NAME¶
Prima::Drawable - 2-D graphic interface
SYNOPSIS¶
if ( $object-> isa('Prima::Drawable')) {
$object-> begin_paint;
$object-> color( cl::Black);
$object-> line( 100, 100, 200, 200);
$object-> ellipse( 100, 100, 200, 200);
$object-> end_paint;
}
DESCRIPTION¶
Prima::Drawable is a descendant of Prima::Component. It provides access to the
object-bound graphic context and canvas through its methods and properties.
The Prima::Drawable descendants Prima::Widget, Prima::Image,
Prima::DeviceBitmap and Prima::Printer are backed by system-dependent routines
that allow drawing and painting on the system objects.
USAGE¶
Prima::Drawable, as well as its ancestors Prima::Component and Prima::Object, is
never used directly, because Prima::Drawable class by itself provides only the
interface. It provides a three-state object access - when drawing and painting
is enabled, when these are disabled, and the information acquisition state. By
default, the object is created in paint-disabled state. To switch to the
enabled state,
begin_paint() method is used. Once in the enabled state,
the object drawing and painting methods apply to the object-bound canvas. To
return to the disabled state,
end_paint() method is called. The
information state can be managed by using
begin_paint_info() and
end_paint_info() methods pair. An object cannot be triggered from the
information state to the enabled state ( and vice versa ) directly. These
states differ on how do they apply to a graphic context and a canvas.
Graphic context and canvas¶
The graphic context is the set of variables, that control how exactly graphic
primitives are rendered. The variable examples are color, font, line width,
etc. Another term used here is 'canvas' - the graphic area of a certain
extent, bound to the object, where the drawing and painting methods are
applied to.
In all three states a graphic context is allowed to be modified, but in
different ways. In the disabled state the graphic context values form a
template values; when a object enters the information or the enabled state,
the values are preserved, but when the object is back to the disabled state,
the graphic context is restored to the values last assigned before entering
new state. The code example below illustrates the idea:
$d = Prima::Drawable-> create;
$d-> lineWidth( 5);
$d-> begin_paint_info;
# lineWidth is 5 here
$d-> lineWidth( 1);
# lineWidth is 1
$d-> end_paint_info;
# lineWidth is 5 again
( Note: "::region", "::clipRect" and "::translate"
properties are exceptions. They can not be used in the disabled state; their
values are neither recorded nor used as a template).
That is, in disabled state any Drawable maintains only the graphic context. To
draw on a canvas, the object must enter the enabled state by calling
begin_paint(). This function can be unsuccessful, because the object
binds with system resources during this stage, and might fail. Only after the
enabled state is entered, the canvas is accessible:
$d = Prima::Image-> create( width => 100, height => 100);
if ( $d-> begin_paint) {
$d-> color( cl::Black);
$d-> bar( 0, 0, $d-> size);
$d-> color( cl::White);
$d-> fill_ellipse( $d-> width / 2, $d-> height / 2, 30, 30);
$d-> end_paint;
} else {
die "can't draw on image:$@";
}
Different objects are mapped to different types of canvases - Prima::Image
canvas pertains its content after
end_paint(), Prima::Widget maps it to
a screen area, which content is of more transitory nature, etc.
The information state is as same as the enabled state, but the changes to a
canvas are not visible. Its sole purpose is to read, not to write information.
Because
begin_paint() requires some amount of system resources, there
is a chance that a resource request can fail, for any reason. The
begin_paint_info() requires some resources as well, but usually much
less, and therefore if only information is desired, it is usually faster and
cheaper to obtain it inside the information state. A notable example is
get_text_width() method, that returns the length of a text string in
pixels. It works in both enabled and information states, but code
$d = Prima::Image-> create( width => 10000, height => 10000);
$d-> begin_paint;
$x = $d-> get_text_width('A');
$d-> end_paint;
is much more 'expensive' than
$d = Prima::Image-> create( width => 10000, height => 10000);
$d-> begin_paint_info;
$x = $d-> get_text_width('A');
$d-> end_paint_info;
for the obvious reasons.
It must be noted that some information methods like
get_text_width() work
even under the disabled state; the object is switched to the information state
implicitly if it is necessary.
Color space¶
Graphic context and canvas operations rely completely on a system
implementation. The internal canvas color representation is therefore
system-specific, and usually could not be described in standard definitions.
Often the only information available about color space is its color depth.
Therefore, all color manipulations, including dithering and antialiasing are
subject to system implementation, and can not be controlled from perl code.
When a property is set in the object disabled state, it is recorded verbatim;
color properties are no exception. After the object switched to the enabled
state, a color value is transformed to a system color representation, which
might be different from Prima's. For example, if a display color depth is 15
bits, 5 bits for every component, then white color value 0xffffff is mapped to
11111000 11111000 11111000
--R----- --G----- --B-----
that equals to 0xf8f8f8, not 0xffffff ( See Prima::gp-problems for inevident
graphic issues discussion ).
The Prima::Drawable color format is RRGGBB, with each component resolution of 8
bit, thus allowing 2^24 color combinations. If the device color space depth is
different, the color is truncated or expanded automatically. In case the
device color depth is small, dithering algorithms might apply.
Note: not only color properties, but all graphic context properties allow all
possible values in the disabled state, which transformed into system-allowed
values in the enabled and the information states. This feature can be used to
test if a graphic device is capable of performing certain operations ( for
example, if it supports raster operations - the printers usually do not ).
