| image = variable holding the file handle to the image |
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When an image is loaded with LoadImage, the image handle (the location within the image where the image is 'drawn from') is always defaulted to the top left corner (coordinates 0,0). This means if you draw an image that is 50x50 pixels at screen location 200,200, the image will begin to be drawn at 200,200 and extend to 250,250.
This command moves the image handle from the 0,0 coordinate of the image to the exact middle of the image. Therefore, in the same scenario above, if you were to draw a 50x50 pixel image at screen location 200,200 with its image handle set to Mid with this command, the image would start drawing at 175,175 and extend to 225,225. You can manual set the location of the image's handle using the HandleImage command. You can retrieve an image's handle using the ImageXHandle and ImageYHandle. Finally, you can make all images automatically load with the image handle set to middle using the AutoMidHandle command. Note about the term 'handle'. There are two types of 'handles' we discuss in these documents. One is the location within an image - as discussed in this command. The other is a 'file handle', a variable used to hold an image, sound, or font loaded with a command. See LoadImage for more information about file handles. |
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; MidHandle/ImageXHandle()/ImageYHandle()/AutoMidHandle
; Initiate Graphics Mode Graphics 640,480,16 ; Set up the image file handle as a global Global gfxBall ; Load the image - you may need to change the location of the file gfxBall=LoadImage ("C:Program FilesBlitz Basicsamplesall.bmp") ; Until the user presses ESC key ... While Not KeyHit(1) Text 0,0,"Default Image Handle for gfxBall... Press ESC ..." Text 0,14,"X handle-" + ImageXHandle(gfxBall) ; Print the location of the image handle x location Text 0,28,"Y handle-" + ImageYHandle(gfxBall) ; Print the location of the image handle y location DrawImage gfxBall,200,200,0 ; draw the image at 200,200 Wend ; Clear the screen Cls ; Set the ball's handle to the center of the image MidHandle gfxBall ; Until the user presses ESC key ... show the new information While Not KeyHit(1) Text 0,0,"New Image Handle for gfxBall... Press ESC ..." Text 0,14,"X handle-" + ImageXHandle(gfxBall) Text 0,28,"Y handle-" + ImageYHandle(gfxBall) DrawImage gfxBall,200,200,0 Wend ; Makes all images load up with their handles in the center of the image AutoMidHandle True Cls ; Load the image again gfxBall=LoadImage ("C:Program FilesBlitz Basicsamplesall.bmp") ; Until the user presses ESC key ... show the new information While Not KeyHit(1) Text 0,0,"Automatic image handle of gfxBall... Press ESC ..." Text 0,14,"X handle-" + ImageXHandle(gfxBall) Text 0,28,"Y handle-" + ImageYHandle(gfxBall) DrawImage gfxBall,200,200,0 Wend |