472 lines
9.9 KiB
C
472 lines
9.9 KiB
C
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#include "fitz.h"
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/*
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The functions in this file implement various flavours of Porter-Duff blending.
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We take the following as definitions:
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Cx = Color (from plane x)
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ax = Alpha (from plane x)
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cx = Cx.ax = Premultiplied color (from plane x)
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The general PorterDuff blending equation is:
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Blend Z = X op Y cz = Fx.cx + Fy. cy where Fx and Fy depend on op
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The two operations we use in this file are: '(X in Y) over Z' and
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'S over Z'. The definitions of the 'over' and 'in' operations are as
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follows:
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For S over Z, Fs = 1, Fz = 1-as
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For X in Y, Fx = ay, Fy = 0
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We have 2 choices; we can either work with premultiplied data, or non
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premultiplied data. Our
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First the premultiplied case:
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Let S = (X in Y)
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Let R = (X in Y) over Z = S over Z
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cs = cx.Fx + cy.Fy (where Fx = ay, Fy = 0)
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= cx.ay
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as = ax.Fx + ay.Fy
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= ax.ay
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cr = cs.Fs + cz.Fz (where Fs = 1, Fz = 1-as)
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= cs + cz.(1-as)
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= cx.ay + cz.(1-ax.ay)
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ar = as.Fs + az.Fz
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= as + az.(1-as)
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= ax.ay + az.(1-ax.ay)
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This has various nice properties, like not needing any divisions, and
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being symmetric in color and alpha, so this is what we use. Because we
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went through the pain of deriving the non premultiplied forms, we list
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them here too, though they are not used.
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Non Pre-multiplied case:
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Cs.as = Fx.Cx.ax + Fy.Cy.ay (where Fx = ay, Fy = 0)
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= Cx.ay.ax
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Cs = (Cx.ay.ax)/(ay.ax)
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= Cx
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Cr.ar = Fs.Cs.as + Fz.Cz.az (where Fs = 1, Fz = 1-as)
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= Cs.as + (1-as).Cz.az
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= Cx.ax.ay + Cz.az.(1-ax.ay)
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Cr = (Cx.ax.ay + Cz.az.(1-ax.ay))/(ax.ay + az.(1-ax-ay))
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Much more complex, it seems. However, if we could restrict ourselves to
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the case where we were always plotting onto an opaque background (i.e.
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az = 1), then:
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Cr = Cx.(ax.ay) + Cz.(1-ax.ay)
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= (Cx-Cz)*(1-ax.ay) + Cz (a single MLA operation)
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ar = 1
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Sadly, this is not true in the general case, so we abandon this effort
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and stick to using the premultiplied form.
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*/
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typedef unsigned char byte;
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/* These are used by the non-aa scan converter */
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void
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fz_paint_solid_alpha(byte * restrict dp, int w, int alpha)
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{
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int t = FZ_EXPAND(255 - alpha);
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while (w--)
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{
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*dp = alpha + FZ_COMBINE(*dp, t);
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dp ++;
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}
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}
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void
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fz_paint_solid_color(byte * restrict dp, int n, int w, byte *color)
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{
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int n1 = n - 1;
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int sa = FZ_EXPAND(color[n1]);
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int k;
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while (w--)
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{
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int ma = FZ_COMBINE(FZ_EXPAND(255), sa);
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for (k = 0; k < n1; k++)
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dp[k] = FZ_BLEND(color[k], dp[k], ma);
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dp[k] = FZ_BLEND(255, dp[k], ma);
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dp += n;
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}
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}
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/* Blend a non-premultiplied color in mask over destination */
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static inline void
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fz_paint_span_with_color_2(byte * restrict dp, byte * restrict mp, int w, byte *color)
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{
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int sa = FZ_EXPAND(color[1]);
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int g = color[0];
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while (w--)
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{
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int ma = *mp++;
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ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
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dp[0] = FZ_BLEND(g, dp[0], ma);
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dp[1] = FZ_BLEND(255, dp[1], ma);
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dp += 2;
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}
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}
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static inline void
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fz_paint_span_with_color_4(byte * restrict dp, byte * restrict mp, int w, byte *color)
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{
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int sa = FZ_EXPAND(color[3]);
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int r = color[0];
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int g = color[1];
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int b = color[2];
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while (w--)
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{
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int ma = *mp++;
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ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
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dp[0] = FZ_BLEND(r, dp[0], ma);
