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authorscuri <scuri>2009-10-27 19:45:36 +0000
committerscuri <scuri>2009-10-27 19:45:36 +0000
commitc4ca69d3fa84dca98dce71c7a71b61413d6be165 (patch)
tree8c149cd3deaf31fa406270b26a45982471c8b88e
parent8a059c0ddda38d88aee6c8657b41ef81adb0171c (diff)
Fixed: compositing in IMAGERGB when canvas has a semi-transparent alpha channel and a color with semi transparent alpha are used.
Diffstat
-rw-r--r--html/en/func/attributes.html4
-rw-r--r--html/en/func/color.html9
-rw-r--r--html/en/history.html5
-rw-r--r--src/drv/cdirgb.c35
4 files changed, 31 insertions, 22 deletions
diff --git a/html/en/func/attributes.html b/html/en/func/attributes.html
index 60768e4..984af01 100644
--- a/html/en/func/attributes.html
+++ b/html/en/func/attributes.html
@@ -17,7 +17,7 @@ canvas:SetForeground(color: lightuserdata) [in Lua]</pre>
color is used in all primitives (lines, areas, marks and text). Default value: <b>
<tt>CD_BLACK</tt></b>. Value <tt><b>CD_QUERY</b> </tt>simply returns the
current value.</p>
- <p>Notice that CD_QUERY conflicts with color RGBA=(255,255,255,255) (full
+ <p>Notice that CD_QUERY conflicts with color RGBA=(255,255,255,0) (full
transparent white). Use <strong>SetForeground</strong> to avoid the
conflict. See also <a href="color.html">Color Coding</a>.</p>
<pre class="function"><span class="mainFunction">long int <a name="cdBackground">cdCanvasBackground</a>(cdCanvas* canvas, long int color); [in C]</span>
@@ -31,7 +31,7 @@ canvas:SetBackground(color: lightuserdata) [in Lua]</pre>
background color only makes sense for <strong>Clear</strong><tt><font> </font></tt>and for
primitives affected by the background opacity attribute. Default value: <b><tt>CD_WHITE</tt></b>.
Value <tt><b>CD_QUERY</b> </tt>simply returns the current value.</p>
- <p>Notice that CD_QUERY conflicts with color RGBA=(255,255,255,255) (full
+ <p>Notice that CD_QUERY conflicts with color RGBA=(255,255,255,0) (full
transparent white). Use <strong>SetBackground</strong> to avoid the
conflict. See also <a href="color.html">Color Coding</a>.</p>
<pre class="function"><span class="mainFunction">int <a name="cdWriteMode">cdCanvasWriteMode</a>(cdCanvas* canvas, int mode); [in C]</span>
diff --git a/html/en/func/color.html b/html/en/func/color.html
index 9ec9928..8efd8a4 100644
--- a/html/en/func/color.html
+++ b/html/en/func/color.html
@@ -52,12 +52,13 @@ cd.DecodeColor(color: lightuserdata) -&gt; (r, g, b: number) [in Lua]</pre>
cd.EncodeAlpha(color: lightuserdata, alpha: number) -&gt; (color: lightuserdata) [in Lua]</pre>
<p>Returns the given color coded with the alpha information. ATENTION: At the
- moment only the Win32 with GDI+ and the IMAGERGB drivers support alpha
- components in color coding. Se in <a href="../drv/gdiplus.html">Windows Using
- GDI+ Base Driver</a> and <a href="../drv/irgb.html">IMAGERGB driver</a>. The
+ moment only the <a href="../drv/gdiplus.html">Win32 with GDI+</a>, the
+ <a href="../drv/xrender.html">XRender</a> and the <a href="../drv/irgb.html">IMAGERGB</a>
+ drivers support alpha components in color coding. The
internal representation of the component is inverted, because the default value
must be 0 and opaque for backward compatibility, so you should use the <strong>cdDecodeAlpha</strong>
- function ot the <strong>cdAlpha</strong> macro to retrieve the alpha component.</p>
+ function or the <strong>cdAlpha</strong> macro to retrieve the alpha component.
