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diff --git a/src/perl/background b/src/perl/background new file mode 100644 index 0000000..bdc6846 --- /dev/null +++ b/src/perl/background @@ -0,0 +1,1566 @@ +#! perl + +#:META:RESOURCE:%.expr:string:background expression +#:META:RESOURCE:%.border:boolean:respect the terminal border +#:META:RESOURCE:%.interval:seconds:minimum time between updates +#:META:RESOURCE:pixmap:file[;geom]:set image as background +#:META:RESOURCE:backgroundPixmap:file[;geom]:set image as background +#:META:RESOURCE:tr:boolean:set root pixmap as background +#:META:RESOURCE:transparent:boolean:set root pixmap as background +#:META:RESOURCE:tint:color:tint background with color +#:META:RESOURCE:tintColor:color:tint background with color +#:META:RESOURCE:sh:number:shade background by number % +#:META:RESOURCE:shading:number:shade background by number % +#:META:RESOURCE:blr:HxV:gaussian-blur background with radii +#:META:RESOURCE:blurRadius:HxV:gaussian-blur background with radii + +=head1 NAME + +background - manage terminal background + +=head1 SYNOPSIS + + urxvt --background-expr 'background expression' + --background-border + --background-interval seconds + +=head1 QUICK AND DIRTY CHEAT SHEET + +Just load a random jpeg image and tile the background with it without +scaling or anything else: + + load "/path/to/img.jpg" + +The same, but use mirroring/reflection instead of tiling: + + mirror load "/path/to/img.jpg" + +Load an image and scale it to exactly fill the terminal window: + + scale keep { load "/path/to/img.jpg" } + +Implement pseudo-transparency by using a suitably-aligned root pixmap +as window background: + + rootalign root + +Likewise, but keep a blurred copy: + + rootalign keep { blur 10, root } + +=head1 DESCRIPTION + +This extension manages the terminal background by creating a picture that +is behind the text, replacing the normal background colour. + +It does so by evaluating a Perl expression that I<calculates> the image on +the fly, for example, by grabbing the root background or loading a file. + +While the full power of Perl is available, the operators have been design +to be as simple as possible. + +For example, to load an image and scale it to the window size, you would +use: + + urxvt --background-expr 'scale keep { load "/path/to/mybg.png" }' + +Or specified as a X resource: + + URxvt.background.expr: scale keep { load "/path/to/mybg.png" } + +=head1 THEORY OF OPERATION + +At startup, just before the window is mapped for the first time, the +expression is evaluated and must yield an image. The image is then +extended as necessary to cover the whole terminal window, and is set as a +background pixmap. + +If the image contains an alpha channel, then it will be used as-is in +visuals that support alpha channels (for example, for a compositing +manager). In other visuals, the terminal background colour will be used to +replace any transparency. + +When the expression relies, directly or indirectly, on the window size, +position, the root pixmap, or a timer, then it will be remembered. If not, +then it will be removed. + +If any of the parameters that the expression relies on changes (when the +window is moved or resized, its position or size changes; when the root +pixmap is replaced by another one the root background changes; or when the +timer elapses), then the expression will be evaluated again. + +For example, an expression such as C<scale keep { load "$HOME/mybg.png" +}> scales the image to the window size, so it relies on the window size +and will be reevaluated each time it is changed, but not when it moves for +example. That ensures that the picture always fills the terminal, even +after its size changes. + +=head2 EXPRESSIONS + +Expressions are normal Perl expressions, in fact, they are Perl blocks - +which means you could use multiple lines and statements: + + scale keep { + again 3600; + if (localtime now)[6]) { + return load "$HOME/weekday.png"; + } else { + return load "$HOME/sunday.png"; + } + } + +This inner expression is evaluated once per hour (and whenever the +terminal window is resized). It sets F<sunday.png> as background on +Sundays, and F<weekday.png> on all other days. + +Fortunately, we expect that most expressions will be much simpler, with +little Perl knowledge needed. + +Basically, you always start with a function that "generates" an image +object, such as C<load>, which loads an image from disk, or C<root>, which +returns the root window background image: + + load "$HOME/mypic.png" + +The path is usually specified as a quoted string (the exact rules can be +found in the L<perlop> manpage). The F<$HOME> at the beginning of the +string is expanded to the home directory. + +Then you prepend one or more modifiers or filtering expressions, such as +C<scale>: + + scale load "$HOME/mypic.png" + +Just like a mathematical expression with functions, you should read these +expressions from right to left, as the C<load> is evaluated first, and +its result becomes the argument to the C<scale> function. + +Many operators also allow some parameters preceding the input image +that modify its behaviour. For example, C<scale> without any additional +arguments scales the image to size of the terminal window. If you specify +an additional argument, it uses it as a scale factor (multiply by 100 to +get a percentage): + + scale 2, load "$HOME/mypic.png" + +This enlarges the image by a factor of 2 (200%). As you can see, C<scale> +has now two arguments, the C<2> and the C<load> expression, while +C<load> only has one argument. Arguments are separated from each other by +commas. + +Scale also accepts two arguments, which are then separate factors for both +horizontal and vertical dimensions. For example, this halves the image +width and doubles the image height: + + scale 0.5, 2, load "$HOME/mypic.png" + +IF you try out these expressions, you might suffer from some sluggishness, +because each time the terminal is resized, it loads the PNG image again +and scales it. Scaling is usually fast (and unavoidable), but loading the +image can be quite time consuming. This is where C<keep> comes in handy: + + scale 0.5, 2, keep { load "$HOME/mypic.png" } + +The C<keep> operator executes all the statements inside the braces only +once, or when it thinks the outcome might change. In other cases it +returns the last value computed by the brace block. + +This means that the C<load> is only executed once, which makes it much +faster, but also means that more memory is being used, because the loaded +image must be kept in memory at all times. In this expression, the +trade-off is likely worth it. + +But back to effects: Other effects than scaling are also readily +available, for example, you can tile the image to fill the whole window, +instead of resizing it: + + tile keep { load "$HOME/mypic.png" } + +In fact, images returned by C<load> are in C<tile> mode by default, so the +C<tile> operator is kind of superfluous. + +Another common effect is to mirror the image, so that the same edges +touch: + + mirror keep { load "$HOME/mypic.png" } + +Another common background expression is: + + rootalign root + +This one first takes a snapshot of the screen background image, and then +moves it to the upper left corner of the screen (as opposed to the upper +left corner of the terminal window)- the result is pseudo-transparency: +the image seems to be static while the window is moved around. + +=head2 COLOUR SPECIFICATIONS + +Whenever an operator expects a "colour", then this can be specified in one +of two ways: Either as string with an X11 colour specification, such as: + + "red" # named colour + "#f00" # simple rgb + "[50]red" # red with 50% alpha + "TekHVC:300/50/50" # anything goes + +OR as an array reference with one, three or four components: + + [0.5] # 50% gray, 100% alpha + [0.5, 0, 0] # dark red, no green or blur, 100% alpha + [0.5, 0, 0, 0.7] # same with explicit 70% alpha + +=head2 CACHING AND SENSITIVITY + +Since some operations (such as C<load> and C<blur>) can take a long time, +caching results can be very important for a smooth operation. Caching can +also be useful to reduce memory usage, though, for