From: Michel Dänzer <michel.daen...@amd.com> X server >= 1.18 already had code for this, but it only caught cases where some pixels have 0 for alpha and non-0 for a non-alpha component. Turns out some apps (e.g. the Civilization VI game) use non-premultiplied cursor data which doesn't have such pixels, but can still result in visual artifacts.
This uses the method suggested by Kamil in https://bugs.freedesktop.org/92309#c19: check for pixels where any colour component value is larger than the alpha value, which isn't possible with premultiplied alpha. There can still be non-premultiplied data which won't be caught by this, but that should result in slightly incorrect colours and/or blending at the worst, not wildly incorrect colours such as shown in the bug report below. Bugzilla: https://bugs.freedesktop.org/108355 (Ported from amdgpu commits ad6dfb0124860cf67730bde85867f81d9258c84d & 426f9a49655f01863cf4d898f525e5f95984e0c4) Signed-off-by: Michel Dänzer <michel.daen...@amd.com> --- src/drmmode_display.c | 81 ++++++++++++++++++++++++++++++++----------- 1 file changed, 61 insertions(+), 20 deletions(-) diff --git a/src/drmmode_display.c b/src/drmmode_display.c index 00d94449d..9a9e092a7 100644 --- a/src/drmmode_display.c +++ b/src/drmmode_display.c @@ -1049,29 +1049,52 @@ drmmode_cursor_src_offset(Rotation rotation, int width, int height, #endif -static uint32_t -drmmode_cursor_gamma(xf86CrtcPtr crtc, uint32_t argb) +static Bool +drmmode_cursor_pixel(xf86CrtcPtr crtc, uint32_t *argb, Bool premultiplied, + Bool apply_gamma) { - uint32_t alpha = argb >> 24; + uint32_t alpha = *argb >> 24; uint32_t rgb[3]; int i; - if (!alpha) - return 0; + if (premultiplied) { +#if XORG_VERSION_CURRENT < XORG_VERSION_NUMERIC(1, 18, 4, 0, 0) + if (alpha == 0 && (*argb & 0xffffff) != 0) + /* Doesn't look like premultiplied alpha */ + return FALSE; +#endif - if (crtc->scrn->depth != 24 && crtc->scrn->depth != 32) - return argb; + if (!apply_gamma) + return TRUE; + } - /* Un-premultiply alpha */ + if (!alpha) { + *argb = 0; + return TRUE; + } + + /* Extract RGB */ for (i = 0; i < 3; i++) - rgb[i] = ((argb >> (i * 8)) & 0xff) * 0xff / alpha; + rgb[i] = (*argb >> (i * 8)) & 0xff; + + if (premultiplied) { + /* Un-premultiply alpha */ + for (i = 0; i < 3; i++) + rgb[i] = rgb[i] * 0xff / alpha; + } + + if (apply_gamma) { + rgb[0] = crtc->gamma_blue[rgb[0]] >> 8; + rgb[1] = crtc->gamma_green[rgb[1]] >> 8; + rgb[2] = crtc->gamma_red[rgb[2]] >> 8; + } - /* Apply gamma correction and pre-multiply alpha */ - rgb[0] = (crtc->gamma_blue[rgb[0]] >> 8) * alpha / 0xff; - rgb[1] = (crtc->gamma_green[rgb[1]] >> 8) * alpha / 0xff; - rgb[2] = (crtc->gamma_red[rgb[2]] >> 8) * alpha / 0xff; + /* Premultiply alpha */ + for (i = 0; i < 3; i++) + rgb[i] = rgb[i] * alpha / 0xff; - return alpha << 24 | rgb[2] << 16 | rgb[1] << 8 | rgb[0]; + *argb = alpha << 24 | rgb[2] << 16 | rgb[1] << 8 | rgb[0]; + return TRUE; } static void @@ -1080,27 +1103,37 @@ drmmode_load_cursor_argb (xf86CrtcPtr crtc, CARD32 *image) ScrnInfoPtr pScrn = crtc->scrn; RADEONInfoPtr info = RADEONPTR(pScrn); drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private; + Bool premultiplied = TRUE; + Bool apply_gamma = TRUE; + uint32_t argb; uint32_t *ptr; /* cursor should be mapped already */ ptr = (uint32_t *)(drmmode_crtc->cursor_bo->ptr); + if (crtc->scrn->depth != 24 && crtc->scrn->depth != 32) + apply_gamma = FALSE; + #if XF86_CRTC_VERSION < 7 if (crtc->driverIsPerformingTransform) { uint32_t cursor_w = info->cursor_w, cursor_h = info->cursor_h; int dstx, dsty; int srcoffset; +retry_transform: for (dsty = 0; dsty < cursor_h; dsty++) { for (dstx = 0; dstx < cursor_w; dstx++) { srcoffset = drmmode_cursor_src_offset(crtc->rotation, cursor_w, cursor_h, dstx, dsty); - - ptr[dsty * info->cursor_w + dstx] = - cpu_to_le32(drmmode_cursor_gamma(crtc, - image[srcoffset])); + argb = image[srcoffset]; + if (!drmmode_cursor_pixel(crtc, &argb, premultiplied, + apply_gamma)) { + premultiplied = FALSE; + goto retry_transform; + } + ptr[dsty * info->cursor_w + dstx] = cpu_to_le32(argb); } } } else @@ -1109,8 +1142,16 @@ drmmode_load_cursor_argb (xf86CrtcPtr crtc, CARD32 *image) uint32_t cursor_size = info->cursor_w * info->cursor_h; int i; - for (i = 0; i < cursor_size; i++) - ptr[i] = cpu_to_le32(drmmode_cursor_gamma(crtc, image[i])); +retry: + for (i = 0; i < cursor_size; i++) { + argb = image[i]; + if (!drmmode_cursor_pixel(crtc, &argb, premultiplied, + apply_gamma)) { + premultiplied = FALSE; + goto retry; + } + ptr[i] = cpu_to_le32(argb); + } } } -- 2.20.1 _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx
