Fix the rendering color channels to be premultiplied with the alpha channel as...

Fix the rendering color channels to be premultiplied with the alpha channel as thats what Xrender expects. Small fixes in X11_CreateTexture. Add some new functions in SDL_x11sym.h as well as support for Xrender.

src/video/x11/SDL_x11dyn.h

@@ -53,7 +53,7 @@
 #endif
 
 #if SDL_VIDEO_DRIVER_X11_XRENDER
-#include <X11/extensions/render.h>
+#include <X11/extensions/Xrender.h>
 #endif
 
 /*

src/video/x11/SDL_x11render.c

@@ -473,7 +473,13 @@ X11_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
                 XShmCreateImage(renderdata->display, renderdata->visual,
                                 renderdata->depth, ZPixmap, shminfo->shmaddr,
                                 shminfo, texture->w, texture->h);
-            if (!data->image) {
+
+            // This Pixmap is used by Xrender
+            data->pixmap =
+                XShmCreatePixmap(renderdata->display, renderdata->xwindow, shminfo->shmaddr,
+                                 shminfo, texture->w, texture->h, renderdata->depth);
+
+            if (!(data->pixmap && data->image)) {
                 XShmDetach(renderdata->display, shminfo);
                 XSync(renderdata->display, False);
                 shmdt(shminfo->shmaddr);
@@ -486,6 +492,14 @@ X11_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
         if (!data->image)
 #endif /* not NO_SHARED_MEMORY */
         {
+            /* This is the case where the server does not have
+               shared memory support and the texture is streaming.
+               It does not make sense to use Xrender here because
+               we would have to copy the data onto a server side
+               pixmap with XPutImage first and only then can we 
+               use Xrender
+            */
+
             data->pixels = SDL_malloc(texture->h * data->pitch);
             if (!data->pixels) {
                 X11_DestroyTexture(renderer, texture);
@@ -505,7 +519,8 @@ X11_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
                 return -1;
             }
         }
-    } else {
+    } 
+    else {
         data->pixmap =
             XCreatePixmap(renderdata->display, renderdata->xwindow, texture->w,
                           texture->h, renderdata->depth);
@@ -514,53 +529,11 @@ X11_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
             SDL_SetError("XCreatePixmap() failed");
             return -1;
         }
-        
-#ifdef SDL_VIDEO_DRIVER_X11_XRENDER
-        if(renderdata->xrender_available) {
-            data->xrender_available = SDL_TRUE;
-            unsigned long x11_fmt_mask; // Format mask
-            XRenderPictFormat x11_templ_fmt; // Format template
-            x11_fmt_mask =
-                (PictFormatDepth | PictFormatRedMask | PictFormatGreenMask
-                | PictFormatBlueMask);
-            Uint32 Rmask, Gmask, Bmask, Amask;
-            int bpp;
-            SDL_PixelFormatEnumToMasks(data->format, &bpp, &Rmask, &Gmask, &Bmask, &Amask);
-            x11_templ_fmt.depth = bpp;
-            x11_templ_fmt.direct.redMask = Rmask;
-            x11_templ_fmt.direct.greenMask = Gmask;
-            x11_templ_fmt.direct.blueMask = Bmask;
-            x11_templ_fmt.direct.alphaMask = Amask;
-            /* Return one matching XRenderPictFormat */
-            data->picture_fmt =
-                XRenderFindFormat(renderdata->display, x11_fmt_mask, &x11_templ_fmt, 1);
-            if(!data->picture_fmt) {
-                data->xrender_available = SDL_FALSE;
-            }
-            data->picture_attr_valuemask = CPGraphicsExposure;
-            (data->picture_attr).graphics_exposures = False;
-            data->picture =
-                XRenderCreatePicture(renderdata->display, data->pixmap, data->picture_fmt,
-                               data->picture_attr_valuemask, &(data->picture_attr));
-            if(!data->picture) {
-                data->xrender_available = SDL_FALSE;
-            }
-        }
-        /* We thought we could render the texture with Xrender but this was
-           not possible for some reason. Now we must ensure that texture  
-           format and window format match to avoid a BadMatch error.
-        */
-        if(data->xrender_available == SDL_FALSE) {
-            if (texture->format != display->current_mode.format) {
-                SDL_SetError("Texture format doesn't match window format");
-                return -1;
-            }
-        }
-#endif
         data->image =
             XCreateImage(renderdata->display, renderdata->visual,
-                         renderdata->depth, ZPixmap, 0, NULL, texture->w,
-                         texture->h, SDL_BYTESPERPIXEL(data->format) * 8,
+                         renderdata->depth, ZPixmap, 0, NULL,
+                         texture->w, texture->h,
+                         SDL_BYTESPERPIXEL(data->format) * 8,
                          data->pitch);
         if (!data->image) {
             X11_DestroyTexture(renderer, texture);
@@ -568,7 +541,48 @@ X11_CreateTexture(SDL_Renderer * renderer, SDL_Texture * texture)
             return -1;
         }
     }
-
+#ifdef SDL_VIDEO_DRIVER_X11_XRENDER
+    if(renderdata->xrender_available && data->pixmap) {
+        data->xrender_available = SDL_TRUE;
+        unsigned long x11_fmt_mask; // Format mask
+        XRenderPictFormat x11_templ_fmt; // Format template
+        x11_fmt_mask =
+            (PictFormatDepth | PictFormatRedMask | PictFormatGreenMask
+            | PictFormatBlueMask);
+        Uint32 Rmask, Gmask, Bmask, Amask;
+        int bpp;
+        SDL_PixelFormatEnumToMasks(data->format, &bpp, &Rmask, &Gmask, &Bmask, &Amask);
+        x11_templ_fmt.depth = bpp;
+        x11_templ_fmt.direct.redMask = Rmask;
+        x11_templ_fmt.direct.greenMask = Gmask;
+        x11_templ_fmt.direct.blueMask = Bmask;
+        x11_templ_fmt.direct.alphaMask = Amask;
+        /* Return one matching XRenderPictFormat */
+        data->picture_fmt =
+            XRenderFindFormat(renderdata->display, x11_fmt_mask, &x11_templ_fmt, 1);
+        if(!data->picture_fmt) {
+            data->xrender_available = SDL_FALSE;
+        }
+        data->picture_attr_valuemask = CPGraphicsExposure;
+        (data->picture_attr).graphics_exposures = False;
+        data->picture =
+            XRenderCreatePicture(renderdata->display, data->pixmap, data->picture_fmt,
+                            data->picture_attr_valuemask, &(data->picture_attr));
+        if(!data->picture) {
+            data->xrender_available = SDL_FALSE;
+        }
+    }
+    /* We thought we could render the texture with Xrender but this was
+        not possible for some reason. Now we must ensure that texture  
+        format and window format match to avoid a BadMatch error.
+    */
+    if(data->xrender_available == SDL_FALSE) {
+        if (texture->format != display->current_mode.format) {
+            SDL_SetError("Texture format doesn't match window format");
+            return -1;
+        }
+    }
+#endif
     return 0;
 }
 
