view docs/html/sdlsetpalette.html @ 1212:7663bb0f52c7

To: sdl@libsdl.org From: Christian Walther <cwalther@gmx.ch> Date: Thu, 15 Dec 2005 21:19:53 +0100 Subject: [SDL] More mouse enhancements for Mac OS X The attached patch brings two more enhancements to mouse handling on Mac OS X (Quartz): 1. Currently, after launching an SDL application, SDL's notion of the mouse position is stuck in the top left corner (0,0) until the first time the mouse is moved. That's because the UpdateMouse() function isn't implemented in the Quartz driver. This patch adds it. 2. When grabbing input while the mouse cursor is hidden, the function CGAssociateMouseAndMouseCursorPosition(0) is called, which prevents the system's notion of the mouse location from moving (and therefore leaving the SDL window) even when the mouse is moved. However, apparently the Wacom tablet driver (and maybe other special pointing device drivers) doesn't care about that setting and still allows the mouse location to go outside of the window. Interestingly, the system cursor, which is made visible by the existing code in SDL in that case, does not follow the mouse location, but appears in the middle of the SDL window. The mouse location being outside of the window however means that mouse button events go to background applications (or the dock or whatever is there), which is very confusing to the user who sees no cursor outside of the SDL window. I have not found any way of intercepting these events (and that's probably by design, as "normal" applications shouldn't prevent the user from bringing other applications' windows to the front by clicking on them). An idea would be placing a fully transparent, screen-filling window in front of everything, but I fear that this might affect rendering performance (by doing unnecessary compositing, using up memory, or whatever). The deluxe solution to the problem would be talking to the tablet driver using AppleEvents to tell it to constrain its mapped area to the window (see Wacom's "TabletEventDemo" sample app, http://www.wacomeng.com/devsupport/mac/downloads.html), but I think that the bloat that solution would add to SDL would outweigh its usefulness. What I did instead in my patch is reassociating mouse and cursor when the mouse leaves the window while an invisible grab is in effect, and restoring the grab when the window is entered. That way, the grab can still be effectively broken by a tablet, but at least it's obvious to the user that it is broken. That change is minimal - it doesn't affect operation with a mouse (or a trackpad), and the code that it adds is not executed on every PumpEvents() call, only when entering and leaving the window. Unless there are any concerns about the patch, please apply. Feel free to shorten the lengthy comment in SDL_QuartzEvents.m if you think it's too verbose. Thanks -Christian
author Ryan C. Gordon <icculus@icculus.org>
date Mon, 02 Jan 2006 00:31:00 +0000
parents 355632dca928
children
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><H1
><A
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>SDL_SetPalette</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN1517"
></A
><H2
>Name</H2
>SDL_SetPalette&nbsp;--&nbsp;Sets the colors in the palette of an 8-bit surface.</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN1520"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN1521"
></A
><P
></P
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include "SDL.h"</PRE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int <B
CLASS="FSFUNC"
>SDL_SetPalette</B
></CODE
>(SDL_Surface *surface, int flags, SDL_Color *colors, int firstcolor, int ncolors);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1527"
></A
><H2
>Description</H2
><P
>Sets a portion of the palette for the given 8-bit surface.</P
><P
>Palettized (8-bit) screen surfaces with the
<TT
CLASS="LITERAL"
>SDL_HWPALETTE</TT
> flag have two palettes, a logical
palette that is used for mapping blits to/from the surface and a
physical palette (that determines how the hardware will map the colors
to the display). <A
HREF="sdlblitsurface.html"
>SDL_BlitSurface</A
>
always uses the logical palette when blitting surfaces (if it has to
convert between surface pixel formats). Because of this, it is often
useful to modify only one or the other palette to achieve various
special color effects (e.g., screen fading, color flashes, screen dimming).</P
><P
>This function can modify either the logical or physical palette by
specifing <TT
CLASS="LITERAL"
>SDL_LOGPAL</TT
> or
<TT
CLASS="LITERAL"
>SDL_PHYSPAL</TT
>the in the <TT
CLASS="PARAMETER"
><I
>flags</I
></TT
>
parameter.</P
><P
>When <TT
CLASS="PARAMETER"
><I
>surface</I
></TT
> is the surface associated with the current
display, the display colormap will be updated with the requested colors.  If
<TT
CLASS="LITERAL"
>SDL_HWPALETTE</TT
> was set in <A
HREF="sdlsetvideomode.html"
>SDL_SetVideoMode</A
> flags,
<TT
CLASS="FUNCTION"
>SDL_SetPalette</TT
> will always return <SPAN
CLASS="RETURNVALUE"
>1</SPAN
>,
and the palette is guaranteed to be set the way you desire, even if the window
colormap has to be warped or run under emulation.</P
><P
>The color components of a
<A
HREF="sdlcolor.html"
><SPAN
CLASS="STRUCTNAME"
>SDL_Color</SPAN
></A
> structure
are 8-bits in size, giving you a total of
256<SUP
>3</SUP
>=16777216 colors.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1547"
></A
><H2
>Return Value</H2
><P
>If <TT
CLASS="PARAMETER"
><I
>surface</I
></TT
> is not a palettized surface, this function
does nothing, returning <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>.  If all of the colors were set
as passed to <TT
CLASS="FUNCTION"
>SDL_SetPalette</TT
>, it will return
<SPAN
CLASS="RETURNVALUE"
>1</SPAN
>.  If not all the color entries were set exactly as
given, it will return <SPAN
CLASS="RETURNVALUE"
>0</SPAN
>, and you should look at the
surface palette to determine the actual color palette.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN1555"
></A
><H2
>Example</H2
><PRE
CLASS="PROGRAMLISTING"
>        /* Create a display surface with a grayscale palette */
        SDL_Surface *screen;
        SDL_Color colors[256];
        int i;
        .
        .
        .
        /* Fill colors with color information */
        for(i=0;i&#60;256;i++){
          colors[i].r=i;
          colors[i].g=i;
          colors[i].b=i;
        }

        /* Create display */
        screen=SDL_SetVideoMode(640, 480, 8, SDL_HWPALETTE);
        if(!screen){
          printf("Couldn't set video mode: %s\n", SDL_GetError());
          exit(-1);
        }

        /* Set palette */
        SDL_SetPalette(screen, SDL_LOGPAL|SDL_PHYSPAL, colors, 0, 256);
        .
        .
        .
        .</PRE
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><A
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><H2
>See Also</H2
><P
><A
HREF="sdlsetcolors.html"
>SDL_SetColors</A
>,
<A
HREF="sdlsetvideomode.html"
>SDL_SetVideoMode</A
>,
<A
HREF="sdlsurface.html"
>SDL_Surface</A
>,
<A
HREF="sdlcolor.html"
>SDL_Color</A
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