to have a depth or "Z direction" scroll bar. The
principal components of a scroll bar are as shown in FIG. 2 as comprising
a rectangular bar 40 within which is a slider 42. The slider 42 is
typically moved by selecting and dragging it using a pointing cursor 44
controlled by the mouse 26 or other pointing device. More particularly,
the pointing cursor 44 displayed on the display screen is placed over the
slider 42 as generally indicated in FIG. 2, the left mouse button (in a
two button mouse) is depressed and held while the mouse is moved to the
left or right to move the slider 42, and finally the button is released
when the slider 42 is at the desired location on the bar 40. Space 46 to
the left of the slider indicates that part of the virtual screen is "off
screen" to the left. If the slider 42 is moved to the left, this part of
the virtual screen is brought "on screen"; i.e. , into the working area
and displayed on the physical screen. The slider 42 indicates by its size
and position that approximately 25% of the virtual screen (from one
quarter to one half) in the horizontal direction is visible in the working
area on the physical display. The unoccupied space 48 to the right of
slider 42 indicates that part of the virtual screen is "off screen" to the
right. If the slider 42 is moved to the right, this part of the virtual
screen is brought "on screen". While a horizontal scroll bar (for
controlling left and right scrolling) is illustrated, the vertical scroll
bar has a similar layout and function. There are a number of minor
variations in appearance and additional functions, but they are not of
concern to an understanding of this invention.
A virtual screen is the total drawing area in the application, such as the
entire drawing or map. At less than maximum scale, only a portion of the
virtual screen, that is the working area, may be shown on the physical
display at any given time. The displayed portion is both indicated and
controlled by the scroll bar(s). An example of a virtual screen is shown
in FIG. 3A, where the solid rectangle 50 represents the working area
(i.e., that portion of the virtual screen denoted by the dotted rectangle
52) displayed on the physical display. In FIG. 3B, the physical screen
display only is shown, where 54 and 56 respectively indicate the
horizontal and vertical sliders.
The size (length) of the slider is a function of the display scale and the
size of the virtual screen. For a given scale, as the virtual screen size
increases in that dimension, the slider would become shorter (indicating
that a smaller fraction of the virtual screen is being displayed). For a
given virtual screen size, as the scale increases ("zooming out") the
slider becomes longer (indicating that a larger fraction of the virtual
screen is being displayed). The position of the slider within the scroll
bar directly indicates the beginning and end of the displayed area of the
virtual screen, and therefore indirectly gives the position of the "center
of interest" (at the center of the slider).
As widely implemented, the size (length) of the slider in the scroll bar is
an "output only" function of the scale and virtual screen size. The method
according to the invention adds an "input" functionality by enabling the
user to directly change the slider's length, thereby changing the display
scale. The advantage of this is that it is intuitive and rapid, making the
slider larger to show more of the virtual screen (zoom out to a larger
scale), or making it smaller to show more detail on a smaller part of the
virtual screen (zoom in to a smaller scale).
The user is able to change the size (length) of the slider in several
alternate ways, of which only one would typically be implemented on any
given system. Using a two button mouse, the user can press the right
button to either drag one end of the slider along the length of the scroll
bar or click that button on the slider or in the empty area of the scroll
bar. Using a one button mouse, the user can select one edge (end) of the
slider and then drag that edge in order to change the size of the slider.
The resizing of the slider, typically at both ends, results in a change of
scale keeping the Center of Interest fixed.
In FIG. 4, the initial position 65 of the pointing cursor is within the
slider and the right mouse button has been pressed. Note that different
pointer style is used in response to pressing the right mouse button so
that the user may distinguish the function. The pointing cursor may be
moved to the right to enlarge the slider 42. In FIG. 5, the end of the
slider 42 is being pulled right, enlarging it, while the right mouse
button is held down. Typically, some sort of ghost or outline slider 42'
will be shown so that the user may gauge the extent of the change. The
opposite end of the slider 42 will typically mirror the changes at the one
end, as indicated by the ghost or outline slider 42", so that the Center
of Interest is not moved. The maximum extension of the slider 42 without
changing the Center of Interest is delimited by the closest edge of the
bar 40. Beyond that, the end of the slider 42 would reach the limit of the
virtual screen, and the Center of Interest would then move to the right
with increased enlargement of the slider 42, effecting a panning operation
with the zoom operation. The maximum extension of the slider would be at
both ends of the bar 40.
In FIG. 6, the pointing curser 44 has been moved inside the slider 42
(after the cursor has been moved at least to the right edge of the slider
42 in order to "pick up" the ghost slider or outline 42') so that the
slider size is reduced when the right mouse button is released at this
point. Again, the opposite end of the slider 42 will mirror the change
made to the other end, as indicated at 42". The Center of the slider 42,
the Center of Interest, is the limit for shrinking the slider. Typically,
there will be no effect if right mouse button is released when the pointer
has passed the center of the slider, as this would create a slider size of
less than or equal to zero. An alternate implementation would be to drop
the edge of the ghost slider and pick up the opposite edge (drop 42' and
pick up 42").
FIGS. 7A and 7B, taken together, are is a flowchart showing the logic of
the process described with respect to FIGS. 4 to 6. Starting in FIG. 7A,
the process begins when the right mouse button is pressed. A test is first
made in decision block 50 to determine if the cursor is within the
horizontal slider. If not, a test is made in decision block 51 in FIG. 7B
to determine if the cursor is within the vertical slider. If not, the
press of the right mouse button is ignored (for this process), and other
processing takes place. Assuming, however, that the cursor is detected to
be within the horizontal slider, the pointing cursor is changed to a
double headed cursor, as shown for example in FIG. 4, in function block
52. A test is then made in decision block 53 to determine if the right
mouse button is still down. If not, that is the right mouse button has
been released, the pointing cursor is restored in function block 54 and
the process exits. Otherwise, the pointer coordinates X, Y are retrieved
in function block 55. In addition, the maximum limits for the size of the
slider are set in order to prevent panning. Next, in decision block 56, a
test is made to determine if an end of the slider has been picked up by
the cursor. If so, the condition currently.sub.-- resizing is set to yes
in function block 57. Then, in decision block 58 a test is made to
determine if the condition currently.sub.-- resizing is no. If so, the
process loops back to decision block 53 where again a test is made to
determine if the right mouse button has been released. If the condition
currently.sub.-- resizing is set to yes as determined in decision block
58, a test is then made in decision block 59 to determine whether the
slider is being made too small. If not, the new scale of the drawing is
set as a function of X, the old scale and the slider size in function
block 60. Next, the vertical slider size is calculated as a function of
the new drawing scale in function block 61. A test is made in decision
block 62 to determine if the vertical slider is too small or too large. If
not, the ghost sliders are updated in function block 63. Optionally, the
drawing is redrawn to the new scale at this time. This option would be
implemented, for example, if the computer on which the process is
installed is capable of real time redrawing of the display screen. While
this is desirable to provide a further level of user feedback, the redraw
process on older computers may be too slow; therefore, the redraw
operation would be delayed until the current process exits at function
block 54. Should, however, the vertical slider be determined in decision
block 62 to be too small or too large, the scale is restored in function
block 64; that is, the scale set in function block 60 is ignored. The
outputs of each of decision block 59 and function blocks 63 and 64 loop
back to decision block 53 where, again, a test is made to determine if the
right mouse button has been released. Since the process for the vertical
slider is substantially identical to that for the horizontal slider, that
process will not be described. It should be noted, however, that the scale
of the | | |
