Bridgetek FT801 - BITMAP_TRANSFORM_A

FT800 Series Programmer Guide
Version 2.1
Document Reference No.: BRT_000030 Clearance No.: BRT#037
99
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4.10 BITMAP_TRANSFORM_A
Specify the A coefficient of the bitmap transform matrix.
Encoding
31 24
23 17
16 0
0x15
Reserved
a
Parameters
a
Coefficient A of the bitmap transform matrix, in signed 8.8 bit fixed-point
form. The initial value is 256.
Description
BITMAP_TRANSFORM_A-F coefficients are used to perform bitmap transform
functionalities such as scaling, rotation and translation. These are similar to openGL
transform functionality.
Examples
A value of 0.5 (128) causes the bitmap appear double width:
dl( BITMAP_SOURCE(0) );
dl( BITMAP_LAYOUT(RGB565, 128, 64) );
dl( BITMAP_TRANSFORM_A(128) );
dl( BITMAP_SIZE(NEAREST, BORDER,
BORDER, 128, 128) );
dl( BEGIN(BITMAPS) );
dl( VERTEX2II(16, 0, 0, 0) );
A value of 2.0 (512) gives a half-width bitmap:
dl( BITMAP_SOURCE(0) );
dl( BITMAP_LAYOUT(RGB565, 128, 64) );
dl( BITMAP_TRANSFORM_A(512) );
dl( BITMAP_SIZE(NEAREST, BORDER,
BORDER, 128, 128) );
dl( BEGIN(BITMAPS) );
dl( VERTEX2II(16, 0, 0, 0) );