+ 0 is transparent, 255 is opaque.</p>
<pre class="function"><span class="mainFunction">unsigned char <a name="cdDecodeAlpha">cdDecodeAlpha</a>(long int color) [in C]</span>
cd.DecodeAlpha(color: lightuserdata) -&gt; (a: number) [in Lua]</pre>
diff --git a/html/en/history.html b/html/en/history.html
index 8dd485a..81db388 100644
--- a/html/en/history.html
+++ b/html/en/history.html
@@ -19,7 +19,7 @@
<body>
<h2>History of Changes</h2>
-<h3>CVS (23/Oct/2009)</h3>
+<h3>CVS (27/Oct/2009)</h3>
<ul>
<li><span class="style1">Changed</span><span class="hist_changed">:</span>
Freetype updated to version 2.3.11.</li>
@@ -37,6 +37,9 @@
objects in Lua.</li>
<li><span style="color: #FF0000">Fixed:</span> <strong>CanvasText</strong>
for WD when using text with multiple lines.</li>
+ <li><span style="color: #FF0000">Fixed:</span> compositing in IMAGERGB when
+ canvas has a semi-transparent alpha channel and a color with semi transparent alpha
+ are used.</li>
</ul>
<h3><a href="http://sourceforge.net/projects/canvasdraw/files/5.2/">Version 5.2</a> (26/Jun/2009)</h3>
<ul>
diff --git a/src/drv/cdirgb.c b/src/drv/cdirgb.c
index 7f6f64b..d623abc 100644
--- a/src/drv/cdirgb.c
+++ b/src/drv/cdirgb.c
@@ -56,13 +56,13 @@ struct _cdCtxCanvas
#define _sNormX(_ctxcanvas, _x) (_x < 0? 0: _x < _ctxcanvas->canvas->w? _x: _ctxcanvas->canvas->w-1)
#define _sNormY(_ctxcanvas, _y) (_y < 0? 0: _y < _ctxcanvas->canvas->h? _y: _ctxcanvas->canvas->h-1)
-#define RGB_COMPOSE(_SRC, _SRC_ALPHA, _DST, _TMP_MULTI, _TMP_ALPHA) (unsigned char)(((_SRC_ALPHA)*(_SRC) + (_TMP_MULTI)*(_DST)) / (_TMP_ALPHA))
+#define RGB_COMPOSE_OVER(_SRC, _SRC_ALPHA, _DST, _TMP_MULTI, _TMP_ALPHA) (unsigned char)(((_SRC_ALPHA)*(_SRC) + (_TMP_MULTI)*(_DST)) / (_TMP_ALPHA))
#define RGBA_COLOR_COMBINE(_ctxcanvas, _pdst_red, _pdst_green, _pdst_blue, _pdst_alpha, _src_red, _src_green, _src_blue, _src_alpha) \
{ \
unsigned char _tmp_red = 0, _tmp_green = 0, _tmp_blue = 0; \
\
- if (_pdst_alpha) /* (_pdst_alpha != NULL) */ \
+ if (_pdst_alpha) /* destiny has alpha */ \
{ \
if (_src_alpha != 255) /* some transparency */ \
{ \
@@ -84,12 +84,17 @@ struct _cdCtxCanvas
} \
else /* (0<*_pdst_alpha<255 && 0<_src_alpha<255) destiny and source are semi-transparent */ \
{ \
- /* Closed Compositing Formulas for SRC over DST, Colors Not Premultiplied by Alpha: */ \
+ /* Closed Compositing SRC over DST (see smith95a.pdf) */ \
+ /* Colors NOT Premultiplied by Alpha */ \
+ /* DST = SRC * SRC_ALPHA + DST * DST_ALPHA * (1 - SRC_ALPHA) */ \
+ /* DST_ALPHA = SRC_ALPHA + DST_ALPHA * (1 - SRC_ALPHA) */ \
+ /* DST /= DST_ALPHA */ \
int _tmp_multi = *_pdst_alpha * (255 - _src_alpha); \
- int _tmp_alpha = _src_alpha + _tmp_multi; \
- _tmp_red = RGB_COMPOSE(_src_red, _src_alpha, *_pdst_red, _tmp_multi, _tmp_alpha); \
- _tmp_green = RGB_COMPOSE(_src_green, _src_alpha, *_pdst_green, _tmp_multi, _tmp_alpha); \
- _tmp_blue = RGB_COMPOSE(_src_blue, _src_alpha, *_pdst_blue, _tmp_multi, _tmp_alpha); \
+ int _tmp_src_alpha = _src_alpha*255; \
+ int _tmp_alpha = _tmp_src_alpha + _tmp_multi; \
+ _tmp_red = RGB_COMPOSE_OVER(_src_red, _tmp_src_alpha, *_pdst_red, _tmp_multi, _tmp_alpha); \
+ _tmp_green = RGB_COMPOSE_OVER(_src_green, _tmp_src_alpha, *_pdst_green, _tmp_multi, _tmp_alpha); \
+ _tmp_blue = RGB_COMPOSE_OVER(_src_blue, _tmp_src_alpha, *_pdst_blue, _tmp_multi, _tmp_alpha); \
*_pdst_alpha = (unsigned char)(_tmp_alpha / 255); \
} \
} \
@@ -109,7 +114,7 @@ struct _cdCtxCanvas
*_pdst_alpha = (unsigned char)255; /* set destiny as opaque */ \
} \
} \
- else /* (_pdst_alpha == NULL) */ \
+ else /* destiny does NOT have alpha */ \
{ \
if (_src_alpha != 255) /* source has some transparency */ \
{ \
@@ -147,9 +152,9 @@ struct _cdCtxCanvas
*_pdst_blue ^= _tmp_blue; \
break; \
case CD_NOT_XOR: \
- *_pdst_red = (unsigned char)~(_tmp_red ^ *_pdst_red); \
- *_pdst_green = (unsigned char)~(_tmp_green ^ *_pdst_green); \
- *_pdst_blue = (unsigned char)~(_tmp_blue ^ *_pdst_blue); \
+ *_pdst_red = (unsigned char)~(_tmp_red ^ *_pdst_red); \
+ *_pdst_green = (unsigned char)~(_tmp_green ^ *_pdst_green); \
+ *_pdst_blue = (unsigned char)~(_tmp_blue ^ *_pdst_blue); \
break; \
} \
}
@@ -406,7 +411,7 @@ static void cdclear(cdCtxCanvas* ctxcanvas)
memset(ctxcanvas->red, cdRed(ctxcanvas->canvas->background), size);
memset(ctxcanvas->green, cdGreen(ctxcanvas->canvas->background), size);
memset(ctxcanvas->blue, cdBlue(ctxcanvas->canvas->background), size);
- if (ctxcanvas->alpha) memset(ctxcanvas->alpha, cdAlpha(ctxcanvas->canvas->background), size);
+ if (ctxcanvas->alpha) memset(ctxcanvas->alpha, cdAlpha(ctxcanvas->canvas->background), size); /* here is the normal alpha coding */
}
static void irgPostProcessIntersect(unsigned char* clip, int size)
@@ -1525,8 +1530,8 @@ static cdCtxImage* cdcreateimage(cdCtxCanvas* ctxcanvas, int w, int h)
if (ctxcanvas->alpha)
ctximage->alpha = ctximage->red + 3*size;
- memset(ctximage->red, 0xFF, 3*size);
- if (ctximage->alpha) memset(ctximage->alpha, 0, size); /* transparent */
+ memset(ctximage->red, 0xFF, 3*size); /* white */
+ if (ctximage->alpha) memset(ctximage->alpha, 0, size); /* transparent, this is the normal alpha coding */
return ctximage;
}
@@ -1927,7 +1932,7 @@ static void cdcreatecanvas(cdCanvas* canvas, void *data)
ctxcanvas->alpha = ctxcanvas->red + 3*size;
memset(ctxcanvas->red, 0xFF, 3*size); /* white */
- if (ctxcanvas->alpha) memset(ctxcanvas->alpha, 0, size); /* transparent */
+ if (ctxcanvas->alpha) memset(ctxcanvas->alpha, 0, size); /* transparent, this is the normal alpha coding */
}
ctxcanvas->clip = (unsigned char*)malloc(w*h);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-24 03:30:49 +0000