[dense] Add drawing functions to rasterizer
* src/dense/ftdense.c: (dense_render_line, dense_render_quadratic, dense_render_cubic, dense_render_glyph, dense_raster_render, Lerp): New Functions
This commit is contained in:
Anurag Thakur
parent
f2ff1dc37e
commit
5e681678f6
@ -32,6 +32,15 @@ typedef struct dense_TRaster_
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} dense_TRaster, *dense_PRaster;
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/* Linear interpolation between P0 and P1 */
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static FT_Vector
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Lerp( float T, FT_Vector P0, FT_Vector P1 )
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{
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FT_Vector p;
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p.x = P0.x + T * ( P1.x - P0.x );
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p.y = P0.y + T * ( P1.y - P0.y );
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return p;
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}
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static int
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dense_move_to( const FT_Vector* to, dense_worker* worker )
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@ -54,11 +63,112 @@ dense_line_to( const FT_Vector* to, dense_worker* worker )
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}
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void
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dense_render_line( dense_worker* worker, TPos tox, TPos toy )
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dense_render_line( dense_worker* worker, FT_Pos tox, FT_Pos toy )
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{
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return;
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float from_x = worker->prev_x;
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float from_y = worker->prev_y;
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if ( from_y == toy )
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return;
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from_x /= 256.0;
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from_y /= 256.0;
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float to_x = tox / 256.0;
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float to_y = toy / 256.0;
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float dir;
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if ( from_y < to_y )
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dir = 1;
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else
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{
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dir = -1;
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FT_SWAP(from_x, to_x );
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FT_SWAP(from_y, to_y );
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}
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// Clip to the height.
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if ( from_y >= worker->m_h || to_y <= 0 )
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return;
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float dxdy = ( to_x - from_x ) / (float)( to_y - from_y );
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if ( from_y < 0 )
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{
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from_x -= from_y * dxdy;
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from_y = 0;
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}
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if ( to_y > worker->m_h )
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{
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to_x -= ( to_y - worker->m_h ) * dxdy;
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to_y = (float)worker->m_h;
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}
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float x = from_x;
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int y0 = (int)from_y;
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int y_limit = (int)ceil( to_y );
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float* m_a = worker->m_a;
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for ( int y = y0; y < y_limit; y++ )
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{
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int linestart = y * worker->m_w;
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float dy = fmin( y + 1.0f, to_y ) - fmax( (float)y, from_y );
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float xnext = x + dxdy * dy;
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float d = dy * dir;
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float x0, x1;
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if ( x < xnext )
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{
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x0 = x;
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x1 = xnext;
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}
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else
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{
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x0 = xnext;
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x1 = x;
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}
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/*
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It's possible for x0 to be negative on the last scanline because of
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floating-point inaccuracy That would cause an out-of-bounds array access at
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index -1.
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*/
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float x0floor = x0 <= 0.0f ? 0.0f : (float)floor( x0 );
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int x0i = (int)x0floor;
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float x1ceil = (float)ceil( x1 );
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int x1i = (int)x1ceil;
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if ( x1i <= x0i + 1 )
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{
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float xmf = 0.5f * ( x + xnext ) - x0floor;
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m_a[linestart + x0i] += d - d * xmf;
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m_a[linestart + ( x0i + 1 )] += d * xmf;
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}
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else
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{
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float s = 1.0f / ( x1 - x0 );
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float x0f = x0 - x0floor;
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float a0 = 0.5f * s * ( 1.0f - x0f ) * ( 1.0f - x0f );
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float x1f = x1 - x1ceil + 1.0f;
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float am = 0.5f * s * x1f * x1f;
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m_a[linestart + x0i] += d * a0;
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if ( x1i == x0i + 2 )
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m_a[linestart + ( x0i + 1 )] += d * ( 1.0f - a0 - am );
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else
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{
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float a1 = s * ( 1.5f - x0f );
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m_a[linestart + ( x0i + 1 )] += d * ( a1 - a0 );
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for ( int xi = x0i + 2; xi < x1i - 1; xi++ )
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m_a[linestart + xi] += d * s;
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float a2 = a1 + ( x1i - x0i - 3 ) * s;
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m_a[linestart + ( x1i - 1 )] += d * ( 1.0f - a2 - am );
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}
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m_a[linestart + x1i] += d * am;
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}
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x = xnext;
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}
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}
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static int
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dense_conic_to( const FT_Vector* control,
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const FT_Vector* to,
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@ -73,7 +183,56 @@ dense_render_quadratic( dense_worker* worker,
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FT_Vector* control,
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FT_Vector* to )
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{
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/*
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Calculate devsq as the square of four times the
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distance from the control point to the midpoint of the curve.
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This is the place at which the curve is furthest from the
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line joining the control points.
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4 x point on curve = p0 + 2p1 + p2
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4 x midpoint = 4p1
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The division by four is omitted to save time.
