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MUSHclient scripting

Description of MUSHclient world function: world.WindowGetImageAlpha

Name WindowGetImageAlpha
Type Method
Summary Draws the alpha channel of an image into a miniwindow
Prototype long WindowGetImageAlpha(BSTR WindowName, BSTR ImageId, long Left, long Top, long Right, long Bottom, long SrcLeft, long SrcTop);

View list of data type meanings


This copies the alpha channel of an image to the miniwindow, showing the alpha information as grayscale.

The alpha channel could be used when copying an image onto the miniwindow using the WindowMergeImageAlpha function.

Thus you could use WindowGetImageAlpha to create a scratch window (one not visible to the player) which holds the alpha information. This could then be turned into another image by using WindowImageFromWindow. This image is now available for use with WindowMergeImageAlpha to selectively copy the image to another miniwindow (this image would be used as the MaskId).

Note that changes to miniwindows will not become visible until the output window is redrawn. This happens when new (visible) lines arrive from the MUD, or if you call WindowShow, or Redraw. (In the case of WindowGetImageAlpha you would probably never want to actually show the image, as it is just the alpha, or mask, channel).


WindowName - the name of an existing miniwindow.

ImageId - an image id that you have loaded (which must have an alpha channel - generally this means it will be 32 bits per pixel, which is 8 bits for each of red, green and blue, and 8 bits for the alpha information).

Left, Top, Right, Bottom - describes the rectangle to be drawn to.

SrcLeft, SrcTop - the source offset in the original image (use 0,0 to get the whole image).

Note: Available in version 4.52 onwards.

Lua example
WindowGetImageAlpha (win, "im", 20, 20, 0, 0)
Returns eNoSuchWindow - no such miniwindow

eImageNotInstalled - that image was not loaded with WindowLoadImage (or WindowLoadImageMemory), or the image does not have an alpha channel.

eOK - completed OK

View list of return code meanings

Introduced in version 4.52

See also ...

Function Description
WindowCreate Creates a miniwindow
WindowCreateImage Creates an image in a miniwindow
WindowDrawImage Draws an image into a miniwindow
WindowDrawImageAlpha Draws an image into a miniwindow respecting the alpha channel
WindowImageInfo Returns information about an image
WindowImageList Lists all images installed into a miniwindow
WindowImageOp Draws an ellipse, rectangle or round rectangle, filled with an image

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