The width (in pixels) to restrict the width of the text to.
The default value is calculated by the width of the output image, minus any padding on the left and right.
If the text exceeds the value of
txtwidth, it will be clipped on a per-character basis; the maximum number of characters that will fit in the specified width will be displayed. The location of the clipping is determined by the value of the
See the API specification for more information about this parameter's value ranges and format.