Hello Thomas,
(I apologize for not writing in German, but my German is barely good enough to read. Attempting to write would have been comical).
If I understand your request correctly, I would imagine that Wolfgang's suggestion of placing the rectangles behind your line plot should do the job. However, if you really need the rectangles to be partially transparent you can still do so. This is how you would do it:
- Create a bitmap with an alpha channel using the NewBitmapEx. The values in the alpha channel determine the level of transparency that you would like to have. Because your bitmap is just a simple rectangle, setting the values for the bitmap should be trivial. The exact width/height dimensions of the bitmap are not very important, since it will be stretched to fit the exact areas of the graph that you need it to occupy.
- Create an empty bitmap plot, using PlotBitmap. Normally you pass the filename that contains the bitmap. But by passing NULL as the filename, you can then set the bitmap later on, from memory.
- Set the bitmap programmatically, using SetCtrlBitmap.
- Discard the bitmap.
Here's some example code:
#define COLOR VAL_RED
#define TRANSPARENCY 128
#define WIDTH 100
#define HEIGHT 20
unsigned char alpha[WIDTH*HEIGHT];
unsigned int data[WIDTH*HEIGHT], i, j;
int bitmap, plot;
for (i = 0; i < WIDTH; i++)
for (j = 0; j < HEIGHT; j++)
{
data[i+j*WIDTH] = COLOR;
alpha[i+j*WIDTH] = TRANSPARENCY;
}
NewBitmapEx (WIDTH*sizeof(int), 32, WIDTH, HEIGHT, 0, (unsigned char *)data, 0, alpha, &bitmap);
plot = PlotBitmap (panelHandle, PANEL_GRAPH, 0.0, 1.5, 120.0, 0.5, 0);
SetCtrlBitmap (panelHandle, PANEL_GRAPH, plot, bitmap);
DiscardBitmap (bitmap);
Message Edited by LuisG on 04-29-2010 11:46 AM
