2 Visual Components Manuals

The C editor is opened by double−clicking on the 'visu.c' file in the Software view.
You will create the actual program in the next step.
4.2.3.5 Visapi − Tutorial − Finishing the C Example
A rectangle, a line, and an ellipse should be drawn in this example. A text should also be output.
To do this, input the following program code in the 'visu.c' file:
#include
#include #include _LOCAL UINT ready; _LOCAL UINT x1; _LOCAL
UINT x2; _LOCAL UINT y1; _LOCAL UINT y2; _LOCAL USINT fill; _LOCAL USINT color; _LOCAL UINT heigth;
_LOCAL UINT width; _LOCAL UDINT VC_HANDLE; _INIT void Initialization(void) { x1 = 150; y1 = 100; x2
= 100; y2 = 150; fill = 255; /* Transparent */ color = 0; /* Black */ heigth = 40; width = 80; ready
= 0; } _CYCLIC void Cyclic(void) { if (!ready) { VC_HANDLE = VA_Setup(1 , "vga"); if (VC_HANDLE) ready
= 1; } if (ready) { if (!VA_Saccess(1,VC_HANDLE)) /* Reserves access to the visualization */ {
VA_Rect (1,VC_HANDLE,x1,y1,x2,y2,fill,color); /* Draw rectangle */ VA_Line
(1,VC_HANDLE,x1,y1,x2,y2,color); /* Draw line */ VA_Ellipse
(1,VC_HANDLE,x2,y2,height,width,fill,color); /* Draw ellipse */ /* Text output */ VA_Textout
(1,VC_HANDLE,1,50,50,color,fill,"A rectangle, a line, and an ellipse"); VA_Srelease(1,VC_HANDLE);
/* Releases the visualization */ } } }
You can naturally use the Windows Clipboard to copy this source code into Automation Studio.
The program is very short and constrained on purpose to encourage experimentation. It would be best to
compile the program now and load it to Automation Runtime. But first change the 'vga' string variable in the
VA_Setup function in the cyclic part and replace it with the name of the visualization project to which output
should take place.
Expand the program to include more output or change the parameters either in the program or using the Watch
command in Automation Studio. If necessary, use the Visapi Documentation in the reference manual to refer to
details.
The following is a brief overview of the example code:
Introduction to Visual Components 2.3
• Some variables are defined in the Initialization part of the task which mostly serve as place holders for
the position and color of the elements to be drawn. An exception is the ready variable. This variable
makes a note of whether the Visapi library was completely and successfully initialized.
• Using VA_Setup, the first part of the program establishes a connection to the Visual Components
interpreter or to its management routine (aplib.br), the runtime. This is necessary, since both the
interpreter and the Visapi functions access the same resources, and accessing these resources must be
managed.
• If the function is successful, a unique VCHandle is returned. This is necessary since several Visual
Components projects can run at the same time. Therefore an exact differentiation must be made
regarding the destination of the Visapi functions (to which project and also to which display).
Subsequently, the handle must be transferred with every other Visapi function.
• If VA_Setup fails (returns 0) , then the function in the example is called cyclically until a valid handle is
returned. As soon as VA_Setup was successfully executed and a handle is available, the ready
variable is set to 1 and the actual working part of the task is 'released'.
270 4.2.3.5 Visapi − Tutorial − Finishing the C Example