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73 | } else { |
73 | } else { |
74 | return load "$HOME/sunday.png"; |
74 | return load "$HOME/sunday.png"; |
75 | } |
75 | } |
76 | } |
76 | } |
77 | |
77 | |
78 | This expression is evaluated once per hour. It will set F<sunday.png> as |
78 | This inner expression is evaluated once per hour (and whenever the |
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79 | temrinal window is resized). It sets F<sunday.png> as background on |
79 | background on Sundays, and F<weekday.png> on all other days. |
80 | Sundays, and F<weekday.png> on all other days. |
80 | |
81 | |
81 | Fortunately, we expect that most expressions will be much simpler, with |
82 | Fortunately, we expect that most expressions will be much simpler, with |
82 | little Perl knowledge needed. |
83 | little Perl knowledge needed. |
83 | |
84 | |
84 | Basically, you always start with a function that "generates" an image |
85 | Basically, you always start with a function that "generates" an image |
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117 | horizontal and vertical dimensions. For example, this halves the image |
118 | horizontal and vertical dimensions. For example, this halves the image |
118 | width and doubles the image height: |
119 | width and doubles the image height: |
119 | |
120 | |
120 | scale 0.5, 2, load "$HOME/mypic.png" |
121 | scale 0.5, 2, load "$HOME/mypic.png" |
121 | |
122 | |
122 | IF you try out these expressions, you might suffer from sluggishness, |
123 | IF you try out these expressions, you might suffer from some sluggishness, |
123 | because each time the terminal is resized, it again loads the PNG image |
124 | because each time the terminal is resized, it loads the PNG image agin |
124 | and scales it. Scaling is usually fast, but loading the image can be quite |
125 | and scales it. Scaling is usually fast (and unavoidable), but loading the |
125 | time consuming. This is where C<keep> comes in handy: |
126 | image can be quite time consuming. This is where C<keep> comes in handy: |
126 | |
127 | |
127 | scale 0.5, 2, keep { load "$HOME/mypic.png" } |
128 | scale 0.5, 2, keep { load "$HOME/mypic.png" } |
128 | |
129 | |
129 | The C<keep> operator executes all the statements inside the braces only |
130 | The C<keep> operator executes all the statements inside the braces only |
130 | once, or when it thinks the outcome might change. In other cases it |
131 | once, or when it thinks the outcome might change. In other cases it |
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155 | |
156 | |
156 | This one first takes a snapshot of the screen background image, and then |
157 | This one first takes a snapshot of the screen background image, and then |
157 | moves it to the upper left corner of the screen (as opposed to the upper |
158 | moves it to the upper left corner of the screen (as opposed to the upper |
158 | left corner of the terminal window)- the result is pseudo-transparency: |
159 | left corner of the terminal window)- the result is pseudo-transparency: |
159 | the image seems to be static while the window is moved around. |
160 | the image seems to be static while the window is moved around. |
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161 | |
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162 | =head2 COLOUR SPECIFICATIONS |
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163 | |
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164 | Whenever an oprator expects a "colour", then this can be specified in one |
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165 | of two ways: Either as string with an X11 colour specification, such as: |
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166 | |
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167 | "red" # named colour |
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168 | "#f00" # simple rgb |
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169 | "[50]red" # red with 50% alpha |
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170 | "TekHVC:300/50/50" # anything goes |
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171 | |
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172 | OR as an array reference with one, three or four components: |
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173 | |
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174 | [0.5] # 50% gray, 100% alpha |
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175 | [0.5, 0, 0] # dark red, no green or blur, 100% alpha |
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176 | [0.5, 0, 0, 0.7] # same with explicit 70% alpha |
160 | |
177 | |
161 | =head2 CACHING AND SENSITIVITY |
178 | =head2 CACHING AND SENSITIVITY |
162 | |
179 | |
163 | Since some operations (such as C<load> and C<blur>) can take a long time, |
180 | Since some operations (such as C<load> and C<blur>) can take a long time, |
164 | caching results can be very important for a smooth operation. Caching can |