example, when an image +is cached by C<load>, it could be shared by multiple terminal windows +running inside urxvtd. + +=head3 C<keep { ... }> caching + +The most important way to cache expensive operations is to use C<keep { +... }>. The C<keep> operator takes a block of multiple statements enclosed +by C<{}> and keeps the return value in memory. + +An expression can be "sensitive" to various external events, such as +scaling or moving the window, root background changes and timers. Simply +using an expression (such as C<scale> without parameters) that depends on +certain changing values (called "variables"), or using those variables +directly, will make an expression sensitive to these events - for example, +using C<scale> or C<TW> will make the expression sensitive to the terminal +size, and thus to resizing events. + +When such an event happens, C<keep> will automatically trigger a +reevaluation of the whole expression with the new value of the expression. + +C<keep> is most useful for expensive operations, such as C<blur>: + + rootalign keep { blur 20, root } + +This makes a blurred copy of the root background once, and on subsequent +calls, just root-aligns it. Since C<blur> is usually quite slow and +C<rootalign> is quite fast, this trades extra memory (for the cached +blurred pixmap) with speed (blur only needs to be redone when root +changes). + +=head3 C<load> caching + +The C<load> operator itself does not keep images in memory, but as long as +the image is still in memory, C<load> will use the in-memory image instead +of loading it freshly from disk. + +That means that this expression: + + keep { load "$HOME/path..." } + +Not only caches the image in memory, other terminal instances that try to +C<load> it can reuse that in-memory copy. + +=head1 REFERENCE + +=head2 COMMAND LINE SWITCHES + +=over 4 + +=item --background-expr perl-expression + +Specifies the Perl expression to evaluate. + +=item --background-border + +By default, the expression creates an image that fills the full window, +overwriting borders and any other areas, such as the scrollbar. + +Specifying this flag changes the behaviour, so that the image only +replaces the background of the character area. + +=item --background-interval seconds + +Since some operations in the underlying XRender extension can effectively +freeze your X-server for prolonged time, this extension enforces a minimum +time between updates, which is normally about 0.1 seconds. + +If you want to do updates more often, you can decrease this safety +interval with this switch. + +=back + +=cut + +our %_IMG_CACHE; +our $HOME; +our ($self, $frame); +our ($x, $y, $w, $h, $focus); + +# enforce at least this interval between updates +our $MIN_INTERVAL = 6/59.951; + +{ + package urxvt::bgdsl; # background language + + sub FR_PARENT() { 0 } # parent frame, if any - must be #0 + sub FR_CACHE () { 1 } # cached values + sub FR_AGAIN () { 2 } # what this expr is sensitive to + sub FR_STATE () { 3 } # watchers etc. + + use List::Util qw(min max sum shuffle); + +=head2 PROVIDERS/GENERATORS + +These functions provide an image, by loading it from disk, grabbing it +from the root screen or by simply generating it. They are used as starting +points to get an image you can play with. + +=over 4 + +=item load $path + +Loads the image at the given C<$path>. The image is set to plane tiling +mode. + +If the image is already in memory (e.g. because another terminal instance +uses it), then the in-memory copy is returned instead. + +=item load_uc $path + +Load uncached - same as load, but does not cache the image, which means it +is I<always> loaded from the filesystem again, even if another copy of it +is in memory at the time. + +=cut + + sub load_uc($) { + $self->new_img_from_file ($_[0]) + } + + sub load($) { + my ($path) = @_; + + $_IMG_CACHE{$path} || do { + my $img = load_uc $path; + Scalar::Util::weaken ($_IMG_CACHE{$path} = $img); + $img + } + } + +=item root + +Returns the root window pixmap, that is, hopefully, the background image +of your screen. + +This function makes your expression root