world.WindowDrawImageAlpha

MUSHclient script function (Method) — introduced in version 4.42

Draws an image into a miniwindow respecting the alpha channel

Prototype

long WindowDrawImageAlpha(BSTR WindowName, BSTR ImageId, long Left, long Top, long Right, long Bottom, double Opacity, long SrcLeft, long SrcTop);

Data type meanings

Description

This copies an image to the miniwindow, using the alpha channel to show transparent areas.

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.

Parameters:

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.

Opacity - the amount of opacity, between 0 and 1 (floating-point number). An opacity of 0 means you will not see the drawn image. An opacity of 1 means the image is fully drawn (apart from where the alpha channel makes part of it opaque). An opacity of 0.5 means the image is merged 50% with the original contents of the miniwindow.

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

The intention of allowing sub-images was so that you could make up a map by having lots of small images (eg. houses, trees, rocks). Now instead of having to load hundreds of tiny image files into memory, which would doubtless take a while to open all those files, you open a single, larger, file in which the various sub-images are "tiled". For example, you might allocate a 32 x 32 pixel square for each image. Now by selecting the appropriate tile you can copy the sub-image from the main image.

For more information, see:

http://www.gammon.com.au/forum/?id=9568

Lua example

WindowDrawImageAlpha (win, "im", 20, 20, 0, 0, 1)

Return value

eNoSuchWindow - no such miniwindow

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

eBadParameter - opacity not in range 0 to 1.

eOK - completed OK

Return code meanings

Related topic

MiniWindows

See also