gdtclft(n)gdtclft(n)NAMEgdtclft - render PNG images
DESCRIPTION
TCL GD EXTENSION
Thomas Boutell's Gd package provides a convenient way to generate
PNG images with a C program. If you, like me, prefer Tcl for CGI
applications, you'll want my TCL GD extension.
A TCL INTERFACE TO THE GD PACKAGE
Spencer W. Thomas
Human Genome Center
University of Michigan
Ann Arbor, MI 48109
spencer.thomas@med.umich.edu
TrueType font support using the FreeType library was added by
John Ellson (ellson@graphviz.org).
FreeBSD port maintained by Mikhail Teterin (mi@aldan.algebra.com).
Overview
This package provides a simple Tcl interface to the gd (PNG drawing)
package. It includes an interface to most of the gd functions
and data structures from Tcl commands.
Reference
One Tcl command, 'gd', is added. All gd package actions are
sub-commands (or "options" in Tcl terminology) of this command.
Each active gd image is referred to with a "handle". The handle is a
name of the form gd# (e.g., gd0) returned by the gd create options.
Almost all the gd commands take a handle as the first argument (after
the option). All the drawing commands take a color_idx as the next
argument.
gd create <width> <height> ?true?
Return a handle to a new gdImage that is width X height.
If "true" is specified, the new image is "TrueColor".
gd createFromGD <file>
gd createFromGD2 <file>
gd createFromGIF <file>
gd createFromJPG <file>
gd createFromPNG <file>
gd createFromWBMP <file>
gd createFromXBM <file>
gd createFromXPM <filename>
Return a handle to a new gdImage created by reading a PNG
(resp. GD or XBM) image from the <file>, which is either
a TCl filehandle, or a filename (except for XPM, which only
accepts filenames).
gd destroy <gdhandle>
Destroy the gdImage referred to by gdhandle.
gd writeGD <gdhandle> <file>
gd writeGD2 <gdhandle> <file>
gd writeGIF <gdhandle> <file>
gd writeJPG <gdhandle> <file> ?quality?
gd writePNG <gdhandle> <file>
gd writeWBMP <gdhandle> <file> fgpixel
Write the image in gdhandle to <file> (filehandle or filename)
in one of the specified formats.
gd writePNGvar <gdhandle> <varname>
Write the image in gdhandle to Tcl variable "varname" as a binary
coded PNG object.
gd interlace <gdhandle> <on-off>
Make the output image interlaced (if on-off is true) or not (if
on-off is false).
gd color new <gdhandle> <red> <green> <blue>
Allocate a new color with the given RGB values. Returns the
color_idx, or -1 on failure (256 colors already allocated).
gd color exact <gdhandle> <red> <green> <blue>
Find a color_idx in the image that exactly matches the given RGB
color. Returns the color_idx, or -1 if no exact match.
gd color closest <gdhandle> <red> <green> <blue>
Find a color in the image that is closest to the given RGB color.
Guaranteed to return a color idx.
gd color resolve <gdhandle> <red> <green> <blue>
Return the index of the best possible effort to get a color.
Guaranteed to return a color idx. Equivalent to:
if {[set idx [gd color exact $gd $r $g $b]] == -1} {
if {[set idx [gd color neW $Gd $r $g $b]] == -1} {
set idx [gd color closest $gd $r $g $b]
}
}
gd color free <gdhandle> <color_idx>
Free the color at the given color_idx for reuse.
gd color transparent <gdhandle> [<color_idx>]
Mark the color at <color_idx> as the transparent background color. Or,
return the transparent color_idx if no color_idx specified.
gd color get <gdhandle> [<color_idx>]
Return the RGB value at <color_idx>, or {} if it is not allocated.
If <color_idx> is not specified, return a list of {color_idx R G B}
values for all allocated colors.
gd brush <gdhandle> <brushhandle>
Set the brush image to be used for brushed lines. Transparent
pixels in the brush will not change the image when the brush is
applied.
gd style <gdhandle> <color_idx> ...
Set the line style to the list of color indices. This is
interpreted in one of two ways. For a simple styled line, each
color is applied to points along the line in turn. The
transparent color_idx value may be used to leave gaps in the line.
For a styled, brushed line, a 0 (or the transparent color_idx)
means not to fill the pixel, and a non-zero value means to
apply the brush.
gd tile <gdhandle> <tilehandle>
Set the tile image to be used for tiled fills. Transparent
pixels in the tile will not change the underlying image during
tiling.
In all drawing functions, the color_idx is a number, or may
be one of the strings styled, brushed, tiled, "styled brushed"
or "brushed styled". The style, brush, or tile currently in
effect will be used. Brushing and styling apply to lines,
tiling to filled areas.
gd set <gdhandle> <color_idx> <x> <y>
Set the pixel at (x,y) to color <color_idx>.
gd line <gdhandle> <color_idx> <x1> <y1> <x2> <y2>
gd rectangle <gdhandle> <color_idx> <x1> <y1> <x2> <y2>
gd fillrectangle <gdhandle> <color_idx> <x1> <y1> <x2> <y2>
Draw the outline of (resp. fill) a rectangle in color <color_idx>
with corners at (x1,y1) and (x2,y2).
gd arc <gdhandle> <color_idx> <cx> <cy> <width> <height> <start> <end>
Draw an arc in color <color_idx>, centered at (cx,cy) in a rectangle width
x height, starting at start degrees and ending at end degrees.
start must be > end.
gd polygon <gdhandle> <color_idx> <x1> <y1> ...
gd fillpolygon <gdhandle> <color_idx> <x1> <y1> ...