sensitive, that means it will be +reevaluated when the bg image changes. + +=cut + + sub root() { + $frame->[FR_AGAIN]{rootpmap} = 1; + $self->new_img_from_root + } + +=item solid $colour + +=item solid $width, $height, $colour + +Creates a new image and completely fills it with the given colour. The +image is set to tiling mode. + +If C<$width> and C<$height> are omitted, it creates a 1x1 image, which is +useful for solid backgrounds or for use in filtering effects. + +=cut + + sub solid($;$$) { + my $colour = pop; + + my $img = $self->new_img (urxvt::PictStandardARGB32, 0, 0, $_[0] || 1, $_[1] || 1); + $img->fill ($colour); + $img + } + +=item clone $img + +Returns an exact copy of the image. This is useful if you want to have +multiple copies of the same image to apply different effects to. + +=cut + + sub clone($) { + $_[0]->clone + } + +=item merge $img ... + +Takes any number of images and merges them together, creating a single +image containing them all. The tiling mode of the first image is used as +the tiling mode of the resulting image. + +This function is called automatically when an expression returns multiple +images. + +=cut + + sub merge(@) { + return $_[0] unless $#_; + + # rather annoyingly clumsy, but optimisation is for another time + + my $x0 = +1e9; + my $y0 = +1e9; + my $x1 = -1e9; + my $y1 = -1e9; + + for (@_) { + my ($x, $y, $w, $h) = $_->geometry; + + $x0 = $x if $x0 > $x; + $y0 = $y if $y0 > $y; + + $x += $w; + $y += $h; + + $x1 = $x if $x1 < $x; + $y1 = $y if $y1 < $y; + } + + my $base = $self->new_img (urxvt::PictStandardARGB32, $x0, $y0, $x1 - $x0, $y1 - $y0); + $base->repeat_mode ($_[0]->repeat_mode); + $base->fill ([0, 0, 0, 0]); + + $base->draw ($_) + for @_; + + $base + } + +=back + +=head2 TILING MODES + +The following operators modify the tiling mode of an image, that is, the +way that pixels outside the image area are painted when the image is used. + +=over 4 + +=item tile $img + +Tiles the whole plane with the image and returns this new image - or in +other words, it returns a copy of the image in plane tiling mode. + +Example: load an image and tile it over the background, without +resizing. The C<tile> call is superfluous because C<load> already defaults +to tiling mode. + + tile load "mybg.png" + +=item mirror $img + +Similar to tile, but reflects the image each time it uses a new copy, so +that top edges always touch top edges, right edges always touch right +edges and so on (with normal tiling, left edges always touch right edges +and top always touch bottom edges). + +Example: load an image and mirror it over the background, avoiding sharp +edges at the image borders at the expense of mirroring the image itself + + mirror load "mybg.png" + +=item pad $img + +Takes an image and modifies it so that all pixels outside the image area +become transparent. This mode is most useful when you want to place an +image over another image or the background colour while leaving all +background pixels outside the image unchanged. + +Example: load an image and display it in the upper left corner. The rest +of the space is left "empty" (transparent or whatever your compositor does +in alpha mode, else background colour). + + pad load "mybg.png" + +=item extend $img + +Extends the image over the whole plane, using the closest pixel in the +area outside the image. This mode is mostly useful when you use more complex +filtering operations and want the pixels outside the image to have the +same values as the pixels near the edge. + +Example: just for curiosity, how does this pixel extension stuff work? + + extend move 50, 50, load "mybg.png" + +=cut + + sub pad($) { + my $img = $_[0]->clone; + $img->repeat_mode (urxvt::RepeatNone); + $img + } + + sub tile($) { + my $img = $_[0]->clone; + $img->repeat_mode (urxvt::RepeatNormal); + $img + } + + sub mirror($) { + my $img = $_[0]->clone; + $img->repeat_mode (urxvt::RepeatReflect); + $img + } + + sub extend($) { + my $img = $_[0]->clone; + $img->repeat_mode (urxvt::RepeatPad); + $img + } + +=back + +=head2 VARIABLE VALUES + +The following functions provide