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Tk_GetDash − convert from string to valid dash structure.
#include <tk.h>
int
Tk_GetDash(interp, string, dashPtr)
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Tcl_Interp *interp (in) |
Interpreter to use for error reporting. | ||
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const char * string (in) |
Textual value to be converted. | ||
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Tk_Dash *dashPtr (out) |
Points to place to store the dash pattern value converted from string. |
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These procedure parses the string and fills in the result in the Tk_Dash structure. The string can be a list of integers or a character string containing only “.,−_” or spaces. If all goes well, TCL_OK is returned. If string does not have the proper syntax then TCL_ERROR is returned, an error message is left in the interpreter’s result, and nothing is stored at *dashPtr.
The first possible syntax is a list of integers. Each element represents the number of pixels of a line segment. Only the odd segments are drawn using the “outline” color. The other segments are drawn transparent.
The second possible syntax is a character list containing only 5 possible characters “.,−_ ”. The space can be used to enlarge the space between other line elements, and can not occur as the first position in the string. Some examples:
−dash . = −dash {2
4}
−dash − = −dash {6 4}
−dash −. = −dash {6 4 2 4}
−dash −.. = −dash {6 4 2 4 2 4}
−dash {. } = −dash {2 8}
−dash , = −dash {4 4}
The main difference of this syntax with the previous is that it is shape-conserving. This means that all values in the dash list will be multiplied by the line width before display. This assures that “.” will always be displayed as a dot and “−” always as a dash regardless of the line width.
On systems where only a limited set of dash patterns, the dash pattern will be displayed as the most close dash pattern that is available. For example, on Windows only the first 4 of the above examples are available. The last 2 examples will be displayed identically as the first one.
dash, conversion