| xy Data Plotter
#include "gd.h"
#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <math.h>
#include <string.h>
#include "gdfontt.h"
#include "gdfonts.h"
int MINX=0, MINY=0, MAXX=250, MAXY=150;
// Default graphic size
double Wxl, Wxr, Wyb, Wyt, Vxl, Vxr, Vyb,
Vyt;
double WVxm,WVxa,WVym,WVya;
gdImagePtr im;
// Declare the image
int green, black;
// Declare color indexes
void SetSize(int minx, int miny, int maxx, int maxy) {
// Set size of graphics in pixels
MINX=minx; MINY=miny; MAXX=maxx; MAXY=maxy;
}
void SetWindowViewport() {
// Determine constants for
if (Wxr != Wxl)
// WorldtoScreen transform
WVxm = (Vxr-Vxl)/(Wxr-Wxl);
else WVxm = 0.0;
WVxa = Vxl-Wxl*WVxm;
if (Wyt != Wyb)
WVym = (Vyt-Vyb)/(Wyt-Wyb);
else WVym = 0.0;
WVya = Vyb-Wyb*WVym;
}
double xWorldToScreen(double x){
// Transform x World to x Screen
return WVxm*x+WVxa;
}
double yWorldToScreen(double y){
// Transform y World to y Screen
return WVym*y+WVya;
}
void SetViewPort(int x1, int y1, int x2, int y2){
// Define screen viewport
//
Adjust y1 & y2 to (0,0) bottom left from screen (0,0) at top left }
Vxl=x1; Vxr=x2; Vyb=MAXY-y1; Vyt=MAXY-y2;
SetWindowViewport();
}
void SetWindow(double x1, double y1, double x2, double y2) {// Define
real-world window
Wxl=x1; Wxr=x2; Wyb=y1; Wyt=y2;
SetWindowViewport();
}
void ShowLine(double x1, double y1, double x2, double y2){
// Display line on device
gdImageLine(im,(int)xWorldToScreen(x1), (int)yWorldToScreen(y1),
(int)xWorldToScreen(x2), (int)yWorldToScreen(y2),
black);
}
void initializeGraphics() {
SetViewPort(0,0,MAXX,MAXY);
im = gdImageCreate(MAXX+MINX+5, MAXY-MINY+2*gdFontTiny->h);
/* Allocate the image */
green = gdImageColorAllocate(im, 0, 255, 255);
/* Allocate the color green
(red, green and blue all minimum).
Since this is the first color in
a new image, it will
be the background color. */
black = gdImageColorAllocate(im, 0, 0, 0);
/* Allocate the color black (red,
green and blue all maximum). */
}
void close() {
printf( "Content-type: image/png\r\n\r\n");
/* Print HTTP header */
_setmode( _fileno( stdout ), _O_BINARY );
/* Setmode for stdout to binary, necessary for
Windows not to convert \n to \r\n */
gdImagePng(im, stdout);
/* Output the image to stdout in PNG format. */
gdImageDestroy(im);
/* Destroy the image in memory. */
}
void xyPlot(double x[], double y[], int nValues, char xaxis[], char
yaxis[]) {
const int NINTERVALS=10;
unsigned char *buffer = (unsigned char *)(new char[20]);
double xmin, ymin, xmax, ymax;
double xinterval, yinterval;
int i;
xmin=x[0]; xmax=xmin; ymin=y[0]; ymax=ymin;
for (i=0; i<nValues; i++) {
xmin = x[i] < xmin ? x[i] : xmin;
ymin = y[i] < ymin ? y[i] : ymin;
xmax = x[i] > xmax ? x[i] : xmax;
ymax = y[i] > ymax ? y[i] : ymax;
}
xinterval = fabs(xmax-xmin)/(NINTERVALS-1);
yinterval = fabs(ymax-ymin)/(NINTERVALS-1);
initializeGraphics();
SetWindow(xmin,ymin,xmax,ymax);
// Graph region in world coordinates
SetViewPort(MAXX/6 , MAXY/5, MAXX, MAXY);
for (i=0; i<nValues-1; i++)
ShowLine(x[i],y[i],x[i+1],y[i+1]);
for (i=0; i<nValues; i++)
gdImageRectangle(im, (int) xWorldToScreen(x[i])-2, (int)
yWorldToScreen(y[i])-2,
(int) xWorldToScreen(x[i])+2,
(int) yWorldToScreen(y[i])+2, black);
ShowLine(xmin,ymax,xmin,ymin);
ShowLine(xmin,ymin,xmax,ymin);
// Axis
SetWindow(xmin,ymin,xmax,ymin+yinterval);
SetViewPort(MAXX/6,0,MAXX,MAXY/5);
for (i=0; i<NINTERVALS; i++) {
// X tics
sprintf( (char *)buffer, "%.2f", xmin+xinterval*i );
gdImageStringUp(im, gdFontTiny, (int) xWorldToScreen(xmin+xinterval*i)
- gdFontSmall->h/2,
(int)
yWorldToScreen(ymin+yinterval)
+(strlen((const
char *)buffer) * gdFontTiny->w),
