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diff src/video/SDL_blendline.c @ 2896:1ef2f1e75ff7

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Date: Sat, 20 Dec 2008 23:25:19 +0100 From: Couriersud Subject: 32 & 16 bit versions of blendrect and blendline attached are 32, 16 and 15 bit versions of the blendrect and blendline functionality. There was an issue with the bresenham alg. in drawline which I also fixed.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 20 Dec 2008 23:19:20 +0000
parents 32e8bbba1e94
children e40448bc7727
line wrap: on
line diff
--- a/src/video/SDL_blendline.c	Sat Dec 20 23:10:20 2008 +0000
+++ b/src/video/SDL_blendline.c	Sat Dec 20 23:19:20 2008 +0000
@@ -24,11 +24,117 @@
 #include "SDL_video.h"
 #include "SDL_blit.h"
 
+#define ABS(_x) ((_x) < 0 ? -(_x) : (_x))
+
+#define SWAP(_x, _y) do { int tmp; tmp = _x; _x = _y; _y = tmp; } while (0)
+
+#define BRESENHAM(x0, y0, x1, y1, op) \
+{ \
+    int deltax, deltay, steep, error, xstep, ystep, x, y; \
+ \
+    deltax = ABS(x1 - x0); \
+    deltay = ABS(y1 - y0); \
+    steep = (deltay > deltax); \
+    if (steep) { \
+        SWAP(x0, y0); \
+        SWAP(x1, y1); \
+        SWAP(deltax, deltay); \
+    } \
+    error = (x1 - x0) / 2; \
+    y = y0; \
+    if (x0 > x1) { \
+        xstep = -1; \
+    } else { \
+        xstep = 1; \
+    } \
+    if (y0 < y1) { \
+        ystep = 1; \
+    } else { \
+        ystep = -1; \
+    } \
+    if (!steep) { \
+        for (x = x0; x != x1; x += xstep) { \
+            op(x, y); \
+            error -= deltay; \
+            if (error < 0) { \
+                y += ystep; \
+                error += deltax; \
+            } \
+        } \
+    } else { \
+        for (x = x0; x != x1; x += xstep) { \
+            op(y, x); \
+            error -= deltay; \
+            if (error < 0) { \
+                y += ystep; \
+                error += deltax; \
+            } \
+        } \
+    } \
+}
+
+#define MUL(_a, _b) (((Uint16)(_a)*(Uint16)(_b))/255)
+#define SHIFTAND(_v, _s, _a) (((_v)>>(_s)) & _a)
+
+#define SETPIXEL_MASK(x, y, type, bpp, rshift, gshift, bshift, rmask, gmask, bmask) \
+do { \
+	type *pixel = (type *)(dst->pixels + y * dst->pitch + x * bpp); \
+	if (a) { \
+		*pixel = (r<<rshift) | (g<<gshift) | (b<<bshift); \
+	} \
+} while (0)
+
+#define SETPIXEL_BLEND(x, y, type, bpp, rshift, gshift, bshift, rmask, gmask, bmask) \
+do { \
+	type *pixel = (type *)(dst->pixels + y * dst->pitch + x * bpp); \
+	Uint8 sr = MUL(inva, SHIFTAND(*pixel, rshift, rmask)) + (Uint16) r; \
+	Uint8 sg = MUL(inva, SHIFTAND(*pixel, gshift, gmask)) + (Uint16) g; \
+	Uint8 sb = MUL(inva, SHIFTAND(*pixel, bshift, bmask)) + (Uint16) b; \
+	*pixel = (sr<<rshift) | (sg<<gshift) | (sb<<bshift);  \
+} while (0)
+
+#define SETPIXEL_ADD(x, y, type, bpp, rshift, gshift, bshift, rmask, gmask, bmask) \
+do { \
+	type *pixel = (type *)(dst->pixels + y * dst->pitch + x * bpp); \
+	Uint16 sr = SHIFTAND(*pixel, rshift, rmask) + (Uint16) r; \
+	Uint16 sg = SHIFTAND(*pixel, gshift, gmask) + (Uint16) g; \
+	Uint16 sb = SHIFTAND(*pixel, bshift, bmask) + (Uint16) b; \
+	if (sr>rmask) sr = rmask;  \
+	if (sg>gmask) sg = gmask;  \
+	if (sb>bmask) sb = bmask;  \
+	*pixel = (sr<<rshift) | (sg<<gshift) | (sb<<bshift);  \
+} while (0)
+
+#define SETPIXEL_MOD(x, y, type, bpp, rshift, gshift, bshift, rmask, gmask, bmask) \
+do { \
+	type *pixel = (type *)(dst->pixels + y * dst->pitch + x * bpp); \
+	Uint8 sr = MUL(SHIFTAND(*pixel, rshift, rmask), r); \
+	Uint8 sg = MUL(SHIFTAND(*pixel, gshift, gmask), g); \
+	Uint8 sb = MUL(SHIFTAND(*pixel, bshift, bmask), b); \
+	*pixel = (sr<<rshift) | (sg<<gshift) | (sb<<bshift);  \
+} while (0)
+
+
+#define SETPIXEL15_MASK(x, y) SETPIXEL_MASK(x, y, Uint16, 2, 10, 5, 0, 0x1f, 0x1f, 0x1f);
+#define SETPIXEL15_BLEND(x, y) SETPIXEL_BLEND(x, y, Uint16, 2, 10, 5, 0, 0x1f, 0x1f, 0x1f);
+#define SETPIXEL15_ADD(x, y) SETPIXEL_ADD(x, y, Uint16, 2, 10, 5, 0, 0x1f, 0x1f, 0x1f);
+#define SETPIXEL15_MOD(x, y) SETPIXEL_MOD(x, y, Uint16, 2, 10, 5, 0, 0x1f, 0x1f, 0x1f);
+
+#define SETPIXEL16_MASK(x, y) SETPIXEL_MASK(x, y, Uint16, 2, 11, 5, 0, 0x1f, 0x3f, 0x1f);
+#define SETPIXEL16_BLEND(x, y) SETPIXEL_BLEND(x, y, Uint16, 2, 11, 5, 0, 0x1f, 0x3f, 0x1f);
+#define SETPIXEL16_ADD(x, y) SETPIXEL_ADD(x, y, Uint16, 2, 11, 5, 0, 0x1f, 0x3f, 0x1f);
+#define SETPIXEL16_MOD(x, y) SETPIXEL_MOD(x, y, Uint16, 2, 11, 5, 0, 0x1f, 0x3f, 0x1f);
+
+#define SETPIXEL32_MASK(x, y) SETPIXEL_MASK(x, y, Uint32, 4, 16, 8, 0, 0xff, 0xff, 0xff);
+#define SETPIXEL32_BLEND(x, y) SETPIXEL_BLEND(x, y, Uint32, 4, 16, 8, 0, 0xff, 0xff, 0xff);
+#define SETPIXEL32_ADD(x, y) SETPIXEL_ADD(x, y, Uint32, 4, 16, 8, 0, 0xff, 0xff, 0xff);
+#define SETPIXEL32_MOD(x, y) SETPIXEL_MOD(x, y, Uint32, 4, 16, 8, 0, 0xff, 0xff, 0xff);
 