Example:
$d-> begin_paint;
$d-> rop( rop::Or);
if ( $d-> rop != rop::Or) { # this assertion is always false without
... # begin_paint/end_paint brackets
}
$d-> end_paint;
There are ( at least ) two color properties on each drawable -
"::color" and "::backColor". The values they operate are
integers in the discussed above RRGGBB format, however, the toolkit defines
some mnemonic color constants:
cl::Black
cl::Blue
cl::Green
cl::Cyan
cl::Red
cl::Magenta
cl::Brown
cl::LightGray
cl::DarkGray
cl::LightBlue
cl::LightGreen
cl::LightCyan
cl::LightRed
cl::LightMagenta
cl::Yellow
cl::White
cl::Gray
As stated before, it is not unlikely that if a device color depth is small, the
primitives plotted in particular colors will be drawn with dithered or
incorrect colors. This usually happens on paletted displays, with 256 or less
colors.
There exists two methods that facilitate the correct color representation. The
first way is to get as much information as possible about the device. The
methods
get_nearest_color() and
get_physical_palette() provide
possibility to avoid mixed colors drawing by obtaining indirect information
about solid colors, supported by a device. Another method is to use
"::palette" property. It works by inserting the colors into the
system palette, so if an application knows the colors it needs beforehand, it
can employ this method - however this might result in system palette flash
when a window focus toggles.
Both of these methods are applicable both with drawing routines and image
output. An image desired to output with least distortion is advised to export
its palette to an output device, because images usually are not subject to
automatic dithering algorithms. Prima::ImageViewer module employs this scheme.
Monochrome bitmaps¶
A special case of "put_image" is taken where the object to be drawn is
a monochrome DeviceBitmap object. This object doesn't possess the color
palette, and is by definition a bitmap, where there are only two values
present, 0s and 1s. When it is drawn, 0s are drawn with the color value of the
target canvas "color" property, and 1s with "backColor".
This means that the following code
$bitmap-> color(0);
$bitmap-> line(0,0,100,100);
$target-> color(cl::Green);
$target-> put_image(0,0,$bitmap);
produces a green line on $target.
When using monochrome bitmaps for logical operations, note that target colors
should not be explicit 0 and 0xffffff, nor "cl::Black" and
"cl::White", but "cl::Clear" and "cl::Set"
instead. The reason is that on paletted displays, system palette may not
necessarily contain the white color under palette index (2^ScreenDepth-1).
"cl::Set" thus signals that the value should be "all
ones", no matter what color it represents, because it will be used for
logical operations.
Fonts¶
Prima maintains its own font naming convention, that usually does not conform to
system's. Since its goal is interoperability, it might be so that some system
fonts would not be accessible from within the toolkit.
Prima::Drawable provides property "::font", that accepts/returns a
hash, that represents the state of a font in the object-bound graphic context.
The font hash keys that are acceptable on set-call are:
- name
- The font name string. If there is no such font, a default
font name is used. To select default font, a 'Default' string can be
passed with the same result ( unless the system has a font named
'Default', of course).
- height
- An integer value from 1 to MAX_INT. Specifies the desired
extent of a font glyph between descent and ascent lines in pixels.
- size
- An integer value from 1 to MAX_INT. Specifies the desired
extent of a font glyph between descent and internal leading lines in
points. The relation between "size" and "height" is
height - internal_leading
size = --------------------------- * 72.27
resolution
That differs from some other system representations: Win32, for example,
rounds 72.27 constant to 72.
- width
- A integer value from 0 to MAX_INT. If greater than 0,
specifies the desired extent of a font glyph width in pixels. If 0, sets
the default ( designed ) width corresponding to the font size or
height.
- style
- A combination of "fs::" ( font style ) constants.
The constants hight
fs::Normal
fs::Bold
fs::Thin
fs::Italic
fs::Underlined
fs::StruckOut
fs::Outline
and can be OR-ed together to express the font style. fs::Normal equals to 0
and usually never used. If some styles are not supported by a
system-dependent font subsystem, they are ignored.
- pitch
- A one of three constants:
fp::Default
fp::Fixed
fp::Variable
fp::Default specifies no interest about font pitch selection. fp::Fixed is
set when a monospaced (all glyphs are of same width) font is desired.
fp::Variable pitch specifies a font with different glyph widths. This key
is of the highest priority; all other keys may be altered for the
consistency of the pitch key.
- direction
- A counter-clockwise rotation angle - 0 is default, 90 is
pi/2, 180 is pi, etc. If a font could not be rotated, it is usually
substituted to the one that can.
- encoding
- A string value, one of the strings returned by
"Prima::Application::font_encodings". Selects desired font
encoding; if empty, picks the first matched encoding, preferably the
locale set up by the user.
The encodings provided by different systems are different; in addition, the
only encodings are recognizable by the system, that are represented by at
least one font in the system.