buffer,
black);
}
SetWindow(xmin,ymin,xmin+xinterval,ymax);
SetViewPort(0,MAXY/5,MAXX/6,MAXY);
strcpy((char *) buffer, xaxis);
gdImageString(im, gdFontTiny,
(int) xWorldToScreen(xmax/2)-(gdFontTiny->h*strlen((const
char *) buffer)),
(int) yWorldToScreen(ymin)+4*(gdFontTiny->h),
buffer, black);
strcpy((char *) buffer, yaxis);
gdImageStringUp(im, gdFontTiny, (int) xWorldToScreen(xmin),
(int) yWorldToScreen(ymax/2)+2*(gdFontTiny->h), buffer, black);
for (i=0; i<NINTERVALS; i++) {
// Y tics
ShowLine(xmin+xinterval/4,ymin+yinterval*i,xmin+xinterval,ymin+yinterval*i);
sprintf( (char *)buffer, "%.2f", ymin+yinterval*i );
gdImageString(im, gdFontTiny, (int) xWorldToScreen(xmin+xinterval/4),
(int)
yWorldToScreen(ymin+yinterval*i-yinterval/nValues),
buffer,
black);
}
close();
}
void main() {
double x[12] = { 1,2,3,4,5,6,7,8,9,10,11,12};
double y[12] = { 1,2,3,4,5,6,-6,-5,-4,-3,-2,-1};
xyPlot(x,y, 12, "X-Axis", "Y-Axis");
} |
| URL - http://localhost/Graphics/xy.exe
|
Example using XY data plotter in an HTML Document
Using the HTML IMG tag the CGI graphic can be placed anywhere
that a regular image would within
an HTML document. Assuming the xy data plotter CGI were on virtual
drive Graphics the following tag would display the data plot
produced by xy.exe within an HTML document:
<img SRC="http://localhost/graphics/xy.exe">
|
Use - A simple xy plot library xy.lib can be used to generate
xy data plots by calling the xyPlot function. In the current version,
the main function must be written to specify:
-
x data
-
y data
-
number of data points to plot
-
label for x-axis
-
label for y-axis
The following plotted the above examples:
void xyPlot(double x[], double y[], int nValues, char xaxis[],
char yaxis[]);
void SetSize(int minxx, int miny, int maxx, int maxy);
void main() {
double x[12] = { 1,2,3,4,5,6,7,8,9,10,11,12};
double y[12] = { 1,2,3,4,5,6,-6,-5,-4,-3,-2,-1};
SetSize(0, 0, 250, 150);
xyPlot(x,y, 12, "X-Axis", "Y-Axis");
}
Example - To run the above example:
-
Download zip file with xy library, test.cpp, and
project file for VC++
-
Unzip to any virtual directory with execute rights, perhaps Graphics.
-
In a browser enter URL: http://localhost/Graphics/Debug/xyPlot.exe
Compiling
-
Download zip file with xy library, test.cpp, and
project file for VC++
-
Unzip to any virtual directory, perhaps Graphics.
-
Point Windows Explorer to the xyPlot.dsw file to use as project
file in VC++.
-
Make any changes to the test.cpp file.
-
In VC++ enter: Build | xyPlot.exe
-
In a browser enter URL: http://localhost/Graphics/Debug/xyPlot.exe
Command line compiling, linking and running test.cpp as xyPlot.exe
C:\"Program Files\Microsoft Visual Studio\VC98\Bin\Vcvars32.bat"
cl /c test.cpp /FoxyPlot.obj
link /NODEFAULTLIB:"MSVCRT" /NODEFAULTLIB:"LIBC" /out:Debug/xyPlot.exe
test.obj gd.lib libpng.lib zlib.lib xy.lib
debug\xyPlot |
Hints
-
Because a box is placed at each data point (x,y) pair, large data sets
will run the boxes together creating an unsightly, fat line. You're welcome
to change the xy source to not do boxes.
-
In VC++, if the linker complains about multiply defined functions, follow
its advice and enter:
Profile | Settings | Link
then add to the Project Options
/NODEFAULTLIB:MSVCRT /NODEFAULTLIB:LIBC
-
Larger or smaller PNG images can be produced by changing the program line:
-
The browser must be told by the server (the xyPlot CGI in this case) that
the file its receiving is an image/png. This is done in the C++
program before the graphics file is written to standard output by:
printf( "Content-type: image/png\r\n\r\n");
|
