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NAME
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tweak – edit image files, subfont files, face files, etc.
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SYNOPSIS
DESCRIPTION
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Tweak edits existing files holding various forms of images. To
create original images, start from an existing image, subfont,
etc.
Tweak reads its argument files and displays the resulting images
in a vertical column. If the image is too wide to fit across the
display, it is folded much like a long line of text in an rio
window. Under each image is displayed one or two lines of text
presenting its parameters. The first line shows the image’s depth,
the number of bits per pixel; r, the
rectangle covered by the image; and the name of the file from
which it was read. If the file is a subfont, a second line presents
a hexadecimal 16-bit offset to be applied to character values
from the subfont (typically as stored in a font file; see font(7));
and the subfont’s n, height, and ascent as defined in cachechars(3).
By means described below, magnified views of portions of the images
may be displayed. The text associated with such a view includes
mag, the magnification. If the view is of a single character from
a subfont, the second line of text shows the character’s value
(including the subfont’s offset) in hexadecimal and as a character
in tweak’s default font; the
character’s x, top, bottom, left, and width as defined in cachechars(3);
and iwidth, the physical width of the image in the subfont’s image.
There are two methods to obtain a magnified view of a character
from a subfont. The first is to click mouse button 1 over the
image of the character in the subfont. The second is to select
the char entry on the button 3 menu, point the resulting gunsight
cursor at the desired subfont and click button 3, and then type
at the text prompt at the bottom of the
screen the character value, either as a multi-digit hexadecimal
number or as a single rune representing the character.
To magnify a portion of other types of image files, click button
1 over the unmagnified file. The cursor will switch to a cross.
Still with button 1, sweep a rectangle, as in rio, that encloses
the portion of the image to be magnified. (If the file is 16x16
or smaller, tweak will just magnify the entire file; no sweeping
is necessary.)
Pressing buttons 1 and 2 within magnified images changes pixel
values. By default, button 1 sets the pixel to all zeros and button
2 sets the pixel to all ones.
Across the top of the screen is a textual display of global parameters.
These values, as well as many of the textual values associated
with the images, may be edited by clicking button 1 on the displayed
value and typing a new value. The values along the top of the
screen are:
mag Default magnification.
val(hex)
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The value used to modify pixels within magnified images. The value
must be in hexadecimal, optionally preceded by a tilde for bitwise
negation.
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but1
but2 The pixel value written when the corresponding button is pressed
over a pixel.
invert−on−copy
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Whether the pixel values are inverted when a copy operation is
performed.
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Under button 3 is a menu holding a variety of functions. Many
of these functions prompt for the image upon which to act by switching
to a gunsight cursor; click button 3 over the selection, or click
a different button to cancel the action.
open Read and display a file. The name of the file is typed to
the prompt on the bottom line.
read Reread a file.
writeWrite a file.
copy Use the copy function, default S, to transfer a rectangle
of pixels from one image to another. The program prompts with
a cross cursor; sweep out a rectangle in one image or just click
button 3 to select the whole image. The program will leave that
rectangle in place and attach another one to the cursor. Move
that rectangle to the desired place
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in any image and click button 3, or another button to cancel the
action.
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char As described above, open a magnified view of a character image
in a subfont.
pixels
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Report the coordinate and value of individual pixels indicated
by pressing button 3. This is a mode of operation canceled by
pressing button 1 or 2.
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closeClose the specified image. If the image is the unmagnified
file, also close any magnified views of that file.
exit Quit tweak. The program will complain once about modified
but unwritten files.
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SOURCE
SEE ALSO
BUGS
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For a program written to adjust width tables in fonts, tweak has
been pushed unreasonably far.
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