Unix systems and the toolkit PostScript interface usually provide the
following encodings:
iso8859-1
iso8859-2
... other iso8859 ...
fontspecific
Win32 returns the literal strings like
Western
Baltic
Cyrillic
Hebrew
Symbol
A hash that "::font" returns, is a tied hash, whose keys are also
available as separate properties. For example,
$x = $d-> font-> {style};
is equivalent to
$x = $d-> font-> style;
While the latter gives nothing but the arguable coding convenience, its usage in
set-call is much more usable:
$d-> font-> style( fs::Bold);
instead of
my %temp = %{$d-> font};
$temp{ style} = fs::Bold;
$d-> font( \%temp);
The properties of a font tied hash are also accessible through
set()
call, like in Prima::Object:
$d-> font-> style( fs::Bold);
$d-> font-> width( 10);
is adequate to
$d-> font-> set(
style => fs::Bold,
width => 10,
);
When get-called, "::font" property returns a hash where more entries
than the described above can be found. These keys are read-only, their values
are discarded if passed to "::font" in a set-call.
In order to query the full list of fonts available to a graphic device, a
"::fonts" method is used. This method is not present in
Prima::Drawable namespace; it can be found in two built-in class instances,
"Prima::Application" and "Prima::Printer".
"Prima::Application::fonts" returns metrics for the fonts available to
a screen device, while "Prima::Printer::fonts" ( or its substitute
Prima::PS::Printer ) returns fonts for the printing device. The result of this
method is an array of font metrics, fully analogous to these returned by
"Prima::Drawable::font" method.
- family
- A string with font family name. The family is a secondary
string key, used for distinguishing between fonts with same name but of
different vendors ( for example, Adobe Courier and Microsoft
Courier).
- vector
- A boolean; true if the font is vector ( e.g. can be scaled
with no quality loss ), false otherwise. The false value does not show if
the font can be scaled at all - the behavior is system-dependent. Win32
and OS/2 can scale all non-vector fonts; X11 only the fonts specified as
the scalable.
- ascent
- Number of pixels between a glyph baseline and descent
line.
- descent
- Number of pixels between a glyph baseline and descent
line.
- internalLeading
- Number of pixels between ascent and internal leading lines.
Negative if the ascent line is below the internal leading line.
- externalLeading
- Number of pixels between ascent and external leading lines.
Negative if the ascent line is above the external leading line.
------------- external leading line
$ ------------- ascent line
$ $
------------- internal leading line
$
$$$
$ $
$ $ $
$$$$$$$ $$$
$ $ $ $
$ $ $ $
$ $ $$$ ---- baseline
$
$
$
$$$$ ---- descent line
- weight
- A font designed weight. Can be one of
fw::UltraLight
fw::ExtraLight
fw::Light
fw::SemiLight
fw::Medium
fw::SemiBold
fw::Bold
fw::ExtraBold
fw::UltraBold
constants.
- maximalWidth
- Maximal extent of a glyph in pixels. Equals to width
in monospaced fonts.
- xDeviceRes
- Designed horizontal font resolution in dpi.
- yDeviceRes
- Designed vertical font resolution in dpi.
- firstChar
- Index of the first glyph present in a font.
- lastChar
- Index of the last glyph present in a font.
- breakChar
- Index of the default character used to divide words. In a
typical western language font it is 32, ASCII space character.
- defaultChar
- Index of a glyph that is drawn instead of nonexistent glyph
if its index is passed to the text drawing routines.
Font ABC metrics¶
Besides these characteristics, every font glyph has an ABC-metric, the three
integer values that describe horizontal extents of a glyph's black part
relative to the glyph extent:
. . . . . . . .
. . $$$. . . . .
. . $$. $ . . . .
. . $$. . . . $$ . .
. $$$$$$$$$$. . .$$$$$ . .
. . $$ . . . $ $$ . .
. . $$ . . . .$$$$$ . .
. . $$ . . . . $$ . .
. .$$ . . . . $$$ $$$. .
$$ .$$ . . . $ $$ .
.$$$ . . . .$$$$$$$$. .
. . . . . . . .
<A>. .<C> <A>. .<C>
.<-.--B--.->. . .<--B--->. .
A = -3 A = 3
B = 13 B = 10
C = -3 C = 3
A and C are negative, if a glyphs 'hangs' over it neighbors, as shown in picture
on the left. A and C values are positive, if a glyph contains empty space in
front or behind the neighbor glyphs, like in picture on the right. As can be
seen, B is the width of a glyph's black part.
ABC metrics returned by
get_font_abc() method.
Raster operations¶
A drawable has two raster operation properties: "::rop" and
"::rop2". These define how the graphic primitives are plotted.
"::rop" deals with the foreground color drawing, and
"::rop2" with the background.
The toolkit defines the following operations:
rop::Blackness # = 0
rop::NotOr # = !(src | dest)
rop::NotSrcAnd # &= !src
rop::NotPut # = !src
rop::NotDestAnd # = !dest & src
rop::Invert # = !dest
rop::XorPut # ^= src
rop::NotAnd # = !(src & dest)
rop::AndPut # &= src
rop::NotXor # = !(src ^ dest)
rop::NotSrcXor # alias for rop::NotXor
rop::NotDestXor # alias for rop::NotXor
rop::NoOper # = dest
rop::NotSrcOr # |= !src
rop::CopyPut # = src
rop::NotDestOr # = !dest | src
rop::OrPut # |= src
rop::Whiteness # = 1
Usually, however, graphic devices support only a small part of the above set,
limiting "::rop" to the most important operations: Copy, And, Or,
Xor, NoOp. "::rop2" is usually even more restricted - it is only
OS/2 system that supports currently rop2 modes others than Copy and NoOp.
The raster operations apply to all graphic primitives except SetPixel.
