Using Metafiles (1.2)
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Using Metafiles
You can use metafile functions to perform the following tasks:
♦ Create a metafile.
♦ Draw into a metafile.
♦ Load a metafile onto disk.
♦ Load a metafile from disk into an application.
♦ Play a metafile.
♦ Edit a metafile.
Creating and Drawing into a Metafile
To create a metafile, you must perform the following tasks:
1 Create a metafile device context by calling the DevOpenDC function.
2 Create a presentation space by calling the GpiCreatePS function, and
associate the presentation space with the metafile device context.
3 Draw into the metafile by calling various Gpi drawing functions.
4 Disassociate the metafile device context from the presentation space by
calling the GpiAssociate function.
5 Close the metafile device context by calling the DevCloseDC function.
The following code fragment shows how to create a simple metafile that draws
text within the borders of a three-color box:
DEVOPENSTRUC dop;
dop.pszLogAddress = NULL;
dop.pszDriverName = "DISPLAY";
dop.pdriv = NULL;
dop.pszDataType = NULL;
hdcMeta = DevOpenDC(hab,
OD_METAFILE, /* metafile device context */
"*", /* ignores os2.ini */
4L, /* uses first four fields */
(PDEVOPENDATA) &dop, /* device information */
hdc); /* compatible device context */
hpsMeta = GpiCreatePS(hab, hdcMeta,
&sizlPage, PU_PELS | GPIA_ASSOC);
/* Draw a box in a metafile. */
GpiSetColor(hpsMeta, CLR_CYAN);
ptl1.x = 150;
ptl1.y = 200;
GpiMove(hpsMeta, &ptl1);
ptl2.x = 300;
ptl2.y = 275;
GpiBox(hpsMeta, DRO_FILL, &ptl2, 0L, 0L);
GpiSetColor(hpsMeta, CLR_GREEN);
ptl1.x = 300;
ptl1.y = 200;
GpiMove(hpsMeta, &ptl1);
ptl2.x = 390;
ptl2.y = 275;
GpiBox(hpsMeta, DRO_FILL, &ptl2, 0L, 0L);
GpiSetColor(hpsMeta, CLR_YELLOW);
ptl1.x = 390;
ptl1.y = 200;
GpiMove(hpsMeta, &ptl1);
ptl2.x = 530;
ptl2.y = 275;
GpiBox(hpsMeta, DRO_FILL, &ptl2, 0L, 0L);
ptl1.x = 175;
ptl1.y = 230;
GpiMove(hpsMeta, &ptl1);
GpiSetColor(hpsMeta, CLR_PINK);
GpiCharString(hpsMeta, 41L,
"METAFILE COPY METAFILE COPY METAFILE COPY");
GpiAssociate(hpsMeta, NULL);
hmf = DevCloseDC(hdcMeta);
Drawing into a Metafile in Retain Mode
To draw into a metafile, you set the drawing mode to the appropriate value
for your application and then perform the drawing operations. If your
application is a drafting, drawing, or computer-aided-design (CAD)
application, you should set the drawing mode to DM_RETAIN, perform your
drawing operations in retained segments, and then copy the segments to the
metafile. The following code fragment shows how to copy the contents of a
segment into a metafile:
/*
* Open a segment, assign it an identifier of 10,
* and draw some text into it.
*/
GpiSetDrawingMode(hps, DM_RETAIN);
GpiOpenSegment(hps, 10L);
ptl1.x = 175; ptl1.y = 230;
GpiMove(hps, &ptl1);
GpiSetColor(hps, CLR_PINK);
GpiCharString(hps, 41L,
"METAFILE COPY METAFILE COPY METAFILE COPY");
GpiCloseSegment(hps);
GpiAssociate(hps, NULL); /* disassociates PS and screen DC */
GpiAssociate(hps, hdcMeta); /* associates PS and meta DC */
GpiDrawSegment(hps, 10L); /* draws segment into metafile */
GpiAssociate(hps, NULL); /* disassociates PS and meta DC */
hmf = DevCloseDC(hdcMeta); /* closes metafile */
GpiAssociate(hps, hdc); /* associates PS and screen DC */
GpiSetDrawingMode(hps, DM_DRAW); /* sets drawing mode to DM_DRAW */
/*
* Load the array of options for GpiPlayMetaFile
* with default values.