Draw the outline of, or fill, a polygon specified by the x, y
coordinate list. There must be at least 3 points specified.
gd fill <gdhandle> <color_idx> <x> <y>
gd fill <gdhandle> <color_idx> <x> <y> <borderindex>
Fill with color <color_idx>, starting from (x,y) within a region of
pixels all the color of the pixel at (x,y) (resp., within a
border colored borderindex).
gd size <gdhandle>
Returns a list {width height} of the image.
gd text <gdhandle> <color_idx> <fontpath> <size> <angle> <x> <y> <string>
Draw text using the .ttf font in <fontpath> in color <color_idx>,
with pointsize <size>, rotation in radians <angle>, with lower left
corner at (x,y). String may contain UTF8 sequences like: "À"
Returns 4 corner coords of bounding rectangle.
Use gdhandle = {} to get boundary without rendering.
Use negative of color_idx to disable antialiasing.
gd copy <desthandle> <srchandle> <destx> <desty> <srcx> <srcy> <w> <h>
gd copy <desthandle> <srchandle> <destx> <desty> <srcx> <srcy> \
<destw> <desth> <srcw> <srch>
Copy a subimage from srchandle(srcx, srcy) to desthandle(destx,
desty), size w x h.
Or, resize the subimage in copying from srcw x srch to destw x
desth.
EXAMPLES
The sample program from the gd documentation can be written thusly:
################################################################ # Sam‐
ple gdtcl program # # Create a 64 x 64 image set im [gd create 64 64]
# Get black and white as colors. Black is the background color because
# it is allocated first from a new image.
set black [gd color new $im 0 0 0] set white [gd color new $im 255 255
255]
# Draw a line from upper left to lower right gd line $im $white 0 0 63
63
# Open a file for writing (Tcl on Unix, at least, doesn't support 'wb'
mode) set out [open test.png w]
# Output the image to the disk file gd writePNG $im $out
# Close the file close $out
# Destroy the image in memory gd destroy $im
GDDEMO
Here's the gddemo.c program translated to tcl.
################################################################ # #
gddemo in tcl #
# Create output image 128 x 128 set im_out [gd create 128 128]
# First color is background set white [gd color new $im_out 255 255
255]
# Set transparent gd color transparent $im_out $white
# Load demoin.png and paste part of it into the output image. if
{[catch {set in [open demoin.png]}]} {
puts stderr "Can't load source image; this demo is much";
puts stderr "more impressive if demoin.png is available";
set im_in ""; } else {
set im_in [gd createFromPNG $in]
close $in
# Copy and shrink
gd copy $im_out $im_in 16 16 0 0 96 96 128 128 }
# Get some colors set red [gd color new $im_out 255 0 0] set green [gd
color new $im_out 0 255 0] set blue [gd color new $im_out 0 0 255]
# Draw a rectangle gd line $im_out $green 8 8 120 8 gd line $im_out
$green 120 8 120 120 gd line $im_out $green 120 120 8 120 gd line
$im_out $green 8 120 8 8
# Text gd text $im_out $red /usr/lib/ttf/arial.ttf 20 0 16 16 hi gd
text $im_out $red /usr/lib/ttf/arial.ttf 20 90 23 23 hi
# Circle gd arc $im_out $blue 64 64 30 10 0 360
# Arc gd arc $im_out $blue 64 64 20 20 45 135
# Flood fill gd fill $im_out $blue 4 4
# Polygon gd fillpolygon $im_out $green 32 0 0 64 64 64
# Brush. A fairly wild example also involving a line style! if {$im_in
!= ""} {
set brush [gd create 8 8];
eval [concat gd copy $brush $im_in 0 0 0 0 [gd size $brush] [gd size
$im_in]]
gd brush $im_out $brush
# Style so they won't overprint each other.
gd style $im_out [concat [replicate "0 " 7] 1]
gd line $im_out "styled brushed" 0 0 128 128 }
# Interlace the result for "fade in" in viewers that support it gd
interlace $im_out true
# Write PNG set out [open demoout.png w] gd writePNG $im_out $out close
$out gd destroy $im_out
GDSHOW
A quick Tcl procedure to display a GD image using the xv program.
################################################################ #
gdshow -- use xv to display an image. # # Waits until xv quits to
return. # proc gdshow {gd} {
set f [open "|xv -" w]
catch {gd writePNG $gd $f}
catch {close $f} xx
if {$xx != {}} {
error "XV error: $xx"
} }
SEE ALSO
You will find Thomas Boutell's documentation for the underlying GD
library quite useful, especially, if you are dealing with WBMP
format.
Tcl-Extensions 8.0 gdtclft(n)