Coordinates¶
The Prima toolkit employs a geometrical XY grid, where X ascends rightwards and
Y ascends upwards. There, the (0,0) location is the bottom-left pixel of a
canvas.
All graphic primitives use inclusive-inclusive boundaries. For example,
$d-> bar( 0, 0, 1, 1);
plots a bar that covers 4 pixels: (0,0), (0,1), (1,0) and (1,1).
The coordinate origin can be shifted using "::translate" property,
that translates the (0,0) point to the given offset. Calls to
"::translate", "::clipRect" and "::region"
always use the 'physical' (0,0) point, whereas the plotting methods use the
transformation result, the 'logical' (0,0) point.
As noted before, these three properties can not be used in when an object is in
its disabled state.
API¶
Graphic context properties¶
- backColor COLOR
- Reflects background color in the graphic context. All
drawing routines that use non-solid or transparent fill or line patterns
use this property value.
- color COLOR
- Reflects foreground color in the graphic context. All
drawing routines use this property value.
- clipRect X1, Y1, X2, Y2
- Selects the clipping rectangle corresponding to the
physical canvas origin. On get-call, returns the extent of the clipping
area, if it is not rectangular, or the clipping rectangle otherwise. The
code
$d-> clipRect( 1, 1, 2, 2);
$d-> bar( 0, 0, 1, 1);
thus affects only one pixel at (1,1).
Set-call discards the previous "::region" value.
Note: "::clipRect" can not be used while the object is in the
paint-disabled state, its context is neither recorded nor used as a
template ( see "Graphic context and canvas").
- fillWinding BOOLEAN
- Affect filling style of complex polygonal shapes filled by
"fillpoly". If 1, the filled shape contains no holes; otherwise,
holes are present where the shape edges cross.
Default value: 0
- fillPattern ( [ @PATTERN ] ) or ( fp::XXX )
- Selects 8x8 fill pattern that affects primitives that plot
filled shapes: bar(), fill_chord(), fill_ellipse(),
fillpoly(), fill_sector(), floodfill().
Accepts either a "fp::" constant or a reference to an array of 8
integers, each representing 8 bits of each line in a pattern, where the
first integer is the topmost pattern line, and the bit 0x80 is the
leftmost pixel in the line.
There are some predefined patterns, that can be referred via
"fp::" constants:
fp::Empty
fp::Solid
fp::Line
fp::LtSlash
fp::Slash
fp::BkSlash
fp::LtBkSlash
fp::Hatch
fp::XHatch
fp::Interleave
fp::WideDot
fp::CloseDot
fp::SimpleDots
fp::Borland
fp::Parquet
( the actual patterns are hardcoded in primguts.c ) The default pattern is
fp::Solid.
An example below shows encoding of fp::Parquet pattern:
# 76543210
84218421 Hex
0 $ $ $ 51
1 $ $ 22
2 $ $ $ 15
3 $ $ 88
4 $ $ $ 45
5 $ $ 22
6 $ $ $ 54
7 $ $ 88
$d-> fillPattern([ 0x51, 0x22, 0x15, 0x88, 0x45, 0x22, 0x54, 0x88 ]);
On a get-call always returns an array, never a "fp::"
constant.
- font \%FONT
- Manages font context. FONT hash acceptable values are
"name", "height", "size", "width",
"style" and "pitch".
Synopsis:
$d-> font-> size( 10);
$d-> font-> name( 'Courier');
$d-> font-> set(
style => $x-> font-> style | fs::Bold,
width => 22
);
See "Fonts" for the detailed descriptions.
Applies to text_out(), get_text_width(),
get_text_box(), get_font_abc().
- lineEnd VALUE
- Selects a line ending cap for plotting primitives. VALUE
can be one of
le::Flat
le::Square
le::Round
constants. le::Round is the default value.
- lineJoin VALUE
- Selects a line joining style for polygons. VALUE can be one
of
lj::Round
lj::Bevel
lj::Miter
constants. lj::Round is the default value.
- linePattern PATTERN
- Selects a line pattern for plotting primitives. PATTERN is
either a predefined "lp::" constant, or a string where each even
byte is a length of a dash, and each odd byte is a length of a gap.
The predefined constants are:
lp::Null # "" /* */
lp::Solid # "\1" /* ___________ */
lp::Dash # "\x9\3" /* __ __ __ __ */
lp::LongDash # "\x16\6" /* _____ _____ */
lp::ShortDash # "\3\3" /* _ _ _ _ _ _ */
lp::Dot # "\1\3" /* . . . . . . */
lp::DotDot # "\1\1" /* ............ */
lp::DashDot # "\x9\6\1\3" /* _._._._._._ */
lp::DashDotDot # "\x9\3\1\3\1\3" /* _.._.._.._.. */
Not all systems are capable of accepting user-defined line patterns, and in
such situation the "lp::" constants are mapped to the
system-defined patterns. In Win9x, for example, lp::DashDotDot is much
different from its string definition therefore.
Default value is lp::Solid.
- lineWidth WIDTH
- Selects a line width for plotting primitives. If a VALUE is
0, then a 'cosmetic' pen is used - the thinnest possible line that a
device can plot. If a VALUE is greater than 0, then a 'geometric' pen is
used - the line width is set in device units. There is a subtle difference
between VALUE 0 and 1 in a way the lines are joined.
Default value is 0.