181 | caching results can be very important for a smooth operation. Caching can |
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172 | ... }>. The C<keep> operator takes a block of multiple statements enclosed |
189 | ... }>. The C<keep> operator takes a block of multiple statements enclosed |
173 | by C<{}> and keeps the return value in memory. |
190 | by C<{}> and keeps the return value in memory. |
174 | |
191 | |
175 | An expression can be "sensitive" to various external events, such as |
192 | An expression can be "sensitive" to various external events, such as |
176 | scaling or moving the window, root background changes and timers. Simply |
193 | scaling or moving the window, root background changes and timers. Simply |
177 | using an expression (such as C<scale> without parameters) that depend on |
194 | using an expression (such as C<scale> without parameters) that depends on |
178 | certain changing values (called "variables"), or using those variables |
195 | certain changing values (called "variables"), or using those variables |
179 | directly, will make an expression sensitive to these events - for example, |
196 | directly, will make an expression sensitive to these events - for example, |
180 | using C<scale> or C<TW> will make the expression sensitive to the terminal |
197 | using C<scale> or C<TW> will make the expression sensitive to the terminal |
181 | size, and thus to resizing events. |
198 | size, and thus to resizing events. |
182 | |
199 | |
183 | When such an event happens, C<keep> will automatically trigger a |
200 | When such an event happens, C<keep> will automatically trigger a |
184 | reevaluation of the whole expression with the new value of the expression. |
201 | reevaluation of the whole expression with the new value of the expression. |
185 | |
202 | |
186 | C<keep> is most useful for expensive operations, such as C<blur>: |
203 | C<keep> is most useful for expensive operations, such as C<blur>: |
187 | |
204 | |
188 | rootalign once { blur 20, root } |
205 | rootalign keep { blur 20, root } |
189 | |
206 | |
190 | This makes a blurred copy of the root background once, and on subsequent |
207 | This makes a blurred copy of the root background once, and on subsequent |
191 | calls, just root-aligns it. Since C<blur> is usually quite slow and |
208 | calls, just root-aligns it. Since C<blur> is usually quite slow and |
192 | C<rootalign> is quite fast, this trades extra memory (for the cached |
209 | C<rootalign> is quite fast, this trades extra memory (for the cached |
193 | blurred pixmap) with speed (blur only needs to be redone when root |
210 | blurred pixmap) with speed (blur only needs to be redone when root |
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272 | uses it), then the in-memory copy us returned instead. |
289 | uses it), then the in-memory copy us returned instead. |
273 | |
290 | |
274 | =item load_uc $path |
291 | =item load_uc $path |
275 | |
292 | |
276 | Load uncached - same as load, but does not cache the image, which means it |
293 | Load uncached - same as load, but does not cache the image, which means it |
277 | is I<always> loaded from the filesystem again. |
294 | is I<always> loaded from the filesystem again, even if another copy of it |
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295 | is in memory at the time. |
278 | |
296 | |
279 | =cut |
297 | =cut |
280 | |
298 | |
281 | sub load_uc($) { |
299 | sub load_uc($) { |
282 | $self->new_img_from_file ($path) |
300 | $self->new_img_from_file ($_[0]) |
283 | } |
301 | } |
284 | |
302 | |
285 | sub load($) { |
303 | sub load($) { |
286 | my ($path) = @_; |
304 | my ($path) = @_; |
287 | |
305 | |
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753 | |
771 | |
754 | The following operators change the pixels of the image. |
772 | The following operators change the pixels of the image. |
755 | |
773 | |
756 | =over 4 |
774 | =over 4 |
757 | |
775 | |
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776 | =item tint $color, $img |
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777 | |
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778 | Tints the image in the given colour. |
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779 | |
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780 | Example: tint the image red. |
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781 | |
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782 | tint "red", load "rgb.png" |
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783 | |
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784 | Example: the same, but specify the colour by component. |
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785 | |
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786 | tint [1, 0, 0], load "rgb.png" |
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787 | |
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788 | =cut |
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789 | |
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790 | sub tint($$) { |