 int
 SDL_BlendLine(SDL_Surface * dst, int x1, int y1, int x2, int y2,
               int blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
 {
+    Uint8 inva = 0xff - a;
     /* This function doesn't work on surfaces < 8 bpp */
     if (dst->format->BitsPerPixel < 8) {
         SDL_SetError("SDL_BlendLine(): Unsupported surface format");
@@ -42,8 +148,71 @@
        }
      */
 
-    SDL_Unsupported();
-    return -1;
+    if ((blendMode == SDL_BLENDMODE_BLEND)
+        || (blendMode == SDL_BLENDMODE_ADD)) {
+        r = MUL(r, a);
+        g = MUL(g, a);
+        b = MUL(b, a);
+    }
+    switch (dst->format->BitsPerPixel) {
+    case 15:
+        switch (blendMode) {
+        case SDL_BLENDMODE_MASK:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL15_MASK);
+            break;
+        case SDL_BLENDMODE_BLEND:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL15_BLEND);
+            break;
+        case SDL_BLENDMODE_ADD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL15_ADD);
+            break;
+        case SDL_BLENDMODE_MOD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL15_MOD);
+            break;
+        }
+        break;
+    case 16:
+        switch (blendMode) {
+        case SDL_BLENDMODE_MASK:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL16_MASK);
+            break;
+        case SDL_BLENDMODE_BLEND:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL16_BLEND);
+            break;
+        case SDL_BLENDMODE_ADD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL16_ADD);
+            break;
+        case SDL_BLENDMODE_MOD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL16_MOD);
+            break;
+        }
+        break;
+    case 24:
+    case 32:
+        if (dst->format->BytesPerPixel != 4) {
+            SDL_Unsupported();
+            return -1;
+        }
+        switch (blendMode) {
+        case SDL_BLENDMODE_MASK:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL32_MASK);
+            break;
+        case SDL_BLENDMODE_BLEND:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL32_BLEND);
+            break;
+        case SDL_BLENDMODE_ADD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL32_ADD);
+            break;
+        case SDL_BLENDMODE_MOD:
+            BRESENHAM(x1, y1, x2, y2, SETPIXEL32_MOD);
+            break;
+        }
+        break;
+    default:
+        SDL_Unsupported();
+        return -1;
+    }
+    return 0;
 }
 
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