1g.pnmcomp(1)                GRASS GIS User's Manual               g.pnmcomp(1)
2
3
4

NAME

6       g.pnmcomp  - Overlays multiple PPM image files.
7

KEYWORDS

9       general, display
10

SYNOPSIS

12       g.pnmcomp
13       g.pnmcomp --help
14       g.pnmcomp    input=name[,name,...]    [mask=name[,name,...]]     [opac‐
15       ity=float[,float,...]]  output=name  [output_mask=name]   width=integer
16       height=integer   [bgcolor=name]    [--overwrite]  [--help]  [--verbose]
17       [--quiet]  [--ui]
18
19   Flags:
20       --overwrite
21           Allow output files to overwrite existing files
22
23       --help
24           Print usage summary
25
26       --verbose
27           Verbose module output
28
29       --quiet
30           Quiet module output
31
32       --ui
33           Force launching GUI dialog
34
35   Parameters:
36       input=name[,name,...] [required]
37           Name of input file(s)
38
39       mask=name[,name,...]
40           Name of input mask file(s)
41
42       opacity=float[,float,...]
43           Layer opacities
44
45       output=name [required]
46           Name for output file
47
48       output_mask=name
49           Name for output mask file
50
51       width=integer [required]
52           Image width
53
54       height=integer [required]
55           Image height
56
57       bgcolor=name
58           Background color
59           Either a standard color name or R:G:B triplet
60

DESCRIPTION

62       g.pnmcomp isn’t meant for end users. It’s an internal tool for  use  by
63       wxGUI.
64
65       In  essence,  g.pnmcomp generates a PPM image by overlaying a series of
66       PPM/PGM pairs (PPM = RGB image, PGM = alpha channel).
67

NOTES

69       The intention is that d.* modules will emit PPM/PGM pairs  (by  way  of
70       the  PNG-driver  code  being  integrated into Display Library). The GUI
71       will manage a set of layers; each layer consists of the data  necessary
72       to  generate  a  PPM/PGM  pair.  Whenever the layer "stack" changes (by
73       adding, removing, hiding, showing or re-ordering layers), the GUI  will
74       render  any  layers for which it doesn’t already have the PPM/PGM pair,
75       then re-run g.pnmcomp to generate the final  image  (just  redoing  the
76       composition is a lot faster than redrawing everything).
77
78       A C/C++ GUI would either have g.pnmcomp’s functionality (image composi‐
79       tion) built-in, or would use the system’s graphics API to perform  com‐
80       position  (for  translucent layers, you would need OpenGL or the Render
81       extension, or something else which supports translucent rendering).
82
83       Tk doesn’t support transparent (masked)  true-colour  images  (it  does
84       support  transparent  GIFs,  but that’s limited to 256 colours), and an
85       image composition routine in Tcl would be unacceptably slow, hence  the
86       existence of g.pnmcomp.
87

SEE ALSO

89        g.cairocomp
90

AUTHOR

92       Glynn Clements
93

SOURCE CODE

95       Available at: g.pnmcomp source code (history)
96
97       Main  index | General index | Topics index | Keywords index | Graphical
98       index | Full index
99
100       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
101
102
103
104GRASS 7.8.5                                                       g.pnmcomp(1)