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dp[1] = FZ_BLEND(g, dp[1], ma);
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dp[2] = FZ_BLEND(b, dp[2], ma);
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dp[3] = FZ_BLEND(255, dp[3], ma);
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dp += 4;
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}
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}
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static inline void
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fz_paint_span_with_color_N(byte * restrict dp, byte * restrict mp, int n, int w, byte *color)
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{
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int n1 = n - 1;
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int sa = FZ_EXPAND(color[n1]);
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int k;
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while (w--)
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{
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int ma = *mp++;
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ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
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for (k = 0; k < n1; k++)
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dp[k] = FZ_BLEND(color[k], dp[k], ma);
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dp[k] = FZ_BLEND(255, dp[k], ma);
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dp += n;
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}
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}
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void
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fz_paint_span_with_color(byte * restrict dp, byte * restrict mp, int n, int w, byte *color)
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{
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switch (n)
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{
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case 2: fz_paint_span_with_color_2(dp, mp, w, color); break;
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case 4: fz_paint_span_with_color_4(dp, mp, w, color); break;
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default: fz_paint_span_with_color_N(dp, mp, n, w, color); break;
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}
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}
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/* Blend source in mask over destination */
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static inline void
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fz_paint_span_with_mask_2(byte * restrict dp, byte * restrict sp, byte * restrict mp, int w)
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{
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while (w--)
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{
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int masa;
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int ma = *mp++;
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ma = FZ_EXPAND(ma);
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masa = FZ_COMBINE(sp[1], ma);
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masa = 255 - masa;
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masa = FZ_EXPAND(masa);
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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}
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}
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static inline void
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fz_paint_span_with_mask_4(byte * restrict dp, byte * restrict sp, byte * restrict mp, int w)
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{
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while (w--)
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{
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int masa;
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int ma = *mp++;
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ma = FZ_EXPAND(ma);
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masa = FZ_COMBINE(sp[3], ma);
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masa = 255 - masa;
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masa = FZ_EXPAND(masa);
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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}
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}
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static inline void
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fz_paint_span_with_mask_N(byte * restrict dp, byte * restrict sp, byte * restrict mp, int n, int w)
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{
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while (w--)
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{
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int k = n;
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int masa;
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int ma = *mp++;
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ma = FZ_EXPAND(ma);
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masa = FZ_COMBINE(sp[n-1], ma);
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masa = 255-masa;
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masa = FZ_EXPAND(masa);
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while (k--)
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{
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*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
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sp++; dp++;
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}
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}
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}
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static void
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fz_paint_span_with_mask(byte * restrict dp, byte * restrict sp, byte * restrict mp, int n, int w)
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{
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switch (n)
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{
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case 2: fz_paint_span_with_mask_2(dp, sp, mp, w); break;
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case 4: fz_paint_span_with_mask_4(dp, sp, mp, w); break;
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default: fz_paint_span_with_mask_N(dp, sp, mp, n, w); break;
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}
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}
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/* Blend source in constant alpha over destination */
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static inline void
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fz_paint_span_2_with_alpha(byte * restrict dp, byte * restrict sp, int w, int alpha)
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{
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alpha = FZ_EXPAND(alpha);
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while (w--)
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{
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int masa = FZ_COMBINE(sp[1], alpha);
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*dp = FZ_BLEND(*sp, *dp, masa);
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dp++; sp++;
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*dp = FZ_BLEND(*sp, *dp, masa);
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dp++; sp++;
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}
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}
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static inline void
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fz_paint_span_4_with_alpha(byte * restrict dp, byte * restrict sp, int w, int alpha)
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{
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alpha = FZ_EXPAND(alpha);
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while (w--)
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{
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int masa = FZ_COMBINE(sp[3], alpha);
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*dp = FZ_BLEND(*sp, *dp, masa);
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sp++; dp++;
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*dp = FZ_BLEND(*sp, *dp, masa);
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sp++; dp++;
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*dp = FZ_BLEND(*sp, *dp, masa);
