TRANS

• 来源: https://www.freebasic.net/wiki/wikka.php?wakka=KeyPgTransGfx
• 最后更新: 2020-12-19

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Put 图形语句的参数，选择透明背景作为位图传输方法

语法

Put [ target, ] [ STEP ] ( x,y ), source [ ,( x1,y1 )-( x2,y2 ) ], Trans

参数

Trans

必填。

说明

Trans 选择透明背景作为图像缓冲区位图传输的方法。这与 PSET 方法类似，但包含遮罩颜色的像素将被跳过。

对于 8 位颜色图像，遮罩颜色是调色板索引 0。对于 16/32 位颜色图像，遮罩颜色是品红色，即 RGB(255, 0, 255)。在 32 位图像中检查遮罩颜色时，alpha 值将被忽略。

注意：对于 32 位图像，像素的 alpha 值可能会被更改为 0。这是出于效率考虑。要保留 alpha 值，可以使用自定义混合函数，如下面第二个示例所示。

示例

start GeSHi

'' set up a screen: 320 * 200, 16 bits per pixel
ScreenRes 320, 200, 16

'' set up an image with the mask color as the background.
Dim img As Any Ptr = ImageCreate( 32, 32, RGB(255, 0, 255) )
Circle img, (16, 16), 15, RGB(255, 255, 0),     ,     , 1, f
Circle img, (10, 10), 3,  RGB(  0,   0, 0),     ,     , 2, f
Circle img, (23, 10), 3,  RGB(  0,   0, 0),     ,     , 2, f
Circle img, (16, 18), 10, RGB(  0,   0, 0), 3.14, 6.28

'' Put the image with PSET (gives the exact contents of the image buffer)
Draw String (110, 50 - 4), "Image put with PSET"
Put (60 - 16, 50 - 16), img, PSet

'' Put the image with TRANS
Draw String (110, 150 - 4), "Image put with TRANS"
Put (60 - 16, 150 - 16), img, Trans

'' free the image memory
ImageDestroy img

'' wait for a keypress
Sleep

end GeSHi

start GeSHi

Function trans32 ( ByVal source_pixel As ulong, ByVal destination_pixel As ulong, ByVal parameter As Any Ptr ) As ulong
    '' returns the source pixel
    '' unless it is &hff00ff (magenta), then return the destination pixel
    If (source_pixel And &hffffff) <> &hff00ff Then
        Return source_pixel
    Else
        Return destination_pixel
    End If
End Function

'' set up a screen: 320 * 200, 16 bits per pixel
ScreenRes 320, 200, 32

'' set up an image with the mask color as the background.
Dim img As Any Ptr = ImageCreate( 32, 32, RGB(255, 0, 255) )
Circle img, (16, 16), 15, RGB(255, 255, 0),     ,     , 1, f
Circle img, (10, 10), 3,  RGB(  0,   0, 0),     ,     , 2, f
Circle img, (23, 10), 3,  RGB(  0,   0, 0),     ,     , 2, f
Circle img, (16, 18), 10, RGB(  0,   0, 0), 3.14, 6.28

'' Put the image with PSET (gives the exact contents of the image buffer)
Draw String (110, 50 - 4), "Image put with PSET"
Put (60 - 16, 50 - 16), img, PSet

'' Put the image with TRANS
Draw String (110, 100 - 4), "Image put with TRANS"
Put (60 - 16, 100 - 16), img, Trans

'' Put the image with TRANS
Draw String (110, 150 - 4), "Image put with trans32"
Put (60 - 16, 150 - 16), img, Custom, @trans32

'' free the image memory
ImageDestroy img

'' wait for a keypress
Sleep

end GeSHi

与 QB 的区别

• FreeBASIC 新增

另请参阅

• Put (Graphics)
• Custom

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