@@ -638,6 +652,7 @@ X11_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
         X11_RenderData *renderdata = (X11_RenderData *) renderer->driverdata;
 
         if (data->pixels) {
+            // If we have already allocated memory or were given memory by XShm
             Uint8 *src, *dst;
             int row;
             size_t length;
@@ -652,6 +667,23 @@ X11_UpdateTexture(SDL_Renderer * renderer, SDL_Texture * texture,
                 src += pitch;
                 dst += data->pitch;
             }
+            /* If this is a static texture we would use Xrender for it
+               but this requires that the server side Pixmap associated
+               with this texture be updated with the data as well and 
+               that the pixmap is not a shared memory pixmap.
+               Hopefully the user will not update static textures so
+               frequently as to cause a slowdown.
+            */
+            if (texture->access == SDL_TEXTUREACCESS_STATIC) {
+#ifndef NO_SHARED_MEMORY
+                if(!data->shminfo.shmaddr)
+#endif
+                {
+                XPutImage(renderdata->display, data->pixmap, renderdata->gc,
+                          data->image, 0, 0, rect->x, rect->y, rect->w, rect->h);
+                }
+            }
+
         } else {
             data->image->width = rect->w;
             data->image->height = rect->h;
@@ -1001,10 +1033,11 @@ X11_RenderFillRects(SDL_Renderer * renderer, const SDL_Rect ** rects, int count)
         if(data->xrender_available == SDL_TRUE)
         {
             XRenderColor xrender_foreground_color;
-            xrender_foreground_color.red = (unsigned short) ((renderer->r / 255.0) * 0xFFFF);
-            xrender_foreground_color.green = (unsigned short) ((renderer->g / 255.0) * 0xFFFF);
-            xrender_foreground_color.blue = (unsigned short) ((renderer->b / 255.0) * 0xFFFF);
-            xrender_foreground_color.alpha = (unsigned short) ((renderer->a / 255.0) * 0xFFFF);
+            // Premultiply the color channels as well as modulate them to a 16 bit color space
+            xrender_foreground_color.red = ((unsigned short)renderer->r + 1) * ((unsigned short)renderer->a + 1) - 1;
+            xrender_foreground_color.green = ((unsigned short)renderer->g + 1) * ((unsigned short)renderer->a + 1) - 1;
+            xrender_foreground_color.blue = ((unsigned short)renderer->b + 1) * ((unsigned short)renderer->a + 1) - 1;
+            xrender_foreground_color.alpha = ((unsigned short)renderer->a + 1) * ((unsigned short)renderer->a + 1) - 1;
             XRenderFillRectangles(data->display, PictOpSrc, data->drawable_pict,
                                   &xrender_foreground_color, xrects, xcount);
         }