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*/
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FT_Vector aP0 = { DOWNSCALE( worker->prev_x ), DOWNSCALE( worker->prev_y ) };
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FT_Vector aP1 = { control->x, control->y };
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FT_Vector aP2 = { to->x, to->y };
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float devx = aP0.x - aP1.x - aP1.x + aP2.x;
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float devy = aP0.y - aP1.y - aP1.y + aP2.y;
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float devsq = devx * devx + devy * devy;
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if ( devsq < 0.333f )
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{
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dense_line_to( &aP2, worker );
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return;
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}
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/*
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According to Raph Levien, the reason for the subdivision by n (instead of
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recursive division by the Casteljau system) is that "I expect the flatness
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computation to be semi-expensive (it's done once rather than on each potential
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subdivision) and also because you'll often get fewer subdivisions. Taking a
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circular arc as a simplifying assumption, where I get n, a recursive approach
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would get 2^ceil(lg n), which, if I haven't made any horrible mistakes, is
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expected to be 33% more in the limit".
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*/
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const float tol = 3.0f;
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int n = (int)floor( sqrt( sqrt( tol * devsq ) ) )/8;
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FT_Vector p = aP0;
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float nrecip = 1.0f / ( n + 1.0f );
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float t = 0.0f;
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for ( int i = 0; i < n; i++ )
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{
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t += nrecip;
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FT_Vector next = Lerp( t, Lerp( t, aP0, aP1 ), Lerp( t, aP1, aP2 ) );
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dense_line_to(&next, worker );
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p = next;
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}
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dense_line_to( &aP2, worker );
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}
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static int
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@ -92,7 +251,43 @@ dense_render_cubic( dense_worker* worker,
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FT_Vector* control_2,
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FT_Vector* to )
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{
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return;
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FT_Vector aP0 = { DOWNSCALE( worker->prev_x ), DOWNSCALE( worker->prev_y ) };
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FT_Vector aP1 = { control_1->x, control_1->y };
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FT_Vector aP2 = { control_2->x, control_2->y };
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FT_Vector aP3 = { to->x, to->y };
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float devx = aP0.x - aP1->x - aP1->x + aP2->x;
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float devy = aP0.y - aP1->y - aP1->y + aP2->y;
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float devsq0 = devx * devx + devy * devy;
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devx = aP1->x - aP2->x - aP2->x + aP3->x;
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devy = aP1->y - aP2->y - aP2->y + aP3->y;
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float devsq1 = devx * devx + devy * devy;
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float devsq = fmax( devsq0, devsq1 );
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if ( devsq < 0.333f )
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{
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dense_render_line( worker, aP3->x, aP3->y );
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return;
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}
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const float tol = 3.0f;
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int n = (int)floor( sqrt( sqrt( tol * devsq ) ) ) / 8;
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FT_Vector p = aP0;
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float nrecip = 1.0f / ( n + 1.0f );
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float t = 0.0f;
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for ( int i = 0; i < n; i++ )
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{
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t += nrecip;
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FT_Vector a = Lerp( t, Lerp( t, aP0, *aP1 ), Lerp( t, *aP1, *aP2 ) );
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FT_Vector b = Lerp( t, Lerp( t, *aP1, *aP2 ), Lerp( t, *aP2, *aP3 ) );
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FT_Vector next = Lerp( t, a, b );
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dense_render_line( worker, next.x, next.y );
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worker->prev_x = next.x;
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worker->prev_y = next.y;
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p = next;
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}
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dense_line_to( &aP3, worker );
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}
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static int
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@ -152,13 +347,78 @@ dense_render_glyph( dense_worker* worker, const FT_Bitmap* target )
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{
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FT_Error error = FT_Outline_Decompose( &( worker->outline ),
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&dense_decompose_funcs, worker );
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// Render into bitmap
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const float* source = worker->m_a;
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unsigned char* dest = target->buffer;
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unsigned char* dest_end = target->buffer + worker->m_w * worker->m_h;
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float value = 0.0f;
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while ( dest < dest_end )
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{
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value += *source++;
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if ( value > 0.0f )
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{
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int n = (int)( fabs( value ) * 255.0f + 0.5f );
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if ( n > 255 )
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n = 255;
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*dest = (unsigned char)n;
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}
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else
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*dest = 0;
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dest++;
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}
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free(worker->m_a);
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return error;
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}
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static int
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dense_raster_render( FT_Raster raster, const FT_Raster_Params* params )
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{
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return 0;
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const FT_Outline* outline = (const FT_Outline*)params->source;
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FT_Bitmap* target_map = params->target;
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dense_worker worker[1];
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if ( !raster )
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return FT_THROW( Invalid_Argument );
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if ( !outline )
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return FT_THROW( Invalid_Outline );
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worker->outline = *outline;
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if ( !target_map )
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return FT_THROW( Invalid_Argument );
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/* nothing to do */
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if ( !target_map->width || !target_map->rows )
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return 0;
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if ( !target_map->buffer )
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return FT_THROW( Invalid_Argument );
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worker->m_origin_x = 0;
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worker->m_origin_y = 0;
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worker->m_w = target_map->pitch;
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worker->m_h = target_map->rows;
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int size = worker->m_w * worker->m_h + 4;
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worker->m_a = malloc( sizeof( float ) * size );
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worker->m_a_size = size;
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memset( worker->m_a, 0, ( sizeof( float ) * size ) );
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/* exit if nothing to do */
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if ( worker->m_w <= worker->m_origin_x || worker->m_h <= worker->m_origin_y )
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{
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return 0;
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}
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// Invert the pitch to account for different +ve y-axis direction in dense array
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// (maybe temporary solution)
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target_map->pitch *= -1;
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return dense_render_glyph( worker, target_map );
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}
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FT_DEFINE_RASTER_FUNCS(
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