variable data such as the terminal window +dimensions. They are not (Perl-) variables, they just return stuff that +varies. Most of them make your expression sensitive to some events, for +example using C<TW> (terminal width) means your expression is evaluated +again when the terminal is resized. + +=over 4 + +=item TX + +=item TY + +Return the X and Y coordinates of the terminal window (the terminal +window is the full window by default, and the character area only when in +border-respect mode). + +Using these functions makes your expression sensitive to window moves. + +These functions are mainly useful to align images to the root window. + +Example: load an image and align it so it looks as if anchored to the +background (that's exactly what C<rootalign> does btw.): + + move -TX, -TY, keep { load "mybg.png" } + +=item TW + +=item TH + +Return the width (C<TW>) and height (C<TH>) of the terminal window (the +terminal window is the full window by default, and the character area only +when in border-respect mode). + +Using these functions makes your expression sensitive to window resizes. + +These functions are mainly useful to scale images, or to clip images to +the window size to conserve memory. + +Example: take the screen background, clip it to the window size, blur it a +bit, align it to the window position and use it as background. + + clip move -TX, -TY, keep { blur 5, root } + +=item FOCUS + +Returns a boolean indicating whether the terminal window has keyboard +focus, in which case it returns true. + +Using this function makes your expression sensitive to focus changes. + +A common use case is to fade the background image when the terminal loses +focus, often together with the C<-fade> command line option. In fact, +there is a special function for just that use case: C<focus_fade>. + +Example: use two entirely different background images, depending on +whether the window has focus. + + FOCUS ? keep { load "has_focus.jpg" } : keep { load "no_focus.jpg" } + +=cut + + sub TX () { $frame->[FR_AGAIN]{position} = 1; $x } + sub TY () { $frame->[FR_AGAIN]{position} = 1; $y } + sub TW () { $frame->[FR_AGAIN]{size} = 1; $w } + sub TH () { $frame->[FR_AGAIN]{size} = 1; $h } + sub FOCUS() { $frame->[FR_AGAIN]{focus} = 1; $focus } + +=item now + +Returns the current time as (fractional) seconds since the epoch. + +Using this expression does I<not> make your expression sensitive to time, +but the next two functions do. + +=item again $seconds + +When this function is used the expression will be reevaluated again in +C<$seconds> seconds. + +Example: load some image and rotate it according to the time of day (as if it were +the hour pointer of a clock). Update this image every minute. + + again 60; + rotate 50, 50, (now % 86400) * -72 / 8640, scale keep { load "myclock.png" } + +=item counter $seconds + +Like C<again>, but also returns an increasing counter value, starting at +0, which might be useful for some simple animation effects. + +=cut + + sub now() { urxvt::NOW } + + sub again($) { + $frame->[FR_AGAIN]{time} = $_[0]; + } + + sub counter($) { + $frame->[FR_AGAIN]{time} = $_[0]; + $frame->[FR_STATE]{counter} + 0 + } + +=back + +=head2 SHAPE CHANGING OPERATORS + +The following operators modify the shape, size or position of the image. + +=over 4 + +=item clip $img + +=item clip $width, $height, $img + +=item clip $x, $y, $width, $height, $img + +Clips an image to the given rectangle. If the rectangle is outside the +image area (e.g. when C<$x> or C<$y> are negative) or the rectangle is +larger than the image, then the tiling mode defines how the extra pixels +will be filled. + +If C<$x> and C<$y> are missing, then C<0> is assumed for both. + +If C<$width> and C<$height> are missing, then the window size will be +assumed. + +Example: load an image, blur it, and clip it to the window size to save +memory. + + clip keep { blur 10, load "mybg.png" } + +=cut + + sub clip($;$$;$$) { + my $img = pop; + my $h = pop || TH; + my $w = pop || TW; + $img->sub_rect ($_[0], $_[1], $w, $h) + } + +=item scale $img + +=item scale $size_factor, $img + +=item scale $width_factor, $height_factor, $img + +Scales the image by the given factors in horizontal +(C<$width>) and vertical (C<$height>) direction. + +If only one factor is given, it is used for both directions. + +If no factors are given, scales the image to the window size without +keeping aspect. + +=item resize $width, $height, $img + +Resizes the image to exactly C<$width> times C<$height> pixels. + +=item fit $img + +=item fit $width, $height, $img + +Fits the image into the given C<$width> and C<$height> without changing +aspect, or the terminal size. That means it will be shrunk or grown until +the whole image fits into the given area, possibly leaving borders. + +=item cover $img + +=item cover $width, $height, $img + +Similar to C<fit>, but shrinks or grows until all of the area is covered +by the image, so instead of potentially leaving borders, it will cut off +image data that doesn't fit. + +=cut + + sub scale($;$;$) { + my $img = pop; + + @_ == 2 ? $img->scale ($_[0] * $img->w, $_[1] * $img->h) + : @_ ? $img->scale ($_[0] * $img->w, $_[0] * $img->h) + : $img->scale (TW, TH) + } + + sub resize($$$) { + my $img = pop; + $img->scale ($_[0], $_[1]) + } + + sub fit($;$$) { + my $img = pop; + my $w = ($_[0] || TW) / $img->w; + my $h = ($_[1] || TH) / $img->h; + scale +(min $w, $h), $img + } + + sub cover($;$$) { + my $img = pop; + my $w = ($_[0] || TW) / $img->w; + my $h = ($_[1] || TH) / $img->h; + scale +(max $w, $h), $img + } + +=item move $dx, $dy, $img + +Moves the image by C<$dx> pixels in the horizontal, and C<$dy> pixels in +the vertical. + +Example: move the image right by 20 pixels and down by 30. + + move 20, 30, ... + +=item align $xalign, $yalign, $img + +Aligns the image according to a factor - C<0> means the image is moved to +the left or top edge (for C<$xalign> or C<$yalign>), C<0.5> means it is +exactly centered and C<1> means it touches the right or bottom edge. + +Example: remove any visible border around an image, center it vertically but move +it to the right hand side. + + align 1, 0.5, pad $img + +=item center $img + +=item center $width, $height, $img + +Centers the image, i.e. the center of the image is moved to the center of +the terminal window (or the box specified by C<$width> and C<$height> if +given). + +Example: load an image and center it. + + center keep { pad load "mybg.png" } + +=item rootalign $img + +Moves the image so that it appears glued to the screen as opposed to the +window. This gives the illusion of a larger area behind the window. It is +exactly equivalent to C<move -TX, -TY>, that is, it moves the image to the +top left of the screen. + +Example: load a background image, put it in mirror mode and root align it. + + rootalign keep { mirror load "mybg.png" } + +Example: take the screen background and align it, giving the illusion of +transparency as long as the window isn't in front of other windows. + + rootalign root + +=cut + + sub move($$;$) { + my $img = pop->clone; + $img->move ($_[0], $_[1]); + $img + } + + sub align($;$$) { + my $img = pop; + + move $_[0] * (TW - $img->w), + $_[1] * (TH - $img->h), + $img + } + + sub center($;$$) { + my $img = pop; + my $w = $_[0] || TW; + my $h = $_[1] || TH; + + move 0.5 * ($w - $img->w), 0.5 * ($h - $img->h), $img + } + + sub rootalign($) { + move -TX, -TY, $_[0] + } + +=item rotate $center_x, $center_y, $degrees, $img + +Rotates the image clockwise by C<$degrees> degrees, around the point at +C<$center_x> and C<$center_y> (specified as factor of image width/height). + +Example: rotate the image by 90 degrees around its center. + + rotate 0.5, 0.5, 90, keep { load "$HOME/mybg.png" } + +=cut + + sub rotate($$$$) { + my $img = pop; + $img->rotate ( + $_[0] * ($img->w + $img->x), + $_[1] * ($img->h + $img->y), + $_[2] * (3.14159265 / 180), + ) + } + +=back + +=head2 COLOUR MODIFICATIONS + +The following operators change the pixels of the image. + +=over 4 + +=item tint $color, $img + +Tints the image in the given colour. + +Example: tint the image red. + + tint "red", load "rgb.png" + +Example: the same, but specify