src/video/x11/SDL_x11sym.h

@@ -177,6 +177,7 @@ SDL_X11_SYM(Status,XShmAttach,(Display* a,XShmSegmentInfo* b),(a,b),return)
 SDL_X11_SYM(Status,XShmDetach,(Display* a,XShmSegmentInfo* b),(a,b),return)
 SDL_X11_SYM(Status,XShmPutImage,(Display* a,Drawable b,GC c,XImage* d,int e,int f,int g,int h,unsigned int i,unsigned int j,Bool k),(a,b,c,d,e,f,g,h,i,j,k),return)
 SDL_X11_SYM(XImage*,XShmCreateImage,(Display* a,Visual* b,unsigned int c,int d,char* e,XShmSegmentInfo* f,unsigned int g,unsigned int h),(a,b,c,d,e,f,g,h),return)
+SDL_X11_SYM(Pixmap,XShmCreatePixmap,(Display *a,Drawable b,char* c,XShmSegmentInfo* d, unsigned int e, unsigned int f, unsigned int g),(a,b,c,d,e,f,g),return)
 SDL_X11_SYM(Bool,XShmQueryExtension,(Display* a),(a),return)
 #endif
 
@@ -232,6 +233,16 @@ SDL_X11_SYM(Status,XScreenSaverQueryVersion,(Display *dpy,int *major_versionp,in
 SDL_X11_SYM(void,XScreenSaverSuspend,(Display *dpy,Bool suspend),(dpy,suspend),return)
 #endif
 
+/* XRender support */
+#if SDL_VIDEO_DRIVER_X11_XRENDER
+SDL_X11_MODULE(XRENDER)
+SDL_X11_SYM(Bool,XRenderQueryExtension,(Display *dpy,int *event_base,int *error_base),(dpy,event_base,error_base),return)
+SDL_X11_SYM(XRenderPictFormat*,XRenderFindVisualFormat,(Display *dpy,_Xconst Visual *visual),(dpy,visual),return)
+SDL_X11_SYM(XRenderPictFormat*,XRenderFindFormat,(Display *dpy,unsigned long mask,_Xconst XRenderPictFormat* templ,int count),(dpy,mask,templ,count),return)
+SDL_X11_SYM(Picture,XRenderCreatePicture,(Display *dpy,Drawable drawable,_Xconst XRenderPictFormat* format,unsigned long valuemask,_Xconst XRenderPictureAttributes* attributes),(dpy,drawable,format,valuemask,attributes),return)
+SDL_X11_SYM(void,XRenderComposite,(Display *dpy,int op,Picture src,Picture mask,Picture dst,int src_x,int src_y,int mask_x,int mask_y,int dst_x,int dst_y,unsigned int width,unsigned int height),(dpy,op,src,mask,dst,src_x,src_y,mask_x,mask_y,dst_x,dst_y,width,height),return)
+SDL_X11_SYM(void,XRenderFillRectangles,(Display *dpy,int op,Picture dst,_Xconst XRenderColor* color,_Xconst XRectangle* rectangles,int n_rects),(dpy,op,dst,color,rectangles,n_rects),return)
+#endif
 /* *INDENT-ON* */
 
 /* vi: set ts=4 sw=4 expandtab: */

src/video/x11/SDL_x11video.h

@@ -46,9 +46,8 @@
 #include <X11/extensions/scrnsaver.h>
 #endif
 #if SDL_VIDEO_DRIVER_X11_XRENDER
-#include <X11/extensions/render.h>
+#include <X11/extensions/Xrender.h>
 #endif
-
 #include "SDL_x11dyn.h"
 
 #include "SDL_x11events.h"