- palette [ @PALETTE ]
- Selects solid colors in a system palette, as many as
possible. PALETTE is an array of integer triplets, where each is R, G and
B component. The call
$d-> palette([128, 240, 240]);
selects a gray-cyan color, for example.
The return value from get-call is the content of the previous set-call, not
the actual colors that were copied to the system palette.
- region OBJECT
- Selects a clipping region applied to all drawing and
painting routines. The OBJECT is either undef, then the clip region is
erased ( no clip ), or a Prima::Image object with a bit depth of 1. The
bit mask of OBJECT is applied to the system clipping region. If the OBJECT
is smaller than the drawable, its exterior is assigned to clipped area as
well. Discards the previous "::clipRect" value; successive
get-calls to "::clipRect" return the boundaries of the region.
Note: "::region" can not be used while the object is in the
paint-disabled state, its context is neither recorded nor used as a
template ( see "Graphic context and canvas").
- resolution X, Y
- A read-only property. Returns horizontal and vertical
device resolution in dpi.
- rop OPERATION
- Selects raster operation that applies to foreground color
plotting routines.
See also: "::rop2", "Raster operations".
- rop2 OPERATION
- Selects raster operation that applies to background color
plotting routines.
See also: "::rop", "Raster operations".
- splinePrecision INT
- Selects number of steps to use for each spline segment in
"spline" and "fill_spline" calls. In other words,
determines smoothness of a curve. Minimum accepted value, 1, produces
straight lines; maximum value is not present, though it is hardly
practical to set it higher than the output device resolution.
Default value: 24
- textOpaque FLAG
- If FLAG is 1, then text_out() fills the text
background area with "::backColor" property value before drawing
the text. Default value is 0, when text_out() plots text only.
See get_text_box().
- textOutBaseline FLAG
- If FLAG is 1, then text_out() plots text on a given
Y coordinate correspondent to font baseline. If FLAG is 0, a Y coordinate
is mapped to font descent line. Default is 0.
- translate X_OFFSET, Y_OFFSET
- Translates the origin point by X_OFFSET and Y_OFFSET. Does
not affect "::clipRect" and "::region". Not
cumulative, so the call sequence
$d-> translate( 5, 5);
$d-> translate( 15, 15);
is equivalent to
$d-> translate( 15, 15);
Note: "::translate" can not be used while the object is in the
paint-disabled state, its context is neither recorded nor used as a
template ( see "Graphic context and canvas").
Other properties¶
- height HEIGHT
- Selects the height of a canvas.
- size WIDTH, HEIGHT
- Selects the extent of a canvas.
- width WIDTH
- Selects the width of a canvas.
Graphic primitives methods¶
- arc X, Y, DIAMETER_X, DIAMETER_Y, START_ANGLE,
END_ANGLE
- Plots an arc with center in X, Y and DIAMETER_X and
DIAMETER_Y axis from START_ANGLE to END_ANGLE.
Context used: color, backColor, lineEnd, linePattern, lineWidth, rop,
rop2
- bar X1, Y1, X2, Y2
- Draws a filled rectangle with (X1,Y1) - (X2,Y2) extents.
Context used: color, backColor, fillPattern, rop, rop2
- chord X, Y, DIAMETER_X, DIAMETER_Y, START_ANGLE,
END_ANGLE
- Plots an arc with center in X, Y and DIAMETER_X and
DIAMETER_Y axis from START_ANGLE to END_ANGLE and connects its ends with a
straight line.
Context used: color, backColor, lineEnd, linePattern, lineWidth, rop,
rop2
- clear <X1, Y1, X2, Y2>
- Draws rectangle filled with pure background color with
(X1,Y1) - (X2,Y2) extents. Can be called without parameters, in this case
fills all canvas area.
Context used: backColor, rop2
- draw_text CANVAS, TEXT, X1, Y1, X2, Y2, [ FLAGS =
dt::Default, TAB_INDENT = 1 ]
- Draws several lines of text one under another with respect
to align and break rules, specified in FLAGS and TAB_INDENT tab character
expansion.
"draw_text" is a convenience wrapper around "text_wrap"
for drawing the wrapped text, and also provides the tilde ( ~ )- character
underlining support.
The FLAGS is a combination of the following constants:
dt::Left - text is aligned to the left boundary
dt::Right - text is aligned to the right boundary
dt::Center - text is aligned horizontally in center
dt::Top - text is aligned to the upper boundary
dt::Bottom - text is aligned to the lower boundary
dt::VCenter - text is aligned vertically in center
dt::DrawMnemonic - tilde-escapement and underlining is used
dt::DrawSingleChar - sets tw::BreakSingle option to
Prima::Drawable::text_wrap call
dt::NewLineBreak - sets tw::NewLineBreak option to
Prima::Drawable::text_wrap call
dt::SpaceBreak - sets tw::SpaceBreak option to
Prima::Drawable::text_wrap call
dt::WordBreak - sets tw::WordBreak option to
Prima::Drawable::text_wrap call
dt::ExpandTabs - performs tab character ( \t ) expansion
dt::DrawPartial - draws the last line, if it is visible partially
dt::UseExternalLeading - text lines positioned vertically with respect to
the font external leading
dt::UseClip - assign ::clipRect property to the boundary rectangle
dt::QueryLinesDrawn - calculates and returns number of lines drawn
( contrary to dt::QueryHeight )
dt::QueryHeight - if set, calculates and returns vertical extension
of the lines drawn
dt::NoWordWrap - performs no word wrapping by the width of the boundaries
dt::WordWrap - performs word wrapping by the width of the boundaries
dt::Default - dt::NewLineBreak|dt::WordBreak|dt::ExpandTabs|
dt::UseExternalLeading
Context used: color, backColor, font, rop, textOpaque, textOutBaseline
- ellipse X, Y, DIAMETER_X, DIAMETER_Y
- Plots an ellipse with center in X, Y and DIAMETER_X and
DIAMETER_Y axis.
Context used: color, backColor, linePattern, lineWidth, rop, rop2
- fill_chord X, Y, DIAMETER_X, DIAMETER_Y, START_ANGLE,
END_ANGLE
- Fills a chord outline with center in X, Y and DIAMETER_X
and DIAMETER_Y axis from START_ANGLE to END_ANGLE (see chord()).
Context used: color, backColor, fillPattern, rop, rop2
- fill_ellipse X, Y, DIAMETER_X, DIAMETER_Y
- Fills an elliptical outline with center in X, Y and
DIAMETER_X and DIAMETER_Y axis.
Context used: color, backColor, fillPattern, rop, rop2
- fillpoly \@POLYGON
- Fills a polygonal area defined by POLYGON set of points.
POLYGON must present an array of integer pair in (X,Y) format. Example:
$d-> fillpoly([ 0, 0, 15, 20, 30, 0]); # triangle
Context used: color, backColor, fillPattern, rop, rop2, fillWinding
Returns success flag; if failed, $@ contains the error.
See also: polyline().
- fill_sector X, Y, DIAMETER_X, DIAMETER_Y, START_ANGLE,
END_ANGLE
- Fills a sector outline with center in X, Y and DIAMETER_X
and DIAMETER_Y axis from START_ANGLE to END_ANGLE (see sector()).
Context used: color, backColor, fillPattern, rop, rop2
- fill_spline \@POLYGON
- Fills a polygonal area defined by a curve, projected by
applying cubic spline interpolation to POLYGON set of points. Number of
vertices between each polygon equals to current value of
"splinePrecision" property. POLYGON must present an array of
integer pair in (X,Y) format. Example:
$d-> fill_spline([ 0, 0, 15, 20, 30, 0]);
Context used: color, backColor, fillPattern, rop, rop2, splinePrecision
Returns success flag; if failed, $@ contains the error.
See also: spline, splinePrecision, render_spline
- flood_fill X, Y, COLOR, SINGLEBORDER = 1
- Fills an area of the canvas in current fill context. The
area is assumed to be bounded as specified by the SINGLEBORDER parameter.
SINGLEBORDER can be 0 or 1.
SINGLEBORDER = 0: The fill area is bounded by the color specified by the
COLOR parameter.
SINGLEBORDER = 1: The fill area is defined by the color that is specified by
COLOR. Filling continues outward in all directions as long as the color is
encountered. This style is useful for filling areas with multicolored
boundaries.
Context used: color, backColor, fillPattern, rop, rop2
- line X1, Y1, X2, Y2
- Plots a straight line from (X1,Y1) to (X2,Y2).
Context used: color, backColor, linePattern, lineWidth, rop, rop2
- lines \@LINES
- LINES is an array of integer quartets in format
(X1,Y1,X2,Y2). lines() plots a straight line per quartet.
Context used: color, backColor, linePattern, lineWidth, rop, rop2
Returns success flag; if failed, $@ contains the error.
- pixel X, Y, <COLOR>
- ::pixel is a property - on set-call it changes the pixel
value at (X,Y) to COLOR, on get-call ( without COLOR ) it does return a
pixel value at (X,Y).
No context is used.
- polyline \@POLYGON
- Draws a polygonal area defined by POLYGON set of points.
POLYGON must present an array of integer pair in (X,Y) format.
Context used: color, backColor, linePattern, lineWidth, lineJoin, lineEnd,
rop, rop2
Returns success flag; if failed, $@ contains the error.
See also: fillpoly().
- put_image X, Y, OBJECT, [ ROP ]
- Draws an OBJECT at coordinates (X,Y). OBJECT must be
Prima::Image, Prima::Icon or Prima::DeviceBitmap. If ROP raster operation
is specified, it is used. Otherwise, value of "::rop" property
is used.
Returns success flag; if failed, $@ contains the error.
Context used: rop; color and backColor for a monochrome DeviceBitmap
- put_image_indirect OBJECT, X, Y, X_FROM, Y_FROM,
DEST_WIDTH, DEST_HEIGHT, SRC_WIDTH, SRC_HEIGHT, ROP
- Copies a OBJECT from a source rectangle into a destination
rectangle, stretching or compressing the OBJECT to fit the dimensions of
the destination rectangle, if necessary. The source rectangle starts at
(X_FROM,Y_FROM), and is SRC_WIDTH pixels wide and SRC_HEIGHT pixels tall.
The destination rectangle starts at (X,Y), and is abs(DEST_WIDTH) pixels
wide and abs(DEST_HEIGHT) pixels tall. If DEST_WIDTH or DEST_HEIGHT are
negative, a mirroring by respective axis is performed.
OBJECT must be Prima::Image, Prima::Icon or Prima::DeviceBitmap.
No context is used, except color and backColor for a monochrome DeviceBitmap
Returns success flag; if failed, $@ contains the error.
