178 lines
7.9 KiB
Diff
178 lines
7.9 KiB
Diff
From 3c0431b8911241552a15a43e4279c50658b50a18 Mon Sep 17 00:00:00 2001
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From: Keith Packard <keithp@keithp.com>
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Date: Wed, 16 Jul 2014 23:03:23 +0000
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Subject: glamor: Fix temp picture coordinates in glamor_composite_clipped_region
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To understand this patch, let's start at the protocol interface where
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the relationship between the coordinate spaces is documented:
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static Bool
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_glamor_composite(CARD8 op,
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PicturePtr source,
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PicturePtr mask,
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PicturePtr dest,
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INT16 x_source,
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INT16 y_source,
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INT16 x_mask,
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INT16 y_mask,
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INT16 x_dest, INT16 y_dest,
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CARD16 width, CARD16 height, Bool fallback)
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The coordinates are passed to this function directly off the wire and
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are all relative to their respective drawables. For Windows, this means
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that they are relative to the upper left corner of the window, in
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whatever pixmap that window is getting drawn to.
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_glamor_composite calls miComputeCompositeRegion to construct a clipped
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region to actually render to. In reality, miComputeCompositeRegion clips
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only to the destination these days; source clip region based clipping
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would have to respect the transform, which isn't really possible. The
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returned region is relative to the screen in which dest lives; offset by
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dest->drawable.x and dest->drawable.y.
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What is important to realize here is that, because of clipping, the
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composite region may not have the same position within the destination
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drawable as x_dest, y_dest. The protocol coordinates now exist solely to
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'pin' the three objects together.
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extents->x1,y1 Screen origin of clipped operation
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width,height Extents of the clipped operation
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x_dest,y_dest Unclipped destination-relative operation coordinate
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x_source,y_source Unclipped source-relative operation coordinate
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x_mask,y_mask Unclipped mask-relative operation coordinate
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One thing we want to know is what the offset is from the original
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operation origin to the clipped origin
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Destination drawable relative coordinates of the clipped operation:
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x_dest_clipped = extents->x1 - dest->drawable.x
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y_dest_clipped = extents->y1 - dest->drawable.y
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Offset from the original operation origin:
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x_off_clipped = x_dest_clipped - x_dest
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y_off_clipped = y_dest_clipped - y_dest
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Source drawable relative coordinates of the clipped operation:
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x_source_clipped = x_source + x_off_clipped;
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y_source_clipped = y_source + y_off_clipped;
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Mask drawable relative coordinates of the clipped operation:
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x_mask_clipped = x_source + x_off_clipped;
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y_mask_clipped = y_source + y_off_clipped;
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This is where the original code fails -- it doesn't subtract the
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destination drawable location when computing the distance that the
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operation has been moved by clipping. Here's what it does when
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constructing a temporary source picture:
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temp_src =
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glamor_convert_gradient_picture(screen, source,
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extent->x1 + x_source - x_dest,
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extent->y1 + y_source - y_dest,
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width, height);
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...
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x_temp_src = -extent->x1 + x_dest;
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y_temp_src = -extent->y1 + y_dest;
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glamor_convert_gradient_picture needs source drawable relative
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coordinates, but that is not what it's getting; it's getting
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screen-relative coordinates for the destination, adjusted by the
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distance between the provided source and destination operation
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coordinates. We want x_source_clipped and y_source_clipped:
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x_source_clipped = x_source + x_off_clipped
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= x_source + x_dest_clipped - x_dest
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= x_source + extents->x1 - dest->drawable.x - x_dest
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x_temp_src/y_temp_src are supposed to be the coordinates of the original
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operation translated to the temporary picture:
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x_temp_src = x_source - x_source_clipped;
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y_temp_src = y_source - y_source_clipped;
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Note that x_source_clipped/y_source_clipped will never be less than
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x_source/y_source because all we're doing is clipping. This means that
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x_temp_src/y_temp_src will always be non-positive; the original source
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coordinate can never be strictly *inside* the temporary image or we
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could have made the temporary image smaller.
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x_temp_src = x_source - x_source_clipped
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= x_source - (x_source + x_off_clipped)
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= -x_off_clipped
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= x_dest - x_dest_clipped
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= x_dest - (extents->x1 - dest->drawable.x)
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Again, this is off by the destination origin within the screen
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coordinate space.
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The code should look like:
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temp_src =
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glamor_convert_gradient_picture(screen, source,
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extent->x1 + x_source - x_dest - dest->pDrawable->x,
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extent->y1 + y_source - y_dest - dest->pDrawable->y,
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width, height);
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x_temp_src = -extent->x1 + x_dest + dest->pDrawable->x;
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y_temp_src = -extent->y1 + y_dest + dest->pDrawable->y;
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Signed-off-by: Keith Packard <keithp@keithp.com>
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Reviewed-by: Markus Wick <markus@selfnet.de>
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(cherry picked from commit 55f5bfb578e934319d1308cbb56c900c5ac7cfa7)
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Signed-off-by: Julien Cristau <jcristau@debian.org>
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---
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diff --git a/glamor/glamor_render.c b/glamor/glamor_render.c
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index 14ab738..e5d5d2c 100644
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--- glamor/glamor_render.c
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+++ glamor/glamor_render.c
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@@ -1450,8 +1450,8 @@ glamor_composite_clipped_region(CARD8 op,
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|| source_pixmap->drawable.height != height)))) {
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temp_src =
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glamor_convert_gradient_picture(screen, source,
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- extent->x1 + x_source - x_dest,
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- extent->y1 + y_source - y_dest,
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+ extent->x1 + x_source - x_dest - dest->pDrawable->x,
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+ extent->y1 + y_source - y_dest - dest->pDrawable->y,
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width, height);
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if (!temp_src) {
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temp_src = source;
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@@ -1459,8 +1459,8 @@ glamor_composite_clipped_region(CARD8 op,
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}
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temp_src_priv =
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glamor_get_pixmap_private((PixmapPtr) (temp_src->pDrawable));
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- x_temp_src = -extent->x1 + x_dest;
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- y_temp_src = -extent->y1 + y_dest;
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+ x_temp_src = -extent->x1 + x_dest + dest->pDrawable->x;
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+ y_temp_src = -extent->y1 + y_dest + dest->pDrawable->y;
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}
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if (mask
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@@ -1474,8 +1474,8 @@ glamor_composite_clipped_region(CARD8 op,
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* to do reduce one convertion. */
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temp_mask =
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glamor_convert_gradient_picture(screen, mask,
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- extent->x1 + x_mask - x_dest,
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- extent->y1 + y_mask - y_dest,
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+ extent->x1 + x_mask - x_dest - dest->pDrawable->x,
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+ extent->y1 + y_mask - y_dest - dest->pDrawable->y,
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width, height);
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if (!temp_mask) {
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temp_mask = mask;
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@@ -1483,8 +1483,8 @@ glamor_composite_clipped_region(CARD8 op,
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}
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temp_mask_priv =
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glamor_get_pixmap_private((PixmapPtr) (temp_mask->pDrawable));
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- x_temp_mask = -extent->x1 + x_dest;
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- y_temp_mask = -extent->y1 + y_dest;
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+ x_temp_mask = -extent->x1 + x_dest + dest->pDrawable->x;
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+ y_temp_mask = -extent->y1 + y_dest + dest->pDrawable->y;
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}
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/* Do two-pass PictOpOver componentAlpha, until we enable
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* dual source color blending.
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--
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cgit v0.9.0.2-2-gbebe
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