sdldisplayformatalpha.html
1
2
3
4
5
6
<HTML
><HEAD
><TITLE
>SDL_DisplayFormatAlpha</TITLE
><META
NAME="GENERATOR"
7
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
"><LINK
REL="HOME"
TITLE="SDL Library Documentation"
HREF="index.html"><LINK
REL="UP"
TITLE="Video"
HREF="video.html"><LINK
REL="PREVIOUS"
TITLE="SDL_DisplayFormat"
HREF="sdldisplayformat.html"><LINK
REL="NEXT"
TITLE="SDL_WarpMouse"
HREF="sdlwarpmouse.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFF8DC"
TEXT="#000000"
LINK="#0000ee"
VLINK="#551a8b"
ALINK="#ff0000"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>SDL Library Documentation</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="sdldisplayformat.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="sdlwarpmouse.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="SDLDISPLAYFORMATALPHA"
>SDL_DisplayFormatAlpha</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
76
NAME="AEN2048"
77
78
79
80
81
82
83
></A
><H2
>Name</H2
>SDL_DisplayFormatAlpha -- Convert a surface to the display format</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
84
NAME="AEN2051"
85
86
87
88
89
90
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
91
NAME="AEN2052"
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>SDL_Surface *<B
CLASS="FSFUNC"
>SDL_DisplayFormatAlpha</B
></CODE
>(SDL_Surface *surface);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
115
NAME="AEN2058"
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
></A
><H2
>Description</H2
><P
>This function takes a surface and copies it to a new surface of the
pixel format and colors of the video framebuffer plus an alpha channel,
suitable for fast blitting onto the display surface. It calls
<A
HREF="sdlconvertsurface.html"
>SDL_ConvertSurface</A
></P
><P
>If you want to take advantage of hardware colorkey or alpha blit
acceleration, you should set the colorkey and alpha value before
calling this function.</P
131
132
133
134
135
136
137
138
><P
>This function can be used to convert a colourkey to an alpha channel,
if the <TT
CLASS="LITERAL"
>SDL_SRCCOLORKEY</TT
> flag is set on the surface.
The generated surface will then be transparent (alpha=0) where the
pixels match the colourkey, and opaque (alpha=255) elsewhere.</P
139
140
141
142
></DIV
><DIV
CLASS="REFSECT1"
><A
143
NAME="AEN2065"
144
145
146
147
148
149
150
151
152
153
154
155
156
></A
><H2
>Return Value</H2
><P
>If the conversion fails or runs out of memory, it returns
<SPAN
CLASS="RETURNVALUE"
>NULL</SPAN
></P
></DIV
><DIV
CLASS="REFSECT1"
><A
157
NAME="AEN2069"
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
></A
><H2
>See Also</H2
><P
><A
HREF="sdlconvertsurface.html"
>SDL_ConvertSurface</A
>,
<A
HREF="sdlsetalpha.html"
>SDL_SetAlpha</A
>,
<A
HREF="sdlsetcolorkey.html"
>SDL_SetColorKey</A
>,
<A
HREF="sdldisplayformat.html"
>SDL_DisplayFormat</A
>,
<A
HREF="sdlsurface.html"
>SDL_Surface</A
></P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="sdldisplayformat.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="sdlwarpmouse.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>SDL_DisplayFormat</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="video.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SDL_WarpMouse</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>