- rect3d X1, Y1, X2, Y2, WIDTH, LIGHT_COLOR, DARK_COLOR, [
BACK_COLOR ]
- Draws 3d-shaded rectangle in boundaries X1,Y1 - X2,Y2 with
WIDTH line width and LIGHT_COLOR and DARK_COLOR colors. If BACK_COLOR is
specified, paints an inferior rectangle with it, otherwise the inferior
rectangle is not touched.
Context used: rop; color and backColor for a monochrome DeviceBitmap
- rect_focus X1, Y1, X2, Y2, [ WIDTH = 1 ]
- Draws a marquee rectangle in boundaries X1,Y1 - X2,Y2 with
WIDTH line width.
No context is used.
- rectangle X1, Y1, X2, Y2
- Plots a rectangle with (X1,Y1) - (X2,Y2) extents.
Context used: color, backColor, linePattern, lineWidth, rop, rop2
- sector X, Y, DIAMETER_X, DIAMETER_Y, START_ANGLE,
END_ANGLE
- Plots an arc with center in X, Y and DIAMETER_X and
DIAMETER_Y axis from START_ANGLE to END_ANGLE and connects its ends and
(X,Y) with two straight lines.
Context used: color, backColor, lineEnd, linePattern, lineWidth, rop,
rop2
- spline \@POLYGON
- Draws a cubic spline defined by set of POLYGON points.
Number of vertices between each polygon equals to current value of
"splinePrecision" property. POLYGON must present an array of
integer pair in (X,Y) format.
Context used: color, backColor, linePattern, lineWidth, lineEnd, rop, rop2
Returns success flag; if failed, $@ contains the error.
See also: fill_spline, splinePrecision, render_spline.
- stretch_image X, Y, DEST_WIDTH, DEST_HEIGHT, OBJECT, [ ROP
]
- Copies a OBJECT into a destination rectangle, stretching or
compressing the OBJECT to fit the dimensions of the destination rectangle,
if necessary. If DEST_WIDTH or DEST_HEIGHT are negative, a mirroring is
performed. The destination rectangle starts at (X,Y) and is DEST_WIDTH
pixels wide and DEST_HEIGHT pixels tall.
If ROP raster operation is specified, it is used. Otherwise, value of
"::rop" property is used.
OBJECT must be Prima::Image, Prima::Icon or Prima::DeviceBitmap.
Returns success flag; if failed, $@ contains the error.
Context used: rop
- text_out TEXT, X, Y
- Draws TEXT string at (X,Y).
Returns success flag; if failed, $@ contains the error.
Context used: color, backColor, font, rop, textOpaque, textOutBaseline
Methods¶
- begin_paint
- Enters the enabled ( active paint ) state, returns success
flag; if failed, $@ contains the error. Once the object is in enabled
state, painting and drawing methods can perform write operations on a
canvas.
See also: "end_paint", "begin_paint_info", "Graphic
context and canvas"
- begin_paint_info
- Enters the information state, returns success flag; if
failed, $@ contains the error. The object information state is same as
enabled state ( see "begin_paint"), except painting and drawing
methods do not change the object canvas.
See also: "end_paint_info", "begin_paint", "Graphic
context and canvas"
- end_paint
- Exits the enabled state and returns the object to a
disabled state.
See also: "begin_paint", "Graphic context and
canvas"
- end_paint_info
- Exits the information state and returns the object to a
disabled state.
See also: "begin_paint_info", "Graphic context and
canvas"
- font_match \%SOURCE, \%DEST, PICK = 1
- Performs merging of two font hashes, SOURCE and DEST.
Returns the merge result. If PICK is true, matches the result with a
system font repository.
Called implicitly by "::font" on set-call, allowing the following
example to work:
$d-> font-> set( size => 10);
$d-> font-> set( style => fs::Bold);
In the example, the hash 'style => fs::Bold' does not overwrite the
previous font context ( 'size => 10' ) but gets added to it ( by
font_match()), providing the resulting font with both font
properties set.
- fonts <FAMILY = "", ENCODING =
"">
- Member of "Prima::Application" and
"Prima::Printer", does not present in
"Prima::Drawable".
Returns an array of font metric hashes for a given font FAMILY and ENCODING.
Every hash has full set of elements described in "Fonts".
If called without parameters, returns an array of same hashes where each
hash represents a member of font family from every system font set. It
this special case, each font hash contains additional
"encodings" entry, which points to an array of encodings
available for the font.
If called with FAMILY parameter set but no ENCODING is set, enumerates all
combinations of fonts with all available encodings.
If called with FAMILY set to an empty string, but ENCODING specified,
returns only fonts that can be displayed with the encoding.
Example:
print sort map {"$_->{name}\n"} @{$::application-> fonts};
- get_bpp
- Returns device color depth. 1 is for black-and-white
monochrome, 24 for true color, etc.
- get_font_abc FIRST_CHAR = -1, LAST_CHAR = -1, UNICODE =
0
- Returns ABC font metrics for the given range, starting at
FIRST_CHAR and ending with LAST_CHAR. If parameters are -1, the default
range ( 0 and 255 ) is assumed. UNICODE boolean flag is responsible of
representation of characters in 127-255 range. If 0, the default,
encoding-dependent characters are assumed. If 1, the U007F-U00FF glyphs
from Latin-1 set are used.