the colour by component. + + tint [1, 0, 0], load "rgb.png" + +=cut + + sub tint($$) { + $_[1]->tint ($_[0]) + } + +=item shade $factor, $img + +Shade the image by the given factor. + +=cut + + sub shade($$) { + $_[1]->shade ($_[0]) + } + +=item contrast $factor, $img + +=item contrast $r, $g, $b, $img + +=item contrast $r, $g, $b, $a, $img + +Adjusts the I<contrast> of an image. + +The first form applies a single C<$factor> to red, green and blue, the +second form applies separate factors to each colour channel, and the last +form includes the alpha channel. + +Values from 0 to 1 lower the contrast, values higher than 1 increase the +contrast. + +Due to limitations in the underlying XRender extension, lowering contrast +also reduces brightness, while increasing contrast currently also +increases brightness. + +=item brightness $bias, $img + +=item brightness $r, $g, $b, $img + +=item brightness $r, $g, $b, $a, $img + +Adjusts the brightness of an image. + +The first form applies a single C<$bias> to red, green and blue, the +second form applies separate biases to each colour channel, and the last +form includes the alpha channel. + +Values less than 0 reduce brightness, while values larger than 0 increase +it. Useful range is from -1 to 1 - the former results in a black, the +latter in a white picture. + +Due to idiosyncrasies in the underlying XRender extension, biases less +than zero can be I<very> slow. + +You can also try the experimental(!) C<muladd> operator. + +=cut + + sub contrast($$;$$;$) { + my $img = pop; + my ($r, $g, $b, $a) = @_; + + ($g, $b) = ($r, $r) if @_ < 3; + $a = 1 if @_ < 4; + + $img = $img->clone; + $img->contrast ($r, $g, $b, $a); + $img + } + + sub brightness($$;$$;$) { + my $img = pop; + my ($r, $g, $b, $a) = @_; + + ($g, $b) = ($r, $r) if @_ < 3; + $a = 1 if @_ < 4; + + $img = $img->clone; + $img->brightness ($r, $g, $b, $a); + $img + } + +=item muladd $mul, $add, $img # EXPERIMENTAL + +First multiplies the pixels by C<$mul>, then adds C<$add>. This can be used +to implement brightness and contrast at the same time, with a wider value +range than contrast and brightness operators. + +Due to numerous bugs in XRender implementations, it can also introduce a +number of visual artifacts. + +Example: increase contrast by a factor of C<$c> without changing image +brightness too much. + + muladd $c, (1 - $c) * 0.5, $img + +=cut + + sub muladd($$$) { + $_[2]->muladd ($_[0], $_[1]) + } + +=item blur $radius, $img + +=item blur $radius_horz, $radius_vert, $img + +Gaussian-blurs the image with (roughly) C<$radius> pixel radius. The radii +can also be specified separately. + +Blurring is often I<very> slow, at least compared or other +operators. Larger blur radii are slower than smaller ones, too, so if you +don't want to freeze your screen for long times, start experimenting with +low values for radius (<5). + +=cut + + sub blur($$;$) { + my $img = pop; + $img->blur ($_[0], @_ >= 2 ? $_[1] : $_[0]) + } + +=item focus_fade $img + +=item focus_fade $factor, $img + +=item focus_fade $factor, $color, $img + +Fades the image by the given factor (and colour) when focus is lost (the +same as the C<-fade>/C<-fadecolor> command line options, which also supply +the default values for C<factor> and C<$color>. Unlike with C<-fade>, the +C<$factor> is a real value, not a percentage value (that is, 0..1, not +0..100). + +Example: do the right thing when focus fading is requested. + + focus_fade load "mybg.jpg"; + +=cut + + sub focus_fade($;$$) { + my $img = pop; + + return $img + if FOCUS; + + my $fade = @_ >= 1 ? $_[0] : defined $self->resource ("fade") ? $self->resource ("fade") * 0.01 : 0; + my $color = @_ >= 2 ? $_[1] : $self->resource ("color+" . urxvt::Color_fade); + + $img = $img->tint ($color) if $color ne "rgb:00/00/00"; + $img = $img->muladd (1 - $fade, 0) if $fade; + + $img + } + +=back + +=head2 OTHER STUFF + +Anything that didn't fit any of the other categories, even after applying +force and closing our eyes. + +=over 4 + +=item keep { ... } + +This operator takes a code block as argument, that is, one or