MGL_putBitmapFxSection

Draw a section of a lightweight bitmap at the specified location, while applying different effects in the process.

Declaration

void MGLAPI MGL_putBitmapFxSection(
MGLDC *dc,
int left,
int top,
int right,
int bottom,
int dstLeft,
int dstTop,
const bitmap_t *bitmap,
bltfx_t *fx)

Prototype In

mgraph.h

Parameters

dc | Device context to display bitmap on
left | Left coordinate of section to draw
top | Top coordinate of section to draw
right | Right coordinate of section to draw
bottom | Bottom coordinate of section to draw
dstLeft | Left coordinate of destination of bitmap section
dstTop | Right coordinate for destination of bitmap section
bitmap | Bitmap to display
fx | Information describing the effects to apply to the blit (bltfx_t)

Description

Draws a section of a lightweight bitmap at the specified location, with optional effects applied. The effects applied to the blit operation range from X and Y bitmap flipping to color transparency and blending. All of these operations can be applied to data being copied between different device context of different color depths and pixel formats if desired (ie: 32-bit ARGB alpha blended bitmap to a 16-bit device context). Please refer to the documentation for the bltfx_t structure and the MGL_bitBltFxFlagsType enumeration that defines the flags passed to this function.

When this function is called for 4 and 8 bit source bitmaps being copied to either 4 or 8bpp destination device contexts, MGL first checks if the color palettes for the source and destination bitmaps are the same. If they are not, MGL translates the pixel values from the source bitmap to the destination color palette, looking for the closest match color if an exact match is not found. In order to obtain maximum performance for blt’ing bitmaps in color index modes, you should ensure that the color palette in the source device matches the color palette in the destination device to avoid on the fly palette translation. If you know in advance that the palette is identical for a series of blit operations, you can turn off all identity palette checking in MGL with the MGL_checkIdentityPalette function.

When this function is called for 4 and 8 bit source bitmaps being copied to RGB destination device contexts, MGL will convert the pixels in the source bitmap using the source bitmap palette to map them to the destination pixel format. If however you know in advance that the palette for all source bitmaps is identical for a series of blit operations, you can use the MGL_checkIdentityPalette function to disable source palette translation. In this case the MGL will translate all color index bitmaps using the pre-defined color translation palette stored in the destination device context. You would then set the destination device context palette to the common palette for all blit operations using MGL_setPalette. If you are translating a lot of color index bitmaps, this will increase performance by avoiding the need to convert the palette entries to the destination pixel format for every blit operation.

Note also that if the source bitmap palette pointer is set to NULL, palette translation is automatically avoided (ie: has the effect of forcing MGL_checkIdentityPalette to false just for that bitmap).

See Also

MGL_loadBitmap, MGL_putBitmap, MGL_putBitmapSection, MGL_putBitmapSrcTrans, MGL_putBitmapSrcTransSection, MGL_putBitmapDstTrans, MGL_putBitmapDstTransSection, MGL_putBitmapMask, MGL_putBitmapPatt, MGL_putBitmapPattSection, MGL_putBitmapFx, MGL_putBitmapFxSection, MGL_stretchBitmap, MGL_stretchBitmapSection, MGL_stretchBitmapFx, MGL_stretchBitmapFxSection, MGL_putIcon

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