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4>SDL_SetColorKey</TITLE
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71><H1
72><A
73NAME="SDLSETCOLORKEY"
74></A
75>SDL_SetColorKey</H1
76><DIV
77CLASS="REFNAMEDIV"
78><A
79NAME="AEN2045"
80></A
81><H2
82>Name</H2
83>SDL_SetColorKey&nbsp;--&nbsp;Sets the color key (transparent pixel) in a blittable surface and
84RLE acceleration.</DIV
85><DIV
86CLASS="REFSYNOPSISDIV"
87><A
88NAME="AEN2048"
89></A
90><H2
91>Synopsis</H2
92><DIV
93CLASS="FUNCSYNOPSIS"
94><A
95NAME="AEN2049"
96></A
97><P
98></P
99><PRE
100CLASS="FUNCSYNOPSISINFO"
101>#include "SDL.h"</PRE
102><P
103><CODE
104><CODE
105CLASS="FUNCDEF"
106>int <B
107CLASS="FSFUNC"
108>SDL_SetColorKey</B
109></CODE
110>(SDL_Surface *surface, Uint32 flag, Uint32 key);</CODE
111></P
112><P
113></P
114></DIV
115></DIV
116><DIV
117CLASS="REFSECT1"
118><A
119NAME="AEN2055"
120></A
121><H2
122>Description</H2
123><P
124> Sets the color key (transparent pixel) in a blittable surface and enables or
125 disables RLE blit acceleration.</P
126><P
127>RLE acceleration can substantially speed up blitting of images with large
128horizontal runs of transparent pixels (i.e., pixels that match the
129<TT
130CLASS="PARAMETER"
131><I
132>key</I
133></TT
134> value). The <TT
135CLASS="PARAMETER"
136><I
137>key</I
138></TT
139> must be of the same pixel format as the <TT
140CLASS="PARAMETER"
141><I
142>surface</I
143></TT
144>, <A
145HREF="sdlmaprgb.html"
146><TT
147CLASS="FUNCTION"
148>SDL_MapRGB</TT
149></A
150> is often useful for obtaining an acceptable value.</P
151><P
152>If <TT
153CLASS="PARAMETER"
154><I
155>flag</I
156></TT
157> is <TT
158CLASS="LITERAL"
159>SDL_SRCCOLORKEY</TT
160> then
161<TT
162CLASS="PARAMETER"
163><I
164>key</I
165></TT
166> is the transparent pixel value in the source image of a
167blit.</P
168><P
169>If <TT
170CLASS="PARAMETER"
171><I
172>flag</I
173></TT
174> is OR'd with
175<TT
176CLASS="LITERAL"
177>SDL_RLEACCEL</TT
178> then the surface will be draw using RLE
179acceleration when drawn with
180<A
181HREF="sdlblitsurface.html"
182>SDL_BlitSurface</A
183>.  The surface will
184actually be encoded for RLE acceleration the first time
185<A
186HREF="sdlblitsurface.html"
187>SDL_BlitSurface</A
188> or
189<A
190HREF="sdldisplayformat.html"
191>SDL_DisplayFormat</A
192> is called on the
193surface.</P
194><P
195>If <TT
196CLASS="PARAMETER"
197><I
198>flag</I
199></TT
200> is 0, this function clears
201any current color key.</P
202></DIV
203><DIV
204CLASS="REFSECT1"
205><A
206NAME="AEN2076"
207></A
208><H2
209>Return Value</H2
210><P
211>This function returns <SPAN
212CLASS="RETURNVALUE"
213>0</SPAN
214>, or
215<SPAN
216CLASS="RETURNVALUE"
217>-1</SPAN
218> if there was an error.</P
219></DIV
220><DIV
221CLASS="REFSECT1"
222><A
223NAME="AEN2081"
224></A
225><H2
226>See Also</H2
227><P
228><A
229HREF="sdlblitsurface.html"
230><TT
231CLASS="FUNCTION"
232>SDL_BlitSurface</TT
233></A
234>,
235<A
236HREF="sdldisplayformat.html"
237><TT
238CLASS="FUNCTION"
239>SDL_DisplayFormat</TT
240></A
241>,
242<A
243HREF="sdlmaprgb.html"
244><TT
245CLASS="FUNCTION"
246>SDL_MapRGB</TT
247></A
248>,
249<A
250HREF="sdlsetalpha.html"
251><TT
252CLASS="FUNCTION"
253>SDL_SetAlpha</TT
254></A
255></P
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