The result is an integer array reference, where every character glyph is
referred by three integers, each triplet containing A, B and C values.
For detailed explanation of ABC meaning, see "Font ABC metrics";
Context used: font
- get_nearest_color COLOR
- Returns a nearest possible solid color in representation of
object-bound graphic device. Always returns same color if the device bit
depth is equals or greater than 24.
- get_paint_state
- Returns paint state value - 0 if the object is in the
disabled state, 1 for the enabled state, 2 for the information state.
- get_physical_palette
- Returns an anonymous array of integers, in (R,G,B) format,
every color entry described by three values, in range 0 - 255.
The physical palette array is non-empty only on paletted graphic devices,
the true color devices return an empty array.
The physical palette reflects the solid colors currently available to all
programs in the system. The information is volatile if the system palette
can change colors, since any other application may change the system
colors at any moment.
- get_text_width TEXT, ADD_OVERHANG = 0
- Returns TEXT string width if it would be drawn using
currently selected font.
If ADD_OVERHANG is 1, the first character's absolute A value and the last
character's absolute C value are added to the string if they are negative.
See more on ABC values at "Font ABC metrics".
Context used: font
- get_text_box TEXT
- Returns TEXT string extensions if it would be drawn using
currently selected font.
The result is an anonymous array of 5 points ( 5 integer pairs in (X,Y)
format). These 5 points are offsets for the following string extents,
given the string is plotted at (0,0):
1: start of string at ascent line ( top left )
2: start of string at descent line ( bottom left )
3: end of string at ascent line ( top right )
4: end of string at descent line ( bottom right )
5: concatenation point
The concatenation point coordinates (XC,YC) are coordinated passed to
consequent text_out() call so the conjoint string would plot as if
it was a part of TEXT. Depending on the value of the
"textOutBaseline" property, the concatenation point is located
either on the baseline or on the descent line.
Context used: font, textOutBaseline
1 3 3 4
** ****
* * *
*** ***
* * *
**** **
2 4 1 2
- render_spline VERTICES, [ PRECISION ]
- Renders cubic spline from set of VERTICES to a polyline
with given precision. The method can be called as static, i.e. with no
object initialized. PRECISION integer, if not given, is read from
"splinePrecision" property if the method was called on an alive
object; in case of static call, default value 24 is used.
The method is internally used by "spline" and
"fill_spline", and is provided for cases when these are
insufficient.
- text_wrap TEXT, WIDTH, OPTIONS, TAB_INDENT = 8
- Breaks TEXT string in chunks that would fit into WIDTH
pixels wide box.
The break algorithm and its result are governed by OPTIONS integer value
which is a combination of "tw::" constants:
- tw::CalcMnemonic
- Use 'hot key' semantics, when a character preceded by ~ has
special meaning - it gets underlined. If this bit is set, the first tilde
character used as an escapement is not calculated, and never appeared in
the result apart from the escaped character.
- tw::CollapseTilde
- In addition to tw::CalcMnemonic, removes '~' character from
the resulting chunks.
- tw::CalcTabs
- If set, calculates a tab ('\t') character as TAB_INDENT
times space characters.
- tw::ExpandTabs
- If set, expands tab ('\t') character as TAB_INDENT times
space characters.
- tw::BreakSingle
- Defines procedure behavior when the text cannot be fit in
WIDTH, does not affect anything otherwise.
If set, returns an empty array. If unset, returns a text broken by minimum
number of characters per chunk. In the latter case, the width of the
resulting text blocks will exceed WIDTH.
- tw::NewLineBreak
- Forces new chunk after a newline character ('\n') is met.
If UTF8 text is passed, unicode line break characters 0x2028 and 0x2029
produce same effect as the newline character.
- tw::SpaceBreak
- Forces new chunk after a space character (' ') or a tab
character ('\t') are met.
- tw::ReturnChunks
- Defines the result of text_wrap() function.
If set, the array consists of integer pairs, each consists of a text offset
within TEXT and a its length.
If unset, the resulting array consists from text chunks.
- tw::ReturnLines
- Equals to 0, is a mnemonic to an unset
tw::ReturnChunks.
- tw::WordBreak
- If unset, the TEXT breaks as soon as the chunk width
exceeds WIDTH. If set, tries to keep words in TEXT so they do not appear
in two chunks, e.g. keeps breaking TEXT by words, not by characters.
- tw::ReturnFirstLineLength
- If set, "text_wrap" proceeds until the first line
is wrapped, either by width or ( if specified ) by break characters.
Returns length of the resulting line. Used for efficiency when the reverse
function to "get_text_width" is needed.
If OPTIONS has tw::CalcMnemonic or tw::CollapseTilde bits set, then the last
scalar in the array result is a special hash reference. The hash contains
extra information regarding the 'hot key' underline position - it is assumed
that '~' - escapement denotes an underlined character. The hash contains the
following keys:
- tildeLine
- Chunk index that contains the escaped character. Set to
undef if no ~ - escapement was found. The other hash information is not
relevant in this case.
- tildeStart
- Horizontal offset of a beginning of the line that
underlines the escaped character.
- tildeEnd
- Horizontal offset of an end of the line that underlines the
escaped character.
- tildeChar
- The escaped character.
AUTHOR¶
Dmitry Karasik, <dmitry@karasik.eu.org>.
SEE ALSO¶
Prima, Prima::Object, Prima::Image