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791 | $_[1]->tint ($_[0]) |
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792 | } |
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793 | |
758 | =item contrast $factor, $img |
794 | =item contrast $factor, $img |
759 | |
795 | |
760 | =item contrast $r, $g, $b, $img |
796 | =item contrast $r, $g, $b, $img |
761 | |
797 | |
762 | =item contrast $r, $g, $b, $a, $img |
798 | =item contrast $r, $g, $b, $a, $img |
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847 | |
883 | |
848 | =over 4 |
884 | =over 4 |
849 | |
885 | |
850 | =item keep { ... } |
886 | =item keep { ... } |
851 | |
887 | |
852 | #TODO# |
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853 | |
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854 | This operator takes a code block as argument, that is, one or more |
888 | This operator takes a code block as argument, that is, one or more |
855 | statements enclosed by braces. |
889 | statements enclosed by braces. |
856 | |
890 | |
857 | The trick is that this code block is only evaluated once - future calls |
891 | The trick is that this code block is only evaluated when the outcome |
858 | will simply return the original image (yes, it should only be used with |
892 | changes - on other calls the C<keep> simply returns the image it computed |
859 | images). |
893 | previously (yes, it should only be used with images). Or in other words, |
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894 | C<keep> I<caches> the result of the code block so it doesn't need to be |
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895 | computed again. |
860 | |
896 | |
861 | This can be extremely useful to avoid redoing the same slow operations |
897 | This can be extremely useful to avoid redoing slow operations - for |
862 | again and again- for example, if your background expression takes the root |
898 | example, if your background expression takes the root background, blurs it |
863 | background, blurs it and then root-aligns it it would have to blur the |
899 | and then root-aligns it it would have to blur the root background on every |
864 | root background on every window move or resize. |
900 | window move or resize. |
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901 | |
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902 | Another example is C<load>, which can be quite slow. |
865 | |
903 | |
866 | In fact, urxvt itself encloses the whole expression in some kind of |
904 | In fact, urxvt itself encloses the whole expression in some kind of |
867 | C<once> block so it only is reevaluated as required. |
905 | C<keep> block so it only is reevaluated as required. |
868 | |
906 | |
869 | Putting the blur into a C<once> block will make sure the blur is only done |
907 | Putting the blur into a C<keep> block will make sure the blur is only done |
870 | once: |
908 | once, while the C<rootalign> is still done each time the window moves. |
871 | |
909 | |
872 | rootlign keep { blur 10, root } |
910 | rootlign keep { blur 10, root } |
873 | |
911 | |
874 | This leaves the question of how to force reevaluation of the block, |
912 | This leaves the question of how to force reevaluation of the block, |
875 | in case the root background changes: If expression inside the block |
913 | in case the root background changes: If expression inside the block |
876 | is sensitive to some event (root background changes, window geometry |
914 | is sensitive to some event (root background changes, window geometry |
877 | changes), then it will be reevaluated automatically as needed. |
915 | changes), then it will be reevaluated automatically as needed. |
878 | |
916 | |
879 | =item once_again |
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880 | |
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881 | Resets all C<once> block as if they had never been called, i.e. on the |
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882 | next call they will be reevaluated again. |
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883 | |
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884 | =cut |
917 | =cut |
885 | |
918 | |
886 | sub once(&) { |
919 | sub keep(&) { |
887 | my $id = $_[0]+0; |
920 | my $id = $_[0]+0; |
888 | |
921 | |
889 | local $frame = $self->{frame_cache}{$id} ||= [$frame]; |
922 | local $frame = $self->{frame_cache}{$id} ||= [$frame]; |
890 | |
923 | |
891 | unless ($frame->[FR_CACHE]) { |
924 | unless ($frame->[FR_CACHE]) { |
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909 | wantarray |
942 | wantarray |
910 | ? @{ $frame->[FR_CACHE] } |
943 | ? @{ $frame->[FR_CACHE] } |
911 | : $frame->[FR_CACHE][0] |
944 | : $frame->[FR_CACHE][0] |
912 | } |
945 | } |
913 | |
946 | |
914 | sub once_again() { |
947 | # sub keep_clear() { |
915 | delete $self->{frame_cache}; |
948 | # delete $self->{frame_cache}; |
916 | } |
949 | # } |
917 | |
950 | |
918 | =back |
951 | =back |
919 | |
952 | |
920 | =cut |
953 | =cut |
921 | |
954 | |