more +statements enclosed by braces. + +The trick is that this code block is only evaluated when the outcome +changes - on other calls the C<keep> simply returns the image it computed +previously (yes, it should only be used with images). Or in other words, +C<keep> I<caches> the result of the code block so it doesn't need to be +computed again. + +This can be extremely useful to avoid redoing slow operations - for +example, if your background expression takes the root background, blurs it +and then root-aligns it it would have to blur the root background on every +window move or resize. + +Another example is C<load>, which can be quite slow. + +In fact, urxvt itself encloses the whole expression in some kind of +C<keep> block so it only is reevaluated as required. + +Putting the blur into a C<keep> block will make sure the blur is only done +once, while the C<rootalign> is still done each time the window moves. + + rootalign keep { blur 10, root } + +This leaves the question of how to force reevaluation of the block, +in case the root background changes: If expression inside the block +is sensitive to some event (root background changes, window geometry +changes), then it will be reevaluated automatically as needed. + +=back + +=head1 OLD BACKGROUND IMAGE SETTINGS + +This extension also provides support for the old options/resources and +OSC sequences for setting a background image. These settings are +B<deprecated> and will be removed in future versions. + +=head2 OPTIONS AND RESOURCES + +=over 4 + +=item B<-pixmap> I<file[;oplist]> + +=item B<backgroundPixmap:> I<file[;oplist]> + +Use the specified image file as the window's background and also +optionally specify a colon separated list of operations to modify it. +Note that you may need to quote the C<;> character when using the +command line option, as C<;> is usually a metacharacter in shells. +Supported operations are: + +=over 4 + +=item B<WxH+X+Y> + +sets scale and position. B<"W" / "H"> specify the horizontal/vertical +scale (percent), and B<"X" / "Y"> locate the image centre (percent). A +scale of 0 disables scaling. + +=item B<op=tile> + +enables tiling + +=item B<op=keep-aspect> + +maintain the image aspect ratio when scaling + +=item B<op=root-align> + +use the position of the terminal window relative to the root window as +the image offset, simulating a root window background + +=back + +The default scale and position setting is C<100x100+50+50>. +Alternatively, a predefined set of templates can be used to achieve +the most common setups: + +=over 4 + +=item B<style=tiled> + +the image is tiled with no scaling. Equivalent to 0x0+0+0:op=tile + +=item B<style=aspect-stretched> + +the image is scaled to fill the whole window maintaining the aspect +ratio and centered. Equivalent to 100x100+50+50:op=keep-aspect + +=item B<style=stretched> + +the image is scaled to fill the whole window. Equivalent to 100x100 + +=item B<style=centered> + +the image is centered with no scaling. Equivalent to 0x0+50+50 + +=item B<style=root-tiled> + +the image is tiled with no scaling and using 'root' positioning. +Equivalent to 0x0:op=tile:op=root-align + +=back + +If multiple templates are specified the last one wins. Note that a +template overrides all the scale, position and operations settings. + +If used in conjunction with pseudo-transparency, the specified image +will be blended over the transparent background using alpha-blending. + +=item B<-tr>|B<+tr> + +=item B<transparent:> I<boolean> + +Turn on/off pseudo-transparency by using the root pixmap as background. + +=item B<-tint> I<colour> + +=item B<tintColor:> I<colour> + +Tint the transparent background with the given colour. Note that a +black tint yields a completely black image while a white tint yields +the image unchanged. + +=item B<-sh> I<number> + +=item B<shading:> I<number> + +Darken (0 .. 99) or lighten (101 .. 200) the transparent background. +A value of 100 means no shading. + +=item B<-blr> I<HxV> + +=item B<blurRadius:> I<HxV> + +Apply gaussian blur with the specified radius to the transparent +background |