*/
alOpt[0] = 0L; /* reserved */
alOpt[1] = LT_DEFAULT; /* default transformations */
alOpt[2] = 0L; /* reserved */
alOpt[3] = LC_DEFAULT; /* uses default lcids */
alOpt[4] = RES_DEFAULT; /* uses default */
alOpt[5] = SUP_DEFAULT; /* uses default */
alOpt[6] = CTAB_DEFAULT; /* uses default */
alOpt[7] = CREA_DEFAULT; /* uses default */
GpiPlayMetaFile(hps, /* plays metafile onto screen */
hmf, 8L, alOpt, 0L, 0L, NULL);
If you merely want to create a simple drawing in a metafile for repeated
display, you can set the drawing mode to DM_DRAW and draw directly into the
metafile. The code in the first code fragment shows how to do this.
Copying a Metafile onto Disk
You can copy a metafile onto disk by calling the GpiSaveMetaFile function,
and you can load the file back into your application by calling the
GpiLoadMetaFile function. The following code fragment shows how to copy a
metafile into a file named meta.met, then load the same file back into the
application and play it:
GpiSaveMetaFile(hmf, "meta.met"); /* saves metafile on disk */
hmf2 = GpiLoadMetaFile(hab, "meta.met"); /* loads metafile */
alOpt[0] = 0L; /* reserved */
alOpt[1] = LT_DEFAULT; /* uses default transforms */
alOpt[2] = 0L; /* reserved */
alOpt[3] = LC_DEFAULT; /* uses default */
alOpt[4] = RES_DEFAULT; /* uses default */
alOpt[5] = SUP_DEFAULT; /* uses default */
alOpt[6] = CTAB_DEFAULT; /* uses default */
alOpt[7] = CREA_DEFAULT; /* uses default */
GpiPlayMetaFile(hps, /* plays metafile */
hmf2, 8L, alOpt, 0L, 0L, NULL);
Playing a Metafile
You can play the contents of a metafile by calling the GpiPlayMetaFile
function. The following code fragment shows how to play the metafile using
the font, color table, and fill-pattern descriptions in your application's
presentation space:
alOpt[0] = 0L; /* reserved */
alOpt[1] = LT_DEFAULT; /* viewing transformation in PS */
alOpt[2] = 0L; /* reserved */
alOpt[3] = LC_DEFAULT; /* font and fill pattern in PS */
alOpt[4] = RES_DEFAULT; /* page units and dimensions in PS */
alOpt[5] = SUP_DEFAULT; /* draws metafile into PS */
alOpt[6] = CTAB_DEFAULT; /* color table in PS */
alOpt[7] = CREA_DEFAULT; /* sets realizable option */
GpiPlayMetaFile(hps, hmf, 8L, alOpt, 0L, 0L, NULL);
The next code fragment shows how to play a metafile using the font, color
table, and fill-pattern descriptions in the metafile:
alOpt[0] = 0L; /* reserved */
alOpt[1] = LT_DEFAULT; /* viewing transformation in PS */
alOpt[2] = 0L; /* reserved */
alOpt[3] = LC_LOADDISC; /* font and fill pattern in metafile */
alOpt[4] = RES_DEFAULT; /* page units and dimensions in PS */
alOpt[5] = SUP_DEFAULT; /* draws metafile into PS */
alOpt[6] = CTAB_REPLACE; /* color table in metafile */
alOpt[7] = CREA_DEFAULT; /* sets realizable option */
GpiPlayMetaFile(hps, hmf, 8L, alOpt, 0L, 0L, NULL);
The last code fragment shows how to play a metafile using the viewing
transformation, page units, and presentation-page dimensions specified in
the metafile:
alOpt[0] = 0L; /* reserved */
alOpt[1] = LT_ORIGINALVIEW; /* viewing transformation in metafile */
alOpt[2] = 0L; /* reserved */
alOpt[3] = LC_DEFAULT; /* font and fill pattern in PS */
alOpt[4] = RES_RESET; /* page units/dimensions in metafile */
alOpt[5] = SUP_DEFAULT; /* draws metafile into PS */
alOpt[6] = CTAB_DEFAULT; /* uses color table in PS */
alOpt[7] = CREA_DEFAULT; /* sets realizable option */
GpiPlayMetaFile(hps, hmf, 8L, alOpt, 0L, 0L, NULL);
♦