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sp++; dp++;
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*dp = FZ_BLEND(*sp, *dp, masa);
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sp++; dp++;
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}
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}
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static inline void
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fz_paint_span_N_with_alpha(byte * restrict dp, byte * restrict sp, int n, int w, int alpha)
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{
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alpha = FZ_EXPAND(alpha);
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while (w--)
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{
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int masa = FZ_COMBINE(sp[n-1], alpha);
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int k = n;
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while (k--)
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{
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*dp = FZ_BLEND(*sp++, *dp, masa);
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dp++;
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}
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}
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}
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/* Blend source over destination */
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static inline void
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fz_paint_span_1(byte * restrict dp, byte * restrict sp, int w)
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{
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while (w--)
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{
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int t = FZ_EXPAND(255 - sp[0]);
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp ++;
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}
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}
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static inline void
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fz_paint_span_2(byte * restrict dp, byte * restrict sp, int w)
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{
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while (w--)
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{
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int t = FZ_EXPAND(255 - sp[1]);
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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}
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}
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static inline void
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fz_paint_span_4(byte * restrict dp, byte * restrict sp, int w)
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{
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while (w--)
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{
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int t = FZ_EXPAND(255 - sp[3]);
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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}
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}
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static inline void
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fz_paint_span_N(byte * restrict dp, byte * restrict sp, int n, int w)
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{
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while (w--)
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{
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int k = n;
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int t = FZ_EXPAND(255 - sp[n-1]);
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while (k--)
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{
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*dp = *sp++ + FZ_COMBINE(*dp, t);
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dp++;
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}
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}
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}
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void
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fz_paint_span(byte * restrict dp, byte * restrict sp, int n, int w, int alpha)
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{
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if (alpha == 255)
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{
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switch (n)
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{
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case 1: fz_paint_span_1(dp, sp, w); break;
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case 2: fz_paint_span_2(dp, sp, w); break;
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case 4: fz_paint_span_4(dp, sp, w); break;
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default: fz_paint_span_N(dp, sp, n, w); break;
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}
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}
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else if (alpha > 0)
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{
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switch (n)
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{
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case 2: fz_paint_span_2_with_alpha(dp, sp, w, alpha); break;
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case 4: fz_paint_span_4_with_alpha(dp, sp, w, alpha); break;
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default: fz_paint_span_N_with_alpha(dp, sp, n, w, alpha); break;
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|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Pixmap blending functions
|
||
|
|
*/
|
||
|
|
|
||
|
|
void
|
||
|
|
fz_paint_pixmap_with_rect(fz_pixmap *dst, fz_pixmap *src, int alpha, fz_bbox bbox)
|
||
|
|
{
|
||
|
|
unsigned char *sp, *dp;
|
||
|
|
int x, y, w, h, n;
|
||
|
|
|
||
|
|
assert(dst->n == src->n);
|
||
|
|
|
||
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(dst));
|
||
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
||
|
|
|
||
|
|
x = bbox.x0;
|
||
|
|
y = bbox.y0;
|
||
|
|
w = bbox.x1 - bbox.x0;
|
||
|
|
h = bbox.y1 - bbox.y0;
|
||
|
|
if ((w | h) == 0)
|
||
|
|
return;
|
||
|
|
|
||
|
|
n = src->n;
|
||
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
||
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
||
|
|
|
||
|
|
while (h--)
|
||
|
|
{
|
||
|
|
fz_paint_span(dp, sp, n, w, alpha);
|
||
|
|
sp += src->w * n;
|
||
|
|
dp += dst->w * n;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void
|
||
|
|
fz_paint_pixmap(fz_pixmap *dst, fz_pixmap *src, int alpha)
|
||
|
|
{
|
||
|
|
unsigned char *sp, *dp;
|
||
|
|
fz_bbox bbox;
|
||
|
|
int x, y, w, h, n;
|
||
|
|
|
||
|
|
assert(dst->n == src->n);
|
||
|
|
|
||
|
|
bbox = fz_bound_pixmap(dst);
|
||
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
||
|
|
|
||
|
|
x = bbox.x0;
|
||
|
|
y = bbox.y0;
|
||
|
|
w = bbox.x1 - bbox.x0;
|
||
|
|
h = bbox.y1 - bbox.y0;
|
||
|
|
if ((w | h) == 0)
|
||
|
|
return;
|
||
|
|
|
||
|
|
n = src->n;
|
||
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
||
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
||
|
|
|
||
|
|
while (h--)
|
||
|
|
{
|
||
|
|
fz_paint_span(dp, sp, n, w, alpha);
|
||
|
|
sp += src->w * n;
|
||
|
|
dp += dst->w * n;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void
|
||
|
|
fz_paint_pixmap_with_mask(fz_pixmap *dst, fz_pixmap *src, fz_pixmap *msk)
|
||
|
|
{
|
||
|
|
unsigned char *sp, *dp, *mp;
|
||
|
|
fz_bbox bbox;
|
||
|
|
int x, y, w, h, n;
|
||
|
|
|
||
|
|
assert(dst->n == src->n);
|
||
|
|
assert(msk->n == 1);
|
||
|
|
|
||
|
|
bbox = fz_bound_pixmap(dst);
|
||
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
||
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(msk));
|
||
|
|
|
||
|
|
x = bbox.x0;
|
||
|
|
y = bbox.y0;
|
||
|
|
w = bbox.x1 - bbox.x0;
|
||
|
|
h = bbox.y1 - bbox.y0;
|
||
|
|
if ((w | h) == 0)
|
||
|
|
return;
|
||
|
|
|
||
|
|
n = src->n;
|
||
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
||
|
|
mp = msk->samples + ((y - msk->y) * msk->w + (x - msk->x)) * msk->n;
|
||
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
||
|
|
|
||
|
|
while (h--)
|
||
|
|
{
|
||
|
|
fz_paint_span_with_mask(dp, sp, mp, n, w);
|
||
|
|
sp += src->w * n;
|
||
|
|
dp += dst->w * n;
|
||
|
|
mp += msk->w;
|
||
|
|
}
|
||
|
|
}
|