pic_drawspecialback

#Pic.DrawSpecialBack

##Syntax Pic.DrawSpecialBack (picID, x, y, mode, transition, duration : int)

##Description Pic.DrawSpecialBack is very similar to pic_drawspecial.html. The onlydifference is that Pic.DrawSpecialBack returns immediatelyafter being called and program execution continues while the specialeffect continues. This allows you to continue to draw other graphicswhile the special effect is continuing.

For example, this procedure is necessary if you want to have two pictures being drawn using special effects simultaneously.

##Details If you are wish to have several images displayed at the same timeusing special effects, you must use Pic.DrawSpecialBack to display all the images but the last and then use Pic.DrawSpecial to display the last image so that Turing will wait until the special effects are completed before continuing execution.

If you want to draw the several special effects continuously overthe same location, do not use Pic.DrawSpecialBack.

**Pic.DrawSpecial** (_pic1_, 10, 10, _picCopy_, _picWipeLeftToRight_, 500)**Pic.DrawSpecial** (_pic2_, 10, 10, _picCopy_, _picFadeIn_, 1000)

If you do, Turing will attempt to run each of the calls at the sametime, and most of the special effects will not be seen.

##Description Pic.DrawSpecialBack is used to draw a picture on the screenwith a special effect such as a wipe, a slide, or a fade-in. Note that all the parameters are identical to the parameters of**pic_drawspecial.html**.The picture is drawn with the lower left corner at (x, y). The duration specifies how long thetransition should take in milliseconds. For example, a fade-in couldbe specified to last 1/2 a second by using a duration of 500.

The mode parameter is the same as in Pic.New and has one of the following values:

picCopy This draws the picture on top of what was underneath, obscuring it completely. picXor This draws the picture XORing it with the background. In DOS, you can use this function to do animation. Drawing an object on top of itself with XOR erases it and restores the background. picMerge This draws the picture like picCopy except that any occurrence of the background color in the picture is not drawn to the screen. This allows you to draw an irregularly-shaped object and draw it to the screen. picUnderMerge This draws the picture, but only where the background color was displayed underneath it. The effect of this is to make the picture appear to be displayed behind the background.

See pic_drawspecial.html for thelist of possible values for the transition parameter.

##Details The Pic.DrawSpecialBack requires a moderately fast machine to operate successfully (Pentium III or higher). The _picFadeIn_and picBlend transitions do not work well on 8-bit (256 color)displays. On Microsoft Windows machines, you can determine the bit-depth of the display (the number of colors available) by selecting the Display control panel from the Start menu. You can also use the

**Config.Display** (**cdNumMaxColors**)

function to determine the bit-depth of the display (anything over 256 colors will produce acceptable results).

##Details If the Pic.DrawSpecialBack call fails, Error.Last will return a non-zero value indicating the reason for the failure. Error.LastMsg will return a string which contains the textual version of the error.

##Example The program draws a blue star on the screen, then a red circle, thenproceeds to have to have the two replace each simultaneously, side-by-side.

    var redID, blueID: int
    Draw.FillStar (0, 0, 100, 100, brightred)
    redID := Pic.New (0, 0, 100, 100)
    cls
    Draw.FillOval (50, 50, 50, 50, brightblue)
    blueID := Pic.New (0, 0, 100, 100)
    cls
Pic.DrawSpecialBack (redID, 10, 10, picCopy, picWipeLeftToRightNoBar, 1000)
Pic.DrawSpecial (blueID, 160, 10, picCopy, picWipeRightToLeftNoBar, 1000)
Pic.DrawSpecialBack (blueID, 10, 10, picCopy, picSlideLeftToRightNoBar, 1000)
Pic.DrawSpecial (redID, 160, 10, picCopy, picSlideRightToLeftNoBar, 1000)
Pic.DrawSpecialBack (redID, 10, 10, picCopy, picGrowRightToLeftNoBar, 1000)
Pic.DrawSpecial (blueID, 160, 10, picCopy, picGrowLeftToRightNoBar, 1000)
Pic.DrawSpecialBack (blueID, 10, 10, picCopy, picWipeTopToBottomNoBar, 1000)
Pic.DrawSpecial (redID, 160, 10, picCopy, picWipeTopToBottomNoBar, 1000)
Pic.DrawSpecialBack (redID, 10, 10, picCopy, picFadeIn, 1000)
Pic.DrawSpecial (blueID, 160, 10, picCopy, picFadeIn, 1000)
    Pic.Free (redID)
    Pic.Free (blueID)

##Status Exported qualified.

This means that you can only call the function by calling Pic.DrawSpecialBack, not by calling DrawSpecialBack.

##See also pic_draw.html for information on the meaningof the mode argument.

pic_drawspecial.html for information on how to draw special effects and wait for completionof the effect.