This shows how to XOR text on top of a gauge in a miniwindow. First - what is the problem? Say I have a gauge that can change colour (using a gradient), and I want to overlay text on top of it. The text might be the text equivalent of what the gauge is showing (eg. 50% mana). The trouble is, on top of a gradient, no one colour of text works well. Let's choose black:
No, that is hard to read. How about white?
What we really want is for the text to continually change colour, so it is readable. This is how to do it. First - the end result:
Here is the code to do that:
win = GetPluginID ()
wint = win .. "/text"
gauge_width = 100
gauge_height = 20
gauge_x = 20
gauge_y = 100
percentage = 80
-- Make visible window to show gauge
WindowCreate (win, 0, 0, 200, 200, 12, 0, 0xFFFFFF) -- create window
WindowShow (win, true) -- show it
-- Make window for text, add font to it
WindowCreate (wint, 0, 0, gauge_width, gauge_height, 12, 0, 0x000000)
WindowFont (wint, "f", "Dina", 9, false, false, false, false) -- define font (Dina)
font_ascent = WindowFontInfo (wint, "f", 2)
-- what to say
message = "Important info"
-- shadow
WindowRectOp (win, 1, gauge_x + 1, gauge_y + 1, gauge_x + gauge_width + 1, gauge_y + gauge_height + 1, 0x999999, 0)
-- draw gradient
WindowGradient (win, gauge_x, gauge_y, gauge_x + gauge_width * percentage / 100, gauge_y + gauge_height,
ColourNameToRGB ("darkred"),
ColourNameToRGB ("green"),
1) -- left to right
-- frame it
WindowRectOp (win, 1, gauge_x, gauge_y, gauge_x + gauge_width, gauge_y + gauge_height, 0x000000, 0)
-- write text in second window
WindowText (wint, "f", message, 0, 0, 0, 0, 0xFFFFFF, false) -- draw message
-- turn into image
WindowImageFromWindow(win, "text", wint)
-- blend text onto gauge (half-way down)
WindowBlendImage (win, "text",
gauge_x + 1, -- left
gauge_y + gauge_height / 2 - font_ascent / 2, -- top
gauge_x + gauge_width, --right
gauge_y + gauge_height, -- bottom
33, -- blend mode - XOR
1) -- opacity - 100%
What this does is draw the text into a second window (called "wint" above). This second window is never shown directly, it is only used to hold an image which is them blended with an XOR (blending mode 33) on top of the gauge. The XOR operation inverts the underlying bits. I have made the text white on black, as black does not change the underlying image with an XOR. However white will invert it - thus each part of the text inverts the gauge under it.
